Dynamic Progressive Damage Modeling of Fiber-reinforced Composites Under Different Strain Rates

Abstract

A dynamic progressive damage model is developed to simulate the crash dynamic behavior of laminated composites. Experimental results are taken from various types of uni-axial quasi-static and dynamic tests on unidirectional plies. The model is an integration of four major components: rate-dependent material model, stress analysis, failure analysis, and material property degradation rules. Material properties of a glass/epoxy unidirectional ply under quasi-static and dynamic loading conditions; in longitudinal, transverse, and shear loadings and at various strain rates, ranging from 0.001 to 100 s-1 which are typical strain-rate range during automobile crash accidents, are fully characterized. The material properties, including strain-rate-dependent effects, are derived. The dynamic behavior of composite specimens exhibited strain-rate dependency, when compared to the static properties. Based on the results obtained, the empirical material model functions are proposed in terms of strain rates. In addition, stress-based dynamic failure criteria including different failure modes of a unidirectional ply under multi-axial states of stress and the strain-rate-dependent behavior of material are developed. The developed failure criteria are used to quantify the damage evolution and corresponding reduction in the stiffness and strength in different modes based on associated rate-dependent material property degradation rules. The developed models are programmed as a user-defined subroutine in LS-DYNA, a nonlinear, explicit dynamic code. The predictive capability of the model is validated by numerical simulations of two representative composite specimens; quasi-isotropic composite flat specimens under tensile dynamic loading and circular composite tubes under axial impact against experimental results. The predictions of the model correlate well with the results obtained by experiments.