Fully Automatic Simulation of Crack Propagation in Plane Structures

In this paper, advanced fully automatic computations of curved crack propagation in combination with the analysis of the plastic limit loading by the lower bound theorem of plasticity in plane structures with multiple cracks are presented. For this purpose a simulation program based on the finite element method (FEM) is developed. A Coffin-Manson-model is implemented to include additionally initiated cracks into the model during the crack growth simulation process. To show the accuracy of the simulation program numerical results of multiple crack growth under proportional loading configurations are presented and compared with experimental data. The results indicate that the proposed solution algorithm provides a powerful tool for flaw assessment with the failure assessment diagram (FAD) procedure in combination with a numerical crack path simulation. Furthermore, it can be observed that local plastic failure occurs in the ligament between two approaching crack tips, which does not lead immediately to a complete loss of load-bearing capacity of the damaged structure.