+publisher:"Penn State University" +contributor:("Clifford Jesse Lissenden III, Committee Member")

Penn State University

1. Gawelko, Lexi Nicole. Can Meta-Soil Attenuate Seismic Waves?.

Degree: 2019, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/16247ang5382

► Stable and resilient civil infrastructure is a key to public safety. However, current structures are vulnerable to damage resulting from excessive ground motion caused by earthquakes or… (more)

Subjects/Keywords: metamaterial; earthquake; civil engineering; perioidic foundation; resonator

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APA (6^th Edition):

Gawelko, L. N. (2019). Can Meta-Soil Attenuate Seismic Waves?. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/16247ang5382

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Gawelko, Lexi Nicole. “Can Meta-Soil Attenuate Seismic Waves?.” 2019. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/16247ang5382.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Gawelko, Lexi Nicole. “Can Meta-Soil Attenuate Seismic Waves?.” 2019. Web. 19 Jan 2021.

Vancouver:

Gawelko LN. Can Meta-Soil Attenuate Seismic Waves?. [Internet] [Thesis]. Penn State University; 2019. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/16247ang5382.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gawelko LN. Can Meta-Soil Attenuate Seismic Waves?. [Thesis]. Penn State University; 2019. Available from: https://submit-etda.libraries.psu.edu/catalog/16247ang5382

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

2. Brennan, Marissa C. INVESTIGATION OF LASER ULTRASONIC EVALUATION FOR USE AS AN IN SITU PROCESS MONITORING TOOL FOR LASER-BASED DIRECTED ENERGY DEPOSITION.

Degree: 2018, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/15744mxb1033

► Directed energy deposition (DED) processes commonly form lack of fusion defects when adjacent passes do not achieve consistent overlap. Insufficient fusion is rooted to the… (more)

▼ Directed energy deposition (DED) processes commonly form lack of fusion defects when adjacent passes do not achieve consistent overlap. Insufficient fusion is rooted to the behavior of the molten pool which is influenced by high temperature thermo-physical material properties. Internal defects have the tendency to be detrimental to mechanical properties. Thus, expensive and time-consuming methods such as post-processing (HIP) are required to repair defects in additively manufactured (AM) parts, otherwise components are scrapped. Efforts to minimize post-processing has been redirected towards developing in situ monitoring techniques based on nondestructive evaluation (NDE) methods to detect defects during processing. Knowledge of defect location and size can then be used as a guide for correcting defects prior to removing the build from the chamber. While thermal and optical techniques have been extensively integrated for in situ measurements, information can only be obtained for the exposed build layer. However, techniques based on ultrasound are capable of detecting subsurface features. Noncontact, laser ultrasonics offers the unique capability of operating in-line and within close proximity to the DED head which makes it attractive for in situ monitoring of the build process. An assessment was completed for choosing laser ultrasonics as feasible tool for in situ monitoring. The feasibility of the laser ultrasonic system was evaluated by measuring the minimum defect diameter and maximum defect depth that could be detected for DED builds processed with intentional lack of fusion conditions. Defect measurements were then cross-correlated to optical microscopy and x-ray computed tomography (CT) which have been extensively used as acceptable techniques for characterizing defects in AM components. Intentional defects were formed upon selecting processing parameters to control melt pool shape and size. Lack of fusion defects were produced by altering hatch spacing, powder flow, and power to replicate defects typically formed during processing for titanium, nickel superalloys, and precipitation hardened martensitic grade stainless steel alloys. X-ray CT results reported the majority of defects were between 0.50 mm and 0.75 mm in diameter, despite the hatch spacing or material. In addition, sphericity values between 0.35 and 0.50 were reported for the majority of defects formed. A general decreasing power law trend was observed upon plotting degree of sphericity as a function of defect diameter, despite the processing conditions and material selected. This concluded the lack of fusion defects formed were non-spherical and elongated in shape. A closer look at the volume percent porosity reported the highest percentages for builds processed with 3.56 mm hatch spacing and disrupted powder flow. A comparison of material conditions, however, indicated while Ti-6Al-4V showed several instances of lack of fusion between passes, Inconel® 718 and 17-4PH stainless steel builds featured most lack of fusion near the ends of the… Advisors/Committee Members: Todd Palmer, Thesis Advisor/Co-Advisor, Allison Michelle Beese, Committee Member, Clifford Jesse Lissenden III, Committee Member, Jayme Scot Keist, Committee Member.

Subjects/Keywords: Laser Ultrasonics; Ti-6Al-4V; Inconel 718; 17-4PH stainless steel; In situ; Directed Energy Deposition; Additive Manufacturing

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APA (6^th Edition):

Brennan, M. C. (2018). INVESTIGATION OF LASER ULTRASONIC EVALUATION FOR USE AS AN IN SITU PROCESS MONITORING TOOL FOR LASER-BASED DIRECTED ENERGY DEPOSITION. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/15744mxb1033

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Brennan, Marissa C. “INVESTIGATION OF LASER ULTRASONIC EVALUATION FOR USE AS AN IN SITU PROCESS MONITORING TOOL FOR LASER-BASED DIRECTED ENERGY DEPOSITION.” 2018. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/15744mxb1033.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Brennan, Marissa C. “INVESTIGATION OF LASER ULTRASONIC EVALUATION FOR USE AS AN IN SITU PROCESS MONITORING TOOL FOR LASER-BASED DIRECTED ENERGY DEPOSITION.” 2018. Web. 19 Jan 2021.

Vancouver:

Brennan MC. INVESTIGATION OF LASER ULTRASONIC EVALUATION FOR USE AS AN IN SITU PROCESS MONITORING TOOL FOR LASER-BASED DIRECTED ENERGY DEPOSITION. [Internet] [Thesis]. Penn State University; 2018. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/15744mxb1033.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Brennan MC. INVESTIGATION OF LASER ULTRASONIC EVALUATION FOR USE AS AN IN SITU PROCESS MONITORING TOOL FOR LASER-BASED DIRECTED ENERGY DEPOSITION. [Thesis]. Penn State University; 2018. Available from: https://submit-etda.libraries.psu.edu/catalog/15744mxb1033

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

3. Neblett, Carter L. Nondestructive Evaluation of Bolt Torque Levels Using Nonlinear Wave Modulation Spectroscopy.

Degree: 2018, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/15913czn20

► The work presented in this thesis is focused on using a nondestructive evaluation (NDE) technique to examine bolt torque levels of heavy, bolted, aluminum plates.… (more)

Subjects/Keywords: Nondestructive Evaluation; Nonlinear Wave Modulation Spectroscopy; Bolted Joints; Damage Indicator

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Neblett, C. L. (2018). Nondestructive Evaluation of Bolt Torque Levels Using Nonlinear Wave Modulation Spectroscopy. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/15913czn20

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Neblett, Carter L. “Nondestructive Evaluation of Bolt Torque Levels Using Nonlinear Wave Modulation Spectroscopy.” 2018. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/15913czn20.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Neblett, Carter L. “Nondestructive Evaluation of Bolt Torque Levels Using Nonlinear Wave Modulation Spectroscopy.” 2018. Web. 19 Jan 2021.

Vancouver:

Neblett CL. Nondestructive Evaluation of Bolt Torque Levels Using Nonlinear Wave Modulation Spectroscopy. [Internet] [Thesis]. Penn State University; 2018. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/15913czn20.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Neblett CL. Nondestructive Evaluation of Bolt Torque Levels Using Nonlinear Wave Modulation Spectroscopy. [Thesis]. Penn State University; 2018. Available from: https://submit-etda.libraries.psu.edu/catalog/15913czn20

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

4. Gao, Yuyan. Experimental and simulated study of flexible electronics – Fabrication of water-soluble Zn/PVA sensor and stretching simulation of GNM/SWNT.

Degree: 2020, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/17790yug31

► Flexible electronics are broadly studied for the potential in wearable devices. Transient and flexible electronics for human health monitoring are promising because this kind of… (more)

Subjects/Keywords: Flexible electronics; ECG sensor

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APA (6^th Edition):

Gao, Y. (2020). Experimental and simulated study of flexible electronics – Fabrication of water-soluble Zn/PVA sensor and stretching simulation of GNM/SWNT. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/17790yug31

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Gao, Yuyan. “Experimental and simulated study of flexible electronics – Fabrication of water-soluble Zn/PVA sensor and stretching simulation of GNM/SWNT.” 2020. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/17790yug31.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Gao, Yuyan. “Experimental and simulated study of flexible electronics – Fabrication of water-soluble Zn/PVA sensor and stretching simulation of GNM/SWNT.” 2020. Web. 19 Jan 2021.

Vancouver:

Gao Y. Experimental and simulated study of flexible electronics – Fabrication of water-soluble Zn/PVA sensor and stretching simulation of GNM/SWNT. [Internet] [Thesis]. Penn State University; 2020. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/17790yug31.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gao Y. Experimental and simulated study of flexible electronics – Fabrication of water-soluble Zn/PVA sensor and stretching simulation of GNM/SWNT. [Thesis]. Penn State University; 2020. Available from: https://submit-etda.libraries.psu.edu/catalog/17790yug31

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

5. Suprock, Andrew David. AN INVESTIGATION INTO THE TEMPERATURE EFFECT ON THE PERFORMANCE OF ULTRASONIC TRANSDUCERS FOR HIGH TEMPERATURE AND HARSH ENVIRONMENT APPLICATIONS.

Degree: 2016, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/13134ads303

► Transducer technology is an in-demand resource particularly in the fields of ultrasonic non-destructive evaluation (UNDE), structural health monitoring (SHM), and biomedical ultrasound. For years, transducers… (more)

▼ Transducer technology is an in-demand resource particularly in the fields of ultrasonic non-destructive evaluation (UNDE), structural health monitoring (SHM), and biomedical ultrasound. For years, transducers have been used to characterize various types of materials, ranging from metals to composites (interwoven conglomeration of various materials) and even organics as well as to establish the integrity of structural components such as bridge struts, subterranean pipelines, and vehicle bodies. Transducers can even be used to find defects, cracks, delaminations, etc on the micro- and nano-scales. Most of these processes occur at room temperature or only slightly elevated temperatures (<100 °C). This means that the physical components have little to fear from the stress and strain of thermal expansion as well as the process of oxidation. However, when higher temperature (>400 °C) capabilities are necessary, only a select few piezoelectric materials can make the cut. The piezoelectric material must be combined with the right components from the casing, to the waveguide, to the coupling, to the matching layer, as well as the backing material and work together cohesively with a lead wire to produce the most consistent and cleanest acoustic signals and data possible for their particular application. The objective of this thesis is to investigate the influence of the temperature effect on ultrasonic transducers based on a comparison of the effects of high temperature conditions versus those of high temperature and irradiation on the transducer system. There will also be a preliminary move towards the establishment of the means for optimizing the bulk single crystal transducer fabrication process in order to achieve peak efficiency and maximum effectiveness in both irradiated and non-irradiated high temperature applications. Optimization of the material components within the transducer will greatly increase non-destructive testing abilities for industry, structural health monitoring, and so much more. The following research involves testing several different piezoelectric materials under high temperature conditions. The viability of aluminum nitride (AlN) as a transducer material in high temperature conditions has been previously explored [1] (Parks, et al, 2010) and shall be further tested to ensure reliability. Zinc oxide (ZnO) and bismuth titanate (BiT) will also be explored as they have shown promising results in the past. Data collected from the ULtrasonic TRAnsducers (ULTRA) project will also be compared to the high temperature data since the construction of the transducer was the same. A preliminary search of various combinations of transducer material components (waveguide and backing materials in order to find the best match for a given piezoelectric material) will be conducted to find the best combination of these components for steady and strong acoustic transmission. Advisors/Committee Members: Bernhard R Tittmann, Thesis Advisor/Co-Advisor, Albert Eliot Segall, Committee Member, Clifford Jesse Lissenden III, Committee Member.

Subjects/Keywords: Ultrasonic Non-Destructive Evaluation; Structural Health Monitoring; Ultrasonic Transducers; High Temperature; Harsh Environment; Radiation; Materials Optimization; NDE; SHM; Piezoelectricity; Piezoelectric Materials; Piezoelectric Crystal Structures

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Suprock, A. D. (2016). AN INVESTIGATION INTO THE TEMPERATURE EFFECT ON THE PERFORMANCE OF ULTRASONIC TRANSDUCERS FOR HIGH TEMPERATURE AND HARSH ENVIRONMENT APPLICATIONS. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/13134ads303

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Suprock, Andrew David. “AN INVESTIGATION INTO THE TEMPERATURE EFFECT ON THE PERFORMANCE OF ULTRASONIC TRANSDUCERS FOR HIGH TEMPERATURE AND HARSH ENVIRONMENT APPLICATIONS.” 2016. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/13134ads303.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Suprock, Andrew David. “AN INVESTIGATION INTO THE TEMPERATURE EFFECT ON THE PERFORMANCE OF ULTRASONIC TRANSDUCERS FOR HIGH TEMPERATURE AND HARSH ENVIRONMENT APPLICATIONS.” 2016. Web. 19 Jan 2021.

Vancouver:

Suprock AD. AN INVESTIGATION INTO THE TEMPERATURE EFFECT ON THE PERFORMANCE OF ULTRASONIC TRANSDUCERS FOR HIGH TEMPERATURE AND HARSH ENVIRONMENT APPLICATIONS. [Internet] [Thesis]. Penn State University; 2016. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/13134ads303.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Suprock AD. AN INVESTIGATION INTO THE TEMPERATURE EFFECT ON THE PERFORMANCE OF ULTRASONIC TRANSDUCERS FOR HIGH TEMPERATURE AND HARSH ENVIRONMENT APPLICATIONS. [Thesis]. Penn State University; 2016. Available from: https://submit-etda.libraries.psu.edu/catalog/13134ads303

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

6. Hakoda, Christopher Nobuo. A Tool and a Process for Finding a Damage Feature for Guided Waves that is Independent of Temperature.

Degree: 2016, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/13452cnh137

► Rotorcraft are periodically removed from operation to get checked for damage or precursors to damage. Built-in SHM methods are being researched that will allow for… (more)

▼ Rotorcraft are periodically removed from operation to get checked for damage or precursors to damage. Built-in SHM methods are being researched that will allow for a condition-based inspection schedule, which increases operation time and reduces the need for periodic inspections. A possible transducer for such an SHM application is a thin-film PVDF linear array. However, since PVDF is a thermoplastic it is susceptible to temperature effects that can significantly reduce the accuracy of a damage feature. To address this issue, the thesis focuses on two main thrusts. The first is the development of a process by which a temperature-independent damage feature can be designed. The second is the efficient implementation of SAFE theory in a commercial FEM software, COMSOL. This would become a tool that allows dispersion curves and wave structures for composites to be accurately and quickly calculated to inform the process mentioned previously.\\ The investigation into developing a temperature-independent damage feature resulted in the demonstration of two possible processes by which such a damage feature could be designed. Both processes use a mode ratio and require that the modes used for the ratio have similar temperature dependence. The first process involves choosing modes for the mode ratio that undergo mode conversion from one mode to the other. The second process involves choosing modes for the mode ratio that have different sensitivities to the defect.\\ The implementation of the SAFE method in COMSOL's weak form PDE module resulted in accurate dispersion curves for most waveguides, but the wave structures were somewhat inconsistent with published solutions. Furthermore, when applied to a composite waveguide neither dispersion curves or wave structures matched published results. This discrepancy is attributed to a lack of enforcement of the traction continuity at the interface between layers. That being the case, an improved implementation that enforces this traction continuity is proposed for future work. Also, a simpler method is demonstrated for calculating dispersion curves of anisotropic waveguides that have a dependence on wave propagation direction. Advisors/Committee Members: Joseph Lawrence Rose, Thesis Advisor/Co-Advisor, Clifford Jesse Lissenden III, Committee Member, Bernhard R Tittmann, Committee Member.

Subjects/Keywords: Guided Waves; SAFE method; PVDF; Temperature

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Hakoda, C. N. (2016). A Tool and a Process for Finding a Damage Feature for Guided Waves that is Independent of Temperature. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/13452cnh137

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Hakoda, Christopher Nobuo. “A Tool and a Process for Finding a Damage Feature for Guided Waves that is Independent of Temperature.” 2016. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/13452cnh137.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Hakoda, Christopher Nobuo. “A Tool and a Process for Finding a Damage Feature for Guided Waves that is Independent of Temperature.” 2016. Web. 19 Jan 2021.

Vancouver:

Hakoda CN. A Tool and a Process for Finding a Damage Feature for Guided Waves that is Independent of Temperature. [Internet] [Thesis]. Penn State University; 2016. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/13452cnh137.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hakoda CN. A Tool and a Process for Finding a Damage Feature for Guided Waves that is Independent of Temperature. [Thesis]. Penn State University; 2016. Available from: https://submit-etda.libraries.psu.edu/catalog/13452cnh137

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

7. Xu, Janet Liang. Practical Ultrasonic Transducers for High-Temperature Applications using Bismuth Titanate and Ceramabind 830.

Degree: 2017, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/14329jqx5082

► Non-destructive testing (NDT) using ultrasonic transducers can help detect and prevent largescale failures in high-temperature environments (>150 degC) such as power plants by using noninvasive… (more)

Subjects/Keywords: Non-destructive evaluation; Ultrasound; Structural Health Monitoring; Ferroelectric Composites; Piezoceramic; High temperature transducer; Transducer; Thick Films; Bismuth titanate; Ceramabind 830; Ultrasonic

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Xu, J. L. (2017). Practical Ultrasonic Transducers for High-Temperature Applications using Bismuth Titanate and Ceramabind 830. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/14329jqx5082

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Xu, Janet Liang. “Practical Ultrasonic Transducers for High-Temperature Applications using Bismuth Titanate and Ceramabind 830.” 2017. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/14329jqx5082.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Xu, Janet Liang. “Practical Ultrasonic Transducers for High-Temperature Applications using Bismuth Titanate and Ceramabind 830.” 2017. Web. 19 Jan 2021.

Vancouver:

Xu JL. Practical Ultrasonic Transducers for High-Temperature Applications using Bismuth Titanate and Ceramabind 830. [Internet] [Thesis]. Penn State University; 2017. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/14329jqx5082.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Xu JL. Practical Ultrasonic Transducers for High-Temperature Applications using Bismuth Titanate and Ceramabind 830. [Thesis]. Penn State University; 2017. Available from: https://submit-etda.libraries.psu.edu/catalog/14329jqx5082

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

8. Searfass, Clifford. Characterization of bismuth titanate thick films fabricated using a spray-on technique for high temperature ultrasonic non-destructive evaluation.

Degree: 2012, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/14489

► Recent shifts towards green power generation have led to renewed interest in nuclear energy. However, the recent incident with the Fukushima Dai-ichi power plant has… (more)

▼ Recent shifts towards green power generation have led to renewed interest in nuclear energy. However, the recent incident with the Fukushima Dai-ichi power plant has been a grim reminder that safety is of utmost importance. Similarly, monitoring of jet engine turbine blades has seen a renewed interest because of incidents such as US Airways Flight 1549, which suffered turbine damage upon take off and a water landing in the Hudson river needed to be performed. As a result, both of these two major industries have set goals for developing and implementing new in-situ systems for damage detection. Inspection via ultrasonic non-destructive evaluation (UNDE) is one of the leading methods being considered for such systems due to the light weight, relatively low cost, and low system footprint required for UNDE. However, UNDE in such real world systems is a non-trivial task due in large to the high temperature environments involved with such systems. Utilization of a spray-on deposition technique of ferroelectric bismuth titanate (Bi4Ti3O12) is investigated. The spray-on technique has several advantages compared to more standard methods of transducer fabrication, particularly for high temperature systems. The primary advantage of this technique is that transducers can be deposited directly onto the structure requiring investigation. Eliminates the need to develop a means of maintaining reliable high temperature mechanical coupling between the transducer and structure under evaluation. Additionally, the ability to analyze structures with complicated geometries with greater ease can potentially be achieved. Moreover, this method allows for fabrication of thick film transducer and therefore transducers with center frequencies typical to industrial UNDE (1-20 MHz) can be realized. Bismuth titanate has been chosen as the material to be investigated due to its high Curie temperature (685 °C) and because it has already been shown that fabrication of bismuth titanate based ultrasonic transducers via the spray-on deposition method is possible. Since initial results with conventional sintering methods were unsuccessful, microwave sintering was pursued and is capable of producing films with superior quality. Industrial partners showed strong interest for on-site deposition transducers. However, with on-site deposition, microwave sintering may not be a viable option. As a result, a crude, but very successful, method of sintering with a blow torch was developed and transducers fabricated in this fashion showed equivalent electromechanical strength. Moreover, the entire temperature range which bismuth titanate fabricated with the spray-on technique had yet to be explored. In this work it has been shown that spray-deposited bismuth titanate transducers are capable of generating ultrasonic signals with strengths equivalent to room temperature signals up to 650 °C for short periods of time. Above this temperature, thermal depoling of the sample occurs rapidly as temperature increases and signal strength diminishes. Furthermore, little has… Advisors/Committee Members: Bernhard R Tittmann, Dissertation Advisor/Co-Advisor, Clifford Jesse Lissenden Iii, Committee Member, Dinesh Kumar Agrawal, Committee Member, Thomas R Shrout, Special Member.

Subjects/Keywords: high temperature ferroelectric; high temperature piezoelectric; high temperature ultrasound; high temperature transducer

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Searfass, C. (2012). Characterization of bismuth titanate thick films fabricated using a spray-on technique for high temperature ultrasonic non-destructive evaluation. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/14489

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Searfass, Clifford. “Characterization of bismuth titanate thick films fabricated using a spray-on technique for high temperature ultrasonic non-destructive evaluation.” 2012. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/14489.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Searfass, Clifford. “Characterization of bismuth titanate thick films fabricated using a spray-on technique for high temperature ultrasonic non-destructive evaluation.” 2012. Web. 19 Jan 2021.

Vancouver:

Searfass C. Characterization of bismuth titanate thick films fabricated using a spray-on technique for high temperature ultrasonic non-destructive evaluation. [Internet] [Thesis]. Penn State University; 2012. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/14489.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Searfass C. Characterization of bismuth titanate thick films fabricated using a spray-on technique for high temperature ultrasonic non-destructive evaluation. [Thesis]. Penn State University; 2012. Available from: https://submit-etda.libraries.psu.edu/catalog/14489

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

9. Reinhardt, Brian T. Nonlinear ultrasonic measurements in nuclear reactor environments.

Degree: 2016, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/28985

► Several Department of Energy Office of Nuclear Energy (DOE-NE) programs, such as the Fuel Cycle Research and Development (FCRD), Advanced Reactor Concepts (ARC), Light Water… (more)

▼ Several Department of Energy Office of Nuclear Energy (DOE-NE) programs, such as the Fuel Cycle Research and Development (FCRD), Advanced Reactor Concepts (ARC), Light Water Reactor Sustainability, and Next Generation Nuclear Power Plants (NGNP), are investigating new fuels, materials, and inspection paradigms for advanced and existing reactors. A key objective of such programs is to understand the performance of these fuels and materials during irradiation. In DOE-NE’s FCRD program, ultrasonic based technology was identified as a key approach that should be pursued to obtain the high-fidelity, high-accuracy data required to characterize the behavior and performance of new candidate fuels and structural materials during irradiation testing. The radiation, high temperatures, and pressure can limit the available tools and characterization methods. In this thesis, two ultrasonic characterization techniques will be explored. The first, finite amplitude wave propagation has been demonstrated to be sensitive to microstructural material property changes. It is a strong candidate to determine fuel evolution; however, it has not been demonstrated for in-situ reactor applications. In this thesis, finite amplitude wave propagation will be used to measure the microstructural evolution in Al-6061. This is the first demonstration of finite amplitude wave propagation at temperatures in excess of 200 °C and during an irradiation test. Second, a method based on contact nonlinear acoustic theory will be developed to identify compressed cracks. Compressed cracks are typically transparent to ultrasonic wave propagation; however, by measuring harmonic content developed during finite amplitude wave propagation, it is shown that even compressed cracks can be characterized. Lastly, piezoelectric transducers capable of making these measurements are developed. Specifically, three piezoelectric sensors (Bismuth Titanate, Aluminum Nitride, and Zinc Oxide) are tested in the Massachusetts Institute of Technology Research reactor to a fast neutron fluence of 8.65x1020 n/cm2. It is demonstrated that Bismuth Titanate is capable of transduction up to 5 x1020 n/cm2, Zinc Oxide is capable of transduction up to 6.27 x1020 n/cm2, and Aluminum Nitride is capable of transduction up to 8.65x x1020 n/cm2. Advisors/Committee Members: Bernhard R Tittmann, Dissertation Advisor/Co-Advisor, Clifford Jesse Lissenden Iii, Committee Member, Albert Eliot Segall, Committee Member, Victor Ward Sparrow, Special Member.

Subjects/Keywords: Nonlinear Ultrasound; Contact Acoustic Nonlinear; Transducers; Neutron

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APA (6^th Edition):

Reinhardt, B. T. (2016). Nonlinear ultrasonic measurements in nuclear reactor environments. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/28985

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Reinhardt, Brian T. “Nonlinear ultrasonic measurements in nuclear reactor environments.” 2016. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/28985.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Reinhardt, Brian T. “Nonlinear ultrasonic measurements in nuclear reactor environments.” 2016. Web. 19 Jan 2021.

Vancouver:

Reinhardt BT. Nonlinear ultrasonic measurements in nuclear reactor environments. [Internet] [Thesis]. Penn State University; 2016. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/28985.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Reinhardt BT. Nonlinear ultrasonic measurements in nuclear reactor environments. [Thesis]. Penn State University; 2016. Available from: https://submit-etda.libraries.psu.edu/catalog/28985

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

10. Waller, Matthew David. Defect Growth Detection Potential Using Guided Waves.

Degree: 2016, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/t435gc96m

► Modern society relies on vast networks of infrastructure such as bridges, pipelines, railroads, and electric generating stations to name a few. Keeping infrastructure operating reliably… (more)

Subjects/Keywords: SHM; NDT; NDE; structural health monitoring; guided waves; ultrasonics; crack detection

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APA (6^th Edition):

Waller, M. D. (2016). Defect Growth Detection Potential Using Guided Waves. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/t435gc96m

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Waller, Matthew David. “Defect Growth Detection Potential Using Guided Waves.” 2016. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/t435gc96m.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Waller, Matthew David. “Defect Growth Detection Potential Using Guided Waves.” 2016. Web. 19 Jan 2021.

Vancouver:

Waller MD. Defect Growth Detection Potential Using Guided Waves. [Internet] [Thesis]. Penn State University; 2016. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/t435gc96m.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Waller MD. Defect Growth Detection Potential Using Guided Waves. [Thesis]. Penn State University; 2016. Available from: https://submit-etda.libraries.psu.edu/catalog/t435gc96m

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

11. Bostron, Jason Henry. Ultrasonic guided wave bondline evaluation of thick metallic structures with viscoelastic coatings and the demonstration of a novel mode sweep technique.

Degree: 2013, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/19716

► Ultrasonic guided waves are becoming more widely used in nondestructive evaluation applications due to their efficiency in defect detection, ability to inspect hidden areas, and… (more)

▼ Ultrasonic guided waves are becoming more widely used in nondestructive evaluation applications due to their efficiency in defect detection, ability to inspect hidden areas, and other reasons. This dissertation addresses two main topics: ultrasonic guided wave bond evaluation of thin and thick coatings on thick metallic structures, and the use of a novel phased array technique for optimal guided wave mode and frequency selection. Bond integrity is of interest to researchers in non-destructive evaluation because it is used as an indicator when assessing the health of structures. We consider both a thin and a thick viscoelastic layer bonded to a metallic plate and use a guided wave ultrasonic signal to assess bond integrity in hidden regions. This work applies to relatively low-curvature pressurized pipe and vessels. Analytical and finite element models are developed to describe wave propagation at high frequencies relative to the plate thickness, where the plate can be approximated as a half space. Finite element models are used to visualize wave propagation. Experiments are performed on a 25 mm thick steel plate with both relatively thin (3 mm) and thick (25 mm) coatings of various stiffnesses bonded to the surface. Physically based wave features, such as amplitude ratio, energy ratio, frequency ratio, pulse width, and arrival time are identified which may be used to assess bond integrity in hidden regions. With a thorough understanding of guided wave mechanics, researchers can predict which guided wave modes will have a high probability of success in a particular nondestructive evaluation application. However, work continues to find optimal mode and frequency selection for a given application. This "optimal" mode could give the highest sensitivity to defects or the greatest penetration power, increasing inspection efficiency. Since material properties used for modeling work may be estimates, in many cases guided wave mode and frequency selection can be adjusted for increased inspection efficiency in the field. In this work, a novel mode sweep technique is described and used to identify optimal mode points based on quantifiable wave characteristics. The technique uses an ultrasonic phased array comb transducer to sweep in phase velocity-frequency space and is demonstrated using interface waves to inspect thick bonded structures. After sweeping through nearby mode points, an optimal mode and frequency can be selected which has the highest sensitivity to a defect, or gives the greatest penetration power. The optimal mode choice for a given application depends on the requirements of the inspection. Advisors/Committee Members: Joseph Rose, Dissertation Advisor/Co-Advisor, Clifford Jesse Lissenden Iii, Committee Member, Bernhard R Tittmann, Committee Member, Kevin L Koudela, Committee Member.

Subjects/Keywords: Guided waves; Phased array; Mode selection; Bond evaluation; Interface wave; Rayleigh wave

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Bostron, J. H. (2013). Ultrasonic guided wave bondline evaluation of thick metallic structures with viscoelastic coatings and the demonstration of a novel mode sweep technique. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/19716

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Bostron, Jason Henry. “Ultrasonic guided wave bondline evaluation of thick metallic structures with viscoelastic coatings and the demonstration of a novel mode sweep technique.” 2013. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/19716.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Bostron, Jason Henry. “Ultrasonic guided wave bondline evaluation of thick metallic structures with viscoelastic coatings and the demonstration of a novel mode sweep technique.” 2013. Web. 19 Jan 2021.

Vancouver:

Bostron JH. Ultrasonic guided wave bondline evaluation of thick metallic structures with viscoelastic coatings and the demonstration of a novel mode sweep technique. [Internet] [Thesis]. Penn State University; 2013. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/19716.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Bostron JH. Ultrasonic guided wave bondline evaluation of thick metallic structures with viscoelastic coatings and the demonstration of a novel mode sweep technique. [Thesis]. Penn State University; 2013. Available from: https://submit-etda.libraries.psu.edu/catalog/19716

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

12. Gardner, Michael D. Ultrasonic Guided Wave Nondestructive Evaluation Using Generalized Anisotropic Interface Waves.

Degree: 2014, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/20035

► The motivation for this work is a goal to inspect interfaces between thick layers of materials that can be anisotropic. The specific application is a… (more)

▼ The motivation for this work is a goal to inspect interfaces between thick layers of materials that can be anisotropic. The specific application is a thick composite bonded to a metal substrate. The interface is inspected for disbonds between the metal and composite. The large thickness allows the problem to be modeled as a half space. The theory behind guided waves in plates is presented. This theory includes the calculation and analysis of dispersion curves and the resulting wave structure. It is noted that for high frequency-thickness values, certain modes will converge to the half-space waves, e.g. the Rayleigh wave and the Stoneley wave. Points of high energy, especially shear energy, at the interface are desirable for interfacial inspection. Therefore, the wave structure for all modes and frequencies is searched for ideal inspection points. Interface waves are inherently good modes to use for interface inspection. Results from the dispersion curves and wave structures are verified in the finite element model software package called Abaqus. It is confirmed that the group speeds and wave structures of the modes match the predicted values. A theoretical development of interface waves is given wherein Rayleigh, Stoneley, and generalized interface waves are discussed. This is applied to both isotropic and anisotropic materials. It is shown that the Stoneley wave only exists for a certain range of material parameters. Because the Stoneley wave is the interface wave between two solid half spaces, it might appear that only certain pairs of solids would allow for inspection via interface wave. However, it is shown that for perturbations of the Stoneley-wave-valid material properties, interface waves which leak energy away from the interface can still propagate. They can also be used for inspection. Certain choices of materials will leak less energy and will therefore allow for longer inspection distances. The solutions to the isotropic leaky wave problem exist on eight different Riemann sheets which allow one to confine multi-valued functions such as the square root onto these single-valued Riemann sheets. The ranges of existence for three of these sheets is presented along with the values of the complex wave speed. The three types of interface waves are Rayleigh-like, Stoneley, and interface. For anisotropic materials, the solutions to the anisotropic leaky wave problem exist on thirty-two different sheets and the possibility of all three displacement components being coupled exists. The predicted values of sound speed and absorption for the leaky waves are confirmed by way of a finite element simulation. The wave structure for leaky waves grows in amplitude away from the boundary in any half space where leaked energy is allowed. The leaked partial waves are visualized via a snapshot of a finite element animation. A discussion of composite materials is given. Classical lamination theory is presented as well as the cube-cutting procedure for elastic constant determination. The composite… Advisors/Committee Members: Joseph Lawrence Rose, Dissertation Advisor/Co-Advisor, Clifford Jesse Lissenden Iii, Committee Member, Bernhard R Tittmann, Committee Member, Kevin L Koudela, Special Member.

Subjects/Keywords: Ultrasonic; Guided Wave; Nondestructive Evaluation; Anisotropic; Interface; Acoustics

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APA (6^th Edition):

Gardner, M. D. (2014). Ultrasonic Guided Wave Nondestructive Evaluation Using Generalized Anisotropic Interface Waves. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/20035

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Gardner, Michael D. “Ultrasonic Guided Wave Nondestructive Evaluation Using Generalized Anisotropic Interface Waves.” 2014. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/20035.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Gardner, Michael D. “Ultrasonic Guided Wave Nondestructive Evaluation Using Generalized Anisotropic Interface Waves.” 2014. Web. 19 Jan 2021.

Vancouver:

Gardner MD. Ultrasonic Guided Wave Nondestructive Evaluation Using Generalized Anisotropic Interface Waves. [Internet] [Thesis]. Penn State University; 2014. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/20035.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gardner MD. Ultrasonic Guided Wave Nondestructive Evaluation Using Generalized Anisotropic Interface Waves. [Thesis]. Penn State University; 2014. Available from: https://submit-etda.libraries.psu.edu/catalog/20035

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

13. Topbasi, Cem. microstructural evolution of ferritic-martensitic steels under heavy ion irradiation.

Degree: 2014, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/22610

► Ferritic-martensitic steels are primary candidate materials for fuel cladding and internal applications in the Sodium Fast Reactor, as well as first-wall and blanket materials in… (more)

▼ Ferritic-martensitic steels are primary candidate materials for fuel cladding and internal applications in the Sodium Fast Reactor, as well as first-wall and blanket materials in future fusion concepts because of their favorable mechanical properties and resistance to radiation damage. Since microstructure evolution under irradiation is amongst the key issues for these materials in these applications, developing a fundamental understanding of the irradiation-induced microstructure in these alloys is crucial in modeling and designing new alloys with improved properties. The goal of this project was to investigate the evolution of microstructure of two commercial ferritic-martensitic steels, NF616 and HCM12A, under heavy ion irradiation at a broad temperature range. An in situ heavy ion irradiation technique was used to create irradiation damage in the alloy; while it was being examined in a transmission electron microscope. Electron-transparent samples of NF616 and HCM12A were irradiated in situ at the Intermediate Voltage Electron Microscope (IVEM) at Argonne National Laboratory with 1 MeV Kr ions to ~10 dpa at temperatures ranging from 20 to 773 K. The microstructure evolution of NF616 and HCM12A was followed in situ by systematically recording micrographs and diffraction patterns as well as capturing videos during irradiation. In these irradiations, there was a period during which no changes are visible in the microstructure. After a threshold dose (~0.1 dpa between 20 and 573 K, and ~2.5 dpa at 673 K) black dots started to become visible under the ion beam. These black dots appeared suddenly (from one frame to the next) and are thought to be small defect clusters (2-5 nm in diameter), possibly small dislocation loops with Burgers vectors of either ½<111> or <100>. The overall density of these defect clusters increased with dose and saturated around 6 dpa. At saturation, a steady-state is reached in which defects are eliminated and created at the same rates so that the defect density is constant. After saturation, defects constantly appeared and disappeared in a time that is shorter than the time in between frames (normally 34 ms). The average diameter and size distribution of the irradiation-induced defect clusters did not vary with dose during a single irradiation in the temperature range of 50 to 573 K in NF616, and 20 to 673 K in HCM12A. At 673 K, the defects in NF616 grew and coalesced under irradiation which led to larger average defect sizes and low defect density. At high doses extended defect structures in NF616 formed as short segments aligned along 100 directions. At 773 K, the frequency of defect formation per unit area was the lowest amongst all irradiations and all the visible defect clusters that formed eventually faded out gradually (in ~28 seconds) leading to no net defect accumulation in NF616 even at the highest irradiation dose of 10 dpa. Under irradiation, a significant fraction of these defect clusters exhibited sudden one-dimensional jumps (over ~5nm) between 20 and 573 K, that is, some… Advisors/Committee Members: Arthur Thompson Motta, Dissertation Advisor/Co-Advisor, Clifford Jesse Lissenden Iii, Committee Member, Zi Kui Liu, Committee Member, Clive A Randall, Committee Member, Brian D Wirth, Special Member.

Subjects/Keywords: nuclear materials; steels; ion irradiation; iron; defects

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Topbasi, C. (2014). microstructural evolution of ferritic-martensitic steels under heavy ion irradiation. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/22610

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Topbasi, Cem. “microstructural evolution of ferritic-martensitic steels under heavy ion irradiation.” 2014. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/22610.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Topbasi, Cem. “microstructural evolution of ferritic-martensitic steels under heavy ion irradiation.” 2014. Web. 19 Jan 2021.

Vancouver:

Topbasi C. microstructural evolution of ferritic-martensitic steels under heavy ion irradiation. [Internet] [Thesis]. Penn State University; 2014. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/22610.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Topbasi C. microstructural evolution of ferritic-martensitic steels under heavy ion irradiation. [Thesis]. Penn State University; 2014. Available from: https://submit-etda.libraries.psu.edu/catalog/22610

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

14. Borigo, Cody J. A Novel Actuator Phasing Method for Ultrasonic De-icing of Aircraft Structures.

Degree: 2014, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/23379

► Aircraft icing is a critical concern for commercial and military rotorcraft and fixed-wing aircraft. In-flight icing can lead to dramatic decreases in lift and increases… (more)

▼ Aircraft icing is a critical concern for commercial and military rotorcraft and fixed-wing aircraft. In-flight icing can lead to dramatic decreases in lift and increases in drag that have caused more than a thousand deaths and hundreds of accidents over the past three decades alone. Current ice protection technologies have substantial drawbacks due to weight, power consumption, environmental concerns, or incompatibility with certain structures. In this research, an actuator phasing method for ultrasonic de-icing of aircraft structures was developed and tested using a series of finite element models, 3D scanning laser Doppler vibrometer measurements, and experimental de-icing tests on metallic and composite structures including plates and airfoils. An independent actuator analysis method was developed to allow for practical evaluation of many actuator phasing scenarios using a limited number of finite element models by properly calculating the phased stress fields and electromechanical impedance curves using a complex coupled impedance model. A genetic algorithm was utilized in conjunction with a series of finite element models to demonstrate that phase inversion, in which only in-phase and anti-phase signal components are applied to actuators, can be utilized with a small number of phasing combinations to achieve substantial improvements in de-icing system coverage. Finite element models of a 48”-long airfoil predicted that phase inversion with frequency sweeping can provide an improvement in the shear stress coverage levels of up to 90% compared to frequency sweeping alone. Experimental evaluation of the phasing approach on an icing grid showed a 189% improvement in de-icing coverage compared to frequency sweeping alone at comparable power levels. 3D scanning laser Doppler vibrometer measurements confirmed the increased variation in the surface vibration field induced by actuator phasing compared to unphased frequency sweeping. Additional contributions were made to facilitate actuator phasing and to advance the state-of-the-art in ultrasonic de-icing technology. These contributions include the development of improved frequency optimization, reduction in the size of the system hardware, and improvements in actuator bonding techniques. It was demonstrated that a dynamic frequency selection method is critical to effectively implementing the actuator phasing method. A miniaturized relay system was also designed and implemented to facilitate actuator phasing in conjunction with a phase splitter circuit and a single amplifier. An improved frequency tuning method was adopted and implemented in the de-icing system to eliminate the need for an impedance analyzer and to provide more accurate frequency selection by directly measuring the forward and reflected power between the amplifier and the de-icing actuators. Overall, it was demonstrated that this novel method can greatly improve the efficiency and effectiveness of the ultrasonic de-icing system by effectively redistributing the shear stress fields at the ice-structure… Advisors/Committee Members: Joseph Lawrence Rose, Dissertation Advisor/Co-Advisor, Joseph Lawrence Rose, Committee Chair/Co-Chair, Clifford Jesse Lissenden Iii, Committee Member, Bernhard R Tittmann, Committee Member, Edward C Smith, Committee Member.

Subjects/Keywords: de-icing; aircraft; ultrasound; ultrasonic; vibration; ice protection; anti-icing; phasing; piezoelectric

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Borigo, C. J. (2014). A Novel Actuator Phasing Method for Ultrasonic De-icing of Aircraft Structures. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/23379

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Borigo, Cody J. “A Novel Actuator Phasing Method for Ultrasonic De-icing of Aircraft Structures.” 2014. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/23379.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Borigo, Cody J. “A Novel Actuator Phasing Method for Ultrasonic De-icing of Aircraft Structures.” 2014. Web. 19 Jan 2021.

Vancouver:

Borigo CJ. A Novel Actuator Phasing Method for Ultrasonic De-icing of Aircraft Structures. [Internet] [Thesis]. Penn State University; 2014. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/23379.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Borigo CJ. A Novel Actuator Phasing Method for Ultrasonic De-icing of Aircraft Structures. [Thesis]. Penn State University; 2014. Available from: https://submit-etda.libraries.psu.edu/catalog/23379

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

15. Last, Beth Anna. Multi-scale Microstructure and Thermo-mechanical Characterization for Shape Memory Alloy Design via Additive Manufacturing.

Degree: 2019, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/15132bab5313

► The layer-by-layer deposition process of additive manufacturing (AM) offers the capability to design material microstructures on multiple length scales. For NiTi shape memory alloys, designing… (more)

▼ The layer-by-layer deposition process of additive manufacturing (AM) offers the capability to design material microstructures on multiple length scales. For NiTi shape memory alloys, designing material microstructures using AM would allow for unparalleled tailoring of the multiscale martensitic transformation and shape memory response. However, the laser-based directed energy deposition (LDED) AM technique produces localized microstructures which are distinct from those found in conventionally processed alloys. This work characterizes the grain and precipitate microstructures on multiple length scales for LDED fabricated NiTi alloys and assess the capability for tailoring the martensitic transformation morphology shape memory response through post-deposition heat treatments. Build coupons were fabricated by LDED AM using elementally blended Ni and Ti powder feedstock. The use of elemental powders allowed for a Ti-rich and a Ni-rich powder feedstock composition to be blended; thus, both shape memory effect (Ti-rich) and superelastic (Ni-rich) behaviors were investigated. Specimens were extracted from the fabricated build coupons to investigate the localized microstructure and shape memory behaviors. A full-field deformation analysis technique was employed to correlate the AM microstructure to the deformation mechanisms. The results of this work show that the NiTi LDED AM builds are inherently spatially varying on multiple microstructure length scales. The grain structure resulting from the AM process was similar for both feedstock compositions: fine grains within the interfacial regions formed by overlapping passes/layers and larger columnar grains within bulk regions (i.e. away from these interfaces). As a result of the spatially varying microstructure, as built LDED NiTi alloys exhibit a hardening like response and localized strain concentrations. Post-deposition heat treatment of the Ni-rich alloys reduced the spatial variation in the Ni4Ti3 precipitate microstructure and increased the localized superelastic strains compared to the as built condition, with the solutionizing and precipitation aging treatment resulting in the most spatially uniform Ni4Ti3 precipitate morphology. For the LDED alloys, shape memory effect recovery strains of 4.0 % (for Ti-rich alloys) and superelastic recovery strains of -6.0 % (for solutionized and aged Ni-rich alloys) were achieved. Advisors/Committee Members: Reginald Felix Hamilton, Dissertation Advisor/Co-Advisor, Reginald Felix Hamilton, Committee Chair/Co-Chair, Todd Palmer, Committee Member, Clifford Jesse Lissenden III, Committee Member, Allison Michelle Beese, Outside Member, Albert Eliot Segall, Committee Member.

Subjects/Keywords: shape memory alloy; additive manufacturing; microstructure; digital image correlation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Last, B. A. (2019). Multi-scale Microstructure and Thermo-mechanical Characterization for Shape Memory Alloy Design via Additive Manufacturing. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/15132bab5313

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Last, Beth Anna. “Multi-scale Microstructure and Thermo-mechanical Characterization for Shape Memory Alloy Design via Additive Manufacturing.” 2019. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/15132bab5313.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Last, Beth Anna. “Multi-scale Microstructure and Thermo-mechanical Characterization for Shape Memory Alloy Design via Additive Manufacturing.” 2019. Web. 19 Jan 2021.

Vancouver:

Last BA. Multi-scale Microstructure and Thermo-mechanical Characterization for Shape Memory Alloy Design via Additive Manufacturing. [Internet] [Thesis]. Penn State University; 2019. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/15132bab5313.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Last BA. Multi-scale Microstructure and Thermo-mechanical Characterization for Shape Memory Alloy Design via Additive Manufacturing. [Thesis]. Penn State University; 2019. Available from: https://submit-etda.libraries.psu.edu/catalog/15132bab5313

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

16. Chen, Xuan. USE OF SEMI-CIRCULAR BEND TEST TO CHARACTERIZE FRACTURE PROPERTIES OF ASPHALT CONCRETE WITH VIRGIN AND RECYCLED MATERIALS.

Degree: 2019, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/16829xxc137

► Cracking in asphalt pavements is a challenging problem and has been the subject of numerous research studies for decades. To properly address this problem, suitable… (more)

▼ Cracking in asphalt pavements is a challenging problem and has been the subject of numerous research studies for decades. To properly address this problem, suitable tests must be conducted to capture material behavior in cracking, such testing must be accompanied by proper mechanistic and empirical modeling of the material behavior in cracking. For mixture design and material quality control/assurance purposes, there is not a commonly accepted protocol for testing asphalt mixtures for cracking resistance characterization, due to variability of test results, non-uniformity in test specimens, and overall complexities of the tests that prevent them from being adopted for daily uses. On the other hands, for the tests that are popular for research purposes, the validity and sensitivity of such tests have not been fully witnessed and proven, due to lack of data quantity. Addressing these problems will help improve mixture design procedures and advance quality control and quality assurance of asphalt mixes, especially when complicated components, such as recycled materials and performance enhancing additives, are commonly incorporated into asphalt concrete nowadays. The overall goal of this research is to characterize the cracking resistance of various types of asphalt concrete mixes via a suitable candidate test. An additional goal is to provide guidelines for performing balanced mixture design on asphalt concrete with virgin and recycled materials when using such a test. Throughout the research, the selected fracture test, namely the semi-circular bend (SCB) fracture test, was first evaluated by investigating the sensitivity of performance indicators under various test conditions and proposing the most appropriate test conditions using a solid theoretical background. Then, the test was used to study fracture behavior of a wide range of asphalt paving materials including, but not limited to, various virgin asphalt mixes, crumb rubber modified (CRM) asphalt mixes, asphalt mixes with recycled materials such as reclaimed asphalt pavement (RAP), and recycled asphalt shingles (RAS), together with asphalt mixes with recycling agents. Not only were these mixtures prepared in a single laboratory, specimens received from different laboratories and plants were also included in the test matrix to reduce bias and to investigate the variation of the performance indicators. Additionally, a method to conduct the performance-based balanced-design using only the SCB fracture test was explored. Finally, the effect of long-term aging on fracture behavior of asphalt mixes was investigated, in order to build foundations for performance prediction commonly used in asphalt pavement design procedures. The main contributions of this study are: 1) verification of the sensitivity of the SCB test using asphalt mixtures with controlled variables under the proposed test conditions that are suitable to the commonwealth of Pennsylvania, 2) investigation of the impacts of material variables and conditioning, namely aging… Advisors/Committee Members: Mansour Solaimanian, Dissertation Advisor/Co-Advisor, Mansour Solaimanian, Committee Chair/Co-Chair, Shihui Shen, Committee Member, Clifford Jesse Lissenden, III, Committee Member, Tong Qiu, Outside Member.

Subjects/Keywords: Asphalt; Cracking; Fracture; Semi-Circular Bend; Recycled Materials; Asphalt Concrete; Performance Test; Balanced Mix Design

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APA (6^th Edition):

Chen, X. (2019). USE OF SEMI-CIRCULAR BEND TEST TO CHARACTERIZE FRACTURE PROPERTIES OF ASPHALT CONCRETE WITH VIRGIN AND RECYCLED MATERIALS. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/16829xxc137

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Chen, Xuan. “USE OF SEMI-CIRCULAR BEND TEST TO CHARACTERIZE FRACTURE PROPERTIES OF ASPHALT CONCRETE WITH VIRGIN AND RECYCLED MATERIALS.” 2019. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/16829xxc137.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Chen, Xuan. “USE OF SEMI-CIRCULAR BEND TEST TO CHARACTERIZE FRACTURE PROPERTIES OF ASPHALT CONCRETE WITH VIRGIN AND RECYCLED MATERIALS.” 2019. Web. 19 Jan 2021.

Vancouver:

Chen X. USE OF SEMI-CIRCULAR BEND TEST TO CHARACTERIZE FRACTURE PROPERTIES OF ASPHALT CONCRETE WITH VIRGIN AND RECYCLED MATERIALS. [Internet] [Thesis]. Penn State University; 2019. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/16829xxc137.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Chen X. USE OF SEMI-CIRCULAR BEND TEST TO CHARACTERIZE FRACTURE PROPERTIES OF ASPHALT CONCRETE WITH VIRGIN AND RECYCLED MATERIALS. [Thesis]. Penn State University; 2019. Available from: https://submit-etda.libraries.psu.edu/catalog/16829xxc137

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

17. Roy, Arjun. Failure-time statistics of a coupled-field damage evolution model via temporal averaging.

Degree: 2012, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/16179

► We study the coupling between dynamics at different time-scales during fatigue damage growth with an objective of understanding the factors that lead to large variations… (more)

▼ We study the coupling between dynamics at different time-scales during fatigue damage growth with an objective of understanding the factors that lead to large variations observed in the statistics of life of specimens subject to periodic loading. For this we study a previously developed 1D coupled-field damage evolution model that couples the dynamics at the macroscopic and microscopic scales. We perform Monte-Carlo life-cycle simulations of large ensembles of initial random micro-states with the objective of determining the effect of initial microsturctural uncertainty on the variability of failure-time statistics. We find through our simulations that the spatial evolution of damage is governed by the spatial distribution of the unperturbed steady-state macroscopic strain and that the failure-time distribution of the bar damage failure-time distributions have oscillations that have a period that is half of the forcing period. However, direct numerical simulations of large ensembles for such multi-scale models are expensive, as the time-scales of the macroscopic and microscopic systems are usually very disparate. To overcome this challenge we use the method of averaging to average out the macroscopic dynamics. We first implement the method of averaging on a 1-DOF version of our continuum problem and use it to determine a universal slow time-scale in which the evolution of damage is independent of the forcing amplitude and the parameter that governs the damage evolution rate. This not only helps us to reduce computational time by orders of magnitude, but also helps us to understand the nature of S-N curves for our model. We also implement the method of averaging on a 2-DOF damage evolution model and demonstrate the existence of a first integral for the system and that the damage phase space can be partitioned into regions corresponding to different damage failure modes. We then develop a numerical scheme, based on the method of averaging, that can be used to extend our averaging scheme numerically to higher dimensions. This helps to reduce the computational time required for life-cycle simulations of our continuum model by a large factor and we therefore then use this method to study failure-time statistics. We first use the averaged equations to develop lower dimensional models that capture the evolution of damage occurring in a bar with seeded faults. We then use the averaged equations to derive approximate expressions for the failure time for a brittle bar and use it to demonstrate the importance of the spatial correlation of initial damage on the convergence of failure-times. Next we perform life-cycle simulations for ensembles of initial damage conditions at different forcing frequency to demonstrate a direct correlation between the spatial localization of damage and the relative variability of failure times. Finally, we use semi-analytical techniques to demonstrate a periodic dependence of the median failure-time on the forcing frequency for fatigue of brittle materials. Advisors/Committee Members: Joseph Paul Cusumano, Dissertation Advisor/Co-Advisor, Joseph Paul Cusumano, Committee Chair/Co-Chair, Francesco Costanzo, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Eric M Mockensturm, Committee Member.

Subjects/Keywords: fatigue; continuum damage mechanics; method of averaging; extreme value statistics; failure-time statistics

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APA (6^th Edition):

Roy, A. (2012). Failure-time statistics of a coupled-field damage evolution model via temporal averaging. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/16179

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Roy, Arjun. “Failure-time statistics of a coupled-field damage evolution model via temporal averaging.” 2012. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/16179.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Roy, Arjun. “Failure-time statistics of a coupled-field damage evolution model via temporal averaging.” 2012. Web. 19 Jan 2021.

Vancouver:

Roy A. Failure-time statistics of a coupled-field damage evolution model via temporal averaging. [Internet] [Thesis]. Penn State University; 2012. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/16179.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Roy A. Failure-time statistics of a coupled-field damage evolution model via temporal averaging. [Thesis]. Penn State University; 2012. Available from: https://submit-etda.libraries.psu.edu/catalog/16179

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

18. Khajeh, Ehsan. Guided Wave Propagation in Complex Curved Waveguides: Flexural Guided Waves and their Application for Defect Classification in Pipes.

Degree: 2013, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/19017

► A new method, called ray-plate theory, is developed to investigate guided wave propagation in complex curved waveguides. This theory is applied to the study of… (more)

▼ A new method, called ray-plate theory, is developed to investigate guided wave propagation in complex curved waveguides. This theory is applied to the study of guided waves in hollow circular cylinders. For the first time analytical relations are derived for longitudinal and torsional dispersion curves in hollow circular cylinders. Dispersion curves, derived using the ray-plate theory, are compared with the results of the Global Matrix Helmholtz decomposition method. It is shown that the predictions of the ray-plate theory are accurate.\\ Flexural modes are investigated in the context of the ray-plate theory. A new consistent understanding is presented for flexural modes in hollow circular cylinders. Several aspects of flexural modes and their relationship with axisymmetric modes are studied. Based on this understanding, helical loading is proposed for pure flexural mode excitation. Analytical relations are derived for the angle of the helical load in order to excite a specific flexural mode. Angular dispersion curves and the concepts of angular dispersivity and angular closeness are introduced for selecting suitable flexural modes for excitation. Finite element analysis and Fourier transforms are utilized to verify the pure excitation of the desired flexural mode at a predicted angle. It is shown that a pure torsional or longitudinal flexural mode is effectively excited by choosing the correct angle for helical load and applying a suitable load.\\ A beam-steering method is proposed in order to excite flexural modes. A linear phased array is used to steer guided waves in hollow circular cylinders. An analytical relation is derived for time delays to excite a desired flexural mode. Finite element analysis is utilized to examine the pure flexural mode excitation using a linear phased array and the reliability of theoretically predicted time delays. It is shown that the proposed beam-steering method can effectively excite pure flexural modes. Pure flexural mode excitation using helical loading and beam-steering are compared; advantages and disadvantages of each method are considered. \\ Experiments are performed to excite flexural modes experimentally. A ring of transducers with 8 channels are used to experimentally excite pure flexural modes using the beam-steering method in a 4[in] schedule 40 steel pipe. The experiments show that pure flexural modes are excited effectively using the beam steering method.\\ A method based on pure flexural modes is proposed for defect detection and classification in pipes. Pure flexural modes with different angles of propagation are utilized in the inspection process. While for a volumetric defect the reflection coefficient for flexural modes are somewhat similar, for a crack-like defect there is a specific flexural mode that shows the maximum reflection coefficient. This property is used to classify defects as volumetric or crack-like. In addition, the angle of the crack-like defect can be determined using the propagation direction of this flexural mode. It is demonstrated that… Advisors/Committee Members: Joseph Lawrence Rose, Dissertation Advisor/Co-Advisor, Reginald Felix Hamilton, Committee Chair/Co-Chair, Clifford Jesse Lissenden Iii, Committee Member, Arthur Thompson Motta, Committee Member.

Subjects/Keywords: Guided Waves; Flexural; Ultrasonic; Inspection; Pipes; Defect; Dispersion Curves

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Khajeh, E. (2013). Guided Wave Propagation in Complex Curved Waveguides: Flexural Guided Waves and their Application for Defect Classification in Pipes. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/19017

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Khajeh, Ehsan. “Guided Wave Propagation in Complex Curved Waveguides: Flexural Guided Waves and their Application for Defect Classification in Pipes.” 2013. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/19017.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Khajeh, Ehsan. “Guided Wave Propagation in Complex Curved Waveguides: Flexural Guided Waves and their Application for Defect Classification in Pipes.” 2013. Web. 19 Jan 2021.

Vancouver:

Khajeh E. Guided Wave Propagation in Complex Curved Waveguides: Flexural Guided Waves and their Application for Defect Classification in Pipes. [Internet] [Thesis]. Penn State University; 2013. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/19017.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Khajeh E. Guided Wave Propagation in Complex Curved Waveguides: Flexural Guided Waves and their Application for Defect Classification in Pipes. [Thesis]. Penn State University; 2013. Available from: https://submit-etda.libraries.psu.edu/catalog/19017

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

19. Yeh, Lin. Modified Mechanistic-Empirical Airfield Unbonded Concrete Overlay Traffic Prediction Model.

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/12626

► Unbonded concrete overlays, one rehabilitation technique applied to rigid pavements, offers benefits by taking advantage of the existing rigid pavement structure. By leaving the original… (more)

▼ Unbonded concrete overlays, one rehabilitation technique applied to rigid pavements, offers benefits by taking advantage of the existing rigid pavement structure. By leaving the original rigid pavement in place, the underlying structure is undisturbed; the existing rigid pavement structure can thus be considered in overlay design, typically resulting in a thinner overlay. In addition, the application of an interlayer between the overlay and the original rigid pavement may reduce pre-overlay repairs. Current procedures for airfield unbonded concrete overlay design are documented in advisory circular AC 150/5320-6E, published in 2009, accompanied by the design software “FAARFIELD.” Due to the lack of comprehensive unbonded concrete overlay experimental data, unbonded concrete overlay design has been considered in the same way as new rigid pavement design, despite the differences in conditions. This thesis utilizes full-scale accelerated testing data from the National Airport Pavement Test Facility to verify both the mechanistic model (stress computation) and empirical model (fatigue relationship) used in the current unbonded overlay design procedure. It is proposed that the mechanistic model be refined by including crack density, in addition to the current Structural Condition Index (SCI). Backcalculation theory is found to affect E-Ratio determination; the E-Ratio from one theory should not directly be used in a model based on another theory. In addition, E-Ratio predicted from a model developed using data for unbonded concrete overlays is larger than E-Ratio predicted from a model developed based on slab test data, especially at low values of SCI. It is suggested that the cracked slab model, developed on the basis of WES data (slab data), should not be used for unbonded concrete overlay E-Ratio prediction in FAARFIELD. For the empirical model, it is concluded that the design factor of an unbonded concrete overlay should consider the interactions between design factors of the overlay and underlying slabs, along with the conditions of the underlying slabs. The method of determination of SCI for a test item has significant effect on prediction of allowable coverages. The difference between predicted and observed coverages for the same SCI is much larger when SCI is determined based on partial slabs within a test item, as compared to when SCI is determined based on all slabs within a test item. Test item SCI, which includes all slabs within a test item for SCI calculation, should be used for failure model development when data from full-scale experiments is used. Based on recomputed test item SCI values for CC2, the proposed rigid pavement traffic prediction model provides a better statistical fit than the current model. Advisors/Committee Members: Shelley Marie Stoffels, Dissertation Advisor/Co-Advisor, Shelley Marie Stoffels, Committee Chair/Co-Chair, Clifford Jesse Lissenden Iii, Committee Member, Farshad Rajabipour, Committee Member, Mansour Solaimanian, Committee Member.

Subjects/Keywords: airfield pavement; unbonded concrete overlay; damaged material characterization; fatigue relationship; distress quantification

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Yeh, L. (2011). Modified Mechanistic-Empirical Airfield Unbonded Concrete Overlay Traffic Prediction Model. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/12626

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Yeh, Lin. “Modified Mechanistic-Empirical Airfield Unbonded Concrete Overlay Traffic Prediction Model.” 2011. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/12626.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Yeh, Lin. “Modified Mechanistic-Empirical Airfield Unbonded Concrete Overlay Traffic Prediction Model.” 2011. Web. 19 Jan 2021.

Vancouver:

Yeh L. Modified Mechanistic-Empirical Airfield Unbonded Concrete Overlay Traffic Prediction Model. [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/12626.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Yeh L. Modified Mechanistic-Empirical Airfield Unbonded Concrete Overlay Traffic Prediction Model. [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/12626

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

20. Qi, Xue. ULTRASONIC GUIDED WAVES FOR DEFECT CHARACTERIZATION IN COMPOSITE STRUCTURES .

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/11427

► Ultrasonic guided waves have been widely applied to the nondestructive evaluation (NDE) and structural health monitoring (SHM) of aircraft structures. Development of the guided wave… (more)

▼ Ultrasonic guided waves have been widely applied to the nondestructive evaluation (NDE) and structural health monitoring (SHM) of aircraft structures. Development of the guided wave technique requires an understanding of wave propagation and scattering principles. The purpose of this research is to advance transducer design and signal processing by investigating ultrasonic guided wave interaction with defects. Both isotropic metallic materials and anisotropic fiber-reinforced composite materials are included. Two approaches are introduced for damage characterization in composite laminates. The first technique is to qualitatively predict guided wave scattering at defects by analyzing wave propagation characteristics. As a sample application, waves in the trailing edge of a helicopter rotor blade, which is a composite skin/honeycomb half-space structure, are analyzed. A global matrix method (GMM) is used to determine complex solutions of both propagating and evanescent waves. The skin/substrate disbond is measured by leaky guided waves. In another example, ultrasonic guided waves are applied to detect and characterize delamination defects inside a 23-layer Alcoa Advanced Hybrid Structural plate. A semi-analytical finite element (SAFE) method is used to generate dispersion curves and wave structures for the purpose of selecting appropriate wave modes that are sensitive to the target defect. One guided wave mode and frequency is chosen as an example to achieve large in-plane particle displacements at regions of interest. The high sensitivity of the selected guided wave mode and frequency is first verified in a finite element model. Theoretically driven experiments are then conducted and compared with bulk wave measurements. It is shown that guided waves can detect and characterize deeply embedded damages inside thick multilayer fiber-metal laminates with suitable mode and frequency selection quite well. The second technique is based on quantitative calculations of guided wave scattering in composite plates. A global-local (GL) method is developed to calculate transmission and reflection coefficients of guided waves scattered by defects. The GL method is verified on both metallic and composite plates by comparing with FEM simulation and experimental results. A parametric study is performed on a unidirectional carbon/epoxy composite plate with a rectangular notch/embedded void. The influence of defect location, width, height, and composite ply orientation to guided waves is discussed. To further verify the GL method, an experiment is carried out on a quasi-isotropic composite plate with delaminations between different plies. The attenuation of through transmission waves at each defect is calculated in the 500kHz-1MHz range. The experimental data matches very well with the simulated results. In summary, this research proves the feasibility of damage characterization in plate and plate-like composite laminates with guided waves. Mode selection criteria are presented and applied to different types of defects. An… Advisors/Committee Members: Joseph Lawrence Rose, Dissertation Advisor/Co-Advisor, Joseph Lawrence Rose, Committee Chair/Co-Chair, Edward C Smith, Committee Member, Bernhard R Tittmann, Committee Member, Clifford Jesse Lissenden Iii, Committee Member.

Subjects/Keywords: Graphite epoxy laminate; Structural health monitoring; Finite element method; Guided waves; Composite; Ultrasonic NDE

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Qi, X. (2011). ULTRASONIC GUIDED WAVES FOR DEFECT CHARACTERIZATION IN COMPOSITE STRUCTURES . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/11427

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Qi, Xue. “ULTRASONIC GUIDED WAVES FOR DEFECT CHARACTERIZATION IN COMPOSITE STRUCTURES .” 2011. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/11427.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Qi, Xue. “ULTRASONIC GUIDED WAVES FOR DEFECT CHARACTERIZATION IN COMPOSITE STRUCTURES .” 2011. Web. 19 Jan 2021.

Vancouver:

Qi X. ULTRASONIC GUIDED WAVES FOR DEFECT CHARACTERIZATION IN COMPOSITE STRUCTURES . [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/11427.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Qi X. ULTRASONIC GUIDED WAVES FOR DEFECT CHARACTERIZATION IN COMPOSITE STRUCTURES . [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/11427

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

21. Cinbiz, Mahmut Nedim. THE EFFECT OF STRESS STATE ON ZIRCONIUM HYDRIDE REORIENTATION.

Degree: 2015, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/27328

► Prior to storage in a dry-cask facility, spent nuclear fuel must undergo a vacuum drying cycle during which the spent fuel rods are heated up… (more)

▼ Prior to storage in a dry-cask facility, spent nuclear fuel must undergo a vacuum drying cycle during which the spent fuel rods are heated up to elevated temperatures of ≤ 400°C to remove moisture the canisters within the cask. As temperature increases during heating, some of the hydride particles within the cladding dissolve while the internal gas pressure in fuel rods increases generating multi-axial hoop and axial stresses in the closed-end thin-walled cladding tubes. As cool-down starts, the hydrogen in solid solution precipitates as hydride platelets, and if the multi-axial stresses are sufficiently large, the precipitating hydrides reorient from their initial circumferential orientation to radial orientation. Radial hydrides can severely embrittle the spent nuclear fuel cladding at low temperature in response to hoop stress loading. Because the cladding can experience a range of stress states during the thermo-mechanical treatment induced during vacuum drying, this study has investigated the effect of stress state on the process of hydride reorientation during controlled thermo-mechanical treatments utilizing the combination of in situ X-ray diffraction and novel mechanical testing analyzed by the combination of metallography and finite element analysis. The study used cold worked and stress relieved Zircaloy-4 sheet containing approx. 180 wt. ppm hydrogen as its material basis. The failure behavior of this material containing radial hydrides was also studied over a range of temperatures. Finally, samples from reactor-irradiated cladding tubes were examined by X-ray diffraction using synchrotron radiation. To reveal the stress state effect on hydride reorientation, the critical threshold stress to reorient hydrides was determined by designing novel mechanical test samples which produce a range of stress states from uniaxial to “near-equibiaxial” tension when a load is applied. The threshold stress was determined after thermo-mechanical treatments by correlating the finite element stress-state results with the spatial distribution of hydride microstructures observed within the optical micrographs for each sample. Experiments showed that the hydride reorientation was enhanced as the stress biaxiality increased. The threshold stress decreased from 150 MPa to 80 MPa when stress biaxiality ratio increased from uniaxial tension to near-equibiaxial tension. This behavior was also predicted by classical nucleation theory based on the Gibbs free energy of transformation being assisted by the far-field stress. An analysis of in situ X-ray diffraction data obtained during a thermo-mechanical cycle typical of vacuum drying showed a complex lattice-spacing behavior of the hydride phase during the dissolution and precipitation. The in-plane hydrides showed bilinear lattice expansion during heating with the intrinsic thermal expansion rate of the hydrides being observed only at elevated temperatures as they dissolve. For radial hydrides that precipitate during cooling under stress, the spacing of the close-packed {111}… Advisors/Committee Members: Arthur Thompson Motta, Dissertation Advisor/Co-Advisor, Arthur Thompson Motta, Committee Chair/Co-Chair, Donald Albert Koss, Committee Member, Kenan Unlu, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Michael Billone, Special Member.

Subjects/Keywords: Zirconium; hydride; reorientation; dry cask storage; radial hydrides; stress; stress state; in situ; X-ray diffraction; biaxiality

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Cinbiz, M. N. (2015). THE EFFECT OF STRESS STATE ON ZIRCONIUM HYDRIDE REORIENTATION. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/27328

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Cinbiz, Mahmut Nedim. “THE EFFECT OF STRESS STATE ON ZIRCONIUM HYDRIDE REORIENTATION.” 2015. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/27328.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Cinbiz, Mahmut Nedim. “THE EFFECT OF STRESS STATE ON ZIRCONIUM HYDRIDE REORIENTATION.” 2015. Web. 19 Jan 2021.

Vancouver:

Cinbiz MN. THE EFFECT OF STRESS STATE ON ZIRCONIUM HYDRIDE REORIENTATION. [Internet] [Thesis]. Penn State University; 2015. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/27328.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Cinbiz MN. THE EFFECT OF STRESS STATE ON ZIRCONIUM HYDRIDE REORIENTATION. [Thesis]. Penn State University; 2015. Available from: https://submit-etda.libraries.psu.edu/catalog/27328

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

22. Narayanan Nampy, Sreenivas. Advanced grid-stiffened composite shells for applications in heavy-lift helicopter rotor blade spars.

Degree: 2012, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/15631

► Modern rotor blades are constructed using composite materials to exploit their superior structural performance compared to metals. Helicopter rotor blade spars are conventionally designed as… (more)

▼ Modern rotor blades are constructed using composite materials to exploit their superior structural performance compared to metals. Helicopter rotor blade spars are conventionally designed as monocoque structures. Blades of the proposed Heavy Lift Helicopter are envisioned to be as heavy as 800 lbs when designed using the monocoque spar design. A new and innovative design is proposed to replace the conventional spar designs with light weight grid-stiffened composite shell. Composite stiffened shells have been known to provide excellent strength to weight ratio and damage tolerance with an excellent potential to reduce weight. Conventional stringer – rib stiffened construction is not suitable for rotor blade spars since they are limited in generating high torsion stiffness that is required for aeroelastic stability of the rotor. As a result, off-axis (helical) stiffeners must be provided. This is a new design space where innovative modeling techniques are needed. The structural behavior of grid-stiffened structures under axial, bending, and torsion loads, typically experienced by rotor blades need to be accurately predicted. The overall objective of the present research is to develop and integrate the necessary design analysis tools to conduct a feasibility study in employing grid-stiffened shells for heavy-lift rotor blade spars. Upon evaluating the limitations in state-of-the-art analytical models in predicting the axial, bending, and torsion stiffness coefficients of grid and grid-stiffened structures, a new analytical model was developed. The new analytical model based on the smeared stiffness approach was developed employing the stiffness matrices of the constituent members of the grid structure such as an arch, helical, or straight beam representing circumferential, helical, and longitudinal stiffeners. This analysis has the capability to model various stiffening configurations such as angle-grid, ortho-grid, and general-grid. Analyses were performed using an existing state-of-the-art and newly developed model to predict the torsion, bending, and axial stiffness of grid and grid-stiffened structures with various stiffening configurations. These predictions were compared to results generated using finite element analysis (FEA) to observe excellent correlation (within 6%) for a range of parameters for grid and grid-stiffened structures such as grid density, stiffener angle, and aspect ratio of the stiffener cross-section. Experimental results from cylindrical grid specimen testing were compared with analytical prediction using the new analysis. The new analysis predicted stiffness coefficients with nearly 7% error compared to FEA results. From the parametric studies conducted, it was observed that the previous state-of-the-art analysis on the other hand exhibited errors of the order of 39% for certain designs. Stability evaluations were also conducted by integrating the new analysis with established stability formulations. A design study was conducted to evaluate the potential weight savings of a simple… Advisors/Committee Members: Edward C Smith, Dissertation Advisor/Co-Advisor, Edward C Smith, Committee Chair/Co-Chair, Charles E Bakis, Committee Member, Farhan S Gandhi, Committee Member, Clifford Jesse Lissenden Iii, Committee Member.

Subjects/Keywords: composites; structures; rotor blades; grid-stiffened; grid; spar; heavy-lift rotor blade; buckling; stiffness; strength

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APA (6^th Edition):

Narayanan Nampy, S. (2012). Advanced grid-stiffened composite shells for applications in heavy-lift helicopter rotor blade spars. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/15631

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Narayanan Nampy, Sreenivas. “Advanced grid-stiffened composite shells for applications in heavy-lift helicopter rotor blade spars.” 2012. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/15631.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Narayanan Nampy, Sreenivas. “Advanced grid-stiffened composite shells for applications in heavy-lift helicopter rotor blade spars.” 2012. Web. 19 Jan 2021.

Vancouver:

Narayanan Nampy S. Advanced grid-stiffened composite shells for applications in heavy-lift helicopter rotor blade spars. [Internet] [Thesis]. Penn State University; 2012. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/15631.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Narayanan Nampy S. Advanced grid-stiffened composite shells for applications in heavy-lift helicopter rotor blade spars. [Thesis]. Penn State University; 2012. Available from: https://submit-etda.libraries.psu.edu/catalog/15631

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

23. Gungor, Sila. Electric-field-induced Alignment of Carbon Nanofillers in Multifunctional Glass-epoxy Composites.

Degree: 2013, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/19871

► Advancing the methods for structural health monitoring (SHM) of composites and controlling the material properties for adapting to existent SHM methods is important for continuous… (more)

▼ Advancing the methods for structural health monitoring (SHM) of composites and controlling the material properties for adapting to existent SHM methods is important for continuous examination of damage in composites. This investigation aims to address these problems by tailoring the electrical properties of glass-epoxy composites by the addition and electric-field-induced alignment of carbon nanofillers in order to develop a new type of material, which is a suitable candidate for damage detection using electrical resistance method. As carbon nanofillers, short unfunctionalized carbon nanotubes (CNTs) and carbon black (CB) nanoparticles were used due to their low aspect ratio, which is believed to ease their motion between the glass fibers. Short CNTs and CB were dispersed in a bisphenol-A based epoxide diluted with alkyl glycidyl ether by using bath sonication and stirring methods. Short CNT-filled epoxy and CB-filled epoxy composites were manufactured with and without electric-field-induced alignment of nanofillers due to dielectrophoresis. In addition to nanofilled-epoxy composites, random and aligned short CNT-filled and CB-filled glass-epoxy composites were also manufactured by using hand lay-up and vacuum bagging techniques. Significant increases were obtained in the electrical conductivity through the thickness of the composites filled with CB by aligning the CB nanoparticles through the thickness. It was further observed that, for a given concentration of nanofiller, higher electrical conductivities are obtained in aligned CB-filled glass-epoxy composites than in aligned short CNT-filled glass-epoxy composites, which turned the focus of this investigation on CBs rather than CNTs for damage detection studies. A parametric experimental investigation was carried out for CB-filled glass-epoxy composites by using different CB concentrations, applied AC field strengths and frequencies. Studies showed that increasing CB concentration and AC field strength up to a point increases the electrical conductivity through the thickness while imposing minor effects on the in-plane conductivities, whereas frequency does not have a significant effect on the conductivities. With the use of a proper CB concentration, AC field strength and frequency, a material with an anisotropy ratio, defined as the ratio of through-thickness conductivity to in-plane transverse conductivity, equal to 3.3 was achieved for CB-filled unidirectional glass-epoxy composites. This is the first investigation which shows that through thickness conductivity can exceed in-plane transverse conductivity. Finite element analyses were conducted to map the place and the size of damage for four different cases. It was shown that perpendicular electrode configuration is better compared to the parallel electrode configuration and it is possible to detect multiple damage and distinguish different sized damage from each other. A graphic user interface code was created to graphically illustrate the place and the size of the damage by a 3D animation, which permits… Advisors/Committee Members: Charles E Bakis, Dissertation Advisor/Co-Advisor, Charles E Bakis, Committee Chair/Co-Chair, Clifford Jesse Lissenden Iii, Committee Member, Kevin L Koudela, Committee Member, James Hansell Adair, Committee Member.

Subjects/Keywords: composites; carbon nanotubes; carbon black; electrical anisotropy; damage detection; glass fiber reinforced plastics

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APA (6^th Edition):

Gungor, S. (2013). Electric-field-induced Alignment of Carbon Nanofillers in Multifunctional Glass-epoxy Composites. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/19871

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Gungor, Sila. “Electric-field-induced Alignment of Carbon Nanofillers in Multifunctional Glass-epoxy Composites.” 2013. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/19871.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Gungor, Sila. “Electric-field-induced Alignment of Carbon Nanofillers in Multifunctional Glass-epoxy Composites.” 2013. Web. 19 Jan 2021.

Vancouver:

Gungor S. Electric-field-induced Alignment of Carbon Nanofillers in Multifunctional Glass-epoxy Composites. [Internet] [Thesis]. Penn State University; 2013. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/19871.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gungor S. Electric-field-induced Alignment of Carbon Nanofillers in Multifunctional Glass-epoxy Composites. [Thesis]. Penn State University; 2013. Available from: https://submit-etda.libraries.psu.edu/catalog/19871

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

24. Liang, Yue. Ultrasonic Vibration Potential in Structural Health Monitoring for Plate-like Structures .

Degree: 2014, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/20590

► Ultrasonic guided waves and low frequency vibration modal analysis are two useful Nondestructive Evaluation (NDT) and Structural Health Monitoring (SHM) techniques. The guided wave method… (more)

▼ Ultrasonic guided waves and low frequency vibration modal analysis are two useful Nondestructive Evaluation (NDT) and Structural Health Monitoring (SHM) techniques. The guided wave method yields good sensitivity to certain defects by optimally selecting different guided wave loading functions. However, actuators and receivers at some distance apart must be placed in different positions in order to get reasonable coverage in a field inspection, since only the defect close to the wave propagation path can be detected. Therefore, the testing process is not always efficient. In contrast, as a global monitoring method, the vibration-based technique can achieve much faster testing speeds. But this technique has very low sensitivity to small defects due to the low operating frequencies. Taking advantage of both the ultrasonic guided wave and vibration techniques, a novel SHM method ultrasonic vibration is developed in this thesis. Ultrasonic vibration is capable of achieving defect detection sensitivity almost as good as ultrasonic guided waves, while maintaining the efficiency of the traditional low frequency vibration by fixing the actuator location and using only a few receivers to cover the whole structure. In this new method, continuous guided wave energy will be impinged into the structure to make the structure vibrate steadily. The steady state vibration depends on the initial ultrasonic guided wave loading function, and the boundary conditions as well as the structural geometry. It is observed that the steady state vibration can be achieved by employing long cycles of guided wave inputs, say 1500 cycles or so. The structural vibration response relates to the guided wave loading. In order to use ultrasonic vibration for defect detection, it is necessary to study the guided wave sensitivity for defect inspection. Guided wave detection for delaminations in composites is studied in a sample problem. The sample problem demonstrates the significance of selecting the right guided wave loading function in defect detection in order to achieve good results. In ultrasonic vibration, before the structure reaches a steady state, there is a transition process, during which the wave energy is bouncing among the edges. The edge reflection of guided waves was also studied here based on the semi-analytical finite element (SAFE) method and the mode expansion technique. The mode conversions are solved quantitatively when a guided wave hits the boundary at an angle. The relation between steady state vibration and transient guided waves is revealed by the guided-wave-based vibration analysis on a 2-D plane strain model. Applying the partial wave technique, a full field solution was constructed, which includes all the guided wave modes traveling forward and backward. Among those guided wave modes, only a combination set satisfying the boundary conditions can exist in the structures. This set composed of guided waves with relative amplitudes and phases is identified as the natural vibration mode. The forced response of the structure is… Advisors/Committee Members: Joseph Lawrence Rose, Dissertation Advisor/Co-Advisor, Joseph Lawrence Rose, Committee Chair/Co-Chair, Clifford Jesse Lissenden Iii, Committee Member, Bernhard R Tittmann, Committee Member, Qiming Zhang, Committee Member.

Subjects/Keywords: guided waves; ultrasonic vibration; structural health monitoring; phased array; finite element methods

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APA (6^th Edition):

Liang, Y. (2014). Ultrasonic Vibration Potential in Structural Health Monitoring for Plate-like Structures . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/20590

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Liang, Yue. “Ultrasonic Vibration Potential in Structural Health Monitoring for Plate-like Structures .” 2014. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/20590.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Liang, Yue. “Ultrasonic Vibration Potential in Structural Health Monitoring for Plate-like Structures .” 2014. Web. 19 Jan 2021.

Vancouver:

Liang Y. Ultrasonic Vibration Potential in Structural Health Monitoring for Plate-like Structures . [Internet] [Thesis]. Penn State University; 2014. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/20590.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Liang Y. Ultrasonic Vibration Potential in Structural Health Monitoring for Plate-like Structures . [Thesis]. Penn State University; 2014. Available from: https://submit-etda.libraries.psu.edu/catalog/20590

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

25. Guers, Manton John. IN-SITU MONITORING OF REMOTE SPECIMENS USING ULTRASONIC GUIDED WAVES .

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/11445

► There are a wide variety of engineering applications where it can be advantageous to perform real time ultrasonic measurements. In structural health monitoring (SHM) applications… (more)

▼ There are a wide variety of engineering applications where it can be advantageous to perform real time ultrasonic measurements. In structural health monitoring (SHM) applications (aircraft, bridges, etc.), real time data can be used to improve safety and reduce maintenance costs. In other applications (such as carbon-carbon production and ceramic sintering) in-situ ultrasonic measurements can be used to study how a material is affected by different manufacturing conditions. Ultrasonic measurements can also be used in place of convention temperature, pressure, fluid flow, or level sensors. The work presented in this dissertation focused on studying an ultrasonic guided waves based system for performing in-situ measurements on specimens which are commonly used in the accelerated life tests conducted in materials and test reactors (MTRs). Using this system, ultrasonic waves could be sent down a thirty foot long waveguide to a specimen while locating the transducer outside of the hostile environment. Both the theoretical and experimental results demonstrated how individual components of the system influenced the monitoring capabilities. As one example, the in-situ monitoring system was studied for use in measuring the change in length of creep specimens. Successful measurements of creep elongation were demonstrated using a pulse-echo configuration of the in-situ monitoring system. In addition, the temperature dependence of the in-situ creep measurement was also studied. Both theoretical calculations and experiments showed that the temperature dependence of group velocity was approximately linear for the creep specimen geometry. ‘Blister’ specimens having a rectangular cross-section were also considered in this work. Theoretically driven semi-analytical finite element (SAFE) calculations, time-domain finite element calculations, and experimental measurements were performed to investigate guided wave propagation in this specimen. The SAFE calculations, finite element predictions, and experimental results all demonstrated good agreement. In general, the guided wave mode with the fastest group velocity appeared to be the most prominent in both the simulated and experimentally measured waveforms. Several types of defects were considered. Defects can sometimes produce temperature anomalies in the specimen. The models indicated that detection of a defect induced temperature gradient in the rectangular ‘blister’ specimen was possible. In the design and operation of an in-situ monitoring system based on guided ultrasonic waves, the transducer design plays an important roll in the performance of the system. In this work, a magnetostrictive sleeve design was tested as an alternative to a wire-wire joint configuration. Results showed that the sleeve design was effective for generating ultrasonic guided waves in the wire waveguide. In addition, the sleeve design simplifies specimen fabrication, minimizes the amount of magnetostrictive material required, and eliminates the artifacts associated with the… Advisors/Committee Members: Bernhard R Tittmann, Dissertation Advisor/Co-Advisor, Bernhard R Tittmann, Committee Chair/Co-Chair, Joseph Lawrence Rose, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Albert Eliot Segall, Committee Member, Karl Martin Reichard, Committee Member.

Subjects/Keywords: structural health monitoring; remote monitoring; ultrasonic guided wave

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Guers, M. J. (2011). IN-SITU MONITORING OF REMOTE SPECIMENS USING ULTRASONIC GUIDED WAVES . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/11445

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Guers, Manton John. “IN-SITU MONITORING OF REMOTE SPECIMENS USING ULTRASONIC GUIDED WAVES .” 2011. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/11445.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Guers, Manton John. “IN-SITU MONITORING OF REMOTE SPECIMENS USING ULTRASONIC GUIDED WAVES .” 2011. Web. 19 Jan 2021.

Vancouver:

Guers MJ. IN-SITU MONITORING OF REMOTE SPECIMENS USING ULTRASONIC GUIDED WAVES . [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/11445.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Guers MJ. IN-SITU MONITORING OF REMOTE SPECIMENS USING ULTRASONIC GUIDED WAVES . [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/11445

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

26. Emerson, Ryan Paul. Viscoelastic Flywheel Rotors: Modelling and Measurement.

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/6018

► An investigation of the creep behavior of polymer composites was performed in developing a closed-form structural model of advanced polymer matrix composite (PMC) flywheels. The… (more)

▼ An investigation of the creep behavior of polymer composites was performed in developing a closed-form structural model of advanced polymer matrix composite (PMC) flywheels. The model is of the linear-viscoelastic type, and is applicable to the design and analysis of multiple concentric-ring PMC flywheel rotors in a state of plane-stress. This model incorporates techniques for approximating the quasi-static response to general time-varying loads including rotation, temperature change, and interference-fits between adjacent rings. The model accounts for the effect of temperature on the material response using the time-temperature superposition principle. The quasi-elastic technique was used to discretize the linear viscoelastic constitutive law, allowing the derivation of approximate solutions for the stress and strain field variables. Experimental work performed in support of this model includes thermo-viscoelastic characterization of a unidirectional glass/epoxy composite. Experimental measurement of pressure loss and strain redistribution in interference-fitted filament-wound glass and carbon fiber PMC ring pairs was performed using moir¨¦ interferometry and electrical resistance strain gages. Good agreement between the data and the plane-stress model at locations away from the ring interfaces was obtained. With the purpose of making creep measurements through the radial thickness of high-speed rotating flywheels, a new optical displacement measurement method was developed. Notable improvements over a known related method include greater displacement sensitivity, the ability to measure rigid body vibrations and separate the associated vibration-induced displacement from the strain-induced displacement, and the ability to compensate for sensor drift during flywheel operation. Displacement measurements made on an aluminum rotor operating at a maximum speed of 16 krpm (255 m/s at the point of measurement) were made with 1-micrometer accuracy. At this speed, hoop strains were found to be within 40 to 125 microstrain of theoretical predictions. Relative to the theoretical hoop strains, the measured hoop strains differed by 5-6% at 16 krpm. Advisors/Committee Members: Heath F Hofmann, Committee Member, Charles E Bakis, Committee Chair/Co-Chair, Clifford Jesse Lissenden Iii, Committee Member, Renata S Engel, Committee Member, George A Lesieutre, Committee Member.

Subjects/Keywords: viscoelastic; strain measurement; rotor; Composite; flywheel

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APA (6^th Edition):

Emerson, R. P. (2008). Viscoelastic Flywheel Rotors: Modelling and Measurement. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/6018

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Emerson, Ryan Paul. “Viscoelastic Flywheel Rotors: Modelling and Measurement.” 2008. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/6018.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Emerson, Ryan Paul. “Viscoelastic Flywheel Rotors: Modelling and Measurement.” 2008. Web. 19 Jan 2021.

Vancouver:

Emerson RP. Viscoelastic Flywheel Rotors: Modelling and Measurement. [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/6018.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Emerson RP. Viscoelastic Flywheel Rotors: Modelling and Measurement. [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/6018

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

27. Mu, Jing. GUIDED WAVE PROPAGATION AND FOCUSING IN VISCOELASTIC MULTILAYERED HOLLOW CYLINDERS.

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/8569

► The understanding of guided wave propagation characteristics, source influence, and mode control in hollow cylindrical structures is crucial for guided wave nondestructive evaluation of pipelines.… (more)

▼ The understanding of guided wave propagation characteristics, source influence, and mode control in hollow cylindrical structures is crucial for guided wave nondestructive evaluation of pipelines. This thesis reviews the previous guided wave theories on single elastic hollow cylinders and develops their application in pipe imaging and defect circumferential sizing. Motivated by the fact that most pipelines are coated with viscoelastic materials, the thesis establishes a systematic procedure targeting on solving the problem of guided wave propagation, source influence, as well as focusing in multilayered hollow cylindrical structures containing viscoelastic materials. A suitable Semi-Analytical Finite Element (SAFE) formulation is first developed to solve the dispersion curves (including axisymmetric and non-axisymmetric guided wave modes) and wave structures in viscoelastic multilayered hollow cylinders. Stress distributions across pipe thickness and the cross sectional deformations for different guided wave modes are illustrated to help interpret modal behavior. A general orthogonality relation applicable for both single-layered and multilayered, elastic and viscoelastic hollow cylindrical structures is then derived. This orthogonality relation is subsequently implemented to sort guided wave modes obtained from the SAFE calculation. Numerical results show that all the guided wave modes are successfully sorted. The mode sorting enables us to trace the modal behavior evolving with frequency for any guided wave mode. It also provides the basis for solving source influence in viscoelastic multilayered hollow cylinders. The guided wave field generated by a specific source loading on a viscoelastic multilayered hollow cylinder is tackled by the employment of the Normal Mode Expansion (NME) technique. Different from the source influence in an elastic single-layered hollow cylinder, the displacement and stress continuity condition must be incorporated in deriving the amplitude factors of the generated normal modes. The displacement angular profiles of a certain loading are consequently obtained by the superposition of all the excited modes with appropriate amplitudes. After the angular profiles are obtained, the focusing deconvolution algorithm is incorporated to provide the amplitude factors and time delays for guided wave phased array focusing in viscoelastic multilayered hollow cylinders. To visualize the focusing in a viscoelastic multilayered hollow cylinder, a viscoelastic coated pipe is taken as an example to build in ABAQUS. Finite Element Modeling (FEM) of guided wave focusing in the coated pipe is conducted. The FEM results agree well (5% difference in focal amplitudes) with the theoretical calculations. Finally, guided wave synthetic focusing experiments are designed to verify the theories. The guided wave synthetic focusing methodology and experiment procedure are introduced in detail. Data are taken on a steel pipe coated with 0.4-mm bitumastic 50. Four channel guided wave synthetic focusing is performed in… Advisors/Committee Members: Joseph Lawrence Rose, Committee Chair/Co-Chair, Bernhard R Tittmann, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Virendra Puri, Committee Member, Samia A Suliman, Committee Member.

Subjects/Keywords: Guided wave; hollow cylinder; focusing; viscoelastic

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Mu, J. (2008). GUIDED WAVE PROPAGATION AND FOCUSING IN VISCOELASTIC MULTILAYERED HOLLOW CYLINDERS. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/8569

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Mu, Jing. “GUIDED WAVE PROPAGATION AND FOCUSING IN VISCOELASTIC MULTILAYERED HOLLOW CYLINDERS.” 2008. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/8569.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Mu, Jing. “GUIDED WAVE PROPAGATION AND FOCUSING IN VISCOELASTIC MULTILAYERED HOLLOW CYLINDERS.” 2008. Web. 19 Jan 2021.

Vancouver:

Mu J. GUIDED WAVE PROPAGATION AND FOCUSING IN VISCOELASTIC MULTILAYERED HOLLOW CYLINDERS. [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/8569.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Mu J. GUIDED WAVE PROPAGATION AND FOCUSING IN VISCOELASTIC MULTILAYERED HOLLOW CYLINDERS. [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/8569

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

28. Zhang, Li. GUIDED WAVE FOCUSING POTENTIAL IN HOLLOW CYLINDERS .

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/6847

► Ultrasonic non-destructive evaluation is generally used in industry because of its excellent defect detection potential. The ultrasonic waves propagating in a bounded waveguide are called… (more)

▼ Ultrasonic non-destructive evaluation is generally used in industry because of its excellent defect detection potential. The ultrasonic waves propagating in a bounded waveguide are called guided waves. Long range ultrasonic guided waves have intrigued investigators for years because of an ability to test structures over a long distance from a single sensor position. Guided waves have much more complex wave behavior than bulk waves in infinite media. Plane-strain guided waves in a single layer plate with traction free boundaries are Lamb waves. The Lamb type guided waves in hollow cylinders spread out and wrap around the circumference when propagating in an axial direction. Therefore, except for the guided waves with axisymmetric energy distributions in a tube, there are an infinite number of non-axisymmetric wave modes called flexural modes that have similar particle behavior as the axisymmetric mode in the same group. Focusing at a certain point in a hollow cylinder is implemented by utilizing the non-axisymmetric energy distributions of flexural wave modes. There are two types of focusing in pipes: natural focusing and phased array focusing. When a partially loaded excitation is used to generate guided waves in cylindrical shells, the excited flexural modes lead to ultrasonic energy naturally focused at certain positions. This special natural focusing phenomenon can be used to improve guided wave inspection results in hollow cylinders. By applying input time delays and amplitudes for a multi-channel ultrasonic signal generation system, one can focus the guided waves at a pre-selected position. The input parameters of the ultrasonic phased array are calculated by implementing a deconvolution computation of the displacement angular profiles excited by one excitation channel. Because the angular profiles of the circumferential displacement distributions in a hollow cylinder are decided by the excitation sources, focusing results are strongly affected by the excitation conditions. A source influence for focusing potential in pipes must be considered. Research shows that excitation focusing potential in hollow cylinders depends highly on the frequencies and sizes of the excitation transducers. An infinitely long transducer along the axis only generates axisymmetric guided waves, although a short axial transducer length has little influence on the focusing results. A transducer with a small circumferential length usually leads to drastic variations of energy distributions in the circumferential direction. These sharp angular profiles could lead to a failure of the phased array focusing technique. If a low frequency guided wave group propagates in a pipe with a small diameter, the flexural modes may be cut-off or have much different velocities from the axisymmetric mode. A single axisymmetric mode can never achieve focusing. Hence, contour charts of focusing potential at different frequencies and with various circumferential excitation lengths are used as directories of the focusing procedures. Because the geometry… Advisors/Committee Members: Joseph Lawrence Rose, Committee Chair/Co-Chair, Bernhard R Tittmann, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Nicholas John Salamon, Committee Member, Edward C Smith, Committee Member.

Subjects/Keywords: pipe inspecton; Guided wave; phased array; focusing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhang, L. (2008). GUIDED WAVE FOCUSING POTENTIAL IN HOLLOW CYLINDERS . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/6847

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Zhang, Li. “GUIDED WAVE FOCUSING POTENTIAL IN HOLLOW CYLINDERS .” 2008. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/6847.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Zhang, Li. “GUIDED WAVE FOCUSING POTENTIAL IN HOLLOW CYLINDERS .” 2008. Web. 19 Jan 2021.

Vancouver:

Zhang L. GUIDED WAVE FOCUSING POTENTIAL IN HOLLOW CYLINDERS . [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/6847.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhang L. GUIDED WAVE FOCUSING POTENTIAL IN HOLLOW CYLINDERS . [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/6847

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

29. Zhang, Rui. NUMERICAL SIMULATION OF SOLID-STATE SINTERING OF METAL POWDER COMPACT DOMINATED BY GRAIN BOUNDARY DIFFUSION.

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/6871

► The research effort is oriented towards the modeling of metal powder sintering to accurately predict the densification and distortion of a sintered part, which is… (more)

▼ The research effort is oriented towards the modeling of metal powder sintering to accurately predict the densification and distortion of a sintered part, which is mainly due to the differential shrinkage of a green compact. This research focuses on the study of the simulation of the sintering process that is dominated by grain boundary diffusion, which is recognized as one of the dominating sintering mechanisms. Specifically, a viscoelasticity model that accounts for the microstructural grain growth has been developed to simulate the thermal induced creep deformation in sintering. Sintering stress is treated as an equivalent hydrostatic pressure that links the microscale evolution to the macroscale deformation. To support that linkage, a grain boundary counting procedure has been modified to quantify the grain size distribution. The material resistance of viscous flow is included in the model as a thermally activated process using an Arrhenius-type temperature relation to represent the apparent viscosity. The finite element method is used to implement the simulation. Results of the compaction simulation such as shape change, residual stress and density distribution data are transferred into the sintering simulation as initial conditions. Since no extra heat source is generated during sintering, the thermal analysis is independent of the creep analysis so that an uncoupled heat transfer analysis yields time-dependent temperature fields that are used to drive the sintering simulation. The simulation is performed in ABAQUS, and an in-house FEM code (SinSolver) is used as a supporting tool and verification. Stainless steel 316L is chosen in this research due to its wide range of industrial applications and representative sintering mechanisms. Comparison and analysis on the simulation versus the dilatometry experiments of shrinkage are consistently close and improve the understanding of when and how the sintering mechanisms act in a sintering cycle. Advisors/Committee Members: Renata S Engel, Committee Chair/Co-Chair, Randall M German, Committee Member, Nicholas John Salamon, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Panagiotis Michaleris, Committee Member.

Subjects/Keywords: sintering simulation; finite element method; viscoelasticity; stainless steel 316L; metallography

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhang, R. (2008). NUMERICAL SIMULATION OF SOLID-STATE SINTERING OF METAL POWDER COMPACT DOMINATED BY GRAIN BOUNDARY DIFFUSION. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/6871

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Zhang, Rui. “NUMERICAL SIMULATION OF SOLID-STATE SINTERING OF METAL POWDER COMPACT DOMINATED BY GRAIN BOUNDARY DIFFUSION.” 2008. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/6871.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Zhang, Rui. “NUMERICAL SIMULATION OF SOLID-STATE SINTERING OF METAL POWDER COMPACT DOMINATED BY GRAIN BOUNDARY DIFFUSION.” 2008. Web. 19 Jan 2021.

Vancouver:

Zhang R. NUMERICAL SIMULATION OF SOLID-STATE SINTERING OF METAL POWDER COMPACT DOMINATED BY GRAIN BOUNDARY DIFFUSION. [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/6871.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhang R. NUMERICAL SIMULATION OF SOLID-STATE SINTERING OF METAL POWDER COMPACT DOMINATED BY GRAIN BOUNDARY DIFFUSION. [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/6871

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

30. Luo, Wei. ULTRASONIC GUIDED WAVES AND WAVE SCATTERING IN VISCOELASTIC COATED HOLLOW CYLINDERS .

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/6860

► Over a million miles of piping is used in the USA in almost every industry that calls for a large scale transportation and distribution of… (more)

▼ Over a million miles of piping is used in the USA in almost every industry that calls for a large scale transportation and distribution of energy or product, like natural gas, oil, water, etc. Pipeline safety is crucial in that defective pipelines can lead to catastrophic failure, property damage and high replacement costs. To preserve the integrity of these pipelines, viscoelastic coatings are widely used on the pipes. However, pipe aging and exposure to a variety of changing environmental conditions reduces the protection effectiveness consequently leading to the occurrence of defects. An effective non-destructive evaluation (NDE) method is needed to provide the current pipeline status to the pipeline operators for any further decisions on repair or replacement actions. Ultrasonic guided waves, with a long range propagation capability, are becoming useful in new solutions for pipeline inspection. It is much more efficient and economical than other commonly used NDE methods like point-by-point bulk waves and magnetic flux leakage. Long pipes can be inspected from a simple sensor position. Among the two methods for the long rang guided wave pipeline inspection, almost decade old axisymmetric waves and recently developed phased array focusing, the latter presenting itself with a tremendous improvement in terms of penetration power, detection sensitivity, and inspection distance. However, guided wave inspection potential in coated pipe has not yet been studied in detail. Many important questions need answers, like focusing feasibility in coated pipes, wave scattering possibilities study for effective inspection of 3-D defects, and quantitative evaluation of inspection distances under various coating conditions. Since a large percentage of the pipelines are covered with viscoelastic coatings, a thorough study of guided waves in viscoelastically coated pipes is strongly called for. In this work, guided wave propagation, scattering and focusing in coated pipes are studied comprehensively for the first time with numerical, analytical and experimental methods. A three-dimensional finite element tool utilizing ABAQUS/Explicit was developed for quantitatively and systematically modeling guided wave behavior in pipes with different viscoelastic materials. A whole process, from experimental measurement to theoretical modeling has been established, including in-situ coating property measurement, transformation of measured properties to model inputs, specific wave mode generation, and output data processing and analysis. With the help of this new powerful modeling tool, it is very exciting to find that guided waves can still be focused very well in a coated pipe for the frequency studied, although there is an amplitude loss due to the viscoelastic nature of the coating materials. The quantitative evaluation of the energy increment and the subsequent inspection distance increment from axisymmetric loading and focusing was studied. Wave scattering from planar and corrosion like defects were investigated under both… Advisors/Committee Members: Joseph Lawrence Rose, Committee Chair/Co-Chair, Bernhard R Tittmann, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Eduard S Ventsel, Committee Member, Qiming Zhang, Committee Member.

Subjects/Keywords: acoustics; wave mechanics; guided wave; finite element analysis; phased array focusing; ultrasonics; viscoelasticity; wave scattering; nondestructive evaluation

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Luo, W. (2008). ULTRASONIC GUIDED WAVES AND WAVE SCATTERING IN VISCOELASTIC COATED HOLLOW CYLINDERS . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/6860

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Luo, Wei. “ULTRASONIC GUIDED WAVES AND WAVE SCATTERING IN VISCOELASTIC COATED HOLLOW CYLINDERS .” 2008. Thesis, Penn State University. Accessed January 19, 2021. https://submit-etda.libraries.psu.edu/catalog/6860.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Luo, Wei. “ULTRASONIC GUIDED WAVES AND WAVE SCATTERING IN VISCOELASTIC COATED HOLLOW CYLINDERS .” 2008. Web. 19 Jan 2021.

Vancouver:

Luo W. ULTRASONIC GUIDED WAVES AND WAVE SCATTERING IN VISCOELASTIC COATED HOLLOW CYLINDERS . [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Jan 19]. Available from: https://submit-etda.libraries.psu.edu/catalog/6860.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Luo W. ULTRASONIC GUIDED WAVES AND WAVE SCATTERING IN VISCOELASTIC COATED HOLLOW CYLINDERS . [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/6860

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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