Compressive behavior of multi-axial multi-layer warp knitted (MMWK) fabric composite at various strain rates

The compressive properties of multi-axial multi-layer E-glass/epoxy warp knitted (MMWK) composites at quasi-static and high strain rates loadings have been investigated to evaluate the compressive failure mode at different strain rates. The through-the-thickness compressive properties at high strain rates from 600/s to 2100/s were tested using the split Hopkinson pressure bar (SHPB) technique. The compressive properties at quasi-static strain rate were also tested and compared with those in high strain rates. The results indicate that the stress strain curves are rate sensitive, and compressive stiffness, maximum compressive stress and corresponding compressive strain are also sensitive to the strain rate. The compressive stiffness, maximum compressive stress of the multi-axial multi-layer warp knitted composites is linearly increased with the strain rate. The compressive failure of the composite specimen tends to be in shear failure mode and becomes debris at high strain rate while only compressive deformation could be observed in quasi-static loading.