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Computational modelling and analysis of crack propagation in ceramic composites containing residual stresses
Černý, Hynek ; Majer, Zdeněk (referee) ; Ševeček, Oldřich (advisor)
The diploma thesis dealt with 3D computational modelling of crack propagation in particle and layered ceramic composites. In first part of thesis, all tools for fracture mechanics implemented in software ANSYS were explored for their suitability in given topic. In the next part, crack propagation in particle composites was analysed, where extra focus was applied on influence of different stiffness and thermal expansion of all components of the composite. First, the crack propagation in homogenous material model was set up, then the effect of different stiffness of the composite components was added, and in the last stage, the effect of the residual stresses was also added. From the achieved results, it was possible to describe the influence of the previously listed factors on the energy required for crack propagation. This created model should be applicable to the model of a real composite, thanks to which it should be possible to quantify whether the composite is more resistant to crack propagation then the homogenous material. In the last part of thesis, the crack growth through layered ceramic laminates was analysed, where emphasis was again placed on the different stiffness and thermal expansion of all components of the laminate. In this part, the great advantage of the ANSYS APDL, creating of macros, were used. Using macros, a parametric model was created, which, after the input data was entered, was able to create geometry of the computational model, enter boundary conditions, create a mesh of the computational model, set up the analysis and start the simulation. The created model can be used, for example, to determine the apparent fracture toughness of laminate, thanks to which it is possible to access how much the used configuration is more suitable than the use of a homogenous material.
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