Numerical modelling of composite structures under impact loads

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 a composite shell impacted at low velocity by a steel impactor, and comparison between predicted structural response and failure modes with observed test results is given.