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 study^1,2 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 micrographs^1,2 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.