Intralaminar crack propagation of glass fiber reinforced composite laminate

The intralaminar crack propagation of unidirectional glass fiber reinforced polymer composite (GFRP) laminate has been investigated by quasi-static tensile/compression experiment and complemented by finite element analysis (FEA). The FEA was conducted using a progressive damage model (PDM)-which was executed by the implicit user material (UMAT) and explicit user material (VUMAT) subroutines. Additionally, based on the UMAT implicit algorithm, the intralaminar crack propagation was predicted by the extended finite element method (XFEM). Finally, XFEM was used to simulate the microscopic crack propagation of representative volume element (RVE). The experimental results showed that the intralaminar crack propagation was accompanied by fiber bridging, which was further observed by scanning electron microscopy (SEM). Besides, multi-crack prop-agation occurred on the specimens without pre-existing crack. The calculated value of intralaminar fracture toughness in stable state was approximately 4.5 N/mm. The PDM revealed the damage status around crack path, stress field at crack tip and the progressive damage mechanical behavior. However, the predicted crack path did not fully agree with those obtained by experiments due to the element delete method. Although the crack propagation process obtained by XFEM was consistent with the experimental result, the damage status could not be observed. The XFEM predictions of the crack state in the RVE was in good agreement with the SEM results; this suggests that crack propagation underpins matrix cracking, interfacial debonding, fiber pulling out, and fiber fracture. In conclusion, using a blended approach by combining the PDM and RVE with XFEM could be a step forward to simulating the intralaminar crack propagation phenomenon in order to gain deeper insights into the micro-macro failure mechanism.