Split Hopkinson Pressure Bar-1


Split Hopkinson Pressure Bar (SHPB) testing machine is one of the most versatile method for determining the dynamic mechanical properties of material at high strain rates (100 to 2000 s-1). Broadly, it comprises of two bars (incident and transmitted) of maraging stainless steel and gas gun assembly for impacting striker on to incident bar. The striker can be made to impact at various velocities by adjusting air pressure in gas gun. The sample to be tested is placed between incident and transmission bar. The strain gauges, for capturing signals are mounted on to both bars at middle location through data acquisition system. It works on principle of one-dimensional wave propagation. The impedance mismatch between bar material and sample generates three signals (two in incident bar: the incident and reflected wave; and one in the transmission bar: transmitted wave) which are captured by strain gauges in terms of micro-strain. These 3 signals are processed further to evaluate deformation history of specimen.