Özet:
This thesis study focuses on the crack propagation analysis in elastomeric isolation bearings. One benchmark problem related to crack propagation analysis in a single-edge notch specimen and two problems related to interface crack modelling were studied. The results such as reaction force, J integral and strain energy values were compared with the findings from literature. In the benchmark problem, conventional FEM and extended finite element method (XFEM) were used for single edge notch specimen. The strain energy values determined from conventional FEM and XFEM were in good agreement. Advantages and limitations of XFEM were investigated and it was found that J integral is not calculated in crack propagation modeling using XFEM. Therefore, a variable that would allow calculation of energy release rate was investigated. It was determined that for small crack advances, dissipated energy values obtained from the XFEM are very close to those based on J integral values calculated from FEM. 2D axisymmetric and 3D FE models of a circular elastomeric isolation bearing containing interface cracks and subjected to compression and shear loading were analyzed. For both models, the effects of fillet radius at sharp corners and coefficient of friction on the convergence of the FE analysis were investigated and optimization of these parameters to overcome convergence difficulties was accomplished. In the analysis, three different models were analyzed to improve the run time of the computation while maintaining the accuracy. J integral and reaction force for several stationary cracks were found to be in good agreement with the results obtained from the literature. In the 3D model, partial convergence was achieved for compression. For the converged combined loading the change of the J integral with the crack size followed the correct trend.
