subject:(Elastodynamic)

1. Βέρμπης, Ιωάννης. Επίλυση προβλημάτων κυματικής διάδοσης σε σύνθετα υλικά με τη μέθοδο των συνοριακών στοιχείων.

Degree: 2000, University of Patras

URL: http://nemertes.lis.upatras.gr/jspui/handle/10889/2086

- Advisors/Committee Members: Δάσιος, Γ., Vermpis, Ioannis, Δάσιος, Γ., Παγιατάκης, Α., Πολύζος, Δ., Κυριάκη, Κ., Παύλου, Σ., Κωστόπουλος, Β., Μπέσκος, Δ..

Subjects/Keywords: Κυματική; Ελαστοδυναμική; 531.382; Wave; Elastodynamic

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APA (6^th Edition):

Βέρμπης, �. (2000). Επίλυση προβλημάτων κυματικής διάδοσης σε σύνθετα υλικά με τη μέθοδο των συνοριακών στοιχείων. (Doctoral Dissertation). University of Patras. Retrieved from http://nemertes.lis.upatras.gr/jspui/handle/10889/2086

Chicago Manual of Style (16^th Edition):

Βέρμπης, Ιωάννης. “Επίλυση προβλημάτων κυματικής διάδοσης σε σύνθετα υλικά με τη μέθοδο των συνοριακών στοιχείων.” 2000. Doctoral Dissertation, University of Patras. Accessed April 13, 2021. http://nemertes.lis.upatras.gr/jspui/handle/10889/2086.

MLA Handbook (7^th Edition):

Βέρμπης, Ιωάννης. “Επίλυση προβλημάτων κυματικής διάδοσης σε σύνθετα υλικά με τη μέθοδο των συνοριακών στοιχείων.” 2000. Web. 13 Apr 2021.

Vancouver:

Βέρμπης �. Επίλυση προβλημάτων κυματικής διάδοσης σε σύνθετα υλικά με τη μέθοδο των συνοριακών στοιχείων. [Internet] [Doctoral dissertation]. University of Patras; 2000. [cited 2021 Apr 13]. Available from: http://nemertes.lis.upatras.gr/jspui/handle/10889/2086.

Council of Science Editors:

Βέρμπης �. Επίλυση προβλημάτων κυματικής διάδοσης σε σύνθετα υλικά με τη μέθοδο των συνοριακών στοιχείων. [Doctoral Dissertation]. University of Patras; 2000. Available from: http://nemertes.lis.upatras.gr/jspui/handle/10889/2086

University of South Carolina

2. Agbasi, Chijioke. Classification of Low Velocity Impactors Using Spiral Sensing of Acousto-Ultrasonic Waves.

Degree: MS, Mechanical Engineering, 2014, University of South Carolina

URL: https://scholarcommons.sc.edu/etd/2660

► The non-linear elastodynamics of a flat plate subjected to low velocity foreign body impacts is studied, resembling the space debris impacts on the space… (more)

▼ The non-linear elastodynamics of a flat plate subjected to low velocity foreign body impacts is studied, resembling the space debris impacts on the space structure. The work is based on a central hypothesis that in addition to identifying the impact locations, the material properties of the foreign objects can also be classified using acousto-ultrasonic signals (AUS). Simultaneous localization of impact point and classification of impact object is quite challenging using existing state-of-the-art structural health monitoring (SHM) approaches. Available techniques seek to report the exact location of impact on the structure, however, the reported information is likely to have errors from nonlinearity and variability in the AUS signals due to materials, geometry, boundary conditions, wave dispersion, environmental conditions, sensor and hardware calibration etc. It is found that the frequency and speed of the guided wave generated in the plate can be quantized based on the impactor's relationship with the plate (i.e. the wave speed and the impactor's mechanical properties are coupled). In this work, in order to characterize the impact location and mechanical properties of imapctors, nonlinear transient phenomenon is empirically studied to decouple the understanding using the dominant frequency band (DFB) and Lag Index (LI) of the acousto-ultrasonic signals. Next the understanding was correlated with the elastic modulus of the impactor to predict transmitted force histories. The proposed method presented in this thesis is especially applicable for SHM where sensors cannot be widely or randomly distributed. Thus a strategic organization and localization of the sensors is achieved by implementing the geometric configuration of Theodorous Spiral Sensor Cluster (TSSC). The performance of TSSC in characterizing the impactor types are compared with other conventional sensor clusters (e.g. square, circular, random etc.) and it is shown that the TSSC is advantageous over conventional localized sensor clusters. It was found that the TSSC provides unbiased sensor voting that boosts sensitivity towards classification of impact events. To prove the concept, a coupled field (multiphysics) finite element model (CFFEM) is developed and a series of experiments were performed. The dominant frequency band (DBF) along with a Lag Index (LI) feature extraction technique was found to be suitable for classifying the impactors. Results show that TSSC with DBF features increase the sensitivity of impactor's elastic modulus, if the covariance of the AUS from the TSSC and other conventional sensor clusters are compared. It is observe that for the impact velocity, geometric and mechanical properties studied herein, longitudinal and flexural waves are excited, and there are quantifiable differences in the Lamb wave signatures excited for different impactor materials. It is found that such differences are distinguishable only by the proposed TSSC, but not by other state-of-the-art sensor configurations used in SHM. This study will be… Advisors/Committee Members: Sourav Banerjee.

Subjects/Keywords: Engineering; Mechanical Engineering; Acousto-ultrasonic; Dissipation; Elastodynamic; Impactor; Probability; Theodorus spiral

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APA (6^th Edition):

Agbasi, C. (2014). Classification of Low Velocity Impactors Using Spiral Sensing of Acousto-Ultrasonic Waves. (Masters Thesis). University of South Carolina. Retrieved from https://scholarcommons.sc.edu/etd/2660

Chicago Manual of Style (16^th Edition):

Agbasi, Chijioke. “Classification of Low Velocity Impactors Using Spiral Sensing of Acousto-Ultrasonic Waves.” 2014. Masters Thesis, University of South Carolina. Accessed April 13, 2021. https://scholarcommons.sc.edu/etd/2660.

MLA Handbook (7^th Edition):

Agbasi, Chijioke. “Classification of Low Velocity Impactors Using Spiral Sensing of Acousto-Ultrasonic Waves.” 2014. Web. 13 Apr 2021.

Vancouver:

Agbasi C. Classification of Low Velocity Impactors Using Spiral Sensing of Acousto-Ultrasonic Waves. [Internet] [Masters thesis]. University of South Carolina; 2014. [cited 2021 Apr 13]. Available from: https://scholarcommons.sc.edu/etd/2660.

Council of Science Editors:

Agbasi C. Classification of Low Velocity Impactors Using Spiral Sensing of Acousto-Ultrasonic Waves. [Masters Thesis]. University of South Carolina; 2014. Available from: https://scholarcommons.sc.edu/etd/2660

University of California – Berkeley

3. McLaskey, Gregory Christofer. Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction.

Degree: Civil and Environmental Engineering, 2011, University of California – Berkeley

URL: http://www.escholarship.org/uc/item/3zz1w8z7

► Rapidly varying forces, such as those associated with impact, rapid crack propagation, and fault rupture, are sources of stress waves which propagate through a solid… (more)

▼ Rapidly varying forces, such as those associated with impact, rapid crack propagation, and fault rupture, are sources of stress waves which propagate through a solid body. This dissertation investigates how properties of a stress wave source can be identified or constrained using measurements recorded at an array of sensor sites located far from the source. This methodology is often called the method of acoustic emission and is useful for structural health monitoring and the noninvasive study of material behavior such as friction and fracture. In this dissertation, laboratory measurements of 1-300 mm wavelength stress waves are obtained by means of piezoelectric sensors which detect high frequency (10 kHz- 3MHz) motions of a specimen's surface, picometers to nanometers in amplitude. Then, stress wave source characterization techniques are used to study ball impact, drying shrinkage cracking in concrete, and the micromechanics of stick-slip friction of Poly(methyl methacrylate) (PMMA) and rock/rock interfaces. In order to quantitatively relate recorded signals obtained with an array of sensors to a particular stress wave source, wave propagation effects and sensor distortions must be accounted for. This is achieved by modeling the physics of wave propagation and transduction as linear transfer functions. Wave propagation effects are precisely modeled by an elastodynamic Green's function, sensor distortion is characterized by an instrument response function, and the stress wave source is represented with a force moment tensor. These transfer function models are verified though calibration experiments which employ two different mechanical calibration sources: ball impact and glass capillary fracture. The suitability of the ball impact source model, based on Hertzian contact theory, is experimentally validated for small (~1 mm) balls impacting massive plates composed of four different materials: aluminum, steel, glass, and PMMA. Using this transfer function approach and the two mechanical calibration sources, four types of piezoelectric sensors were calibrated: three commercially available sensors and the Glaser-type conical piezoelectric sensor, which was developed in the Glaser laboratory. The distorting effects of each sensor are modeled using autoregressive-moving average (ARMA) models, and because vital phase information is robustly incorporated into these models, they are useful for simulating or removing sensor-induced distortions, so that a displacement time history can be retrieved from recorded signals. The Glaser-type sensor was found to be very well modeled as a unidirectional displacement sensor which detects stress wave disturbances down to about 1 picometer in amplitude. Finally, the merits of a fully calibrated experimental system are demonstrated in a study of stress wave sources arising from sliding friction, and the relationship between those sources and earthquakes. A laboratory friction apparatus was built for this work which allows the micro-mechanisms of friction to be studied with stress wave…

Subjects/Keywords: Mechanics; Civil Engineering; Geophysics; acoustic emission; elastodynamic; Green's function; nanoseismic; sensor calibration; transfer function

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APA (6^th Edition):

McLaskey, G. C. (2011). Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/3zz1w8z7

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):

McLaskey, Gregory Christofer. “Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction.” 2011. Thesis, University of California – Berkeley. Accessed April 13, 2021. http://www.escholarship.org/uc/item/3zz1w8z7.

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

MLA Handbook (7^th Edition):

McLaskey, Gregory Christofer. “Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction.” 2011. Web. 13 Apr 2021.

Vancouver:

McLaskey GC. Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction. [Internet] [Thesis]. University of California – Berkeley; 2011. [cited 2021 Apr 13]. Available from: http://www.escholarship.org/uc/item/3zz1w8z7.

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

Council of Science Editors:

McLaskey GC. Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction. [Thesis]. University of California – Berkeley; 2011. Available from: http://www.escholarship.org/uc/item/3zz1w8z7

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

University of Arizona

4. Fooladi, Samaneh. Numerical Implementation of Elastodynamic Green's Function for Anisotropic Media .

Degree: 2016, University of Arizona

URL: http://hdl.handle.net/10150/623144

► Displacement Green's function is the building block for some semi-analytical methods like Boundary Element Method (BEM), Distributed Point Source Method (DPCM), etc. In this thesis,… (more)

▼ Displacement Green's function is the building block for some semi-analytical methods like Boundary Element Method (BEM), Distributed Point Source Method (DPCM), etc. In this thesis, the displacement Green`s function in anisotropic media due to a time harmonic point force is studied. Unlike the isotropic media, the Green's function in anisotropic media does not have a closed form solution. The dynamic Green's function for an anisotropic medium can be written as a summation of singular and non-singular or regular parts. The singular part, being similar to the result of static Green's function, is in the form of an integral over an oblique circular path in 3D. This integral can be evaluated either by a numerical integration technique or can be converted to a summation of algebraic terms via the calculus of residue. The other part, which is the regular part, is in the form of an integral over the surface of a unit sphere. This integral needs to be evaluated numerically and its evaluation is considerably more time consuming than the singular part. Obtaining dynamic Green's function and its spatial derivatives involves calculation of these two types of integrals. The spatial derivatives of Green's function are important in calculating quantities like stress and stain tensors. The contribution of this thesis can be divided into two parts. In the first part, different integration techniques including Gauss Quadrature, Simpson's, Chebyshev, and Lebedev integration techniques are tried out and compared for evaluation of dynamic Green’s function. In addition the solution from the residue theorem is included for the singular part. The accuracy and performance of numerical implementation is studied in detail via different numerical examples. Convergence plots are used to analyze the numerical error for both Green's function and its derivatives. The second part of contribution of this thesis relates to the mathematical derivations. As mentioned above, the regular part of dynamic Green's function, being an integral over the surface of a unit sphere, is responsible for the majority of computational time. From symmetry properties, this integration domain can be reduced to a hemisphere, but no more simplification seems to be possible for a general anisotropic medium. In this thesis, the integration domain for regular part is further reduced to a quarter of a sphere for the particular case of transversely isotropic material. This reduction proposed for the first time in this thesis nearly halves the number of integration points for the evaluation of regular part of dynamic Green's function. It significantly reduces the computational time. Advisors/Committee Members: Kundu, Tribikram (advisor), Kundu, Tribikram (committeemember), Nikravesh, Parviz (committeemember), Missoum, Samy (committeemember).

Subjects/Keywords: Elastodynamic Green’s function; Anisotropic medium; Time-harmonic solutio; Residue method; Chebyshev integration; Lebedev integration

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

APA (6^th Edition):

Fooladi, S. (2016). Numerical Implementation of Elastodynamic Green's Function for Anisotropic Media . (Masters Thesis). University of Arizona. Retrieved from http://hdl.handle.net/10150/623144

Chicago Manual of Style (16^th Edition):

Fooladi, Samaneh. “Numerical Implementation of Elastodynamic Green's Function for Anisotropic Media .” 2016. Masters Thesis, University of Arizona. Accessed April 13, 2021. http://hdl.handle.net/10150/623144.

MLA Handbook (7^th Edition):

Fooladi, Samaneh. “Numerical Implementation of Elastodynamic Green's Function for Anisotropic Media .” 2016. Web. 13 Apr 2021.

Vancouver:

Fooladi S. Numerical Implementation of Elastodynamic Green's Function for Anisotropic Media . [Internet] [Masters thesis]. University of Arizona; 2016. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10150/623144.

Council of Science Editors:

Fooladi S. Numerical Implementation of Elastodynamic Green's Function for Anisotropic Media . [Masters Thesis]. University of Arizona; 2016. Available from: http://hdl.handle.net/10150/623144

RMIT University

5. Vagh, H. Distributed-elementary-source self-regularized dyadic Green's functions for modeling the massloading effect in micro-acoustic devices.

Degree: 2011, RMIT University

URL: http://researchbank.rmit.edu.au/view/rmit:160531

► A Surface-Integral-Modeling technique has been developed to solve time-harmonic boundary value problems in acoustics. The thesis focuses on describing the methodology and testing the consistency… (more)

Subjects/Keywords: Fields of Research; Elastodynamic simulations; Greenâ€™s function analysis; Dynamic interface problems; Galerkin variational method; Micro-acoustic device modeling

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APA (6^th Edition):

Vagh, H. (2011). Distributed-elementary-source self-regularized dyadic Green's functions for modeling the massloading effect in micro-acoustic devices. (Thesis). RMIT University. Retrieved from http://researchbank.rmit.edu.au/view/rmit:160531

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):

Vagh, H. “Distributed-elementary-source self-regularized dyadic Green's functions for modeling the massloading effect in micro-acoustic devices.” 2011. Thesis, RMIT University. Accessed April 13, 2021. http://researchbank.rmit.edu.au/view/rmit:160531.

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

MLA Handbook (7^th Edition):

Vagh, H. “Distributed-elementary-source self-regularized dyadic Green's functions for modeling the massloading effect in micro-acoustic devices.” 2011. Web. 13 Apr 2021.

Vancouver:

Vagh H. Distributed-elementary-source self-regularized dyadic Green's functions for modeling the massloading effect in micro-acoustic devices. [Internet] [Thesis]. RMIT University; 2011. [cited 2021 Apr 13]. Available from: http://researchbank.rmit.edu.au/view/rmit:160531.

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

Council of Science Editors:

Vagh H. Distributed-elementary-source self-regularized dyadic Green's functions for modeling the massloading effect in micro-acoustic devices. [Thesis]. RMIT University; 2011. Available from: http://researchbank.rmit.edu.au/view/rmit:160531

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

Delft University of Technology

6. Reinicke Urruticoechea, C. Elastodynamic Marchenko inverse scattering: A multiple-elimination strategy for imaging of elastodynamic seismic reflection data.

Degree: 2020, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; 2122e7cc-0f07-40af-88cd-b5b789974562 ; 10.4233/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:isbn:978-94-6384-111-5 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562

► The Marchenko method offers a new perspective on eliminating internal multiples. Instead of predicting internal multiples based on events, the Marchenko method formulates an inverse… (more)

▼ The Marchenko method offers a new perspective on eliminating internal multiples. Instead of predicting internal multiples based on events, the Marchenko method formulates an inverse problem that is solved for an inverse transmission response. This approach is particularly advantageous when internal multiples generate complicated interference patterns, such that individual events cannot be identified. Moreover, the retrieved inverse transmissions can be used for a wide range of applications. For instance, we present a numerical example of the single-sided homogeneous Green's function representation in elastic media. These applications require a generalization of the Marchenko method beyond the acoustic case. Formally these extensions are nearly straightforward, as can be seen in the chapter on plane-wave Marchenko redatuming in elastic media. Despite the formal ease of these generalizations, solving the aforementioned inverse problem becomes significantly more difficult in the elastodynamic case. We analyze fundamental challenges of the elastodynamic Marchenko method. Elastic media support coupled wave-modes with different propagation velocities. These velocity differences lead to fundamental limitations, which are due to differences between the temporal ordering of reflection events and the ordering of reflectors in depth. Other multiple-elimination methods such as the inverse scattering series encounter similar limitations, due to violating a so-called monotonicity assumption. Nevertheless, we show that the Marchenko method imposes a slightly weaker form of the monotonicity assumption because it does not rely on event-based multiple prediction. Another challenge arises from the initial estimate that is required by the Marchenko method. In the acoustic case, this initial estimate can be as simple as a direct transmission from the recording surface to the redatuming level. In the presence of several wave-modes, an acoustic direct transmission generalizes to a so-called forward-scattered transmission, which is not a single event but a wavefield with a finite temporal duration. Former formulations of the elastodynamic Marchenko method require this forward-scattered transmission as an initial estimate. However, in practice, this initial estimate is often unknown. We present an alternative formulation of the elastodynamic Marchenko method that simplifies the initial estimate to a trivial one. This approach replaces the inverse transmission, which is often referred to as a focusing function, by a so-called backpropagated focusing function. This strategy allows us to remove internal multiples, however, unwanted forward-scattered waves persist in the data. This insight suggests that forward-scattered waves cannot be predicted by the Marchenko method: either they are provided as prior knowledge, or they remain unaddressed. The remaining forward-scattered waves may be eliminated by exploiting minimum-phase behavior as additional constraint. This approach is inspired by recent developments of the acoustic Marchenko method that… Advisors/Committee Members: Wapenaar, C.P.A., Delft University of Technology.

Subjects/Keywords: Marchenko; de-multiple; inverse scattering; elastodynamic waves; multiples

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APA (6^th Edition):

Reinicke Urruticoechea, C. (2020). Elastodynamic Marchenko inverse scattering: A multiple-elimination strategy for imaging of elastodynamic seismic reflection data. (Doctoral Dissertation). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; 2122e7cc-0f07-40af-88cd-b5b789974562 ; 10.4233/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:isbn:978-94-6384-111-5 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562

Chicago Manual of Style (16^th Edition):

Reinicke Urruticoechea, C. “Elastodynamic Marchenko inverse scattering: A multiple-elimination strategy for imaging of elastodynamic seismic reflection data.” 2020. Doctoral Dissertation, Delft University of Technology. Accessed April 13, 2021. http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; 2122e7cc-0f07-40af-88cd-b5b789974562 ; 10.4233/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:isbn:978-94-6384-111-5 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562.

MLA Handbook (7^th Edition):

Reinicke Urruticoechea, C. “Elastodynamic Marchenko inverse scattering: A multiple-elimination strategy for imaging of elastodynamic seismic reflection data.” 2020. Web. 13 Apr 2021.

Vancouver:

Reinicke Urruticoechea C. Elastodynamic Marchenko inverse scattering: A multiple-elimination strategy for imaging of elastodynamic seismic reflection data. [Internet] [Doctoral dissertation]. Delft University of Technology; 2020. [cited 2021 Apr 13]. Available from: http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; 2122e7cc-0f07-40af-88cd-b5b789974562 ; 10.4233/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:isbn:978-94-6384-111-5 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562.

Council of Science Editors:

Reinicke Urruticoechea C. Elastodynamic Marchenko inverse scattering: A multiple-elimination strategy for imaging of elastodynamic seismic reflection data. [Doctoral Dissertation]. Delft University of Technology; 2020. Available from: http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; 2122e7cc-0f07-40af-88cd-b5b789974562 ; 10.4233/uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; urn:isbn:978-94-6384-111-5 ; urn:NBN:nl:ui:24-uuid:2122e7cc-0f07-40af-88cd-b5b789974562 ; http://resolver.tudelft.nl/uuid:2122e7cc-0f07-40af-88cd-b5b789974562

University of South Carolina

7. Patra, Subir. Ultrasonic Analysis and Tools for Quantitative Material State Awarness of Engineered Materials.

Degree: PhD, Mechanical Engineering, 2018, University of South Carolina

URL: https://scholarcommons.sc.edu/etd/5057

► The objective of this research is to devise new methods and tools to generate real time awareness of the material state of composite and… (more)

▼ The objective of this research is to devise new methods and tools to generate real time awareness of the material state of composite and metallic structures through ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) at its very early stage of failure. To device new methodology it is also important to verify the method through virtual experiments and hence computational NDE is getting popular in the recent years. In this thesis, while experimental methodology is developed to understand the material state at its early stage of failure, a new peridynamic based Peri-Elastodynamic (PED) computational method is also developed for virtual NDE and SHM experiments. In the experimental part, material state awareness through precursor damage quantification is proposed for composite materials and in the predictive part modelling of ultrasonic wave propagation in the engineered materials is developed. Symbiotic information fusion between the Guided Coda Wave Interferometry (CWI) and Quantitative Ultrasonic Image Correlation (QUIC) was devised for the awareness and the quantification of the precursor damage state in composites. The proposed research work is divided into two major parts a) Experimental and b) Computational. a) Experimental: In composite materials, the precursor damages (for example matrix cracking, microcracks, voids, fiber micro-buckling, local fiber breakage, local debonding, etc.) are insensitive to the low-frequency ultrasonic NDE or Structural Health Monitoring (SHM) (~100–~500 kHz) methods. Overcoming this barrier, an online method using the later part of the guided wave signal, which is often neglected is proposed for the precursor damage quantification. Although the first-arrival wave packets that contain the fundamental guided Lamb wave modes are unaltered, the following part of the wave packets however carry significant information about the precursor events with predictable phase shifts. The Cross-correlation and Taylor-series-based modified CWI technique is proposed to quantify the stretch parameter to compensate the phase shifts in the coda wave as a result of precursor damage in composites. The results are thoroughly validated with newly formulated high frequency (>~25MHz) QUIC method. The proposed process is validated and verified with American Society of Testing of Materials (ASTM) standards woven composite-fiber-reinforced-laminate specimens (CFRP). Both online CWI and offline QUIC was performed to prove the feasibility and reliability of the proposed precursor damage quantification process. Visual proof of the precursor events is provided from the digital micro optical microscopy and scanning electron microscopy. Additionally, acoustic-nonlinearity of analysis Lamb wave propagation was employed to investigate, stress-relaxation phenomena in composites. Fatigue loading on composite specimens followed by relaxation experiments were conducted to examine influence of damage and relaxation on acoustic-nonlinearity. It was observed that the… Advisors/Committee Members: Sourav Banerjee.

Subjects/Keywords: Engineering; Mechanical Engineering; nondestructive evaluation (NDE); structural health monitoring (SHM); peridynamic based Peri-Elastodynamic (PED) computational method

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

APA (6^th Edition):

Patra, S. (2018). Ultrasonic Analysis and Tools for Quantitative Material State Awarness of Engineered Materials. (Doctoral Dissertation). University of South Carolina. Retrieved from https://scholarcommons.sc.edu/etd/5057

Chicago Manual of Style (16^th Edition):

Patra, Subir. “Ultrasonic Analysis and Tools for Quantitative Material State Awarness of Engineered Materials.” 2018. Doctoral Dissertation, University of South Carolina. Accessed April 13, 2021. https://scholarcommons.sc.edu/etd/5057.

MLA Handbook (7^th Edition):

Patra, Subir. “Ultrasonic Analysis and Tools for Quantitative Material State Awarness of Engineered Materials.” 2018. Web. 13 Apr 2021.

Vancouver:

Patra S. Ultrasonic Analysis and Tools for Quantitative Material State Awarness of Engineered Materials. [Internet] [Doctoral dissertation]. University of South Carolina; 2018. [cited 2021 Apr 13]. Available from: https://scholarcommons.sc.edu/etd/5057.

Council of Science Editors:

Patra S. Ultrasonic Analysis and Tools for Quantitative Material State Awarness of Engineered Materials. [Doctoral Dissertation]. University of South Carolina; 2018. Available from: https://scholarcommons.sc.edu/etd/5057

Iowa State University

8. Gurrala, Praveen. Full-wave modeling of ultrasonic scattering for non-destructive evaluation.

Degree: 2020, Iowa State University

URL: https://lib.dr.iastate.edu/etd/18133

► The physical modeling and simulation of nondestructive evaluation (NDE) measurements has a major role in the advancement of NDE and structural health monitoring (SHM). In… (more)

▼ The physical modeling and simulation of nondestructive evaluation (NDE) measurements has a major role in the advancement of NDE and structural health monitoring (SHM). In ultrasonic NDE (UNDE) simulations, evaluating the scattering of ultrasound by defects is a computationally-intensive process. Many UNDE system models treat the scattering process using exact analytical methods or high-frequency approximations such as the Kirchhoff approximation (KA) to make the simulation effort tractable. These methods naturally have a limited scope. This thesis aims to supplement the existing scattering models with fast and memory-efficient full-wave models that are based on the boundary element method (BEM). For computational efficiency, such full-wave models should be applied only to those problems wherein the existing approximation methods are not suitable. Therefore, the adequacy of different scattering models for representing various test scenarios has to be studied. Although analyzing scattering models by themselves is helpful, their true adequacy is revealed only when they are combined with models of other elements of the NDE system, and the resulting predictions are evaluated against measurements. Very few comprehensive studies of this nature exist, particularly for full-wave scattering models. To fill this gap, two different scattering models – the KA and a boundary-element method – are integrated into a UNDE system model in this work, and their predictions for standard measurement outputs are compared with experimental data for various benchmark problems. This quantitative comparison serves as a guideline for selecting between the KA and full-wave scattering models for performing UNDE simulations. In accordance with theoretical expectations, the KA is shown to be inappropriate for modeling penetrable (inclusion-type) defects and non-specular scattering, such as diffraction from thin cracks above certain angles of incidence. A key challenge to the use of full-wave scattering methods in UNDE system models is the high computational cost incurred during simulations. Whereas the development of fast finite element methods (FEM) has inspired various applications of the FEM for ultrasound modeling in 3D heterogeneous and anisotropic media, very few applications of the BEM exist despite the progress in accelerated BEMs for elastodynamics. The BEM is highly efficient for modeling scattering from arbitrary shaped 3D defects in homogeneous isotropic media due to a reduction in the dimensionality of the scattering problem, and this potential has not been exploited for UNDE. Therefore, building on recent developments, this work proposes a fast and memory-efficient implementation of the BEM for elastic-wave scattering in UNDE applications. This method features three crucial elements that provide robustness and fast convergence. They include the use of (1) high-order discretization methods for fast convergence, (2) the combined-field integral equation (CFIE) formulation for overcoming the fictitious eigenfrequency problem, and (3) the…

Subjects/Keywords: Boundary Element Method; Elastodynamic Scattering; Fast Multipole Method; High-order BEM; Hypersingular Boundary Integral Equation; Ultrasonic Nondestructive Evaluation

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

APA (6^th Edition):

Gurrala, P. (2020). Full-wave modeling of ultrasonic scattering for non-destructive evaluation. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/18133

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):

Gurrala, Praveen. “Full-wave modeling of ultrasonic scattering for non-destructive evaluation.” 2020. Thesis, Iowa State University. Accessed April 13, 2021. https://lib.dr.iastate.edu/etd/18133.

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

MLA Handbook (7^th Edition):

Gurrala, Praveen. “Full-wave modeling of ultrasonic scattering for non-destructive evaluation.” 2020. Web. 13 Apr 2021.

Vancouver:

Gurrala P. Full-wave modeling of ultrasonic scattering for non-destructive evaluation. [Internet] [Thesis]. Iowa State University; 2020. [cited 2021 Apr 13]. Available from: https://lib.dr.iastate.edu/etd/18133.

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

Council of Science Editors:

Gurrala P. Full-wave modeling of ultrasonic scattering for non-destructive evaluation. [Thesis]. Iowa State University; 2020. Available from: https://lib.dr.iastate.edu/etd/18133

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

Iowa State University

9. Chen, Kun. Boundary integral equation method for electromagnetic and elastic waves.

Degree: 2016, Iowa State University

URL: https://lib.dr.iastate.edu/etd/15679

► In this thesis, the boundary integral equation method (BIEM) is studied and applied to electromagnetic and elastic wave problems. First of all, a spectral domain… (more)

▼ In this thesis, the boundary integral equation method (BIEM) is studied and applied to electromagnetic and elastic wave problems. First of all, a spectral domain BIEM called the spectral domain approach is employed for full wave analysis of metal strip grating on grounded dielectric slab (MSG-GDS) and microstrips shielded with either perfect electric conductor (PEC) or perfect magnetic conductor (PMC) walls. The modal relations between these structures are revealed by exploring their symmetries. It is derived analytically and validated numerically that all the even and odd modes of the latter two (when they are mirror symmetric) find their correspondence in the modes of metal strip grating on grounded dielectric slab when the phase shift between adjacent two unit cells is 0 or π. Extension to non-symmetric case is also made. Several factors, including frequency, grating period, slab thickness and strip width, are further investigated for their impacts on the effective permittivity of the dominant mode of PEC/PMC shielded microstrips. It is found that the PMC shielded microstrip generally has a larger wave number than the PEC shielded microstrip. Secondly, computational aspects of the layered medim doubly periodic Green's function (LMDPGF) in matrix-friendly formulation (MFF) are investigated. The MFF for doubly periodic structures in layered medium is derived, and the singularity of the periodic Green's function when the transverse wave number equals zero in this formulation is analytically extracted. A novel approach is proposed to calculate the LMDPGF, which makes delicate use of several techniques including factorization of the Green's function, generalized pencil of function (GPOF) method and high order Taylor expansion to derive the high order asymptotic expressions, which are then evaluated by newly derived fast convergent series. This approach exhibits robustness, high accuracy and fast and high order convergence; it also allows fast frequency sweep for calculating Brillouin diagram in eigenvalue problem and for normal incidence in scattering problem. Thirdly, a high order Nyström method is developed for elastodynamic scattering that features a simple local correction scheme due to a careful choice of basis functions. A novel simple and efficient singularity subtraction scheme and a new effective near singularity subtraction scheme are proposed for performing singular and nearly singular integrals on curvilinear triangular elements. The robustness, high accuracy and high order convergence of the proposed approached are demonstrated by numerical results. Finally, the multilevel fast multipole algorithm (MLFMA) is applied to accelerate the proposed Nyström method for solving large scale problems. A Formulation that can significantly reduce the memory requirements in MLFMA is come up with. Numerical examples in frequency domain are first given to show the accuracy and efficiency of the algorithm. By solving at multiple frequencies and performing the inverse Fourier transform, time domain results are…

Subjects/Keywords: Elastodynamic scattering; Electromagnetic scattering; High order method; Integral equation method; Multilevel fast multipole algorithm; Periodic structure; Acoustics, Dynamics, and Controls; Electrical and Electronics; Electromagnetics and Photonics

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APA (6^th Edition):

Chen, K. (2016). Boundary integral equation method for electromagnetic and elastic waves. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/15679

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, Kun. “Boundary integral equation method for electromagnetic and elastic waves.” 2016. Thesis, Iowa State University. Accessed April 13, 2021. https://lib.dr.iastate.edu/etd/15679.

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, Kun. “Boundary integral equation method for electromagnetic and elastic waves.” 2016. Web. 13 Apr 2021.

Vancouver:

Chen K. Boundary integral equation method for electromagnetic and elastic waves. [Internet] [Thesis]. Iowa State University; 2016. [cited 2021 Apr 13]. Available from: https://lib.dr.iastate.edu/etd/15679.

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

Council of Science Editors:

Chen K. Boundary integral equation method for electromagnetic and elastic waves. [Thesis]. Iowa State University; 2016. Available from: https://lib.dr.iastate.edu/etd/15679

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

10. Athale, Madhura, Athale. Elastodynamic Characterization of Material Interfaces Using Spring Models.

Degree: MS, Mechanical Engineering, 2017, The Ohio State University

URL: http://rave.ohiolink.edu/etdc/view?acc_num=osu1503262542890538

► Understanding wave phenomena at material interfaces is an important problem in non-destructive evaluation / material characterization. Modeling the behavior of the interface presents interesting opportunities… (more)

Subjects/Keywords: Mechanical Engineering; Elastodynamic Characterization; Material Interfaces; Spring Models

…elastodynamic wave propagation in two linear elastic isotropic joined half spaces with a graded…

11 more images…

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APA (6^th Edition):

Athale, Madhura, A. (2017). Elastodynamic Characterization of Material Interfaces Using Spring Models. (Masters Thesis). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1503262542890538

Chicago Manual of Style (16^th Edition):

Athale, Madhura, Athale. “Elastodynamic Characterization of Material Interfaces Using Spring Models.” 2017. Masters Thesis, The Ohio State University. Accessed April 13, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503262542890538.

MLA Handbook (7^th Edition):

Athale, Madhura, Athale. “Elastodynamic Characterization of Material Interfaces Using Spring Models.” 2017. Web. 13 Apr 2021.

Vancouver:

Athale, Madhura A. Elastodynamic Characterization of Material Interfaces Using Spring Models. [Internet] [Masters thesis]. The Ohio State University; 2017. [cited 2021 Apr 13]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1503262542890538.

Council of Science Editors:

Athale, Madhura A. Elastodynamic Characterization of Material Interfaces Using Spring Models. [Masters Thesis]. The Ohio State University; 2017. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1503262542890538

11. Putta, Sriram. Elastodynamic Numerical Characterization of Adhesive Interfaces Using Spring and Cohesive Zone Models.

Degree: MS, Mechanical Engineering, 2019, The Ohio State University

URL: http://rave.ohiolink.edu/etdc/view?acc_num=osu156338398610629

► Elastodynamic characterization of adhesive layers at bimaterial interfaces is important in the field of adhesive bonding. The present thesis is an investigation of the mechanical… (more)

Subjects/Keywords: Mechanical Engineering; Elastodynamic Characterization; Material Interfaces; Spring Models; BEM formulation

…methodology using BEM to investigate the elastodynamic response of bimaterial adhesive interfaces… …reciprocal theorem for elastodynamics, which relates two elastodynamic states, defined by the… …elastodynamic states in equation 2.11 can be considered to be governed by ∗ σijk,j − ρu¨ik ∗ = −δik δ…

10 more images…

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APA (6^th Edition):

Putta, S. (2019). Elastodynamic Numerical Characterization of Adhesive Interfaces Using Spring and Cohesive Zone Models. (Masters Thesis). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu156338398610629

Chicago Manual of Style (16^th Edition):

Putta, Sriram. “Elastodynamic Numerical Characterization of Adhesive Interfaces Using Spring and Cohesive Zone Models.” 2019. Masters Thesis, The Ohio State University. Accessed April 13, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu156338398610629.

MLA Handbook (7^th Edition):

Putta, Sriram. “Elastodynamic Numerical Characterization of Adhesive Interfaces Using Spring and Cohesive Zone Models.” 2019. Web. 13 Apr 2021.

Vancouver:

Putta S. Elastodynamic Numerical Characterization of Adhesive Interfaces Using Spring and Cohesive Zone Models. [Internet] [Masters thesis]. The Ohio State University; 2019. [cited 2021 Apr 13]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu156338398610629.

Council of Science Editors:

Putta S. Elastodynamic Numerical Characterization of Adhesive Interfaces Using Spring and Cohesive Zone Models. [Masters Thesis]. The Ohio State University; 2019. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu156338398610629

Université Paris-Sud – Paris XI

12. Burel, Aliénor. Contributions à la simulation numérique en élastodynamique : découplage des ondes P et S, modèles asymptotiques pour la traversée de couches minces : Numerical methods for elastic wave propagation : P and S wave decoupling, asymptotic models for thin layers.

Degree: Docteur es, Mathématiques appliquées, 2014, Université Paris-Sud – Paris XI

URL: http://www.theses.fr/2014PA112140

►

Cette thèse porte sur la modélisation des ondes élastodynamiques dans deux situations particulières qui pénalisent les méthodes numériques utilisées pour simuler ces phénomènes. Dans la… (more)

▼

Cette thèse porte sur la modélisation des ondes élastodynamiques dans deux situations particulières qui pénalisent les méthodes numériques utilisées pour simuler ces phénomènes. Dans la première partie, on se place dans le cas où les ondes de pression (ondes P) se propagent à une vitesse beaucoup plus grande que celle des ondes de cisaillement (ondes S). Les modèles numériques utilisés habituellement pour traiter cette configuration sont pénalisés par la plus petite vitesse qui dicte le choix du pas du schéma. Nous proposons ici un schéma qui découple numériquement, dans le volume, les ondes P et les ondes S, pour deux types de conditions de bord en utilisant la décomposition du déplacement en potentiels de Lamé, en deux dimensions. Les conditions aux limites de Dirichlet homogènes, qui sont des conditions essentielles pour la formulation classique en déplacement, deviennent des conditions naturelles, mais non standard, pour la formulation en potentiels qui se présente comme un système de deux équations d’ondes couplées par les conditions aux limites. Cette formulation préserve une énergie équivalente à l'énergie élastodynamique. Nous construisons un schéma éléments finis en espace et utilisons un thêta-schéma en temps sur les termes de bord afin de ne pas pénaliser la CFL et mener à une condition sur le pas de temps indépendante des termes de couplage au bord. Ce schéma préserve une énergie discrète. Le cas des conditions de surface libre mène à des instabilités. Nous les avons traitées comme des perturbations des conditions de Dirichlet, ce qui permet d'obtenir de bons résultats dans le domaine fréquentiel mais donne naissance à de sévères instabilités après discrétisation en temps. La seconde partie de la thèse est consacrée à la construction, l'analyse et la validation de conditions de transmission effectives (CTE) à travers une couche mince de matériau homogène et isotrope d'épaisseur constante h. Ici, la finesse de la couche affecte les schémas explicites usuels car le maillage de la couche avec des éléments suffisamment petits entraîne une diminution analogue du pas de temps critique via la condition CFL, tandis que l'on espère avec les CTE obtenir un pas de temps indépendant de l'épaisseur de la couche. Une analyse complète du cas de la bande mince rectiligne est donnée en deux et trois dimensions. Les conditions obtenues sont stables via la conservation d'une énergie et l'ordre de l'erreur d'approximation par rapport à l'épaisseur de la couche pour les conditions d'ordre 2 est de O(h³). Des résultats numériques sont présentés pour les configurations bi et tridimensionnelles, ils valident les résultats de stabilité, d'estimation d'erreur et de conditions de stabilité de schémas en temps proposés, qui sont des modifications du schéma explicite utilisé en l'absence de couche mince. Enfin, le traitement d'une couche curviligne est effectué dans le cas bidimensionnel. Sa stabilité est à nouveau vérifiée par conservation d'énergie et des résultats numériques sont également présentés.

This work is dedicated to…

Advisors/Committee Members: Joly, Patrick (thesis director), Bonnet, Marc (thesis director).

Subjects/Keywords: Ondes élastodynamiques; Ondes de pression et de cisaillement; Couches minces; Schémas préservant une énergie; Stabilité numérique; Éléments finis d'ordre élevé; Conditions de transmission équivalentes; Elastodynamic waves; Pressure and shear waves; Thin layers; Energy-preserving schemes; Numerical stability; High order finite elements; Equivalent transmission conditions

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

APA (6^th Edition):

Burel, A. (2014). Contributions à la simulation numérique en élastodynamique : découplage des ondes P et S, modèles asymptotiques pour la traversée de couches minces : Numerical methods for elastic wave propagation : P and S wave decoupling, asymptotic models for thin layers. (Doctoral Dissertation). Université Paris-Sud – Paris XI. Retrieved from http://www.theses.fr/2014PA112140

Chicago Manual of Style (16^th Edition):

Burel, Aliénor. “Contributions à la simulation numérique en élastodynamique : découplage des ondes P et S, modèles asymptotiques pour la traversée de couches minces : Numerical methods for elastic wave propagation : P and S wave decoupling, asymptotic models for thin layers.” 2014. Doctoral Dissertation, Université Paris-Sud – Paris XI. Accessed April 13, 2021. http://www.theses.fr/2014PA112140.

MLA Handbook (7^th Edition):

Burel, Aliénor. “Contributions à la simulation numérique en élastodynamique : découplage des ondes P et S, modèles asymptotiques pour la traversée de couches minces : Numerical methods for elastic wave propagation : P and S wave decoupling, asymptotic models for thin layers.” 2014. Web. 13 Apr 2021.

Vancouver:

Burel A. Contributions à la simulation numérique en élastodynamique : découplage des ondes P et S, modèles asymptotiques pour la traversée de couches minces : Numerical methods for elastic wave propagation : P and S wave decoupling, asymptotic models for thin layers. [Internet] [Doctoral dissertation]. Université Paris-Sud – Paris XI; 2014. [cited 2021 Apr 13]. Available from: http://www.theses.fr/2014PA112140.

Council of Science Editors:

Burel A. Contributions à la simulation numérique en élastodynamique : découplage des ondes P et S, modèles asymptotiques pour la traversée de couches minces : Numerical methods for elastic wave propagation : P and S wave decoupling, asymptotic models for thin layers. [Doctoral Dissertation]. Université Paris-Sud – Paris XI; 2014. Available from: http://www.theses.fr/2014PA112140

University of Illinois – Urbana-Champaign

13. Abedi, Reza. Spacetime damage-based cohesive model for elastodynamic fracture with dynamic contact.

Degree: PhD, 0242, 2010, University of Illinois – Urbana-Champaign

URL: http://hdl.handle.net/2142/15502

► Dynamic material failure is important in a number of scientific and engineering applications and a variety of numerical methods for its modeling have been proposed.… (more)

▼ Dynamic material failure is important in a number of scientific and engineering applications and a variety of numerical methods for its modeling have been proposed. This thesis presents the formulation and implementation of an interfacial-damage, cohesive-fracture model, including contact and friction effects, for dynamic failure of brittle materials. The model is implemented within a spacetime discontinuous Galerkin (SDG) finite element method. An adaptive meshing procedure generates %When implemented on suitable spacetime grids that satisfy a special causality constraint to enable an efficient patch-by-patch, advancing-front solution scheme with O(N) computational complexity. Per-element balance properties, local adaptive operations, and the use of Riemann fluxes provide to the SDG method the extreme accuracy and efficiency required to solve multiscale fracture problems. A dimensional analysis of linear elastodynamics, with extensions to fracture models based on cohesive traction – separation laws, supports the formulation. The problem is formulated and analyzed using differential forms and the exterior calculus in spacetime. The analysis demonstrates that the velocity scalings implied by the spatial and temporal coordinate scalings and by the scalings of the material properties must be identical to obtain a self-similar scaling of an elastodynamic process. The use of differential forms reveals intrinsic structure and relations between the spacetime mechanics fields which are otherwise obscured by conventional tensorial analysis. For example, only four distinct scalings are required to define a scaled elastodynamic process when we work directly with forms, while eight are required when tensorial analysis is used. In the context of dynamic cohesive fracture, the analysis shows that, among the nondimensional variables, the ratio of the stress-loading scale to the cohesive strength is proportional to the ratio of the radius of the singularity-dominant zone from Linear Elastodynamic Fracture Mechanics (LEFM), to the cohesive-process-zone size. These ratios are, in turn, useful indicators of whether the small-scale-yielding caveat of LEFM is satisfied. A novel continuum formulation of the linear elastodynamic contact problem also supports the SDG finite element model. In contrast to previous contact models that invoke quasi-static contact conditions, the proposed model enforces dynamic contact conditions by prescribing momentum flux and compatibility conditions obtained from the local Riemann problems for bonded, separation, contact – stick, and contact – slip modes. This approach preserves the characteristic structure of the underlying equations at the contact interface, a property that is lacking in previous formulations. The fully-bonded and contact – stick conditions are identical, as expected, so the non-penetration and tangential slip constraints are treated exactly in the new continuum formulation. Furthermore, the direction of the tangential contact traction (friction) is shown to be continuous through… Advisors/Committee Members: Haber, Robert B. (advisor), Haber, Robert B. (Committee Chair), Paulino, Glaucio H. (committee member), Gioia, Gustavo (committee member), Duarte, C. Armando (committee member).

Subjects/Keywords: fracture; finite element methods; spacetime discontinuous; cohesive models; interfacial damage; Riemann solution; dimensional analysis; Linear Elastodynamic Fracture Mechanics (LEFM)

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APA (6^th Edition):

Abedi, R. (2010). Spacetime damage-based cohesive model for elastodynamic fracture with dynamic contact. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/15502

Chicago Manual of Style (16^th Edition):

Abedi, Reza. “Spacetime damage-based cohesive model for elastodynamic fracture with dynamic contact.” 2010. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed April 13, 2021. http://hdl.handle.net/2142/15502.

MLA Handbook (7^th Edition):

Abedi, Reza. “Spacetime damage-based cohesive model for elastodynamic fracture with dynamic contact.” 2010. Web. 13 Apr 2021.

Vancouver:

Abedi R. Spacetime damage-based cohesive model for elastodynamic fracture with dynamic contact. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2010. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2142/15502.

Council of Science Editors:

Abedi R. Spacetime damage-based cohesive model for elastodynamic fracture with dynamic contact. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2010. Available from: http://hdl.handle.net/2142/15502

Universidade Estadual de Campinas

14. Rossi, Eliana Maria de Mello Francisco, 1955-. Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos.

Degree: Faculdade de Engenharia Civil, Arquitetura e Urbanismo; Programa de Pós-Graduação em Engenharia Civil, 2007, Universidade Estadual de Campinas

URL: ROSSI, Eliana Maria de Mello Francisco. Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos. 2007. 229p. Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/257815>. Acesso em: 9 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/257815

►

Orientador: Isaias Vizotto

Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo

Made available in DSpace on 2018-08-09T23:33:25Z (GMT). No.… (more)

▼

Orientador: Isaias Vizotto

Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo

Made available in DSpace on 2018-08-09T23:33:25Z (GMT). No. of bitstreams: 1 Rossi_ElianaMariadeMelloFrancisco_D.pdf: 5414575 bytes, checksum: a7297eb374b268f3bf484ab58acbe942 (MD5) Previous issue date: 2007

Resumo: Neste trabalho é estudado o problema da elastodinâmica translento através da formulação do Método dos Elementos de Contorno (MEC) e da formulação combinada desse método com o Método dos Elementos Finítos (MEF). O estudo dos problemas governados por uma equação de campo vetorlal através do Método dos Elementos de Contorno, com a solução fundamental de Kelvin, resulta numa de domínio que tem sido tratada através de duas técnicas. A primeira desenvolve a Integração no domínio por células e permite determinar a contribuição Inercial dos nós do contorno e dos pontos internos. A segunda, conhecida como Reciprocidade Dual, transforma a de domínio em uma série de integrais de contorno. Foi desenvolvida uma tecnica para a manipulação das matrizes globais do sistema de equações obtido através do Método dos Elementos de Contorno, que permitiu resolver o problema da dependência linear de linhas e colunas decorrente da análise de regiões com cantos ou angulosidades. O algorítmo criado para condensação dos nós foi testado para o caso estático e dinâmico. Diversos exemplos são apresentados para os dois métodos e para o acoplamnento. Os resultados obtidos foram comparados com as analíticas disponíveis ou então com as soluções provenientes da aplicação de outros métodos numéricos

In this work is studied the problem of olastodynamic transient through the farmulation of Boundary Element Method (BEM) and the formulation of this method combined with the Finite Elements Method The study of the problems governed by an oquation of vector fieid through the BEM with Kevin fundamental solution, comes up in domain that has been handled by two techniques. The first develops the integration in the domain by cells and determines the nodes contribution of the inertíal rame and internal points. The second, known as Dual Recíprocíty, transforms the domain integral in boundary integrais. It was developed a tochnique for handling the matrix of the system of equations obtained by BEM, whích It solves the problem of the linear dependence of rows and Golumns arlsing frem the analysls of regions wlth comers ar sharp boundaries. The algorithm created for node condensation has been tested for statle and dynamie cases. Several examples are presented using the both methods and the coupling technique. The results obtained were comparod with the anal.ytical solutions avaílable or wíth solutions obtained from other numerícal methods

Doutorado

Estruturas

Doutor em Engenharia Civil

Advisors/Committee Members: UNIVERSIDADE ESTADUAL DE CAMPINAS, Vizotto, Isaias, 1955-, Moreira, Loir Afonso, Filho, Athail Rangel Pulino, Arcaro, Vinicius Fernando, Mascia, Nilson Tadeu.

Subjects/Keywords: Métodos de elementos de contorno; Método dos elementos finitos; Dinâmica; Estática; Boundary elements methods; Dual reciprocity; Elastodynamic; Coupling of finite

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APA (6^th Edition):

Rossi, Eliana Maria de Mello Francisco, 1. (2007). Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos. (Doctoral Dissertation). Universidade Estadual de Campinas. Retrieved from ROSSI, Eliana Maria de Mello Francisco. Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos. 2007. 229p. Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/257815>. Acesso em: 9 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/257815

Chicago Manual of Style (16^th Edition):

Rossi, Eliana Maria de Mello Francisco, 1955-. “Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos.” 2007. Doctoral Dissertation, Universidade Estadual de Campinas. Accessed April 13, 2021. ROSSI, Eliana Maria de Mello Francisco. Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos. 2007. 229p. Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/257815>. Acesso em: 9 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/257815.

MLA Handbook (7^th Edition):

Rossi, Eliana Maria de Mello Francisco, 1955-. “Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos.” 2007. Web. 13 Apr 2021.

Vancouver:

Rossi, Eliana Maria de Mello Francisco 1. Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos. [Internet] [Doctoral dissertation]. Universidade Estadual de Campinas; 2007. [cited 2021 Apr 13]. Available from: ROSSI, Eliana Maria de Mello Francisco. Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos. 2007. 229p. Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/257815>. Acesso em: 9 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/257815.

Council of Science Editors:

Rossi, Eliana Maria de Mello Francisco 1. Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos. [Doctoral Dissertation]. Universidade Estadual de Campinas; 2007. Available from: ROSSI, Eliana Maria de Mello Francisco. Analise de problemas elastodinamicos atraves do metodo dos elementos de contorno e do acoplamento elementos de contorno e elementos finitos. 2007. 229p. Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/257815>. Acesso em: 9 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/257815

Universidade Estadual de Campinas

15. Barros, Renato Marques de. Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos.

Degree: Faculdade de Engenharia Mecânica; Programa de Pós-Graduação em Engenharia Mecânica, 1996, Universidade Estadual de Campinas

URL: BARROS, Renato Marques de. Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos. 1996. 190f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/263941>. Acesso em: 21 jul. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/263941

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Orientador: Euclides de Mesquita Neto

Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica

Made available in DSpace on 2018-07-21T18:42:03Z (GMT). No. of… (more)

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Orientador: Euclides de Mesquita Neto

Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica

Made available in DSpace on 2018-07-21T18:42:03Z (GMT). No. of bitstreams: 1 Barros_RenatoMarquesde_M.pdf: 29996661 bytes, checksum: 4ad59a26788d8dfab7be1c94a4ccce46 (MD5) Previous issue date: 1996

Resumo: Este trabalho apresenta uma revisão e uma implementação numérica do método dos elementos finitos (MEF) no qual foram incluídos os chamados ¿elementos infinitos¿ visando a modelagem da condição de radiação de Sommerfeld ou do amortecimento geométrico em meios contínuos (visco-) elastodinâmico sem regime estacionário e cujos domínios são ilimitados. Após uma revisão geral sobre os tipos de elementos infinitos, o trabalho aborda formulações e implementações de elementos infinitos unidimensionais. Em particular são discutidos os elementos de decaimento exponencial e de mapeamento. Suas propriedades são investigadas através da modelagem da propagação de ondas em colunas ilimitadas de seção transversal variável, cônica e exponencial. Uma análise dos elementos infinitos propostos para tratamento de problemas multidimensionais segue à revisão da teoria da propagação de ondas em meios (visco-)elastodinâmicos. A análise bidimensional contida no trabalho utiliza um elemento de decaimento exponencial. As propriedades deste elemento são discutidas através da simulação da dinâmica de fundações rígidas, superficiais e engastadas, interagindo com solos modelados como semi-espaço, homogêneo e estratificado. Estas análises, de caráter inovador, revelam que o elemento escolhido é capaz de reproduzir acuradamente o comportamento de ondas não refletidas, se propagando ao infinito, ou seja a condição de radiação ou amortecimento geométrico

The present thesis reports an overview and a numerical implementation of the Finite Element Method (FEM) in wich the so called ¿infinite elements¿ are included to model the Sommerfeld's radiation condition or the geometric damping in the stationary response of unbounded (visco-) elastic domains. Initially one dimensional infinite elements are formulated and implemented. The properties of the exponencial decay type and the mapping elements are investigated by means of the stationary response of semi-infinitecolumns of variable cross-section, conical and exponential. In the sequence the main issues of multidimensional (visco-) elastic wave propagation are presented, followed by a revision of the proposed infinite elements for two-and three dimensional analysis. For the two dimensional case a exponential decay type element is formulated and implemented. The properties of the 2D element are discussed on hand of the dynamic analysis of rigid foundations, surface and embeded, interacting with homogeneous and layered half-spaces. This rather innovative analysis reveals that the considered element is able to model accurately the rdiation condition on homogeneous and stratified unbounded domains

Mestrado

Mecanica dos Sólidos e Projeto Mecanico

Mestre em…

Advisors/Committee Members: UNIVERSIDADE ESTADUAL DE CAMPINAS, Mesquita Neto, Euclides de, 1956-, Neto, Euclides de Mesquita, Pavanello, Renato, Devloo, Philippe Remy Bernard.

Subjects/Keywords: Método dos elementos finitos; Propagação de ondas; Viscoelasticidade; Fundações (Engenharia); Finite elements; Infinite elements; Wave propagation; Visco-elastodynamic; Foundations

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

APA (6^th Edition):

Barros, R. M. d. (1996). Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos. (Masters Thesis). Universidade Estadual de Campinas. Retrieved from BARROS, Renato Marques de. Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos. 1996. 190f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/263941>. Acesso em: 21 jul. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/263941

Chicago Manual of Style (16^th Edition):

Barros, Renato Marques de. “Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos.” 1996. Masters Thesis, Universidade Estadual de Campinas. Accessed April 13, 2021. BARROS, Renato Marques de. Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos. 1996. 190f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/263941>. Acesso em: 21 jul. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/263941.

MLA Handbook (7^th Edition):

Barros, Renato Marques de. “Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos.” 1996. Web. 13 Apr 2021.

Vancouver:

Barros RMd. Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos. [Internet] [Masters thesis]. Universidade Estadual de Campinas; 1996. [cited 2021 Apr 13]. Available from: BARROS, Renato Marques de. Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos. 1996. 190f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/263941>. Acesso em: 21 jul. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/263941.

Council of Science Editors:

Barros RMd. Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos. [Masters Thesis]. Universidade Estadual de Campinas; 1996. Available from: BARROS, Renato Marques de. Elementos infinitos para tratamento de problemas da viscoelastodinamica estacionaria pelo metodo dos elementos finitos. 1996. 190f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/263941>. Acesso em: 21 jul. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/263941

16. Dudouit, Yohann. Spatio-temporal refinement using a discontinuous Galerkin approach for elastodynamic in a high performance computing framework : Raffinement spatio-temporel par une approche de Galerkin discontinue en élastodynamique pour le calcul haute performance.

Degree: Docteur es, Mathématiques appliquées et calcul scientifique, 2014, Bordeaux

URL: http://www.theses.fr/2014BORD0248

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Cette thèse étudie le raffinement local de maillage à la fois en espace et en temps pour l’équation de l’elastodynamique du second ordre pour le… (more)

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Cette thèse étudie le raffinement local de maillage à la fois en espace et en temps pour l’équation de l’elastodynamique du second ordre pour le calcul haute performance. L’objectif est de mettre en place des méthodes numériques pour traiter des hétérogénéités de petite taille ayant un impact important sur la propagation des ondes. Nous utilisons une approche par éléments finis de Galerkin discontinus avec pénalisation pour leur flexibilité et facilité de parallélisation. La formulation éléments finis que nous proposons a pour particularité d’être élasto-acoustique, pour pouvoir prendre en compte des hétérogénéités acoustiques de petite taille. Par ailleurs, nous proposons un terme de pénalisation optimisé qui est mieux adapté à l’équation de l’élastodynamique, conduisant en particulier à une meilleure condition CFL. Nous avons aussi amélioré une formulation PML du second ordre pour laquelle nous avons proposé une nouvelle discrétisation temporelle qui rend la formulation plus stable. En tirant parti de la p-adaptivité et des maillages non-conformes des méthodes de Galerkin discontinues combiné à une méthode de pas de temps local, nous avons grandement réduit le coût du raffinement local. Ces méthodes ont été implémentées en C++, en utilisant des techniques de template metaprogramming, au sein d’un code parallèle à mémoire distribuée (MPI) et partagée (OpenMP). Enfin, nous montrons le potentiel de notre approche sur des cas tests de validation et sur des cas plus réalistes avec des milieux présentant des hydrofractures.

This thesis studies local mesh refinement both in time and space for the second order elastodynamic equation in a high performance computing context. The objective is to develop numerical methods to treat small heterogeneities that have global impact on wave propagation. We use an internal penalty discontinuous Galerkin finite element approach for its flexibity and parallelization capabilities. The elasto-acoustic finite element formulation we discuss is elasto-acoustic in order to handle local acoustic heterogeneities. We also propose an optimized penalty term more suited to the elastodynamic equation that results in better CFL condition. We improve a second order PML formulation with an original time discretization that results in a more stable formulation. Using the p-adaptivity and nonconforming mesh capabilities of discontinuous Galerkin methods combined with a local time stepping method, we greatly reduce the high computational cost of local refinements. These methods have been implemented in C++, using template metaprogramming, in a distributed memory (MPI) and shared memory (OpenMP) parallel code. Finally, we show the potential of our methods on validation test cases and on more realistic test cases with medium including hydrofractures.

Advisors/Committee Members: Giraud, Luc (thesis director), Pernet, Sébastien (thesis director).

Subjects/Keywords: Élastodynamique; Schéma hp; Stabilité; IPDG; PML; MPI; OpenMP; Hpc; Hydrofracture; Couplage élasto-acoustique; Pas de temps local; Non-conforme; Maillage cartésien; Raffinement spatio-temporel; Galerkin discontinu; Elastodynamic; Hp scheme; Stability; IPDG; PML; MPI; OpendMP; Hpc; Hydrofracture; Elasto-acoustic coupling; Local time step; Non-conforming; Cartesian mesh; Spatio-temporal refinement; Discontinuous Galerkin

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

APA (6^th Edition):

Dudouit, Y. (2014). Spatio-temporal refinement using a discontinuous Galerkin approach for elastodynamic in a high performance computing framework : Raffinement spatio-temporel par une approche de Galerkin discontinue en élastodynamique pour le calcul haute performance. (Doctoral Dissertation). Bordeaux. Retrieved from http://www.theses.fr/2014BORD0248

Chicago Manual of Style (16^th Edition):

Dudouit, Yohann. “Spatio-temporal refinement using a discontinuous Galerkin approach for elastodynamic in a high performance computing framework : Raffinement spatio-temporel par une approche de Galerkin discontinue en élastodynamique pour le calcul haute performance.” 2014. Doctoral Dissertation, Bordeaux. Accessed April 13, 2021. http://www.theses.fr/2014BORD0248.

MLA Handbook (7^th Edition):

Dudouit, Yohann. “Spatio-temporal refinement using a discontinuous Galerkin approach for elastodynamic in a high performance computing framework : Raffinement spatio-temporel par une approche de Galerkin discontinue en élastodynamique pour le calcul haute performance.” 2014. Web. 13 Apr 2021.

Vancouver:

Dudouit Y. Spatio-temporal refinement using a discontinuous Galerkin approach for elastodynamic in a high performance computing framework : Raffinement spatio-temporel par une approche de Galerkin discontinue en élastodynamique pour le calcul haute performance. [Internet] [Doctoral dissertation]. Bordeaux; 2014. [cited 2021 Apr 13]. Available from: http://www.theses.fr/2014BORD0248.

Council of Science Editors:

Dudouit Y. Spatio-temporal refinement using a discontinuous Galerkin approach for elastodynamic in a high performance computing framework : Raffinement spatio-temporel par une approche de Galerkin discontinue en élastodynamique pour le calcul haute performance. [Doctoral Dissertation]. Bordeaux; 2014. Available from: http://www.theses.fr/2014BORD0248

17. Saulo Faria Almeida Barretto. Análise elastodinâmica de placas através do método dos elementos de contorno com interação solo-estrutura.

Degree: 1995, University of São Paulo

URL: http://www.teses.usp.br/teses/disponiveis/18/18134/tde-24042018-140337/

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A combinação do Método dos Elementos de Contorno e do Método dos Elementos Finitos é o procedimento usualmente empregado na análise da flexão de placas… (more)

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A combinação do Método dos Elementos de Contorno e do Método dos Elementos Finitos é o procedimento usualmente empregado na análise da flexão de placas interagindo com o solo. Usando-se da associação de ambos os métodos pode-se tirar vantagens de cada um deles e, consequentemente, chegar a uma técnica melhorada para tratar com problemas práticos. Contudo, a formulação do MEF não representa bem as tensões e os esforços concentrados ao longo do contorno, que podem ocorrer devido à maior rigidez da placa quando comparada com o meio solo, como a formulação do MEC faz. Por isso, a flexão de placas sobre base elástica é aqui proposta utilizando-se apenas das formulações do MEC, ou seja, tanto os problemas tridimensionais quanto os problemas de placas são tratados pela formulação de contorno para casos elastostáticos e elastodinâmicos. Duas diferentes formas de tratar problemas de flexão elastodinâmica de placas são discutidas, enfatizando possíveis instabilidades numéricas que as duas técnicas podem exibir. Finalmente, depois de propor a combinação dos problemas tridimensional e de placas, os resultados de exemplos numéricos apresentados mostram as vantagens e desvantagens da técnica proposta.

The combination of the boundary element and the finite element methods is the usually employed procedure to analyse plates in the bending interacting with the supporting soil. By using the association of both methods one can take the advantage of each method and consequently reach an improved technique to deal with practical problems. However, the FEM formulation can not represent well the stress and effort concentrations along the boundary, that may occur due to the higher plate stiffness when compared with the soil media, as the BEM technique does. Therefore, the plate bending on elastic foundation is proposed here using only BEM formulations, i.e. both the three-dimensional and the plate problems are formulated by boundary formulations for the elastostatic and elastodynamic cases. Two different ways to deal with the elastodynamic plate bending problem are discussed, emphasizing possible numerical instabilities that those techniques may exhibit. Finally, after proposing the combination of the three-dimensional and plate problems, results of numerical examples presented to show the advantages and disadvantages of the proposed technique.

Advisors/Committee Members: Wilson Sérgio Venturini, Humberto Breves Coda, José Elias Laier, Webe João Mansur, Euclides de Mesquita Neto.

Subjects/Keywords: Interação solo-estrutura; Método dos elementos de contorno; Placas (Estruturas) - Análise elastodinâmica; Placas (Estruturas) - Análise elastostática; Boundary element method; Plates (Structures) - Elastodynamic analysis; Plates (Structures) - Elastostatic analysis; Soil-structure interaction

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

APA (6^th Edition):

Barretto, S. F. A. (1995). Análise elastodinâmica de placas através do método dos elementos de contorno com interação solo-estrutura. (Doctoral Dissertation). University of São Paulo. Retrieved from http://www.teses.usp.br/teses/disponiveis/18/18134/tde-24042018-140337/

Chicago Manual of Style (16^th Edition):

Barretto, Saulo Faria Almeida. “Análise elastodinâmica de placas através do método dos elementos de contorno com interação solo-estrutura.” 1995. Doctoral Dissertation, University of São Paulo. Accessed April 13, 2021. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-24042018-140337/.

MLA Handbook (7^th Edition):

Barretto, Saulo Faria Almeida. “Análise elastodinâmica de placas através do método dos elementos de contorno com interação solo-estrutura.” 1995. Web. 13 Apr 2021.

Vancouver:

Barretto SFA. Análise elastodinâmica de placas através do método dos elementos de contorno com interação solo-estrutura. [Internet] [Doctoral dissertation]. University of São Paulo; 1995. [cited 2021 Apr 13]. Available from: http://www.teses.usp.br/teses/disponiveis/18/18134/tde-24042018-140337/.

Council of Science Editors:

Barretto SFA. Análise elastodinâmica de placas através do método dos elementos de contorno com interação solo-estrutura. [Doctoral Dissertation]. University of São Paulo; 1995. Available from: http://www.teses.usp.br/teses/disponiveis/18/18134/tde-24042018-140337/

18. Wobker, Hilmar. Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems.

Degree: 2010, Technische Universität Dortmund

URL: http://hdl.handle.net/2003/26998

► Bei der Simulation realistischer strukturmechanischer Probleme können Gleichungssysteme mit mehreren hundert Millionen Unbekannten entstehen. Für die effiziente Lösung solcher Systeme sind parallele Multilevel-Methoden unerlässlich, die… (more)

▼ Bei der Simulation realistischer strukturmechanischer Probleme können Gleichungssysteme mit mehreren hundert Millionen Unbekannten entstehen. Für die effiziente Lösung solcher Systeme sind parallele Multilevel-Methoden unerlässlich, die in der Lage sind, die Leistung moderner Hardware-Technologien auszuschöpfen. Die Finite-Elemente- und Löser-Toolbox FEAST, die auf die Behandlung skalarer Gleichungen ausgelegt ist, verfolgt genau dieses Ziel. FEAST kombiniert Hardware-orientierte Implementierungstechniken mit einer Multilevel-Gebietszerlegungsmethode namens ScaRC. In der vorliegenden Arbeit wird ein Konzept entwickelt, multivariate Elastizitätsprobleme basierend auf der FEAST-Bibliothek zu lösen. Die generelle Herangehensweise besteht darin, die Lösung multivariater Probleme auf die Lösung einer Reihe von skalaren Problemen zurückzuführen. Dieser Ansatz ermöglicht eine strikte Trennung von skalaren "low level" Kernfunktionalitäten (in Form der FEAST-Bibliothek) und multivariatem "high level" Anwendungscode (in Form des Elastizitätsproblems), was aus Sicht der Softwareentwicklungstechnik sehr vorteilhaft ist: Alle Bemühungen zur Verbesserung der Hardware-Effizienz, sowie Anpassungen an zukünftige technologische Entwicklungen können auf skalare Operationen beschränkt werden, während die multivariate Anwendung automatisch von diesen Erweiterungen profitiert. Im ersten Teil der Arbeit werden substantielle Verbesserungen der skalaren ScaRC-Löser entwickelt, die dann als essentielle Bausteine zur Lösung multivariater Elastizitätsprobleme eingesetzt werden. Ausführliche numerische Untersuchungen zeigen, wie sich die Effizienz der skalaren FEAST-Bibliothek auf den multivariaten Lösungsprozess überträgt. Die Löserstrategie wird dann auf nichtlineare Probleme der Elastizität mit finiter Deformation angewandt. Durch Einsatz einer Liniensuche-Methode wird die Robustheit des Newton-Raphson-Verfahrens signifikant erhöht. Es werden verschiedene Strategien miteinander verglichen, wie genau die linearen Probleme innerhalb der nichtlinearen Iteration zu lösen sind. Zur Behandlung der wichtigen Klasse von (fast) inkompressiblen Materialien wird eine gemischte Verschiebung/Druck-Formulierung gewählt, die mit Hilfe von stabilisierten bilinearen finiten Elementen (Q1/Q1) diskretisiert wird. Eine erweiterte Version der klassischen "Druck-Poisson"-Stabilisierung wird präsentiert, die auch für hochgradig irreguläre Gitter geeignet ist. Es werden Vor- und Nachteile der Q1/Q1-Diskretisierung erörtert, insbesondere in Bezug auf zeitabhängige Rechnungen. Zwei Löser-Klassen zur Behandlung der entstehenden Sattelpunkt-Probleme werden beschrieben und miteinander verglichen: einerseits verschiedene Arten von (beschleunigten) entkoppelten Lösern (Uzawa, Druck-Schurkomplement-Methoden, Block-Vorkonditionierer), andererseits gekoppelte Mehrgitter-Verfahren mit Vanka-Glättern. Effiziente Schurkomplement-Vorkonditionierer, die für die erste Löser-Klasse notwendig sind, werden im Rahmen statischer und zeitabhängiger Probleme besprochen. Die zentrale… Advisors/Committee Members: Turek, S..

Subjects/Keywords: Adaptive coarse grid correction; Adaptive Grobgitterkorrektur; Damped Newton-Raphson; Domain decomposition; Elasticity; Elastizität; Elastodynamic; Elastodynamisch; Elastostatic; Elastostatisch; Equal-order finite elements; FEAST; FEAST; Festkörpermechanik; Finite deformation; Finite Deformation; Finite-Elemente-Methode; Finite element method; Gebietszerlegung; Gedämpftes Newton-Raphson; Gemischte Formulierung; Globales Newton-Raphson; Global Newton-Raphson; Große Deformation; Großskalig; Hardware-oriented; Hardware-orientiert; High performance computing; Incompressible material; Inexact Newton-Raphson; Inexaktes Newton-Raphson; Inkompressibles Material; Irreguläres Gitter; Irregular grids; Iterativer Löser; Iterative solver; Large deformation; Large-scale; LBB stabilisation; LBB Stabilisierung; Line-search; Liniensuche; Mehrgitter; Mehrgitter-Krylov; Minimale Überlappung; Minimal overlap; Mixed formulation; Multigrid; Multigrid-Krylov; Multilevel; Multilevel; Newton-Raphson; Nicht-konformes Mehrgitter; Nonconforming multigrid; Parallel computing; Parallele Effizienz; Parallel efficiency; Paralleles Rechnen; Saddle point problem; Sattelpunkt-Problem; ScaRC; ScaRC; Schubversteifung; Schur complement preconditioning; Schurkomplement-Vorkonditionierer; Shear locking; Solid mechanics; Structural mechanics; Strukturmechanik; Transient; Vanka; Vanka; Volume locking; Volumenversteifung; Zeitabhängig; 510

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

APA (6^th Edition):

Wobker, H. (2010). Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems. (Thesis). Technische Universität Dortmund. Retrieved from http://hdl.handle.net/2003/26998

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):

Wobker, Hilmar. “Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems.” 2010. Thesis, Technische Universität Dortmund. Accessed April 13, 2021. http://hdl.handle.net/2003/26998.

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

MLA Handbook (7^th Edition):

Wobker, Hilmar. “Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems.” 2010. Web. 13 Apr 2021.

Vancouver:

Wobker H. Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems. [Internet] [Thesis]. Technische Universität Dortmund; 2010. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2003/26998.

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

Council of Science Editors:

Wobker H. Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems. [Thesis]. Technische Universität Dortmund; 2010. Available from: http://hdl.handle.net/2003/26998

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

19. Wobker, Hilmar. Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems.

Degree: 2010, Technische Universität Dortmund

URL: http://dx.doi.org/10.17877/DE290R-497

► In the simulation of realistic solid mechanical problems, linear equation systems with hundreds of million unknowns can arise. For the efficient solution of such systems,… (more)

▼ In the simulation of realistic solid mechanical problems, linear equation systems with hundreds of million unknowns can arise. For the efficient solution of such systems, parallel multilevel methods are mandatory that are able to exploit the capabilities of modern hardware technologies. The finite element and solution toolbox FEAST, which is designed to solve scalar equations, pursues exactly this goal. It combines hardware-oriented implementation techniques with a multilevel domain decomposition method called ScaRC that achieves high numerical and parallel efficiency. In this thesis a concept is developed to solve multivariate elasticity problems based on the FEAST library. The general strategy is to reduce the solution of multivariate problems to the solution of a series of scalar problems. This approach facilitates a strict separation of 'low level' scalar kernel functionalities (in the form of the FEAST library) and 'high level' multivariate application code (in the form of the elasticity problem), which is very attractive from a software-engineering point of view: All efforts to improve hardware-efficiency and adaptations to future technology trends can be restricted to scalar operations, and the multivariate application automatically benefits from these enhancements. In the first part of the thesis, substantial improvements of the scalar ScaRC solvers are developed, which are then used as essential building blocks for the efficient solution of multivariate elasticity problems. Extensive numerical studies demonstrate how the efficiency of the scalar FEAST library transfers to the multivariate solution process. The solver strategy is then applied to treat nonlinear problems of finite deformation elasticity. A line-search method is used to significantly increase the robustness of the Newton-Raphson method, and different strategies are compared how to choose the accuracy of the linear system solves within the nonlinear iteration. In order to treat the important class of (nearly) incompressible material, a mixed displacement/pressure formulation is used which is discretised with stabilised bilinear finite elements (Q1/Q1). An enhanced version of the classical 'pressure Poisson' stabilisation is presented which is suitable for highly irregular meshes. Advantages and disadvantages of the Q1/Q1 discretisation are discussed, especially in the context of transient computations. Two solver classes for the resulting saddle point systems are described and compared: on the one hand various kinds of (accelerated) segregated solvers (Uzawa, pressure Schur complement methods, block preconditioners), and on the other hand coupled multigrid solvers with Vanka-smoothers. Efficient Schur complement preconditioners, which are required for the former class, are discussed for the static and the transient case. The main strategy to reduce the solution of multivariate systems to the solution of scalar systems is only applicable in the case of segregated methods. It is shown that for the class of elasticity problems considered in this… Advisors/Committee Members: Turek, S. (advisor), Suttmeier, F.-T. (referee).

Subjects/Keywords: Iterativer Löser; Multilevel; Mehrgitter; Gebietszerlegung; Mehrgitter-Krylov; Nicht-konformes Mehrgitter; ScaRC; Adaptive Grobgitterkorrektur; Minimale Überlappung; Sattelpunkt-Problem; Schurkomplement-Vorkonditionierer; Vanka; Gedämpftes Newton-Raphson; Globales Newton-Raphson; Inexaktes Newton-Raphson; Liniensuche; FEAST; Hardware-orientiert; Großskalig; Paralleles Rechnen; Parallele Effizienz; Finite-Elemente-Methode; Gemischte Formulierung; LBB Stabilisierung; Irreguläres Gitter; Festkörpermechanik; Strukturmechanik; Elastizität; Elastostatisch; Elastodynamisch; Zeitabhängig; Inkompressibles Material; Finite Deformation; Große Deformation; Volumenversteifung; Schubversteifung; Iterative solver; Multilevel; Multigrid; Domain decomposition; Multigrid-Krylov; Nonconforming multigrid; ScaRC; Adaptive coarse grid correction; Minimal overlap; Saddle point problem; Schur complement preconditioning; Vanka; Newton-Raphson; Damped Newton-Raphson; Global Newton-Raphson; Inexact Newton-Raphson; Line-search; FEAST; High performance computing; Hardware-oriented; Large-scale; Parallel computing; Parallel efficiency; Finite element method; Mixed formulation; LBB stabilisation; Equal-order finite elements; Irregular grids; Solid mechanics; Structural mechanics; Elasticity; Elastostatic; Elastodynamic; Transient; Incompressible material; Finite deformation; Large deformation; Volume locking; Shear locking; 510

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APA (6^th Edition):

Wobker, H. (2010). Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems. (Doctoral Dissertation). Technische Universität Dortmund. Retrieved from http://dx.doi.org/10.17877/DE290R-497

Chicago Manual of Style (16^th Edition):

Wobker, Hilmar. “Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems.” 2010. Doctoral Dissertation, Technische Universität Dortmund. Accessed April 13, 2021. http://dx.doi.org/10.17877/DE290R-497.

MLA Handbook (7^th Edition):

Wobker, Hilmar. “Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems.” 2010. Web. 13 Apr 2021.

Vancouver:

Wobker H. Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems. [Internet] [Doctoral dissertation]. Technische Universität Dortmund; 2010. [cited 2021 Apr 13]. Available from: http://dx.doi.org/10.17877/DE290R-497.

Council of Science Editors:

Wobker H. Efficient multilevel solvers and high performance computing techniques for the finite element simulation of large-scale elasticity problems. [Doctoral Dissertation]. Technische Universität Dortmund; 2010. Available from: http://dx.doi.org/10.17877/DE290R-497

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