Computational Methods for Predicting Impact Damage in Composite Structures

Abstract

This paper describes recent progress on the materials modelling and numerical simulation of the impact response of fibre reinforced composite structures. A continuum damage mechanics (CDM) model for fabric reinforced composites is developed as a framework within which both in-ply and delamination failure may be modelled during impact loads. Damage evolution equations are derived and appropriate materials parameters determined from experiment. The CDM model for in-plane failure has been implemented in a commercial explicit FE code, and new techniques are used to model the laminate as a stack of shell elements tied via contact interface conditions. This approach allows the interlaminar layers and strength reduction due to delamination to be correctly modelled. The code is applied to predict the response of carbon fabric reinforced epoxy plates impacted at different velocities by a steel impactor. A comparison of structural response and failure modes from numerical simulations and impact tests is given which shows a good agreement for the prediction of delamination damage at low impact energies and fracture and penetration at higher impact energies.