The Implementation of Regularized Extended Finite Element Method (Rx-FEM) in ABAQUS

摘要

Rx-FEM is a discrete damage modeling (DDM) method, which represents an approach to progressive failure modeling in composites when multiple individual damage events such as matrix cracks and delamination are introduced into the model via displacement discontinuities. Rx-FEM is a variant of the extended Finite Element Method (x-FEM), where a continuous approximation is used in place of the Heaviside step function. To date, this methodology has been implemented in BSAM, an in-house program, and extensively applied to static and fatigue analysis of laminated composite structures. The regularization of the Heaviside step function offers unique possibility for implementation of Rx-FEM in commercial software by using superimposed native elements of the parent software. The proposed implementation capitalizes on utilization of original Gauss integration schema in Rx-FEM even after the enrichment is introduced to accommodate a mesh independent crack. Thus, the enrich displacement field is represented by superposition of native ABAQUS elements such as CPS4, which is used in the present work. Several examples of unnotched and open hole composite unidirectional coupons are considered, including the splitting phenomenon of an axially loaded open-hole coupon. The method correctly predicts separation and fiber direction stress concentration reduction as a result of the splitting.