Low-velocity impact damage of composites by the element- failure method and strain invariant failure theory

Abstract

This thesis presents the simulation and prediction of low-velocity impact damage in carbon-fiber reinforced composite plates by the use of the element-failure method (EFM). This project implements EFM in a 3-D code to investigate low-velocity impact damage in composites with general lay-up sequences. 3-D brick element type is used for the explicit finite element analysis (FEA). The failure criterion for the analysis is the Strain Invariant Failure Theory (SIFT). A scheme for the modification of the nodal forces (according to EFM) for failed elements has been incorporated into the code. The Impact Damage Rules Algorithm (IDRA) has been introduced and implemented into the SIFT-EFM analysis. Excellent qualitative agreement with experimental results on low-velocity impact damage of cross-ply and quasi-isotropic laminated composites have been observed.