Progressive failure modelling of woven carbon composite under impact

Abstract

The design of composite structures or components, subject to extreme loading conditions, such as crash, blast, etc. requires a fundamental understanding of the deterioration mechanism within the composite meso-structure. Existing predictive techniques for the analysis of composite structures and components near and beyond their ultimate strength are either based on simple scalar stress functions, or use very complex damage formulations with many material constants, some of which may be difficult to characterise. This paper presents a simple damage mechanics based progressive failure model for thin woven carbon composites under impact loading. The approach is based on an unconventional thermodynamic maximum energy dissipation approach, which entails controlling damage evolution and hence energy dissipation per second, rather than damage. The method has been implemented into the explicit dynamic finite element code DYNA3D. Numerical simulation results using the proposed model are compared with two experimental impact tests. The analysis methodology proposed in this paper reflects a very simple, but effective technique that can be used to model a wide range of problems from extreme events, such as crash or blast, to birdstrike, when tearing and perforation are major failure mechanisms. As damage is cumulative, the technique allows initial or/and post-impact static loads to be applied to the composite structure or component, thus allowing a cradle-to-grave design methodology.