The use of curvilinear fibers for enhancement of progressive failure performance of perforated composite panels

This paper aims to examine the progressive failure performance of an open-hole variable stiffness composite (VSC) panel manufactured by the continuous tow shearing (CTS) technique under uniform edge shortening. A finite element (FE) model based on the Puck failure criterion in combination with a material stiffness degradation and damage evolution model is developed to perform the progressive failure analysis (PFA). The linear variation of the fiber orientation along a reference axis is assumed. The progressive failure performances of two constant stiffness composite (CSC) counterparts are also carried out for comparison. The results indicate that both the buckling load and the ultimate strength of the VSC panel are much higher than those of the CSC counterparts. Moreover, a significant decrease in the stiffness is observed after entering the post-buckling regime for CSC panels, while it maintains a high level for the VSC panel. Another interesting finding is that the VSC behaves notch-insensitive under the studied loading condition. The novel findings demonstrate the superior buckling, post-buckling, and failure-resistance properties of VSC fabricated by the CTS technique.