Calculations of crack stress intensity factors based on FEM and XFEM models

The basis of describing stress intensity factor and predicting residual life of structure is the right numerical model of dynamic crack propagation. 'FEM+M integral' and 'XFEM+M integral' methods were, respectively, adopted. Difficulties of 'FEM+M integral' method were solved, such as the singularity of crack tip, nodal uncoincidence of rubber layer unit and plate unit during mesh repartition and calculation convergence. In addition, difficulties of 'XFEM+M integral' method were overcome, such as difficult crack tip coordinates, difficult cutting point of crack and element and crack deflection in the element. On this basis, the effective calculation of stress intensity factor was realised. Through simulation and calculation, it is found that the error value is within 5%. The model reliability is further verified within the allowable error range.