Experimental and numerical analysis of low-velocity impact damage of CFRP laminates with negative Poisson ratio (NPR) rubber protective layer

Carbon fiber-reinforced polymer (CFRP) structures are widely used in aviation industry, which can sustain damage during assembly from low-velocity impact events, decreasing residual stress and bearing capacity. A method of negative Poisson ratio rubber protective layer placing on the CFRP structures has been proposed to address this. The influence of cell angle on the impact response and protection effect were first investigated in this study. The experimental results indicate that the negative Poisson ratio rubber protective layer enhanced the impact resistance of the CFRP laminates, which reduces 33.1% the impact peak force and 17.5% the absorbed energy. Moreover, the impact resistance of CFRP with increases with the increasement of the cell angle. A low-velocity impact finite element model was developed with mixed-mode damage criterion for laminates and the hyperelastic model for rubber. The simulation results were validated with the experiment results in impact response and delamination damage. Additionally, the impact response and resistance were analyzed by varying seven different structural parameters of the protective layer to reveal the influence of relative volume. The experiment and simulation results demonstrated that the impact resistance increased with increasing cell angle and relative volume of the negative Poisson ratio rubber protective layer.