XFEM analysis of fiber bridging in mixed-mode crack propagation in composites

In this work, the extended finite element method (XFEM) is further generalized to study the fiber bridging phenomenon in fracture analysis of unidirectional composites. Treating composites as a biphase material, fibers effects on increasing fracture toughness are modeled by non-linear springs integrated in the XFEM formulation of displacement discontinuity. Combining the capability of XFEM in modeling arbitrary crack path with the traction-separation representation of the fracture process zone in the crack-bridged zone model, this formulation allows for simulation of fiber bridging in a crack propagation process without a priori knowledge of the crack path. Moreover, the criterion originally proposed for predicting the crack propagation path in orthotropic solids is modified to incorporate the effects of fiber orientation. Several numerical simulations of mode I and mixed-mode problems are provided, and the corresponding force-displacement curves are analyzed to address the accuracy and efficiency of the proposed method.