The Application Of CZM And Xfem Methods On Crack Propagation Simulation

This thesis introduced the basic principles of cohesive zone model and extended finite element method, and derived the theoretical formula of extended finite element method. The aims of this dissertation compared with tests are to confirm the The effectiveness of the cohesive zone model and extended finite element method on crack propagation simulation, and investigate the crack propagation behavior and linkage mechanisms of cracks. Based on experimental and simulation study, the most important conclusions were resaerched as follows:1) Cohesive zone method without gaps and notch in SiC matrix of C/SiC bundle model were presented to investigate the propagation of interface crack induced by temperature changes. The matrix gap may change the stress distribution of C fibers and SiC matrix. the interface crack extended more reflected in the radial direction.2) The simulation of Grey cast iron with a cracked body under tensile loading showed that the crack propagation process of unilateral-crack specimens can be explained by and classical Griffith I-crack theory. The crack propagation paths of specimens with bilateral parallel crack under tensile loading are different depending on the axial distance of the two cracks. The precrack may propagate straightly independent with another precrack faraway, and be effected with another and propagate curved because of the short axial distance of the two cracks.3) The expansion of the of grey cast iron with cracked body finite element analysis model, simulation results show that:Numerical simulation of crack propagation and with a cracked body test, the unilateral crack tensile test and bilateral dislocation crack test, the theoretical and practical comparison of the results to verify the applicability of the extended finite element simulation on metallic materials with cracks, the results test results and numerical simulation results agree, to lay the foundation for further crack propagation studies.