Quasi-static and dynamic mechanical properties of Kevlar/epoxy composite laminates and its constitutive equation

The MTS810 and SHPB were used to experimentally study the quasi-static and dynamic mechanical properties of Kevlar/epoxy composite laminates. Effects of the strain rate and lay-up types of fiber on the mechanical behaviors of laminated Kevlar were discussed. Based on the strain-rate curves of laminated Kevlar, an empirical constitutive equation was proposed in which the strain-rate hardening and damage softening effects of the material were taken into consideration. A stiffness-strengthened factor was introduced into the proposed constitutive equation to describe the influences of fiber lay-up types on the mechanical properties of the laminates. Results show that the introduced factor is reasonable in the fitted and experimental stress-stain curves.