High Strain Rate Compression Response of Kevlar and Interyarn Hybrid Carbon-Kevlar Polymer Composites

Development and characterization of carbon-kevlar interyarn hybrid textile composites (CKI-HTCs) may direct their utilization beyond the intended service conditions of monolithic carbon and Kevlar textile composites. This work presents the response of hybrid C-K and monolithic kevlar composites under high strain rate compression (HSRC) loading. Experiments are conducted to characterize and quantify the hybridization effect on stiffness and toughness of CKI-HTCs. During laminate fabrication for sample preparation, plain and twill weaving architectures of the fabrics are considered for reinforcement into the epoxy matrix. HSRC tests are performed using a Split Hopkinson Pressure Bar (SHPB) testing apparatus. SHPB generates the strain pulses (strain rate of 1000-2300 s(-1) range) on cylindrical specimens placed in between the incident and transmitted bars. The effects of strain rate variation and the fabric weaving pattern on the dynamic mechanical behavior and failure mechanisms of the textile composites are quantified through HSRC tests. The strain rate stiffening phenomenon is also analyzed. Material response to HSRC is plotted as stress-strain curves. Results suggest that the strain value for damage initiation reduces with increasing the applied strain rate. Fractography is performed on the broken samples to identify the failure mechanisms, namely the matrix fracture, fiber pull out, fiber breakage, splitting, shear fracture of plies, and fiber-matrix debonding.