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Stress-strain analysis of aneurysms of arteries
Mucha, Petr ; Janíček, Přemysl (referee) ; Burša, Jiří (advisor)
This diploma thesis deals with the creation of computational model of arterial aneurysm, which respects its real geometry and constitutive behaviour. Subsequently there is explored the risk of rupture, comparing the values of the highest main stress in aneurysm´s and intact aorta´s wall. This thesis also offers the comprehensive summary and mutual comparision of current constitutive (hyperelastic) models, which are for simplicity isochoric considered. The main task of this thesis is to formulate the method for finding of „unloaded“ = „outstressed“ = „primary“ = reduced geometry, which is generally unavailable. Models of aneurysm´s geometry, used so far, present already deformed configurations from blood pressure, axial prestrech and rezidual strain.
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Material nonlinear static response of civil structures
Kinclová, Radka ; Vlk, Zbyněk (referee) ; Nevařil, Aleš (advisor)
The aim of this bachelor’s thesis is the non-linear elastic and plastic response of the simple beam structures. Also the problematics of the plastic hinges development is adressed. This thesis will then describe the origin and magnitude of the residual stresses caused by welding. Ideal elastic-plastic behavior of materials and elastic behavior with strenghtening will be used to determine the limit load capacity of the simple structures and will be compared to solution in the ANSYS software.
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Additional axial stress of rubber cylinder at torsion deformations and large strains
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Košina, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to enhance the theoretical background for experimental evaluation of material behaviour of hard rubbers on our test rig. First the Mooney Rivlin model (MRM) for shear case of loading was developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. Then the tuned MRM cylindrical model was tested under torsion loading for evaluation of stress state. Besides the radial distribution of shear stress and strain the attention was paid for evaluation of additional axial stresses. It helps to assess the influence of the tension stresses on the tangential deformations of the test sample during large torsion strains.
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Stress analysis under torsion loading hard rubber for a large deformation and hyperelastic behaviour
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Košina, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to enhance the theoretical background for experimental evaluation of material behaviour of hard rubbers on our test rig. First the Mooney Rivlin model (MRM) for shear case of loading was developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. Then the tuned MRM cylindrical model was tested under torsion loading for evaluation of stress state. Besides the radial distribution of shear stress and strain the attention was paid for evaluation of axial stresses. It could help to assess the influence of the tension stresses on the tangential deformations of the test sample during large torsion.
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Konstitutivní modelování tepenné stěny
Horný, L. ; Chlup, Hynek ; Adámek, T. ; Zitny, R. ; Macková, H.
Inflation tests and uni–axial extension tests of arterial tissue were performed. Experimental data were used in nonlinear regression analysis to identify material model. Arterial tissue was assumed to be incompressible hyperelastic material. 5–parameter strain energy density function based on combination of isotropic Neo–Hookean expression and Fung–type orthotropic expression was used. Computational model for material parameters identification was based on thick–wall tube with axial pre–strains. Residual strains were included. Internal structure of arterial wall was not considered. Fitted material models correspond to experimental data very well.
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Hyperelesticita pryžového segmentu při jednoosých tlakových zkouškách
Potel, S. ; Pešek, Luděk ; Svoboda, Jaroslav
The plane strain model of hyperelastic material was developed in the ANSYS. For this model, hyperelastic behavior of rubber block and identification of Mooney-Rivlin coefficients from real experimental data for uniaxial compression tests are presented. Furthermore rubber-steel contact problem including tangential Coulomb forces with various friction coefficients were solved. This research is aimed at evaluation of material hyperelastic parameters from static tests and for evaluation of stress state of the rubber segments used as resilient elements in railway wheels. hicle.
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Numerical solution of problems of finite hyperelasticity
Poživilová, Alena
Hyperelastic material model based on the logarithmic description is implemented in the finite element code. Procedure for the calculation of all the necessery quantities at the Gaussintegration points is described in details. The second-rank update BFGS solver is used to process the governing equilibrium equations. The solution algorithm is then combined with the prediscretization contact search method in order to include contact boundary conditions. As an example, numerical simulation of the compression test of a rubber cylindrical specimen is presented.
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