Development and implementation of a multi-scale model for matrix micro-cracking prediction in composite structures subjected to low velocity impact

In this paper, a novel multi-scale damage model has been developed to predict the progression of matrix micro-cracking in a prototype car bumper under low-velocity impact. The methodology is based on FE micro-damage modelling to calibrate the parameters of a Synergistic Damage Mechanics model considering multi-axial loading, combined with a matrix micro-crack multiplication model. Python scripting was used to model a series of micro-mechanical FE models to determine the damage parameters, which were then used to simulate damage evolution at the structural scale, using a VUMAT subroutine. Following validation, the effects of the impactor's initial velocity, stacking sequence, rate-dependency and bumper's cross sectional profile have been evaluated for different material systems. The patterns of damage progression show that the damage model can accurately predict the progression of matrix micro-cracking, paving the way for the utilization of accurate multi-scale analysis tools in composite structures.