Improved XFEM (IXFEM): 3D dynamic crack propagation under impact loading

An improved XFEM (IXFEM) for three-dimensional non-planar crack propagation under impact loadings is developed. The proposed method couples the IXFEM (Tian and Wen, 2015; Wen and Tian, 2016) and the B-spline ruled surface method (BRSM) proposed previously by authors (Xiao, Wen and Tian (2021)). The issues of the standard XFEM for dynamic crack propagation, such as energy inconsistency, null critical time step size and optimal mass lumping at crack tip, are fundamentally avoided with an extra-DOF free PU approximation (Tian, 2013). The tip singularity enrichment is introduced to assure high accuracy through the extra-DOF free PU approximation. The BRSM, which is designed to solve the challenge about robust and efficient geometry representation of 3D non-planar surface crack growth, is applied to model the geometry of the 3D dynamic crack propagation in this paper. The interaction integral for 2D dynamic stress intensity factor (SIF) evaluation is extended to 3D. Efficiency of the proposed approach is demonstrated via numerical tests. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

An improved XFEM (IXFEM) method is proposed for three-dimensional non-planar crack propagation under impact loadings. The method combines IXFEM and the B-spline ruled surface method (BRSM) to overcome the issues of standard XFEM in dynamic crack propagation. The proposed method employs an extra-DOF free PU approximation and tip singularity enrichment to ensure high accuracy. The BRSM is used to model the geometry of 3D dynamic crack propagation, and the interaction integral for 2D dynamic stress intensity factor (SIF) evaluation is extended to 3D. The efficiency of the proposed approach is demonstrated through numerical tests.