Compressive behavior of biaxial spacer weft knitted fabric reinforced composite at various strain rates

The in-plane and out-of-plane compressive properties of biaxial weft knitted E-glass fabric reinforced vinyl ester composite at quasi-static strain rate of 0.001/s and high strain rates from 700/s to 2200/s were tested to investigate the strain rate effect on the compressive behavior. The compressive tests were conducted on split Hopkinson pressure bar at high strain rate and on MTS 810.23 system at quasi-static state. The experimental results indicated the strain rate sensitivity of compressive stiffness, failure stress, and strain of the composite in both out-of-plane and in-plane compressive direction. The compressive stiffness and failure stress linearly increased with the increase of strain rate. The failure strain linearly decreased with the increase of strain rate. As the strain rate increased, the main failure mode at out-of-plane compression is the interlaminar shear failure and at in-plane direction is the delamination. At the high strain rate of 2200/s, the composite coupon was compressed into debris with the shear or delamination failure.