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University of Illinois – Chicago
1.
Houshiar, Majid.
Direct Design Method and Design Diagram For Reinforced Concrete Columns and Shear walls.
Degree: 2016, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/21554 
► Design of reinforced concrete columns and shear walls is an iterative process. Whether done manually or computer aided, the capacity of an assumed section is…
(more)
▼ Design of reinforced concrete columns and shear walls is an iterative process. Whether done manually or computer aided, the capacity of an assumed section is checked using interaction diagrams and the procedure continues until a satisfactory section is found. This research introduces two new concepts for design of reinforced concrete columns, “Direct Design” method and “Design Diagram”. Direct design method is an analytical approach by which the required area of reinforcement is determined directly without using an interaction diagram. In this approach, location of the neutral axis and required area of reinforcement is found directly by solving a non-linear system of equations. Direct design method provides an optimum solution for a reinforced concrete section; the capacity of the section is exactly equal to the applied load and moments. For each column or shear wall, there are many optimum sections with different sizes and bar arrangements. A design diagram shows all possible optimum sections for a column or shear wall. This study provides an algorithm and a computer program for making design diagrams. Having a design diagram, designers do not need to go through a trial-and-error procedure to find an acceptable section; they can simply pick up an optimum section that best fits their requirements from the design diagram.
Advisors/Committee Members: Mahamid, Mustafa (advisor), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Ozevin, Didem (chair).
Subjects/Keywords: Direct Design; Design Diagram
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APA (6th Edition):
Houshiar, M. (2016). Direct Design Method and Design Diagram For Reinforced Concrete Columns and Shear walls. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/21554
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Houshiar, Majid. “Direct Design Method and Design Diagram For Reinforced Concrete Columns and Shear walls.” 2016. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/21554.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Houshiar, Majid. “Direct Design Method and Design Diagram For Reinforced Concrete Columns and Shear walls.” 2016. Web. 21 Jan 2021.
Vancouver:
Houshiar M. Direct Design Method and Design Diagram For Reinforced Concrete Columns and Shear walls. [Internet] [Thesis]. University of Illinois – Chicago; 2016. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/21554.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Houshiar M. Direct Design Method and Design Diagram For Reinforced Concrete Columns and Shear walls. [Thesis]. University of Illinois – Chicago; 2016. Available from: http://hdl.handle.net/10027/21554
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
2.
Newton, Ashley.
Transient Liquid Phase Bonding of High Strength Aluminum Alloy.
Degree: 2017, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/22087
► The focus of the research and experiments in this thesis is Transient Liquid Phase (TLP) Bonding of high strength aluminum alloy using pure zinc as…
(more)
▼ The focus of the research and experiments in this thesis is Transient Liquid Phase (TLP) Bonding of high strength aluminum alloy using pure zinc as an interlayer material. The primary goal of this research was to determine if high strength TLP bonding of aluminum alloy 7075, the most common alloy used in aerospace structures, could be achieved, and if so, without causing significant loss of strength to the aluminum alloy. In order to do this, many experiments were conducted to determine the appropriate bonding parameters.
Preliminary experiments involving various heat treatments of aluminum 7075 samples were conducted to establish an acceptable range of bonding temperatures. Before and after heat treatment, each sample was tested for ultrasonic pulse velocities and hardness values. These values were compared and an initial bonding temperature was determined.
Several sets of bonding experiments were performed applying variations of surface treatment, bonding temperature, bonding duration, and interlayer material. After bonding, each sample was subjected to multiple types of analysis to assess the quality of the bond. Samples were visually inspected, scanned using a high definition Scanning Acoustic Microscope (SAM), tested for shear strength using a Mechanical Testing System (MTS), and inspected with an optical metallographic microscope. Results of each set of bonds determined the variations applied to the following set. After many experimental bonds were tested, conclusions were drawn to establish optimal bonding temperature and duration. Shear strength results were analyzed considering structural aspects of the test specimens and limitations of the MTS. Future research and experiments that could be done to further understanding of this subject matter was then identified.
Advisors/Committee Members: Ozevin , Didem (advisor), Indacochea, Ernesto (committee member), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Ozevin , Didem (chair).
Subjects/Keywords: Transient Liquid Phase Bonding; High-Strength Aluminum Alloy
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APA (6th Edition):
Newton, A. (2017). Transient Liquid Phase Bonding of High Strength Aluminum Alloy. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/22087
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Newton, Ashley. “Transient Liquid Phase Bonding of High Strength Aluminum Alloy.” 2017. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/22087.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Newton, Ashley. “Transient Liquid Phase Bonding of High Strength Aluminum Alloy.” 2017. Web. 21 Jan 2021.
Vancouver:
Newton A. Transient Liquid Phase Bonding of High Strength Aluminum Alloy. [Internet] [Thesis]. University of Illinois – Chicago; 2017. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/22087.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Newton A. Transient Liquid Phase Bonding of High Strength Aluminum Alloy. [Thesis]. University of Illinois – Chicago; 2017. Available from: http://hdl.handle.net/10027/22087
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
3.
Kamali Zonouzi, Negar.
Enriched Numerical Method for Wave Propagation and Assessing Material Damage Using Nonlinear Acoustics.
Degree: 2018, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/23285
► When ultrasonic waves propagate through media, the material nonlinearity triggers the generation of higher-order harmonics (HOH), the frequency of which are integer multiples of the…
(more)
▼ When ultrasonic waves propagate through media, the material nonlinearity triggers the generation of higher-order harmonics (HOH), the frequency of which are integer multiples of the excitation frequency. In nonlinear ultrasonic techniques, the HOH can be measured and related to material damage. In order to enhance the measurement of HOH, wavelet-based signal processing algorithms are introduced to obtain the second harmonic-based and third harmonic-based acoustic nonlinearity parameters. The HOH generation, however, can be triggered by many sources. Finite element numerical modeling with mesoscale heterogeneities explicitly modeled for the nonlinear wave propagation is presented to understand HOH generation due to heterogeneity and non-uniform deformations. Numerical studies indicate that non-uniform variations in different length scales affect the generation of both the second and the third-harmonics and that both second- and third-harmonics acoustic nonlinearity parameters grow with the increase of plastic strain level. However, the third-harmonics acoustic nonlinearity parameter is more sensitive when micro-, meso- and macrostructural variations are considered. The numerical results and predictions are validated with nonlinear ultrasonic experiments and microscale imaging, including X-ray Diffraction (XRD) scanning.
Since the frequency of ultrasonic signals are generally high, excessively fine mesh is required to obtain desired solution accuracy for HOH. Therefore, second part of this thesis is devoted to the development of enhanced numerical methods to effectively solve for linear and nonlinear wave propagation problems. Two specific enriched methods are developed: enriched Finite Element (FE) and Harmonic-Enriched Reproducing Kernel Particle Method (RKPM). In enriched FE, standard FE shape functions are enriched with the characteristic solution of the wave propagation problems under the framework of partition of unity. Additional degrees of freedom are introduced in the discrete system for the enrichment functions. To further reduce the computational cost and benefit from the advantages of element free methods, a harmonic-enriched RKPM (H-RKPM) is newly developed. The desired harmonic functions are introduced as the basis function for construction of reproducing kernel and the reproducing condition is enforced. This approach allows the characteristic function to be embedded in the approximation without adding more degrees of freedom. As a result, the high frequency wave problem can be solved using less nodes, enhancing both computational efficiency and accuracy. The methods are verified with benchmark problems and their performance is compared with other conventional methods.
Advisors/Committee Members: Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (advisor),
Foster, Craig (committee member),
Ozevin, Didem (committee member),
Awanou, Gerard (committee member),
Indacochea, Ernesto (committee member),
Wei%22%29&pagesize-30">Chi, Sheng-Wei (chair).
Subjects/Keywords: Computational mechanics; nonlinear ultrasonics; acoustics; enriched finite elements; finite elements; simulations; wave propagation
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APA (6th Edition):
Kamali Zonouzi, N. (2018). Enriched Numerical Method for Wave Propagation and Assessing Material Damage Using Nonlinear Acoustics. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/23285
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Kamali Zonouzi, Negar. “Enriched Numerical Method for Wave Propagation and Assessing Material Damage Using Nonlinear Acoustics.” 2018. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/23285.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Kamali Zonouzi, Negar. “Enriched Numerical Method for Wave Propagation and Assessing Material Damage Using Nonlinear Acoustics.” 2018. Web. 21 Jan 2021.
Vancouver:
Kamali Zonouzi N. Enriched Numerical Method for Wave Propagation and Assessing Material Damage Using Nonlinear Acoustics. [Internet] [Thesis]. University of Illinois – Chicago; 2018. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/23285.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Kamali Zonouzi N. Enriched Numerical Method for Wave Propagation and Assessing Material Damage Using Nonlinear Acoustics. [Thesis]. University of Illinois – Chicago; 2018. Available from: http://hdl.handle.net/10027/23285
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
4.
Siriaksorn, Thanakorn.
Meshfree Methods for Geotechnical Disaster Simulation and Prediction.
Degree: 2016, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/21622
► This thesis presents meshfree frameworks based on the semi-Lagrangian Reproducing Kernel (RK) approximation to effectively handle extreme geotechnical events within one mathematical framework. The semi-Lagrangian…
(more)
▼ This thesis presents meshfree frameworks based on the semi-Lagrangian Reproducing Kernel (RK) approximation to effectively handle extreme geotechnical events within one mathematical framework. The semi-Lagrangian RK approximation combines advantages of the Eulerian and Lagrangian formulations, that is, state variables follow material points while the approximation function is updated in the current configuration to allow extreme deformation and material separation. The approximation is extended to the u-p (displacement-pressure) formulation based on Biot's theory for considering poromechanics of geomaterials. Drucker-Prager plasticity with a single-parameter damage model is also employed to properly represent the behavior of the solid phase of geomaterials. Additionally, variationally consistent stabilized nodal integration schemes and kernel contact algorithms are introduced in the u-p semi-Lagrangian RK framework to enhance accuracy and stability of solutions using the Galerkin formulation and to naturally model arbitrary contacts. Detailed studies of the temporal stability of the frameworks are performed using the von Neumann method to provide a guideline of time step selection when explicit time integration schemes are adopted. The robustness and effectiveness of the proposed u-p semi-Lagrangian RK formulation is verified with FEM solutions in several slope stability analyses. The run-out simulation capability of the presented method is also validated with experimental data and actual data from a landslide site. The proposed framework can be applied to study other geotechnical events under extreme conditions, which is demonstrated in simulating the penetration process of a projectile penetrating into the soil.
Additionally, the strong form collocation method with the RK approximation is introduced to study the poromechanics of geomaterials, as an alternative approach. The governing equations are directly solved in the strong formulation with the point collocation method, in which the domain integration is not required in contrast to the Galerkin weak formulation. The effectiveness of the method is studied and demonstrated in hyperelasticity, elastodynamics, and poroelasticity problems.
Advisors/Committee Members: Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (advisor),
Foster, Craig D. (committee member),
Ozevin, Didem (committee member),
Karpov, Eduard (committee member),
Shabana, Ahmed (committee member),
Wei%22%29&pagesize-30">Chi, Sheng-Wei (chair).
Subjects/Keywords: meshfree methods; landslide simulations
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APA (6th Edition):
Siriaksorn, T. (2016). Meshfree Methods for Geotechnical Disaster Simulation and Prediction. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/21622
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Siriaksorn, Thanakorn. “Meshfree Methods for Geotechnical Disaster Simulation and Prediction.” 2016. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/21622.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Siriaksorn, Thanakorn. “Meshfree Methods for Geotechnical Disaster Simulation and Prediction.” 2016. Web. 21 Jan 2021.
Vancouver:
Siriaksorn T. Meshfree Methods for Geotechnical Disaster Simulation and Prediction. [Internet] [Thesis]. University of Illinois – Chicago; 2016. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/21622.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Siriaksorn T. Meshfree Methods for Geotechnical Disaster Simulation and Prediction. [Thesis]. University of Illinois – Chicago; 2016. Available from: http://hdl.handle.net/10027/21622
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
5.
Mahdav, Ashkan.
Meshfree Methods for Fracture and High-Velocity Impact Simulation.
Degree: 2019, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/23757
► The study of projectile penetration has a long history with a great military research interest for various applications such as projectile’s design to maximize depth…
(more)
▼ The study of projectile penetration has a long history with a great military research interest
for various applications such as projectile’s design to maximize depth of penetration into different materials, or penetration depth prediction for munitions removal for military training sites. The nature of the problem involves complex physics and mechanics, leading to extremely large deformations, high velocity penetration, and highly fragmented configurations, which in turn posts immense challenges in computational simulations. The aims of this study is to develop computational tools, addressing challenges at micro- and macro-scales, to simulate and study mechanisms of projectile penetration into soils.
Within a hierarchical multiscale framework, a microscale model accounting micro defeats and their evolution can be simulated in detail in order to develop physically based constitutive models for geomaterials. However, simulating an excessive amount of defeats and how they propagate, branch, and nuclear, remains a big challenge in computation. The phase-field variational approaches have gained considerable amount of interest to address challenges abovementioned. However, phase-field becomes a computationally expensive method when narrow-width crack with a small value for length-scale parameter is required, which demands an extremely fine mesh close to the crack initiation location and on its propagation path. Moreover, Galerkin methods require quadrature rule for numerical integration which leads to either integration inaccuracy and instability or excessively high computational cost. To overcome domain integration issues and mesh-size dependency of the phase-field approach, two new methods are introduced within the Reproducing Kernel (RK) collocation method. A high-order gradient reproducing kernel collocation method (HGRKCM) is introduced for solving higher order phase-field formulation, such as the fourth-order formulation which increases the regularity of the phase-field solution. The method provides stable and accurate solutions by solving the determined system of equations and gradient derivatives of RK shape functions, which boost the computational efficiency compared to regular RK collocation methods. Besides, a Harmonic RK (HRK) method is introduced to address the mesh-decency of the phase-field problem. The method provides exact approximation for the phase-field solution up to machine limit with considerably coarser nodal distant size compared to other methods. Harmonic-enriched RK in the HGRKCM framework provide a robust method for solving the phase-field problem in term of both accuracy and efficiency.
To simulate the penetration process at the macroscale, a two-field (u - p) formulation based on the Biot theory has been developed and implemented under the semi-Lagrangian RK framework, where displacement and pressure fields are independently approximated by the semi-Lagrangian RK shape functions. A Drucker-Prager type constitutive model including a one-parameter damage model is employed to simulate the…
Advisors/Committee Members: Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (advisor),
Foster, Craig (committee member),
Ozevin, Didem (committee member),
Karpov, Eduard (committee member),
Shabana, Ahmed (committee member),
Wei%22%29&pagesize-30">Chi, Sheng-Wei (chair).
Subjects/Keywords: Meshfree methods; Reproducing Kernel Collocation; Fracture; Phase-field model; Semi-Lagrangian Reproducing Kernel; Penetration; High-Velocity Impact
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APA ·
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Export
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APA (6th Edition):
Mahdav, A. (2019). Meshfree Methods for Fracture and High-Velocity Impact Simulation. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/23757
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Mahdav, Ashkan. “Meshfree Methods for Fracture and High-Velocity Impact Simulation.” 2019. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/23757.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Mahdav, Ashkan. “Meshfree Methods for Fracture and High-Velocity Impact Simulation.” 2019. Web. 21 Jan 2021.
Vancouver:
Mahdav A. Meshfree Methods for Fracture and High-Velocity Impact Simulation. [Internet] [Thesis]. University of Illinois – Chicago; 2019. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/23757.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Mahdav A. Meshfree Methods for Fracture and High-Velocity Impact Simulation. [Thesis]. University of Illinois – Chicago; 2019. Available from: http://hdl.handle.net/10027/23757
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
6.
Saboonchi, Hossain.
Design and Characterization of the MEMS Sensor Fusion for Real Time Damage Detection in Structures.
Degree: 2015, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/19387
► Micro-electro-mechanical systems (MEMS) have diverse manufacturing capabilities to design and manufacture various sensing elements in order to monitor various mechanical behaviors in structures. In this…
(more)
▼ Micro-electro-mechanical systems (MEMS) have diverse manufacturing capabilities to design and manufacture various sensing elements in order to monitor various mechanical behaviors in structures. In this study, capacitive acoustic emission sensors are integrated with piezoresistive strain sensors on a small footprint device. The integrated sensing allows redundant data measurement from a given point and intelligent data collection strategy in order to increase the reliability of Structural Health Monitoring (SHM) methods. The acoustic emission (AE) sensors are designed with the principle of capacitance change under dynamic excitation, and tuned to the range of 60 kHz to 150 kHz via changing spring and mass geometry. The MetalMUMPs (Multi-User-MEMS-Processes) are implemented to manufacture the sensors on a 1 cm x 1 cm device area. The experimental characterization includes capacitance and
impedance measurement, and mechanical simulation experiments including laser, ball impact
and pencil lead break for the comparison with conventional piezoelectric sensors. The MEMS strain sensors are designed with the principle of piezoresistivity property of polysilicon, which have higher gauge factor as compared to conventional metal gauges. For the design of strain sensors, trenching concept is implemented to increase the strain transfer. Three strain sensors are placed in horizontal, vertical and angled directions to extract the principle strains. The influences of the sensor position on the silicon substrate and the trenching to the strain transfer from structure under loading to polysilicon layer are numerically demonstrated, and experimentally validated. The characterization experiments include monotonic, cyclic and fatigue mechanical loading, and thermal loading.
Combining acoustic emission and strain sensors on the same package can tackle several limitations of SHM methods such as the need of redundant measurement to increase the reliability and defining idle/active mode of acoustic emission sensor using strain sensor to reduce the power consumption, and enabling the integration of the energy harvesting devices. The concurrent performance of MEMS strain sensors and acoustic emission sensors is tested under fatigue loading of two notched aluminum specimens. The strain sensor strengthens the interpretation of complex acoustic emission data via monitoring the driving force and allowing on-chip data filtering in order to process the data recorded from high stress levels.
Advisors/Committee Members: Ozevin, Didem (advisor), Ansari, Farhad (committee member), Karpov, Eduard (committee member), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Saggere, Laxman (committee member).
Subjects/Keywords: Micro-electro-mechanical system (MEMS); Structual Health Monitoring; Non-destructive evaluation (NDE); Acoustic Emission (AE); strain; sensor
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APA ·
Chicago ·
MLA ·
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Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Saboonchi, H. (2015). Design and Characterization of the MEMS Sensor Fusion for Real Time Damage Detection in Structures. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/19387
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Saboonchi, Hossain. “Design and Characterization of the MEMS Sensor Fusion for Real Time Damage Detection in Structures.” 2015. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/19387.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Saboonchi, Hossain. “Design and Characterization of the MEMS Sensor Fusion for Real Time Damage Detection in Structures.” 2015. Web. 21 Jan 2021.
Vancouver:
Saboonchi H. Design and Characterization of the MEMS Sensor Fusion for Real Time Damage Detection in Structures. [Internet] [Thesis]. University of Illinois – Chicago; 2015. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/19387.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Saboonchi H. Design and Characterization of the MEMS Sensor Fusion for Real Time Damage Detection in Structures. [Thesis]. University of Illinois – Chicago; 2015. Available from: http://hdl.handle.net/10027/19387
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
7.
Wallin, Michael S.
Fully Coupled Analysis of Large Scale Tracked Vehicle Systems with Flexible Link Chains.
Degree: 2016, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/21176
► This thesis examines multiple multibody dynamic formulations and their effects in the large displacement analysis of flexible bodies. The second chapter will examine the effect…
(more)
▼ This thesis examines multiple multibody dynamic formulations and their effects in the large displacement analysis of flexible bodies. The second chapter will examine the effect of using independent finite rotation fields in the large displacement analysis of flexible beams first formulated 30 years ago. This finite rotation description is at the core of the large rotation vector formulation (LRVF), which has been used in the dynamic analysis of bodies experiencing large rotation and deformation. The LRVF employs two independently interpolated meshes for describing the flexible body dynamics: the position mesh and the rotation mesh. The use of these two geometrically independent meshes can lead to coordinate and geometric invariant redundancy that can be the source of fundamental problems in the analysis of large deformations. It is demonstrated in this thesis that the two geometry meshes can define different space curves, which can differ by arbitrary rigid body displacements. The material points of the two meshes occupy different positions in the deformed configuration, and as a consequence, the geometries of the two meshes can differ significantly. Other issues including energy conservation and the inextensibility of the rotation mesh will also be discussed. Simple examples are presented in order to shed light on these fundamental issues.
The third chapter of this thesis focuses on the dynamic formulation of mechanical joints using different approaches that lead to different models with different numbers of degrees of freedom. Some of these formulations allow for capturing the joint deformations using discrete elastic model while the others are continuum-based and capture joint deformation modes that cannot be captured using the discrete elastic joint models. Specifically, four types of joint formulations are considered in this chapter; the ideal, penalty, compliant discrete element, and compliant continuum-based joint models. The ideal joint formulation, or constrained dynamics approach, which does not allow for deformation degrees of freedom in the case of rigid body or small deformation analysis, requires introducing a set of algebraic constraint equations that can be handled in computational multibody system (MBS). When the constrained dynamics approach is used, the constraint equations must be satisfied at the position, velocity, and acceleration levels. The penalty method, on the other hand, ensures that the same algebraic equations are satisfied at the position level only with a force-based approach. In the compliant discrete element joint formulation, no constraint conditions are used; instead the connectivity conditions between bodies are enforced using forces that can be defined in their most general form in MBS algorithms using bushing elements that allow for the definition of general nonlinear forces and moments. The new compliant continuum-based joint formulation, which is based on the finite element (FE) absolute nodal coordinate formulation (ANCF), has several advantages: (1) It captures modes of…
Advisors/Committee Members: Shabana, Ahmed A. (advisor), Karpov, Eduard (committee member), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Hamed, Asharf (committee member),
Jayakumar, Paramsothy (committee member).
Subjects/Keywords: Multibody system dynamics; joint formulations; tracked vehicles; ANCF finite elements; flexible multibody dynamics; large rotation vector formulation; floating frame of reference
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APA ·
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MLA ·
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APA (6th Edition):
Wallin, M. S. (2016). Fully Coupled Analysis of Large Scale Tracked Vehicle Systems with Flexible Link Chains. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/21176
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Wallin, Michael S. “Fully Coupled Analysis of Large Scale Tracked Vehicle Systems with Flexible Link Chains.” 2016. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/21176.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Wallin, Michael S. “Fully Coupled Analysis of Large Scale Tracked Vehicle Systems with Flexible Link Chains.” 2016. Web. 21 Jan 2021.
Vancouver:
Wallin MS. Fully Coupled Analysis of Large Scale Tracked Vehicle Systems with Flexible Link Chains. [Internet] [Thesis]. University of Illinois – Chicago; 2016. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/21176.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Wallin MS. Fully Coupled Analysis of Large Scale Tracked Vehicle Systems with Flexible Link Chains. [Thesis]. University of Illinois – Chicago; 2016. Available from: http://hdl.handle.net/10027/21176
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
8.
Al Hijaj, Mutaz.
Behavior and Design of Skewed Extended Shear Tab Connections.
Degree: 2016, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/21548
► Extended shear tab connections has been introduced in the thirteenth edition of the American Institute of Steel Construction Manual to the structural engineering practice as…
(more)
▼ Extended shear tab connections has been introduced in the thirteenth edition of the American Institute of Steel Construction Manual to the structural engineering practice as an alternative to the single plate or as known the shear tab connections. The function of the extended shear tab connection is to transfer the shear force from the beam to the supporting member (column or girder). The main advantage of using extended shear tab connections is to avoid coping of beams in the vicinity of the joint to bring the beam close to the web of the supporting member. Previous studies investigated the behavior of extended shear tab connections for members, joined at right angle, experimentally and analytically. Skewed connections, in general, are commonly used in practice to frame members that their longitudinal axes do not meet at a right angle; the use of extended shear tab connections for skewed members eliminates the excessive beam ends cutting and modifications which makes this type of connections attractive to engineers and fabricators. This study investigates the behavior and design of different configurations of skewed extended shear tab connections using the finite element analysis software ABAQUS.
The study investigated three configurations of the skewed extended shear tab connections: 1) With the plate unstiffened and welded to supporting member web (flexible support), 2) With the plate unstiffened and welded to the supporting member flange (rigid support), 3) And with the plate welded to stiffener plates and supporting member web. To achieve the study goals, finite element analysis for orthogonal configurations were performed. Results were compared with their counterparts obtained from experimental investigation to verify the finite element models. Then, the models were skewed at different angles with results obtained and compared.
It was observed that for stiffened configurations and unstiffened configurations with rigid support, the connection bending and torsional behavior slightly affected by the connections orientation. On the other hand, for the unstiffened configuration with flexible support, the connection behavior significantly affected by the connection orientation, especially the torsional behavior.
A design procedure was proposed based on a parametric study that was performed for skewed extended shear tab connections based on results obtained from finite element analysis for 300 models with different configurations. The variable parameters used for this study are: plate thickness, the distance between the weld line and the bolt line, skewed angle, and number of bolts. These parameters were investigated in terms of the connection vertical displacement, plate twist along the bolt line, plate twist along the weld line, and the connection shear capacity. Based on the parametric study results, a specific design procedure for the skewed extended shear tab connections was proposed and compared with the current design procedure in the AISC Manual 14th edition. Modifications to the current connection lateral…
Advisors/Committee Members: Mahamid, Mustafa (advisor), Foster, Craig (committee member), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Ozevin, Didem (committee member),
Fanella, David (committee member),
Ansari, Farhad (chair).
Subjects/Keywords: Extended Shear Tab; Skewed Connections; Flexible Supports; Rigid Supports; Twist; Torsional Moment; ABAQUS.
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APA (6th Edition):
Al Hijaj, M. (2016). Behavior and Design of Skewed Extended Shear Tab Connections. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/21548
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Al Hijaj, Mutaz. “Behavior and Design of Skewed Extended Shear Tab Connections.” 2016. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/21548.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Al Hijaj, Mutaz. “Behavior and Design of Skewed Extended Shear Tab Connections.” 2016. Web. 21 Jan 2021.
Vancouver:
Al Hijaj M. Behavior and Design of Skewed Extended Shear Tab Connections. [Internet] [Thesis]. University of Illinois – Chicago; 2016. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/21548.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Al Hijaj M. Behavior and Design of Skewed Extended Shear Tab Connections. [Thesis]. University of Illinois – Chicago; 2016. Available from: http://hdl.handle.net/10027/21548
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
9.
Nazarian, Ebrahim.
Machine Learning, Probabilistic and Mathematical Models for Damage Recognition in Structural Systems.
Degree: 2017, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/21922
► An increasing percentage of building and bridge structures across United States are exceeding their design life. Ensuring the structural integrity of such structures demands health…
(more)
▼ An increasing percentage of building and bridge structures across United States are exceeding their design life. Ensuring the structural integrity of such structures demands health monitoring strategies. Over the past years, various structural health monitoring approaches have been developed for detection of the intensity and the location of damages in various structures such as building and bridges. Advancements in structural health monitoring rely on development of sensors, and development of mathematical models that can interpret the sensor data to meaningful information about the health of the structure. As an example, cables of cable-stayed bridges play a critical role in cable-stayed bridges by transmitting the forces from the bridge deck to the pylons. Hence, assurance of integrity of the cables during the design life of the bridge is inevitable. In this research, two mathematical models were developed to detect and quantify damage in cable-stayed structures. The first model uses the distributed measurement of strains along the bridge deck to detect the cables that have totally or partially lost their tensile force. The fundamental principle employed in formulating the method is the interrelationship between the individual cable forces and the bending moment along the bridge span. The efficiency of the methodology was evaluated through both numerical simulations and experimentations on a reduced-scale cable-stayed bridge. The second proposed model utilizes point-style sensors to estimate the deck element shear forces adjacent to the supports. An analytical approach was developed to quantify the damage in the cables using the shear forces. The formulations are based on a recursive optimization technique, in which model updating is employed to account for the changes in the cable stiffness as a result of damage.
In addition to mathematical models for damage recognition in cable-stayed bridges, the current research proposes a hybrid approach based on machine learning models to determine damages in the structural elements of building structures. The implemented machine learning methods in this thesis are Support Vector Machines, Neural Networks and Gaussian Naïve Bayes. The efficiency of the proposed approach was evaluated through numerical simulations and actual experimentations on a six-story heritage timber-masonry building.
Advisors/Committee Members: Ansari, Farhad (advisor), Ozevin, Didem (committee member), Karpov, Eduard (committee member), Pagano, Michael (committee member), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Ansari, Farhad (chair).
Subjects/Keywords: Machine learning; Mathematical Models; Statistical Models; Structural Health Monitoring
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APA (6th Edition):
Nazarian, E. (2017). Machine Learning, Probabilistic and Mathematical Models for Damage Recognition in Structural Systems. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/21922
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Nazarian, Ebrahim. “Machine Learning, Probabilistic and Mathematical Models for Damage Recognition in Structural Systems.” 2017. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/21922.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Nazarian, Ebrahim. “Machine Learning, Probabilistic and Mathematical Models for Damage Recognition in Structural Systems.” 2017. Web. 21 Jan 2021.
Vancouver:
Nazarian E. Machine Learning, Probabilistic and Mathematical Models for Damage Recognition in Structural Systems. [Internet] [Thesis]. University of Illinois – Chicago; 2017. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/21922.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Nazarian E. Machine Learning, Probabilistic and Mathematical Models for Damage Recognition in Structural Systems. [Thesis]. University of Illinois – Chicago; 2017. Available from: http://hdl.handle.net/10027/21922
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
10.
Desai, Chintan Janak.
Generalization of Strain Split Method for Locking Alleviation of Initially Curved Structures.
Degree: 2018, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/23336
► This thesis discusses the generalization of the strain-split method (SSM) for the locking alleviation of curved structures. The generalization is achieved by using proper definitions…
(more)
▼ This thesis discusses the generalization of the strain-split method (SSM) for the locking alleviation of curved structures. The generalization is achieved by using proper definitions of the stress and strain tensors along the curved-coordinate lines using the matrix of position vector gradients in the reference configuration. This matrix, which accurately captures the element geometry at the integration points, allows using consistent gradient transformation in the calculation of the stress and strain tensors. The generalized SSM implementation is used to develop benchmark problems for verifying the results and evaluating the performance of the absolute nodal coordinate formulation (ANCF) finite elements (FE). The focus of this study is on the Poisson locking that characterizes fully parameterized ANCF elements that employ different orders of interpolation in different directions. ANCF benchmark beam and plate problems are presented, and the obtained simulation results are compared with analytical solution as well as results obtained using commercial FE computer programs. These results are also compared with the results obtained using straight and curved ANCF beam and plate elements with no locking alleviation method in order to demonstrate the SSM effectiveness in alleviating the Poisson locking. It is shown that a much smaller number of ANCF elements is required to achieve approximately 0.9% difference from the results obtained using commercial FE computer programs.
Advisors/Committee Members: Shabana, Ahmed A (advisor), Foster, Craig (committee member), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Shabana, Ahmed A (chair).
Subjects/Keywords: ANCF benchmarking; locking problems; strain split method; beam structures; plate structures; Multi-Body Dynamics; Poisson locking
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APA (6th Edition):
Desai, C. J. (2018). Generalization of Strain Split Method for Locking Alleviation of Initially Curved Structures. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/23336
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Desai, Chintan Janak. “Generalization of Strain Split Method for Locking Alleviation of Initially Curved Structures.” 2018. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/23336.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Desai, Chintan Janak. “Generalization of Strain Split Method for Locking Alleviation of Initially Curved Structures.” 2018. Web. 21 Jan 2021.
Vancouver:
Desai CJ. Generalization of Strain Split Method for Locking Alleviation of Initially Curved Structures. [Internet] [Thesis]. University of Illinois – Chicago; 2018. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/23336.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Desai CJ. Generalization of Strain Split Method for Locking Alleviation of Initially Curved Structures. [Thesis]. University of Illinois – Chicago; 2018. Available from: http://hdl.handle.net/10027/23336
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
11.
Motamedi, MohammadHosein.
Numerical Simulation of Mechanical Response of Geomaterials from Strain Hardening to Localized Failure.
Degree: 2016, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/20834
► The Sandia GeoModel is a continuum elastoplastic constitutive model which captures many features of the mechanical response for geological materials over a wide range of…
(more)
▼ The Sandia GeoModel is a continuum elastoplastic constitutive model which captures many features of the mechanical response for geological materials over a wide range of porosities and strain rates. Among the specific features incorporated into the formulation are a smooth compression cap, isotropic/kinematic hardening, nonlinear pressure dependence, strength differential effect, and rate sensitivity. This study attempts to provide enhancements regarding computational tractability, domain of applicability, and robustness of the model. A new functional form is presented for the yield and plastic potential functions. The model is also furnished with a smooth, elliptical tension cap to account for the tensile failure. This reformulation renders a more accurate, robust and efficient model as it eliminates spurious solutions attributed to the original form. In addition, this constitutive model is adopted in bifurcation analysis to track the inception of new localization and crack path propagation. For the post-localization regime, a cohesive-law fracture model, able to address mixed-model failure condition, is implemented to characterize the constitutive softening behavior on the surface of discontinuity. To capture propagating fracture, the Assumed Enhanced Strain (AES) method is invoked. Particular mathematical treatments are incorporated into the simulation concerning numerical efficiency and robustness issues. Finally, the aforementioned modified cap plasticity model is employed to investigate the nonlinear dynamic response of the earthen substructure of the rail. Studying the effects of high-speed trains on the track substructure.
Advisors/Committee Members: Foster, Craig D. (advisor), Ansari, Farhad (committee member), Shabana, Ahmed A. (committee member), Karpov, Eduard G. (committee member), Ozevin, Didem (committee member), Chi, Sheng Wei (committee member).
Subjects/Keywords: Plasticity; Numerical Methods; Fracture Mechanics; Crack Propagation; Geomechanics
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APA ·
Chicago ·
MLA ·
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CSE |
Export
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APA (6th Edition):
Motamedi, M. (2016). Numerical Simulation of Mechanical Response of Geomaterials from Strain Hardening to Localized Failure. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/20834
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Motamedi, MohammadHosein. “Numerical Simulation of Mechanical Response of Geomaterials from Strain Hardening to Localized Failure.” 2016. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/20834.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Motamedi, MohammadHosein. “Numerical Simulation of Mechanical Response of Geomaterials from Strain Hardening to Localized Failure.” 2016. Web. 21 Jan 2021.
Vancouver:
Motamedi M. Numerical Simulation of Mechanical Response of Geomaterials from Strain Hardening to Localized Failure. [Internet] [Thesis]. University of Illinois – Chicago; 2016. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/20834.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Motamedi M. Numerical Simulation of Mechanical Response of Geomaterials from Strain Hardening to Localized Failure. [Thesis]. University of Illinois – Chicago; 2016. Available from: http://hdl.handle.net/10027/20834
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
12.
Abbasi, Zeynab.
Stress Quantification of Complexly Loaded Structural Components using Acoustoelasticity.
Degree: 2017, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/22145
► The ultrasonic monitoring of steels and other structural materials relies on measuring the velocity of elastic waves, which varies with the existing stress state in…
(more)
▼ The ultrasonic monitoring of steels and other structural materials relies on measuring the velocity of elastic waves, which varies with the existing stress state in the material—a phenomenon known as acoustoelasticity. This research is focused on applying the acoustoelastic method for stress analysis to thick steel plates (9-12 mm) of the type commonly used for gusset plates of steel truss bridges, where shear stress is significant.
The acoustoelastic coefficients are determined in thick steel plates in normal, orthogonal, and angled directions using an array of ultrasonic sensors. A three-dimensional material model is developed which includes Murnaghan hyper-elasticity and can determine the effects of plate thickness and excitation frequency on the acoustoelastic coefficients. This model is experimentally validated by tensile loading of a thick steel plate by measuring the ultrasonic signals in three directions. Numerical and experimental results agree within the measurement uncertainties of each method. The 1.0 MHz ultrasonic frequency has the highest resolution for measuring normal and shear stresses in plates typically used in highway bridges.
Additionally, the ultrasonic velocity and stress equation is modified to add the shear effect in addition to normal stresses. As a result, the theory of acoustoelasticity in a homogenous and isotropic plate is developed for the presence of multi-directional stress in a cross section considering normal and shear stresses. The resulting analytical equations are solved to understand the influence of shear stress on the acoustoelastic coefficients.
Advisors/Committee Members: Ozevin, Didem (advisor), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Indacochea, J. Ernesto (committee member),
Ansari, Farhad (committee member),
Shabana, Ahmed (committee member),
Ozevin, Didem (chair).
Subjects/Keywords: Shear Stress; Acoustoelasticity
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Abbasi, Z. (2017). Stress Quantification of Complexly Loaded Structural Components using Acoustoelasticity. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/22145
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Abbasi, Zeynab. “Stress Quantification of Complexly Loaded Structural Components using Acoustoelasticity.” 2017. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/22145.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Abbasi, Zeynab. “Stress Quantification of Complexly Loaded Structural Components using Acoustoelasticity.” 2017. Web. 21 Jan 2021.
Vancouver:
Abbasi Z. Stress Quantification of Complexly Loaded Structural Components using Acoustoelasticity. [Internet] [Thesis]. University of Illinois – Chicago; 2017. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/22145.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Abbasi Z. Stress Quantification of Complexly Loaded Structural Components using Acoustoelasticity. [Thesis]. University of Illinois – Chicago; 2017. Available from: http://hdl.handle.net/10027/22145
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
13.
Patel, Mohil D.
Integration of a Continuum-Based Finite Element Tire Modeling Framework in Multibody Dynamics Algorithms.
Degree: 2018, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/22593
► Flexible multibody systems (MBS) are systems of interconnected rigid and flexible bodies and are typically characterized by large reference translations and rotations. Examples of such…
(more)
▼ Flexible multibody systems (MBS) are systems of interconnected rigid and flexible bodies and are typically characterized by large reference translations and rotations. Examples of such systems include automotive vehicles, trains, aircrafts and musculoskeletal systems. The flexible bodies found in MBS models can be characterized by small and large deformation. The MBS dynamics literature consists of various methods of formulating the governing equations of motion, describing the MBS models and incorporating component flexibility. In case of flexible MBS models, the fidelity, accuracy and efficiency of the model will depend on the formulation and numerical methods used by the MBS software, which keep evolving and improving over time. The goal of this thesis is to develop a new computational framework for the modeling and integration of finite element (FE) tires in MBS dynamics algorithms. Historically tire modeling techniques used in MBS computer programs have consisted of curve-fitted analytical formulations, discrete/compliant-type elastic tire models and co-simulated classical FE models. This thesis proposes a new method of FE-based tire modeling that utilizes the absolute nodal coordinate formulation (ANCF) elements and can be systematically implemented in non-incremental MBS dynamics algorithms. The advantages of such a type of tire modeling are two-fold: the distributed inertia and elasticity of the tire can be successfully represented, and the model can exploit the existing MBS dynamics algorithms for obtaining efficient and reliable solutions. Along with the overall structural modeling aspects of tires, a new approach for the inclusion of surface geometry within ANCF FEs is developed, with tire tread details being a good example of such type of geometry. This thesis also reviews and discusses locking phenomena in classical FEs and fully parameterized ANCF beam and plate/shell elements and proposes a new locking alleviation technique called the strain split method. Finally, this thesis demonstrates the feasibility of developing new and detailed vehicle models that include many interconnected rigid and flexible bodies that could have structural discontinuities and are subjected to small and large deformation. The vehicle models developed and studied in this thesis includes a flexible chassis which is modeled using the floating frame of reference (FFR) formulation and pneumatic and airless tires which use the ANCF approach.
Advisors/Committee Members: Shabana, Ahmed A (advisor), Foster, Craig (committee member), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Karpov, Eduard (committee member),
Afshari, Ali (committee member),
Shabana, Ahmed A (chair).
Subjects/Keywords: Flexible multibody dynamics; tires; nonlinear finite element analysis; absolute nodal coordinate formulation; large deformation; vehicle dynamics; floating frame of reference; constrained mechanical systems; computational geometry
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Patel, M. D. (2018). Integration of a Continuum-Based Finite Element Tire Modeling Framework in Multibody Dynamics Algorithms. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/22593
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Patel, Mohil D. “Integration of a Continuum-Based Finite Element Tire Modeling Framework in Multibody Dynamics Algorithms.” 2018. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/22593.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Patel, Mohil D. “Integration of a Continuum-Based Finite Element Tire Modeling Framework in Multibody Dynamics Algorithms.” 2018. Web. 21 Jan 2021.
Vancouver:
Patel MD. Integration of a Continuum-Based Finite Element Tire Modeling Framework in Multibody Dynamics Algorithms. [Internet] [Thesis]. University of Illinois – Chicago; 2018. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/22593.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Patel MD. Integration of a Continuum-Based Finite Element Tire Modeling Framework in Multibody Dynamics Algorithms. [Thesis]. University of Illinois – Chicago; 2018. Available from: http://hdl.handle.net/10027/22593
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
14.
Zhang, Lu.
Quantitative Acoustic Emission for Damage Detection in Complex Geometries.
Degree: 2018, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/22717
► Acoustic Emission (AE) method is a passive nondestructive evaluation (NDE) method based on the release of elastic waves by active flaws in structures. Since 1950s,…
(more)
▼ Acoustic Emission (AE) method is a passive nondestructive evaluation (NDE) method based on the release of elastic waves by active flaws in structures. Since 1950s, the AE method has been applied as a qualitative NDE method to detect discontinuities by real time monitoring. While the AE method is successful in identifying and localizing active flaws, the method has not been fully utilized as a quantitative NDE method due to several challenges: unknown conversion behavior of sensor, complex source mechanism and influence of background noise. In this study, the goal is to address the major challenges of AE in terms of sensor behavior, influence of operational noise, and quantitative AE measurement and contribute our effort to achieve better understandings of acoustic emission. The study has three major components: (i) The multi-physics numerical models of AE sensors are built and validated by experiments. (ii) With the proper design of the laboratory scale test, the fatigue crack growth is simulated, and the corresponding AE signals are collected. Spline geometry of helicopter gearbox system is selected as the test structure to simulate a complex geometry and integrate with the field data obtained from the NAVAIR test facility. (iii) The recorded AE signals are embedded into the streamed signals obtained from the NAVAIR prototype test to evaluate the detectable AE signal in highly noisy operational environment and develop an efficient signal processing method. The purpose is to show the ability to extract fatigue crack signal embedded in noise signal and released from a complex geometry.
Advisors/Committee Members: Ozevin, Didem (advisor), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Indacochea, J. Ernesto (committee member),
Mahamid, Mustafa (committee member),
He, David (committee member),
Ozevin, Didem (chair).
Subjects/Keywords: Quantitative Acoustic Emission; Sensor Calibration; Gearbox Spline; Streamed Signals
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Zhang, L. (2018). Quantitative Acoustic Emission for Damage Detection in Complex Geometries. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/22717
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Zhang, Lu. “Quantitative Acoustic Emission for Damage Detection in Complex Geometries.” 2018. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/22717.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Zhang, Lu. “Quantitative Acoustic Emission for Damage Detection in Complex Geometries.” 2018. Web. 21 Jan 2021.
Vancouver:
Zhang L. Quantitative Acoustic Emission for Damage Detection in Complex Geometries. [Internet] [Thesis]. University of Illinois – Chicago; 2018. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/22717.
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. Quantitative Acoustic Emission for Damage Detection in Complex Geometries. [Thesis]. University of Illinois – Chicago; 2018. Available from: http://hdl.handle.net/10027/22717
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
15.
Mostavi, Amir.
The Enhancement of Nonlinear Ultrasonic Testing to Detect Micro-structural Defects in Metals.
Degree: 2018, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/23134
► Second harmonic generation (SHG) is a nonlinear ultrasonic testing (NLUT) method, which is based on the distortion of a single frequency wave confronting the micro-structural…
(more)
▼ Second harmonic generation (SHG) is a nonlinear ultrasonic testing (NLUT) method, which is based on the distortion of a single frequency wave confronting the micro-structural features as it passes through the material. This distortion generates higher frequency components of the fundamental frequency. The amplitudes of the fundamental and second harmonics are used to calculate the acoustic non-linearity parameter (β). The acoustic non-linearity parameter is correlated with the extent of micro-structural features in materials; however, the major challenges of this method are high sensitivity of harmonic amplitudes to the signal processing method and the experimental variables, such as coupling condition and instrumental non-linearities, which introduce significant variability in the reported non-linearity parameters representing different defects. The objective of this research is to minimize the variability of non-linearity parameter in relation to damage by introducing wavelet-based signal decomposition approach, and blocking the non-linearity in medium and instruments by phononic crystals (PCs). The research has two major components: (i) understanding the major drawback of the most prevalent signal processing method and formulating a more robust harmonic decomposition method, and evaluating the proposed method in the NLUT experiments to detect plastic strain and creep damage; (ii) blocking the non-linearity generated in instrument and couplant (water for the case of immersed NLUT) by implementing one-dimensional PCs, known as superlattices (SLs). It is demonstrated that the wavelet-based signal decomposition reduces the variability of harmonic amplitudes as compared to Fourier transform-based signal decomposition. SLs are numerically modeled to block higher harmonics selected in this research, and evaluated experimentally. It is shown that non-linearity in water and electronics in the transmission side of data acquisition equipment can be blocked while the NLUT method can be used with immersion method with the reduced coupling effect. The NLUT method integrated with SLs is demonstrated on detecting plastic deformation in aluminum and creep damage in steel.
Advisors/Committee Members: Ozevin, Didem (advisor), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Karpov, Eduard (committee member),
Indacochea, J. Ernesto (committee member),
Shahbazian-Yassar, Reza (committee member),
Ozevin, Didem (chair).
Subjects/Keywords: Nondestructive Testing; Immersion Nonlinear Ultrasonic Testing; Phononic Crystals
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APA (6th Edition):
Mostavi, A. (2018). The Enhancement of Nonlinear Ultrasonic Testing to Detect Micro-structural Defects in Metals. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/23134
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Mostavi, Amir. “The Enhancement of Nonlinear Ultrasonic Testing to Detect Micro-structural Defects in Metals.” 2018. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/23134.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Mostavi, Amir. “The Enhancement of Nonlinear Ultrasonic Testing to Detect Micro-structural Defects in Metals.” 2018. Web. 21 Jan 2021.
Vancouver:
Mostavi A. The Enhancement of Nonlinear Ultrasonic Testing to Detect Micro-structural Defects in Metals. [Internet] [Thesis]. University of Illinois – Chicago; 2018. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/23134.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Mostavi A. The Enhancement of Nonlinear Ultrasonic Testing to Detect Micro-structural Defects in Metals. [Thesis]. University of Illinois – Chicago; 2018. Available from: http://hdl.handle.net/10027/23134
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
16.
Klein, John T.
Mechanical Metamaterials with Negative Extensibility: Nonlinear Analysis and Phase Diagram Calculation.
Degree: 2017, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/22036
► Mechanical metamaterials are characterized by their unnatural elastic constants. The metamaterial property of negative extensibility is investigated. A five-member unit-cell structure is able to contract…
(more)
▼ Mechanical metamaterials are characterized by their unnatural elastic constants. The metamaterial property of negative extensibility is investigated. A five-member unit-cell structure is able to contract against the line of increasing applied tension. If stiffness were to be measured during this contraction it would appear to be negative. More accurately, it would be a negative `incremental’ stiffness since the slope of the force-response curve shifts from positive to negative after the load is applied. Negative extensibility is contrasted with other mechanical phenomena including negative compressibility, negative Poisson’s ratio, stretch-densification and the reversal of St.-Venant’s edge effects. The potential function of the unit-cell is highly nonlinear due to geometry. The unit-cell is bistable. For certain combinations of member stiffnesses and geometry, the force-response curve is hysteretic. The structure is characterized by five basic nonlinear mechanical responses: monostability (MS), superelasticity (SE), superplasticity (SP), negative extensibility of the superelastic type (NESE) and negative extensibility of the superplastic type (NESP). The negative extensibility response is defined by a `pinched’ hysteresis loop. Over the `pinched’ region the work done by the system is negative. Energy methods used in computational thermodynamics for the calculation of phase diagrams are re-purposed in order to map the mechanical responses of the unit-cell structure to regions in a phase diagram. The axes of the phase diagram are dimensionless system parameters that define the unit-cell geometry and element stiffnesses. The boundary lines represent the onset of a particular mechanical response. The process of computing boundary lines is informed by the principles of catastrophe theory. For instance, it is possible to compute with precision the onset of a hysteresis loop using a mathematical set of conditions. Similar to thermodynamics, on the phase diagram there are `triple points’ which simultaneously satisfy three conditions of mechanical equilibrium. The discussion ends by showing how the unit-cell structure can be arranged into a periodic array. The response of the periodic array is shown to be similar to that of its constituent unit-cell. Fabrication of a periodic structure that is able to contract against applied tension remains an open question. Viability of the phenomenon in practice is evaluated.
Advisors/Committee Members: Karpov, Eduard (advisor), Foster, Craig (committee member), McNallan, Michael (committee member), Mahamid, Mustafa (committee member), Wei%22%29&pagesize-30">
Chi,
Sheng-
Wei (committee member),
Karpov, Eduard (chair).
Subjects/Keywords: metamaterials; mechanical metamaterials; negative extensibility; negative compressibility; negative longitudinal compressibility; negative stiffness; phase diagram; phase diagram calculation; unit-cell; bistability; hysteresis; computational mechanics; nonlinear analysis; geometric nonlinearity; catastrophe theory
Record Details
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Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Klein, J. T. (2017). Mechanical Metamaterials with Negative Extensibility: Nonlinear Analysis and Phase Diagram Calculation. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/22036
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Klein, John T. “Mechanical Metamaterials with Negative Extensibility: Nonlinear Analysis and Phase Diagram Calculation.” 2017. Thesis, University of Illinois – Chicago. Accessed January 21, 2021.
http://hdl.handle.net/10027/22036.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Klein, John T. “Mechanical Metamaterials with Negative Extensibility: Nonlinear Analysis and Phase Diagram Calculation.” 2017. Web. 21 Jan 2021.
Vancouver:
Klein JT. Mechanical Metamaterials with Negative Extensibility: Nonlinear Analysis and Phase Diagram Calculation. [Internet] [Thesis]. University of Illinois – Chicago; 2017. [cited 2021 Jan 21].
Available from: http://hdl.handle.net/10027/22036.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Klein JT. Mechanical Metamaterials with Negative Extensibility: Nonlinear Analysis and Phase Diagram Calculation. [Thesis]. University of Illinois – Chicago; 2017. Available from: http://hdl.handle.net/10027/22036
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
. 
Open Access Theses and Dissertations
