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A non-associated plasticity model for predicting ductile fracture of metallic materials
Vobejda, Radek ; Kotoul, Michal (referee) ; Halama, Radim (referee) ; Šebek, František (advisor)
This thesis is focused on the study of the applicability of plasticity models based on associated and non-associated flow rule for the prediction of ductile fracture of metallic materials. Firstly, a new isotropic plasticity model is proposed based on the non-associated flow rule, which guarantees the convexity of the yield surface by its definition for any combination of material coefficients. This model, together with models adopted from the literature, is calibrated on the experiments carried out on aluminium alloy 2024-T351. The state variables obtained from numerical simulations of experiments using different plasticity models are used to calibrate the ductile fracture criteria. Numerical simulations indicate that using a non-quadratic plasticity model based on a non-associated flow rule gives the best agreement with experiments in terms of force responses and deformations. The calibrated ductile fracture criterion is further used to simulate the fracture of the experimental specimens used for calibration and to design additional experimental specimens. Finally, an experimental program is designed on this aluminum alloy to map the anisotropy of the material and based on the obtained experimental data, the proposed isotropic plasticity model is extended to anisotropy, calibrated and compared to several models from literature.
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Fracture Toughness of Metallic Materials and its Testing
Kosek, Lukáš ; Zapletal, Josef (referee) ; Němec, Karel (advisor)
The purpose of the work is to introduce the basic of the fracture toughness of metallic materials and its measuring under the conditions of the plane strain. There are shown essential concepts of the linear elastic fracture mechanics, which is used for the description of the material behavior at fracture of the material with a crack. It defines stress intensity factor and describes the main elements influencing the fracture toughness. Furthermore, the work contains the particular testing methods, specimens and testing equipments. In the conclusion it recapitulates the availability and the application of the linear elastic fracture mechanics.
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Fracture Toughness of Metallic Materials and its Testing
Kosek, Lukáš ; Zapletal, Josef (referee) ; Němec, Karel (advisor)
The purpose of the work is to introduce the basic of the fracture toughness of metallic materials and its measuring under the conditions of the plane strain. There are shown essential concepts of the linear elastic fracture mechanics, which is used for the description of the material behavior at fracture of the material with a crack. It defines stress intensity factor and describes the main elements influencing the fracture toughness. Furthermore, the work contains the particular testing methods, specimens and testing equipments. In the conclusion it recapitulates the availability and the application of the linear elastic fracture mechanics.
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