Stress Wave Propagation in Split Hopkinson Pressure Bar

Abstract

Civil structures are exposed to various impacts due to blast explosion caused by people intentionally or accidentally. Thus buildings in those areas which have threats from explosions should be blast resistant. For this purpose, the dynamic stress-strain responses of various samples of different materials at high strain rates should be found out. The most widely used experimental setup, Split Hopkinson Pressure Bar, has given significant results at high strain rates. It can test the materials at various strain rates in the range of 10 to 104/sec. This apparatus comprises of a short cylinder-like specimen sandwich between two long slender bars. A compressive stress wave is generated by hitting the end of a bar and the wave immediately begins to traverse towards the specimen. The mechanism involved in the apparatus is well explained in the thesis. By tracking the strains in the two bars using different instruments, stress-strain properties of the specimen can be determined. The intent of this thesis is to study the one dimensional wave propagation on which the SHPB setup is established and to model the one dimensional wave propagation – incidence, reflection and transmission in SIMULINK, a tool in MATLAB. Also, 3D finite element analysis of various types of materials has been done in ABAQUS/Explicit to explore the dynamic behaviour of different types of soft materials which shows plastic properties. The various materials which are modelled and simulated are three types of rocks; limestone, sandstone and granite along with soft materials like cement mortar and concrete