Analysis of failure modes in three-dimensional woven composites subjected to quasi-static indentation

Abstract

Finite element models are developed to predict potential failure initiation sites and associated failure modes in S2-Glass/SC15 three-dimensional (3D) woven composites under quasi-static indentation. As part of this modeling effort, experimental micrographs of the composite specimen obtained from a previous experimental study1,2 are analyzed. In conjunction with these micrographs, model outcomes demonstrate the ability of warp weavers or through-thickness Z-yarns to shield inter-laminar cracks. Quasi-static indentation is modeled as a contact interaction between a rigid cylindrical indenter and a deformable S2-Glass/SC15 3D woven composite laminate using ABAQUS®. Tow elements are modeled as transversely isotropic elastic-plastic material entities, whereas the inter-tow matrix is modeled as an isotropic elastic-plastic material. Through-thickness failure modes are predicted based on the Tsai-Hill criterion. Contour maps of these failure modes point to the location and corresponding damage initiation mode within the material. Experimentally obtained micrographs1,2 are then analyzed on the basis of these contour maps, thereby serving to validate the modeling methodology. The effect of Z-yarns is demonstrated with the aid of two-dimensional plane strain linear elastic fracture mechanics analysis. Crack shielding abilities of the Z-yarns manifest as the variation of strain energy release rate as a function of crack length and location. In the vicinity of a Z-yarn, the energy release rate decreases precipitously, indicating the inability of the crack to penetrate the Z-yarns.