Mechanical behavior and damage kinetics of a unidirectional carbon/epoxy laminated composite under dynamic compressive loading

In this work, mechanical behavior and damage kinetics of a unidirectional carbon/epoxy laminated composite (CFRP) under dynamic compressive loading were investigated. An Instron testing machine and a pulse-shaped split Hopkinson pressure bar (SHPB) apparatus were employed to test the quasi-static and dynamic mechanical properties of the material, respectively. Digital image correlation (DIC) combined with ultra high-speed photography was used to study the deformation and failure process of the specimen under dynamic loading. The results show that the failure modes of the material along the main direction were strain-rate sensitive. The failure mode along the fiber direction was observed to change from crushing followed by fiber kink banding to predominantly interlaminar delamination, longitudinal cracking and fiber buckling delamination as the strain rate increases from quasi-static to high strain rates. Furthermore, an empirical formula for dynamic compression strength was established based on the test data. Model predictions and experimental data are in very good agreement. Finally, a simplified Zhu-Wang-Tang (ZWT) nonlinear visco-hyperelastic constitutive model ZWT nonlinear viscoelastic model was developed to predict the mechanical behaviors of CFRP under dynamic impact loading. The predicted values are observed to essentially match the trends of the experimental results. This research will further improve the design of CFRP composites subjected to high-speed impact loads during service.