Chapter Seven - Dynamic experimental study on the distortional law of materials

Abstract

In the studies of dynamic response of materials under impact loading, two dynamic effects, i.e., the strain rate effect and the inertia effect, should be taken into consideration. However, these two effects are usually intercoupled, which makes the problem much more complicated. This chapter will introduce two methods to experimentally determine the dynamic behavior of materials: the split Hopkinson pressure bar (SHPB) technique and the wave propagation inverse analysis (WPIA) technique. The SHPB technique can decouple the inertia effect and the strain rate effect by using the elastic pressure thin bars propagating one-dimensional stress waves and the short specimen ignoring stress wave effect, so that can directly measure the dynamic response of materials. Various modified split Hopkinson bar (SHB) techniques are also introduced for meeting different requirements, such as the tensile SHB technique, the torsional/shear SHB technique, the SHB technique under combined stress states, the polymer SHB technique, etc. By WPIA technique, the rate-dependent constitutive relation of materials is inversely deduced from a series of wave propagation measurements taking into account the coupled effects. This chapter also introduces three modified Lagrangian inverse analysis methods (1sv+nv method, 1sv+nε method, and nv+T0 method) and two dynamic experimental methods combining the WPIA technique with Hopkinson bar.