Novel simulation framework for compression-after-impact failure in CFRP

This study investigates the compression-after-impact (CAI) strength of carbon fibre-reinforced epoxy composite laminates subjected to low-velocity (LVI) and medium-velocity (MVI) impacts. Impact experiments at varying energy levels were conducted to characterise the dynamic response and damage modes. A strain rate-dependent finite element (FE) model was developed by integrating the Puck failure criterion, continuum damage mechanics (CDM), and surface-based cohesive behaviour to simulate intra- and inter-laminar damage. The intralaminar model was implemented via a VUMAT subroutine in Abaqus/Explicit. A Python-based interface was developed to extract and transfer key damage variables, such as matrix cracking and permanent indentation, into the CAI model with corresponding boundary and loading conditions. This novel modelling approach avoids empirical damage equivalence and enables more accurate simulation of progressive intralaminar and delamination damage. Predicted force-displacement curves, energy absorption, and delamination areas showed strong agreement with experimental results. Finally, the effects of varying impact energies on impact response, failure mechanisms, and CAI strength were systematically analysed, providing an efficient and validated numerical framework for assessing the damage tolerance of composite structures.