Development and Verification of Crack-Enriched Elements Based on XFEM

Concrete structures often develop penetrating cracks due to the initiation and propagation of local cracks during service, which may lead to the fracture and failure of the entire structure. The propagation modes and laws of cracks in structural members are closely related to the safety of the overall structure. Conducting research on crack propagation and predicting crack propagation paths for cracked structures can provide technical support for the safety design and reinforcement of structures. Based on the basic framework of the extended finite element method (XFEM), this paper develops a user-defined element (UEL) for ABAQUS using the level set method, and simulates in a two-dimensional space the crack propagation in concrete beam bending tests with the self-developed UEL and the built-in XFEM module of the software. The solution results of the self-developed UEL are consistent in trend with those of the XFEM module, yet the cracks simulated by the XFEM module can only propagate along element boundaries and cannot cross elements, and the accuracy of its results is highly dependent on mesh size. The crack tip simulated by the self-developed UEL can stay inside the element, and the simulated crack propagation paths show a higher degree of agreement with the experimental results. The correctness of the UEL is verified through comparative analysis with the results of the four-point bending tests of concrete beams and the XFEM module of the software. The UEL developed in this paper can effectively predict the crack propagation paths of concrete beams and reveal the multi-crack propagation laws of concrete beams.