Strain-rate dependence of impact behaviour in carbon fibre composites

The dynamic responses of carbon fibre reinforced polymer (CFRP) composites under impact loading are critical for structural applications; however, existing models inadequately capture strain rate-dependent damage mechanisms across different impact velocity regimes. This study develops and validates a strain rate dependent modelling framework that integrates a modified Puck failure criterion with logarithmic strain rate-dependent constitutive relations and cohesive zone modelling for progressive damage analysis. Dynamic tensile tests conducted across strain rates from 10 −4 to 10 3 s −1 demonstrate significant strain rate sensitivity, with failure strength increasing up to 1.6 times at high rates. The strain rate effects on material strength and stiffness are incorporated through logarithmic scaling laws from the literature, implemented via user-defined VUMAT subroutines. Experimental validation against low-velocity impact (LVI) and medium-velocity impact (MVI) tests demonstrates excellent agreement in predicting peak force, absorbed energy, and damage morphology. Through systematic comparison between strain rate-dependent and rate-independent models, this study explicitly quantifies the governing role of strain rate effects in failure progression—particularly in matrix-dominated failure modes—providing an experimentally validated framework for dynamic impact analysis of composite laminates.