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Singh, Yash Pal. "Finite element analyses of cellular cofferdams." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/49896.
Full textAbstract:
Cellular cofferdams have primarily been used as temporary systems which serve to allow construction of facilities in open bodies of water. Applications for these structures have been increasing and today they may serve as permanent retaining walls or as navigation or waterfront structures. Conventional design methods for cellular cofferdams are based on semi-empirical approaches largely developed in the 1940s and 1950s. None of the available traditional procedures are capable of predicting cofferdam deformations, a parameter of key importance to the cofferdam performance, and which is often observed during construction for purposes of safety monitoring. Also, there is evidence that much of the conventional design technology is conservative, in some cases predicting loading by more than twice that which actually occurs. Recently, the finite element method has shown promise as a tool which can be used to help resolve some of the outstanding problems with cofferdam design.
There are three primary objectives of this work: (1) enhance existing finite element program to allow for more accurate and refined analysis of cellular cofferdams, (2) use the enhanced finite element programs to assess the degree of conservatism in conventional design methods for cofferdams founded on sandy soils, and (3) use the results of parametric studies of cofferdams founded on sandy soils to develop a simplified procedure to predict cofferdam movements and determine potential for internal failure. The first of the objectives involves adding better bending elements to the program SOILSTRUCT to represent the sheet pile system In axisymmetric and plane strain analyses. Also, in the case of the plane strain program, a new method is developed to allow shear transfer through the sheet pile system. Through case history and theoretical analyses, the enhanced programs are demonstrated to yield accurate and realistic results.
Parametric studies using the axisymmetric program show that conventional design methods overpredict, in some areas strongly, the interlock forces which develop during filling of the cofferdam. Parametric studies using the plane strain program suggest that there is also considerable conservatism in design methods to predict internal stability of the cofferdam. A new, simplified method is proposed for this type of analysis. In addition, it is shown that the deformations of cofferdams on sand follow consistent trends and can be set into a nondimensionalized context which can be used to predict future cofferdam movements.<br>Ph. D.<br>incomplete_metadata
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Karmi, M. S. "Finite/discrete element analyses of masonry structures." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637762.
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In contrast to concrete, masonry is a complex inhomogenous material, which exhibits distinct directional properties due to the presence of mortar joints. In the past, both finite element and discrete element techniques have been used for modelling of masonry structures. However, no comparison of these two different approaches has been made. In this study, to achieve a fundamental insight into the behaviour of masonry structures, a series of numerical analyses have been carried out using Finite and Discrete Element methods for structures such as shear walls with/out opening, masonry panel under point load, and masonry arches. In Discrete Element analyses, bricks were modelled as conventional continuum elements, while an interface contact law (instead of mortar joints) was used to capture masonry failure mechanisms in the <i>2D</i> plane-strain analyses. The contact law included softening in tension, shear and compression modes. In Finite Element modelling of the same structures, separate continuum elements were used for both constituents, i.e. the brick and mortar. The results were compared with experimental data. Both methods were able to reproduce the complete deformation pattern of the structures up to and beyond the peak until total degradation of strength, without major numerical difficulties. Parametric studies of the above problems have also been carried out to demonstrate the crucial role of some of the parameters. Comparative studies using the Finite Element and Discrete Element methods have shown that collapse load as well as mechanisms of failure are significantly influenced by the choice of interface parameters used in the Discrete Element method. These parameters are also difficult to determine from experiments. On the other hand, Finite Element analyses indicate lesser influence of parameters of the constituents and no anomalies arise in their choice from experimental data.
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She, Jairus Lai Yan. "Prediction of P-Y curves from finite element analyses." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26736.
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The prediction of P-Y curves for undrained clay and sand based on the results of finite element analyses is presented in this thesis.
A higher-ordered finite element program was used in the analyses. The ability of the program to accurately model the undrained soil condition was verified by comparing predicted load-deflection responses with closed form solutions for the cylindrical cavity expansion problem.
Pressuremeter curves were predicted from plane strain axisymmetric finite element analyses. The effect of pressuremeter size on the predicted results was examined.
P-Y curves were predicted for plane strain and plane stress conditions. Values for the initial slope and Pun- of the curves were obtained. The curves were normalized for comparison, and simplified methods presented for determining P-Y curves.
Finite element predictions for the pressuremeter and laterally loaded pile problems were also compared. Factors were determined from these comparisons to generate P-Y curves from pressuremeter curves.<br>Applied Science, Faculty of<br>Civil Engineering, Department of<br>Graduate
4
Ho, David Kar Hung. "Analyses of geotechnical construction by the finite element method." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277388.
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El-Hamalawi, Ashraf Abdul-Rahman. "Adaptive refinement of finite element meshes for geotechnical analyses." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627406.
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Bhowmick, Sauradeep. "Advanced Smoothed Finite Element Modeling for Fracture Mechanics Analyses." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623240613376967.
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Ho, I.-Hsuan. "Optimization of pile reinforced slopes using finite element analyses." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3389104.
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El-Hage, Hicham. "Multiaxial fatigue analyses and life predictions using finite element method." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62209.pdf.
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Li, C. O. "Finite element analyses of seepage and stability problems in geomechanics." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233378.
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Roberts, S. Mark. "Remeshing applied to 3-D, elastic-plastic, finite-element analyses." Thesis, University of Birmingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503724.
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Within the Finite-Element Plasticity Research Group at the University of Birmingham the interest in finite elements is principally confined to their use in the modelling of elastic-plastic problems (specifically metal-forming processes). The methods employed allow a process to be studied as it develops through time. A number of problems in the modelling of such processes give rise to errors, most notably due to singularities and other complex geometrical anomalies which are the result of complicated die surfaces and other boundaries. These boundary conditions can give rise to severe mesh distortions. The results of this thesis will show that improvements may be made to the modelling of such processes, by using a computer tool to allow remeshing to be carried out where such inaccuracies occur. A number of investigations have been made into such tools in other areas of study and it is hoped, eventually, that those techniques, together with ones developed here may be applied to metal forming in 3-dimensions. The aims of this thesis are to formulate the initial steps towards such an analysis. The work demonstrates how the basics of such techniques might be implemented, concentrating specifically on the transfer of data from an old mesh to a new mesh and simple error measures. Once this data transfer has been implemented it is hoped that future work will produce a fully self-adaptive process, ensuring that remeshing occurs based on algorithms continuously monitoring the potential for errors throughout the process The initial work in this thesis was confined to plane-strain applications. Its methods and implementation are discussed and some results shown. This gave some understanding of the difficulties which would be involved when transferring the techniques developed to a fully 3-dimensional solution. In the 3-dimensional application area are more quantitative work was also undertaken to assess the errors arising from element degeneracy and the ability of the mesh to model steep strain gradients. It should be noted by that full 3-dimensional remeshing, when applied to general metal forming problems, will involve far more sophisticated mesh generation software than is currently, or in the short term future, available.
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Potgieter, Jean-Timothy. "Finite element versus limit equilibrium stability analyses for surface excavations." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/63001.
Full textAbstract:
Limit equilibrium methods are widely and routinely used in practice. In several codes, limit
equilibrium methods are recommended to evaluate the stability of a lateral support systems,
such as soil-nails and anchors, to an acceptable defined factor of safety.
For decades, limit equilibrium methods have been used successfully in providing an acceptable
margin of safety against failure (movements, which can be significantly more complex, is not
considered). However, due to the advances in computational power offered by personal
computers, finite element modelling has become increasingly accessible.
Since the idea immerged of using a strength reduction factor in finite element displacement
analyses, an increase in the use thereof to calculate the factor of safety has been observed.
However, the use of finite elements has often led to misinterpretation of the results. Several
authors have cautioned engineers to the complexities involved in using finite element analyses
to model geotechnical problems. Studies have been conducted comparing the use of finite
elements to other methods. However, most of these studies consider only slope problems. Few
studies have been conducted for lateral support systems.
Several codes of practice use the numerical quantity of ‘factor of safety’ to define the suitability
of geotechnical design. Whether finite element- or limit equilibrium methods are used, the accurate calculation of the factor of safety remains paramount to quantifying the stability of a
geotechnical structure.
The aim of this research is to compare limit equilibrium and finite element methods in
evaluating the stability, in terms of factor of safety, of soil-nailed and anchored lateral support
systems in surface excavations.
This was done by using four methods of analysis to calculate the factor of safety. Two
traditional limit equilibrium methods were used (trail wedge and method of slices). The newer,
finite element strength reduction technique was used. Finally, a hybrid method which combines
a finite element analysis with limit equilibrium slip surface analysis was used.
These methods of analysis were applied to three different geometries. A uniform slope without
any reinforcing was analysed. This was followed by the analysis of an 8.5m soil-nail supported
face and a 17m face supported by anchors.
A parametric study was conducted for the soil-nailed and anchored excavations. Material
properties (friction angle, cohesion etc.), modelling parameters (boundary distances, mesh
resolution etc.) and engineering design variables (reinforcement capacity etc.) were varied in
order to observe the influence on the factor of safety.
It is concluded that limit equilibrium methods, such as a trial wedge method and the method of
slices, compare well with each other throughout the analyses. Using a combination of finite
elements with a slip surface analysis compares poorly with the other methods. By using the
finite element strength reduction technique, an optimised failure mechanism is found. The finite
element strength reduction technique compares well with limit equilibrium methods if the
following two conditions are met:
• The same failure mechanism is evaluated for both methods; and
• the capacity of reinforcement is consistently specified in both methods.<br>Dissertation (MEng)--University of Pretoria, 2017.<br>Civil Engineering<br>MEng<br>Unrestricted
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Koch, Thorsten M. "Non-linear finite element analyses of the aortic heart valve." Thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/6756.
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Includes bibliographical references.<br>Finite element models of the aortic heart valve have been successfully used in the past to gain insight into the mechanics of the valve and to aid in understanding of valve failure. Moreover such models are indispensable tools for further developments in heart valve prosthetic design. In previous stress analyses linear elastic constitutive models have predominantly been used to model aortic valve leaflets, despite aortic valve tissue showing highly non-linear behaviour in tension tests. In view of recent developments towards tissue engineering of heart valves, these linear constitutive models of aortic valve leaflets are not likely to produce results sufficiently accurate to correlate cell behaviour with mechanical stimuli. To study how non-linear material behaviour affects the results of stress analyses of the aortic valve, static finite element analyses of the valve including the aortic root and leaflets have been carried out. An isotropic linear elastic material model was assigned to the aortic root with Young's modulus adjusted for the simulated compliance to match physiological values. Linear elastic models for the aortic valve leaflets with parameters used in previous studies were then compared with hyperelastic materials. The parameters used for the exponential strain energy function of the latter were obtained from fits of uniaxial tension test results of fresh porcine aortic valve leaflets. As natural leaflets show anisotropy with a pronounced stiff direction along the circumference of the valve, isotropic models of the leaflets were extended to account for this behaviour by incorporating transverse isotropy. The results display a stark impact of a transversely isotropic hyperelastic material on leaflet mechanics, Le. increased coaptation with peak values of stress and strain in the elastic limit. Interestingly, the alignment of maximum principal stress of all models seems to approximately follow the coarse collagen fibre distribution found ill aortic valve leaflets.
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ROJAS, MARIO EDILBERTO ROCA. "APPLICATION OF THE FINITE ELEMENT METHOD FOR SOIL SLOPE STABILITY ANALYSES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1276@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>O principal objetivo deste trabalho é a aplicação do método
dos elementos finitos (MEF) na análise da estabilidade de
taludes em solo, para identificação da superfície crítica
de deslizamento e cálculo do correspondente fator de
segurança.
Ainda que o método dos elementos finitos tenha se tornado
ferramenta popular para análise de muitos problemas da
engenharia geotécnica, existem relativamente poucas
aplicações específicas publicadas na literatura sobre
estabilidade de taludes.
Dois métodos podem ser empregados para a utilização do MEF
na área da estabilidade de taludes: o método direto, onde
os resultados numéricos são exclusivamente usados para
localização da potencial superfície de deslizamento e
cálculo do fator de segurança, e o método indireto, onde
seus resultados são acoplados a uma técnica para auxiliar a
pesquisa da superfície crítica.
Comparações entre resultados obtidos pelo método dos
elementos finitos e de equilíbrio limite são feitas em
vários exemplos numéricos investigados nesta dissertação,
comentando-se a aplicabilidade, vantagens e limitações de
ambas as metodologias em estudos da estabilidade de taludes
em solos.<br>The main objective of this research is the application of
the finite element method
(FEM) to analyze the stability of soil slopes, searching
the position of the failure slip surface
in the soil mass and its corresponding safety factor.
The finite element method has become a popular tool for the
study of many
geotechnical engineering problems but, in the specific area
of slope stability analysis, there
are relatively few applications reported in the literature.
Basically, two methods have evolved for application of the
FEM results in slope
stability problems: the direct method, that uses the
numerical results only for establishing the
slip surface and computation of the related safety factor,
and the indirect method, where the
FEM results are combined with another numerical technique
to improve the search process of
slip surfaces.
Several numerical examples have been studied in this
dissertation, making comparisons
among the results obtained using the finite element and
limit equilibrium methods. The
applicability, advantages and shortcomings of both
approaches are also discussed.<br>1276
El objetivo principal de este trabajo es la aplicación del método de los elementos finitos (MEF) al análisis de
estabilidad de taludes de suelo, con el próposito de identificar la superfície crítica de deslizamento y cálculo del
correspondiente factor de seguridad. Aunque el método de los elementos finitos se haya convertido en una
herramienta popular en el análisis de muchos problemas de la ingeniería geotécnica, existen relativamente pocas
aplicaciones específicas publicadas en la literatura sobre la estabilidad de taludes. Dos métodos pueden ser
empleados para la utilización del MEF en el área de estabilidad de taludes: el método directo, donde los
resultados numéricos son exclusivamente usados para localización de la potencial superficie de deslizamento y el
cálculo del factor de seguridad; y el método indirecto, donde los resultados se acoplan a una técnica para auxiliar
la investigación de la superficie crítica. Se utilizan varios ejemplos con el fin de comparar los resultados obtenidos
por el método de los elementos finitos y por el método de equilibrio límite investigados en esta disertación. Se
incluyen comentarios sobre la aplicabilidad, ventajas y limitaciones de ambas metodologías en estudios de la
estabilidad de taludes en suelos.
14
Condax, Peter. "Finite element analyses of pathological changes in the lumbar vertebral body." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13961.
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Neto, Dorival Piedade. "On the Generalized Finite Element Method in nonlinear solid mechanics analyses." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-20012014-094606/.
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The Generalized Finite Element Method (GFEM) is a numerical method based on the Partition of Unity (PU) concept and inspired on both the Partition of Unity Method (PUM) and the hp-Cloud method. According to the GFEM, the PU is provided by first-degree Lagragian interpolation functions, defined over a mesh of elements similar to the Finite Element Method (FEM) meshes. In fact, the GFEM can be considered an extension of the FEM to which enrichment functions can be applied in specific regions of the problem domain to improve the solution. This technique has been successfully employed to solve problems presenting discontinuities and singularities, like those that arise in Fracture Mechanics. However, most publications on the method are related to linear analyses. The present thesis is a contribution to the few studies of nonlinear analyses of Solid Mechanics by means of the GFEM. One of its main topics is the derivation of a segment-to-segment generalized contact element based on the mortar method. Material and kinematic nonlinear phenomena are also considered in the numerical models. An Object-Oriented design was developed for the implementation of a GFEM nonlinear analyses framework written in Python programming language. The results validated the formulation and demonstrate the gains and possible drawbacks observed for the GFEM nonlinear approach.<br>O Método dos Elementos Finitos Generalizados (MEFG) é um método numérico baseado no conceito de partição da unidade (PU) e inspirado no Método da Partição da Unidade (MPU) e o método das Nuvens-hp. De acordo com o MEFG, a PU é obtida por meio de funções de interpolação Lagragianas de primeiro grau, definidas sobre uma rede de elementos similar àquela do Método dos Elementos Finitos (MEF). De fato, o MEFG pode ser considerado uma extensão do MEF para a qual se pode aplicar enriquecimentos em regiões específicas do domínio, buscando melhorias na solução. Esta técnica já foi aplicada com sucesso em problemas com descontinuidades e singularidades, como os originários da Mecânica da Fratura. Apesar disso, a maioria das publicações sobre o método está relacionada a análises lineares. A presente tese é uma contribuição aos poucos estudos relacionados a análises não-lineares de Mecânica dos Sólidos por meio do MEFG. Um de seus principais tópicos é o desenvolvimento de um elemento de contato generalizado do tipo segmento a segmento baseado no método mortar. Fenômenos não lineares devidos ao material e à cinemática também são considerados nos modelos numéricos. Um projeto de orientação a objetos para a implementação de uma plataforma de análises não-lineares foi desenvolvido, escrito em linguagem de programação Python. Os resultados validam a formulação e demonstram os ganhos e possíveis desvantagens da abordagem a problemas não lineares por meio do MEFG.
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Regalado, Levi R. "Finite element analyses of gravity earth retaining structures founded on soil." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/40142.
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Grant, C. L. "Finite element analyses of a wave loaded pile : deterministic and probabilistic." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/9634.
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Includes bibliography.<br>The problem of pile stick-up, where the pile has been stabbed into the pile guide of the platform to be fixed to the sea-bed and is loaded by the current and waves of the ocean, was recently of concern when the fixation of the first local offshore production platform took place. A previous investigation considered the resonant behaviour of the undriven pile subjected to various predicted sea states and various methods were examined to limit the large displacements anticipated. In the present work, a refined model of the problem is developed using the ABAQUS finite element program. Of particular interest is the applicability of the , probabilistic finite element method (PFEM). It is important to appreciate that a mere deterministic dynamic analysis - however accurate analytically - may be of limited value when applied to structures in the ocean. The response achieved thus will either be unelegantly conservative or very unreliable due to the many uncertain parameters that pervade the field of structural dynamics in the ocean. Traditionally, statistical methods are reverted to with uncertainty analyses, but they seldom have much appeal because of the computational effort involved. The PFEM was found quite attractive with a formulation where the uncertainty of the drag coefficient and the inertia coefficient were investigated. It was concluded that the uncertainty in these coefficients should be limited to a coefficient of variation of approximately 20% and that the simplified model on which the formulation was based should be refined if acceptable results for the purposes of design were required.
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Rouhani, Siamak. "Temperature analyses of Concrete Frame Bridges with Finite Elements." Thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145904.
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FE-modeling is a rapidly spreading method to analyze structures nowadays. With this theunderstanding of the outcome is of very high importance and potential inaccuracies areimportant to find so that faulty and over dimensioning of the structure does not occur whichleads to unnecessary costs. One of these inaccuracies is the unrealistic sectional forces that occurdue to thermal effects in the transversal direction for concrete frame bridges which leads to anexcessive amount much reinforcement in the structure than actually needed. This has beenstudied with several cases by using two approaches on how to apply the temperature in the framebridge, only in the superstructure and in the whole structure, but also by analyzing severalboundary conditions. By examining the results for the sectional forces and stresses one of thetemperature approaches could be disregarded because of the extreme values in the transitionbetween superstructure and support. But the other approach was much more useful because ofits better compliance with reality. With these results and by calculating the reinforcement neededfor the worst case, one model has been found to be the most favorable and can be used whenmodeling concrete frame bridges with acceptable outcome. The study resulted in a model whereone applies a varying temperature on the whole structure, with spring boundary conditions over asurface that represents the bottom slab.
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Guven, Ibrahim. "A coupled finite element-boundary element method for two dimensional transient heat conduction and thermoelastic analyses." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289183.
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A new algorithm for coupling boundary and finite element methods is developed for transient two dimensional heat conduction and thermoelastic analyses of regions with dissimilar materials and geometric discontinuities. Such regions are susceptible to failure initiation in electronic devices. As the component size decreases while enhancing performance, the accurate prediction of thermal and thermoelastic response of such devices is critical for achieving acceptable design. This study concerns both the conduction heat transfer and thermoelasticity. Solution to transient heat conduction equation provides the non-uniform thermal field for the thermoelastic analysis. Although the finite element method (FEM) is highly efficient and commonly used, its application with conventional elements to complex layered structures with length parameters varying in order of magnitudes leads to inaccurate and mesh dependent results. The accuracy of the results from the boundary element method (BEM) formulation, which requires computationally intensive integration schemes, is much higher than that of the FEM. This new algorithm combines the advantages of both methods while not requiring the commonly accepted iterations along the interfaces between BEM and FEM domains. The BEM part of the solution, acting as a global element, captures the singular nature of the solution variables arising from geometrical and material discontinuities and, eliminates the mesh dependency.
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Sheng, Ni. "Trefftz boundary and polygonal finite element methods for piezoelectric and ferroelectric analyses." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31483434.
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Hashmi, Atta-Ur-Rehman. "Statistical comparison of customized and traditional knee implants using Finite Element Analyses." Thesis, Wichita State University, 2007. http://hdl.handle.net/10057/1548.
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According to the National Center for Health Statistics in 2004 over 478,000 people Underwent Total Knee Replacement surgeries in 2004. The number is rapidly growing due to advances in implant surgeries, knee implants, and longevity but is limited to patients older than 60 years. Knee implant surgery failures have also increased which has lead to increased number of revisions. Recent attempts have been made to design and optimize customized knee implants for young patients and provide a solution for current failures in knee replacements. The objective of this research is to compare the femoral components of customized and traditional implant designs using femur bone interface. The comparison was made using three load levels of body weight acting on the femur bone with attached femoral components at two gait angles with four orthopaedic materials. Statistical analysis was conducted using a general factorial design to quantify the effect of these factors. Finite Element Analysis (FEA) was performed to measure the maximum stress level (_max) for design comparison. The statistical analysis concluded that the two-factor interaction involving knee design and angle had a significant effect on the average stress level. Based on the assumptions the FEA results indicated that the femoral component of the traditional knee implant design was better than the customized knee implant design with respect to maximum stress level (o-max)<br>Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering<br>"July 2007."
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Sheng, Ni, and 盛妮. "Trefftz boundary and polygonal finite element methods for piezoelectric and ferroelectric analyses." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31483434.
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WILLIAMS, GEORGE CLAY. "STEEL CONNECTION DESIGNS BASED ON INELASTIC FINITE ELEMENT ANALYSES (GUSSET, BRACING, STRUCTURES)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/188168.
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Analytical and experimental studies were made to develop design procedures for steel gusset plate connections in diagonally braced frames. Stiffness and strength models of structural fasteners based on physical tests were incorporated into inelastic finite element analyses. The modeling techniques were verified by comparing analytical and experimental results of full scale connection tests. Finite element models of bracing connections were generated to determine gusset plate force, stress, strain, and displacement distributions for a variety of connection designs including K-bracing and X-bracing. Based on these results current design procedures were scrutinized and new design procedures were proposed for predicting the tensile strength, buckling strength, and force distributions for bracing connections. Additionally, it was found that gusseted beam-to-column connections are rigid (AISC Type I) and the centroidal axes of the brace, beam, and column members do not necessarily need to intersect at a common working point.
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Alagbada, Adefemi Samuel. "Thermo-Mechanical Fatigue Assessment of Marine Boiler : Using linear Finite Element Analyses." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-95439.
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This thesis is on fatigue crack growth assessments of a thermomechanical loaded Marine Boiler- Sunrod CPDB12. The installation position of the marine boiler in the ship in relation to its fatigue life under mode 1 loading is investigated. Thermomechanical loading embodies pressures, temperatures, RAO, subjected to the rigid body dynamic of ship in the marine environment. Linear elastic fracture mechanics (LEFM) method was used is predicting the growth rates of the welding flaws at the joint based on stress range of the Paris law relationship. FEA Numerical simulation delivered better crack growth rate assessments and life predictions of the smallest detectable flaws in the boiler. The identified smallest detestable flaws at the welding joint diminishing the designed safe life of the boiler significantly. Also, installation position within the ship do affect the fatigue life of the boiler.
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Shirasuna, Takeshi. "Finite element analyses on cohesive soil behavior due to advanced shield tunneling." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/50010.
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Soil tunnels are usually constructed using a shield with an open face. However, in the past decade, innovations in shield tunneling technology have brought closed-faced shields that provide continuous support to the face and permit tunneling through even the most difficult conditions of soft ground. These new machines are typically operated in such a way that during tunneling the soil at the face is actually heaved away from the shield. This operating procedure has been said to allow greater control of the ground movements around and above the shield, and to minimize detrimental settlements. However, there is little hard evidence to this effect and there is no rational basis to judge the actual influence of the soil heave.
Building on former researchers’ efforts, this thesis is directed towards developing a suitable finite element method (FEM) approach to the advanced shield problem. The FEM program developed includes the Prevost elasto-plastic soil model, allows for analysis of development and dissipation of excess pore pressure, large deformation, and simulation of the construction procedure of advanced shield tunneling.
This is the first time that the Prevost model was applied to a soft clay. Modifications were made, in particular for the parameter determination, to make the model applicable for the soft clay of San Francisco Bay Mud. Examination of two other soil models for the tunnel analysis, nonlinear pseudo-elastic and Cam Clay models, showed the Prevost model to be preferable. Loading procedures were also examined to accurately simulate the heaving and tail void closure effects.
The finite element simulation of the N-2 sewer project, which is the first advanced shield project in the United States, demonstrated that the prediction agreed consistently well with the observations in the field. Further analyses indicated that heave at the face of the shield increases long·term consolidation settlements while it decreases immediate settlements and thus the final settlement may be reduced. The tail void simply increases settlements.
The results suggest that strict control of heaving and elimination of tail void with proper and prompt grouting are crucial for mitigating ground movements with advanced shield tunneling.<br>Ph. D.<br>incomplete_metadata
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Hashmi, Atta Weheba Gamal. "Statistical comparison of customized and traditional knee implants using Finite Element Analyses /." Thesis, A link to full text of this thesis in SOAR, 2007. http://hdl.handle.net/10057/1548.
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Giorelli, Massimo. "Methodology for correlating experimental and finite element modal analyses on valve trains." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0426102-130749.
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Gidla, Stephen Sunadh Jeevan Kotha Shiva. "Load-strain response of a rat ulna using experimental and finite element analyses." Diss., UMK access, 2006.
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Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2006.<br>"A thesis in mechanical engineering." Typescript. Advisor: Shiva Kotha P. Vita. Title from "catalog record" of the print edition Description based on contents viewed Jan. 29, 2007. Includes bibliographical references (leaves 31-32). Online version of the print edition.
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Tanfener, Tugrul. "Finite Element Analyses Of Differential Shrinkage-induced Cracking In Centrifugally Cast Concrete Poles." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614847/index.pdf.
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Poles are used as an important constituent of transmission, distribution and communication structures<br>highway and street lighting systems and other various structural applications. Concrete is the main production material of the pole industry. Concrete is preferred to steel and wood due not only to environmental and economic reasons but also because of its high durability to environmental effects and relatively less frequent maintenance requirements.
Centrifugal casting is the most preferred way of manufacturing concrete poles. However, misapplication of the method may lead to a significant reduction in strength and durability of the poles. Segregation of concrete mixture is a frequent problem of centrifugal casting. The segregated concrete within the pole cross-section possesses different physical properties. In particular, the shrinkage tendency of the inner concrete, where the cement paste is accumulated, becomes significantly larger. Differential shrinkage of hardened concrete across the pole section gives rise to the development of internal tensile stresses, which, in turn, results in longitudinal cracking along the poles.
There is a vast literature on experimental studies of parameters affecting differential shrinkage of centrifugally cast poles. This research aims to computationally investigate the differential shrinkage-induced internal stress development and cracking of concrete poles. To this end, two and three-dimensional mathematical models of the poles are constructed and
finite element analyses of these models are carried out for different scenarios. The computationally obtained results that favorably agree with the existing experimental data open the possibility to improve the centrifugal manufacturing technique by using computational tools.
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Creech, G. "Mesoscopic finite element modelling of non-crimp fabrics for drape and failure analyses." Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/1432.
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To date, macroscopic analysis methods have been invariably used to analyse textile composite structures for forming and mechanical performance. Techniques such as geometric ‘mapping’ for the draping of textile fabrics and classical laminate analysis combined with simplified failure criteria to determine mechanical performance have formed the basis of most of these methods. The limited accuracy of the physical laws applied is appropriate to macro- analysis methods in which the fibre-matrix composite is treated as homogeneous medium. Today, however, modern high performance computers are opening new possibilities for composites analysis in which far greater detail of the composite constituent materials may be made. This paper presents Finite Elements techniques for the draping simulation of textile composites, specifically biaxial Non Crimp Fabrics, in which the complex deformation mechanisms of the dry tows and stitching may be properly modelled at the individual tow and stitch mesoscopic level. The resulting ‘deformed’ Finite Element model is then used to provide a basis for accurate simulation of the impregnated composite structure. The modelling techniques for both draping and structural analysis are presented, together with validation results for the study of a relatively large scale hemisphere composite part.
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ESPINHA, RODRIGO DE SOUZA LIMA. "PARALLEL TOPOLOGICAL SUPPORT FOR FINITE ELEMENT MESHES IN DYNAMIC FRACTURE AND FRAGMENTATION ANALYSES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=17794@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>Fenômenos de propagação de fraturas e fragmentação em sólidos podem ser descritos por Modelos de Zona Coesiva e simulados com o Método dos Elementos Finitos. Entre as abordagens computacionais de recente interesse para a representação de fraturas em malhas de elementos finitos, encontram-se as baseadas em elementos coesivos. Nelas, o comportamento de fraturas é representado por elementos coesivos inseridos nas interfaces entre elementos volumétricos da malha original. Os modelos de elementos coesivos podem ser classificados como intrínsecos ou extrínsecos. Modelos intrínsecos requerem elementos coesivos pré-inseridos em todas as interfaces volumétricas passíveis de fraturas. Por outro lado, modelos extrínsecos requerem que elementos coesivos sejam inseridos de forma adaptativa, apenas onde e quando necessários. Porém, a representação de malhas tradicional (elementos e nós) não é suficiente para tratar malhas adaptativas eficientemente, o que faz necessário um suporte topológico apropriado. Em geral, modelos coesivos de fratura também requerem um alto nível de refinamento de malha, para que resultados precisos sejam obtidos. Isso implica em um consumo de memória e processamento que pode ser proibitivo a estações de trabalho tradicionais. Assim, ambientes paralelos tornam-se importantes na solução de problemas de fraturas. Entretanto, devido às dificuldades de paralelização de modelos extrínsecos, as abordagens existentes utilizam modelos intrínsecos ou implementam simulações extrínsecas baseadas em elementos coesivos pré-inseridos ou representados como atributos de elementos volumétricos. Com o objetivo de viabilizar a simulação de fraturas e fragmentação extrínsecas em grandes modelos de forma simples e eficiente, esta tese propõe o sistema ParTopS, um suporte topológico em paralelo para malhas de elementos finitos em análises dinâmicas de fratura e fragmentação. Em especial, é apresentada uma representação compacta e eficiente de malhas de fraturas distribuídas.
Elementos coesivos são representados explicitamente e tratados como elementos regulares da malha. Com base na representação de malha distribuída, propõe-se um algoritmo paralelo escalável para a inserção adaptativa de elementos coesivos em malhas bidimensionais e tridimensionais. Operações topológicas simétricas são exploradas para reduzir a comunicação entre partições de malha. O sistema ParTopS foi empregado na paralelização de simulações sequenciais extrínsecas existentes. A escalabilidade e a corretude do suporte topológico em paralelo são demonstradas através de experimentos computacionais realizados em um ambiente massivamente paralelo. Os resultados alcançados mostram que o sistema ParTopS pode ser aplicado de forma eficaz para viabilizar simulações de grandes modelos.<br>Fracture propagation and fragmentation phenomena in solids can be described by Cohesive Zone Models and simulated with the Finite Element Method. Among the computational approaches of recent interest for fracture representation in finite element meshes are those based on cohesive elements. In those approaches, fracture behavior is represented by cohesive elements inserted at the interfaces between volumetric (bulk) elements of the original mesh. Cohesive element models can be classified into intrinsic or extrinsic. Intrinsic models require pre-inserted cohesive elements at every volumetric interface in which fracture is allowed to happen. On the other hand, extrinsic models require that cohesive elements be adaptively inserted, wherever and whenever necessary. However, the traditional mesh representation (elements and nodes) is not sufficient for handling adaptive meshes, which makes an appropriate topological support necessary. In general, cohesive models of fracture also require a high level of mesh refinement near crack tips, such that accurate results can be achieved. This implies in memory and processor consumption that may be prohibitive for traditional workstations. Thus, parallel environments become important for the solution of fracture problems. However, due to the difficulties for the parallelization of extrinsic models, the existing approaches use intrinsic models or implement extrinsic simulations based on pre-inserted cohesive elements or cohesive elements represented as attributes of volumetric elements. In order to allow fracture and fragmentation simulations of large models in a simple and efficient way, this thesis proposes the ParTopS system, a parallel topological support for finite element meshes in dynamic fracture and fragmentation analyses. Specifically, a compact and efficient representation of distributed fracture meshes is presented. Cohesive elements are explicitly represented and treated as regular elements in the mesh. Based on the distributed mesh representation, we propose a scalable parallel algorithm for adaptive insertion of cohesive elements in both bidimensional and tridimensional meshes. Symmetrical topological operations are exploited in order to reduce communication among mesh partitions. The ParTopS system has been employed in order to parallelize existing serial extrinsic simulations. The scalability and correctness of the parallel topological support is demonstrated through computational experiments executed on a massively parallel environment. The achieved results show that ParTopS can be effectively applied in order to enable simulations of large models.
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Pang, Derrick Yat Bond 1976. "Estimating settlements and capacities of piled foundations with non-linear finite element analyses." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/46132.
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Austin, Gregory Alan. "Two-and three dimensional finite element analyses of the intact and reconstructed hemipelvis." Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/26335.
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Jones, Andrew D. "Biomechanical and Finite Element Analyses of Alternative Cements for use in Vertebral Kyphoplasty." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1364828764.
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Batool, Abeera. "Advanced Undersepage Analyses for Levees." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/52507.
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The events of Hurricane Katrina in 2005 prompted the US Army Corps of Engineers
(USACE) to commission studies to identify the failure mechanisms of levees and I-walls. This involves updating of the current USACE Engineering Manual (EM) 1110-2-1913, "Design and Construction of Levees," which uses Blanket Theory for seepage analysis. Blanket Theory entails analytical methods for calculating seepage pressures and flows beneath levees. The revision of the manual will address the design seepage criteria for levees, with a focus on incorporating new seepage analysis procedures besides Blanket Theory. Finite element analysis is one such method that has more recently become the method of choice for general seepage analyses in geotechnical engineering. The focus of this research is mainly on underseepage analyses of levees in the lower Mississippi valley using numerical modeling, with a goal of helping engineers in making the transition from current Corps methods to finite element analysis. General guidelines are provided to conduct seepage analysis using finite element analysis for pre-defined Blanket Theory cases as
well as for the design of seepage berms. In addition, the 3D finite element modeling is conducted for a full-scale field load test involving complex geometry and stratigraphy, which is useful in better understanding the response of levees and I-walls.<br>Ph. D.
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Marcano, Jose Abigail. "Nonlinear Finite Element Analyses of the End Web Crippling Strength of W-Shape Steel Beams." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34502.
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The 1999 AISC Specification for Structural Steel Buildings establishes two design equations for the web crippling limit state at the supports. However, investigators have suggested that the basis of these equations, which is based on an assumed collapse mechanism, is conservative especially for long bearing lengths. Most of the experimental studies conducted to validate those formulas have considered short span lengths and relatively small bearing-to-depth ratios. Therefore, a further investigation of the web crippling capacity of W-shape steel beams for larger span lengths and larger bearing-to-length ratios was undertaken.
<p>
The primary objective of this study is to analytically investigate the web crippling strength of W-shape steel beams for large bearing-to-depth ratios on large span beams, and to compare the results with the 1999 AISC LRFD web crippling design equation (K1-5b). The web crippling strength of W-shape steel beams was investigated by means of the finite element technique. The commercial finite element package ANSYS 6.0 was used to model the steel beams. Material nonlinearities, large deformation effects and initial geometric imperfections were taken into account in the finite element models.
<p>
The validation results shown that the finite element models closely predicted the ultimate load and web crippling failure mode shape of the tested beams. Conclusions based on the predictions of the finite element analyses and the current 1999 AISC end web crippling design equation (K1-5b) are presented in the study.<br>Master of Science
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Johnson, Dona Jacqueline. "Investigation of the performance of flexible pavement systems under moving loads using finite element analyses /." Full text available online, 2008. http://www.lib.rowan.edu/find/theses.
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Parsapour, Bahman. "Experimental and finite-element analyses of deformation of a material model containing an inclusion." Thesis, University of Birmingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251473.
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Hengprathanee, Songwut. "Linear and Nonlinear Finite Element Analyses of Anchorage Zones in Post-Tensioned Concrete Structures." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/11253.
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Linear and nonlinear finite element analyses are used for the investigation of rectangular anchorage zones with the presence of a support reaction. The investigation is conducted based on four load configurations consisting of concentric, inclined concentric, eccentric, and inclined eccentric loads. The method of model construction is illustrated thoroughly. The influence of several parameters, including anchorage ratio, inclination of prestressing load, eccentricity, magnitude of the reaction force, bearing plate ratio, and the location of the reaction force, is studied. Both graphical and numerical presentations of the results from each load configuration are given. Improved equations, which are modified from the equations presented in the AASHTO Standard Specifications (2002), are proposed. The results from the equations are compared to those from the finite element method. Nonlinear finite element analysis is used to verify the applicability of the equations and to study a new bursting steel arrangement.
Linear and nonlinear finite element analyses are also used for the study of non-rectangular anchorage zones. Four basic load configurations, including concentric, eccentric, inclined concentric, and inclined eccentric loads, are investigated. The shell element is selected for the construction of the finite element models. Several parameters, consisting of anchorage ratio, inclination of prestressing load, eccentricity, web thickness, ratio of web thickness to flange thickness, and flange width, are chosen for parametric studies. The results from the studies are presented graphically and numerically. Equations to calculate the bursting force and location of the force are developed from the Strut-and-Tie Model approach. The verification of the formulations and the investigation of bursting steel arrangement are conducted using nonlinear finite element analysis.<br>Ph. D.
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Zhang, Dichuan. "EXAMINATION OF PRECAST CONCRETE DIAPHRAGM SEISMIC RESPONSE BY THREE-DIMENSIONAL NONLINEAR TRANSIENT DYNAMIC ANALYSES." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195277.
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The primary objective of the dissertation research is to establish the seismic demands of precast concrete floor diaphragms designed with an emerging design methodology. To accomplish this, three-dimensional (3D) finite element (FE) models of diaphragm-sensitive precast concrete structures have been developed by extending two-dimensional (2D) diaphragm model developed previously for nonlinear static "pushover" analyses. Using these models, diaphragm seismic demands under expected hazard are evaluated through the nonlinear transient dynamic analyses (NLTDA).The research work is composed of four major parts:(1) Developing 3D NLTDA analytical model for diaphragm-sensitive precast concrete structures: The 3D structure model is extended from a 2D FE diaphragm model developed by a previous researcher. This process involves properly handling comparability conditions in 3D, incorporating proper hysteresis behavior for the diaphragm reinforcement, and developing appropriate lateral force resisting system (LFRS) models. A sensitivity analysis is performed for 3D NLTDA modeling to assist in creating an appropriate model.(2) Application of the model in integrated analysis-driven physical testing: These experiments occurred at Lehigh University (LU) with project collaborators. The loading in these tests were controlled by NLTDA of the 3D analytical model. The tests were used to examine the seismic response of key joints (critical flexure and shear joints) in the diaphragm under realistic demands and to further calibrate the analytical model.(3) Analytical modeling in support of shake table testing: The shake table test was performed at University of California San Diego (UCSD). The test involved a half scale three-story diaphragm-sensitive precast concrete structure. NLTDA using the 3D analytical model is used to assist in design and performance prediction of the test specimen. The test results are being used to calibrate/verify the analytical model.(4) Calibrating design factors for the emerging diaphragm design methodology: In the last research step, the 3D analytical model is used to calibrate trial design factors for the emerging diaphragm design methodology. These factors are established based on a parametric study of NLDTA at different seismic hazard levels using simple structure configurations. These factors will be evaluated on models of realistic structures to determine design factors for the final design procedure.
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Wan, Ka-ho, and 溫家豪. "Transition finite elements for mesh refinement in plane and plate bending analyses." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29478546.
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Brolin, Karin. "Cervical Spine Injuries - Numerical Analyses and Statistical Survey." Doctoral thesis, KTH, Aeronautical Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3418.
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<p>Injuries to the neck, or cervical region, are very importantsince there is a potential risk of damage to the spinal cord.Any neck injury can have devastating if not life threateningconsequences. High-speed transportation as well as leisure-timeadventures have increased the number of serious neck injuriesand made us increasingly aware of its consequences.Surveillance systems and epidemiological studies are importantprerequisites in defining the scope of the problem. Thedevelopment of mechanical and clinical tools is important forprimary prevention of neck injuries.</p><p>Thus, the main objectives of the present doctoral thesisare:- To illustrate the dimension of cervical injuries inSweden,- To develop a Finite Element (FE) model of the uppercervical spine, and- To study spinal stability for cervical injuries.</p><p>The incidence studies were undertaken with data from theinjury surveillance program at the Swedish National Board ofHealth and Welfare. All in-patient data from Swedish hospitals,ranging over thirteen years from 1987 to 1999, were analyzed.During this period 14,310 nonfatal and 782 fatal cervicalinjuries occurred. The lower cervical spine is the mostfrequent location for spinal trauma, although, this changeswith age so that the upper cervical spine is the most frequentlocation for the population over 65 years of age. The incidencefor cervical fractures for the Swedish population decreased forall age groups, except for those older than 65 years of age.The male population, in all age groups, has a higher incidencefor neck fractures than females. Transportation relatedcervical fractures have dropped since 1991, leaving fallaccidents as the sole largest cause of cervical trauma.</p><p>An anatomically detailed FE model of the human uppercervical spine was developed. The model was validated to ensurerealistic motions of the joints, with significant correlationfor flexion, extension, lateral bending, axial rotation, andtension. It was shown that an FE-model could simulate thecomplex anatomy and mechanism of the upper cervical spine withgood correlation to experimental data. Three studies wereconducted with the FE model. Firstly, the model of the uppercervical spine was combined with an FE model of the lowercervical spine and a head model. The complete model was used toinvestigate a new car roof structure. Secondly, the FE modelwas used for a parameter study of the ligament materialcharacteristics. The kinematics of the upper cervical spine iscontrolled by the ligamentous structures. The ligaments have tomaintain spinal stability while enabling for large rotations ofthe joints. Thirdly, the FE-model was used to study spinalinjuries and their effect on cervical spinal stability inflexion, extension, and lateral bending. To do this, the intactupper cervical spine FE model was modified to implementruptures of the various spinal ligaments. Transection of theposterior atlantooccipital membrane, the ligametum flavum andthe capsular ligament had the most impact on flexion, while theanterior longitudinal ligament and the apical ligamentinfluenced extension.</p><p>It is concluded that neck injuries in Sweden is a problemthat needs to be address with new preventive strategies. It isespecially important that results from the research on fallaccidents among the elderly are implemented in preventiveprograms. Secondly, it is concluded that an FE model of thecervical region is a powerful tool for development andevaluation of preventive systems. Such models will be importantin defining preventive strategies for the future. Lastly, it isconcluded that the FE model of the cervical spine can increasethe biomechanical understanding of the spine and contribute inanalyses of spinal stability.</p>
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Dow, Douglas Donald. "Finite Element and Experimental Analyses of Hybrid Joints Subjected to Fully Reversed Flexure Fatigue Loading." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/DowDD2008.pdf.
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Daoulas, John Christos. "Finite element analyses of pile load tests performed in the Yorktown formation, Newport News, Virginia." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43588.
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Adkins, Keith A. "A Model for Prediction of Fracture Initiation in Finite Element Analyses of Welded Steel Connections." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1399624062.
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Providas, Efthimios. "On the geometrically nonlinear constant moment triangle (with a note on drilling rotations)." Thesis, Brunel University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277518.
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Mitchell, Caleb. "Finite Element Analyses and Proposed Strengthening of a Reinforced Concrete Box Girder Bridge Subjected to Differential Settlement." Thesis, Kansas State University, 2018. http://hdl.handle.net/2097/38789.
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Master of Science<br>Department of Civil Engineering<br>Hayder A. Rasheed<br>The Kansas Department of Transportation’s (KDOT) Bridge 059-045 is a reinforced concrete box girder bridge constructed in 1965 to connect the rural Shawnee Drive across Interstate 135 near McPhearson, Kansas, in between Salina and Wichita. The bridge was observed, during an annual inspection in 1998, to have experienced some settlement, which was further found to be due to its proximity to a sinkhole. This settlement progressed to noticeable levels in 2012 necessitating a semi-annual elevation profile survey that was consistently conducted by KDOT. In April 2016, KDOT determined that the bridge required a detailed finite element analysis to determine the safety and suitability of the bridge to stay open to traffic. Accordingly, a two-level Finite Element Analysis was performed using RISA 3D and Abaqus to assess the level of distress in the bridge due to the continuous differential settlement as a result of the active sinkhole deep in the soil under the bridge. The force-moment results were taken from the RISA 3D model for further analysis of various structural components that make up the bridge, including the box girder, piers, and piles. The stress distribution results from the Abaqus model were investigated for the same components of the bridge. A strengthening design scheme using near surface mounted fiber reinforced polymer rebar was developed to extend the service life of the bridge.
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Ngo, Ngoc Son Civil & Environmental Engineering Faculty of Engineering UNSW. "Limit and shakedown analyses by the p-version fem." Awarded by:University of New South Wales. Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/23463.
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This thesis provides a contribution towards a general procedure for solving robustly and efficiently limit and shakedown analyses of engineering structures within the static approach which has been chosen for its simplicity of implementation. Throughout the thesis, attempts at improving the robustness and efficiency of the computations are presented. Beginning with efforts to prevent volumetric locking, which is a severe shortcoming of traditional low order h-type displacement elements, the investigation proposes the use of the high order p-version of the finite element method. It is shown theoretically and confirmed numerically that this p-method is not only robust in preventing locking, but also provides very accurate results. However, the use of uniformly distributed high order p-elements may be computationally demanding when the size of the problem becomes large. This difficulty is tackled by two main approaches: use of a p-adaptive procedure at the elastic computation stage and use of approximate piecewise linear yield functions. The p-adaptive scheme produces a non-uniform p-distribution and helps to greatly reduce the number of degrees of freedom needed while still guaranteeing the required level of accuracy. The overall gain is that the sizes of the models are reduced significantly and hence also the computational effort. The adoption of piecewise linear yield surfaces helps to further increase the efficiency at the expense of possibly slightly less accurate, but still very acceptable, results. State-of-the-art linear programming solvers based on the very efficient interior point methodology are used. Significant gains in efficiency are achieved. A heuristic, semi-adaptive scheme to piecewise linearize the yield surfaces is then developed to further reduce the size of the underlying optimization problems. The results show additional gains in efficiency. Finally, major conclusions are summarized, and various aspects suitable for further research are highlighted.
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Ladak, Hanif M. "Finite-element and experimental analyses of the response of the cat eardrum to large static pressures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ44481.pdf.
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Raymond, Scott David. "On modeling of the weld line in finite element analyses of tailor-welded blank forming operations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2002. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65644.pdf.
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