Strain Rate Effect on Four-Step Three-Dimensional Braided Composite Compressive Behavior.

The mechanical properties of four-step three-dimensional braided composite at high strain rates are important in evaluating this kind of composite under dynamic and impulsive loading. The in-plane and out-of-plane compressive properties of E-glass/epoxy four-step three-dimensional braided composite at strain rates from 300 to 3500 s-1 were tested with split Hopkinson pressure bar. The compressive properties at quasi-static strain rate (10-3 s-1) were also tested and compared with those at high strain rates. From the experimental data, the stress-strain curves, compressive stiffness, and compressive deformation of the composite are rate-sensitive in in-plane and out-of-plane compressive directions. In the out-of-plane direction, the compressive deformation mode was observed to have a deformation transition from axial compression to shear as the increase of strain rate, whereas only compressive deformation was found for in-plane direction compression. The failure stress and strain under compression at various strain rates have no regular tendency as the strain rate increased from 10-3 to 3500 s-1. [ABSTRACT FROM AUTHOR]