Discussions on Standardization of Hopkinson Bars Technique

Abstract

It is well known that the constitutive behaviour of most materials exhibits rate sensitivity and that the rate dependent (tensile/compressive) properties of such materials should be experimentally studied. The Split Hopkinson Bar (SHB) technique has been successfully applied to investigate the visco-elastic and visco-plastic behaviour of plastics and metals under high strain rates. Recently, it has widely been used to study the dynamic behaviour of materials, such as rubbers, composites, foams and concretes. Then, it often happens that the measured data by SHB in one laboratory are different from those in another laboratory. Even in the same laboratory, sometimes, the SHB measured data by one person are different from those by another one. The cause to produce the difference, as revealed by our experiments and the related theoretical analysis, is mainly attributed to that there are some important factors which do affect the accuracy of data measured in SHB tests, and that researchers sometimes ignore the basic assumptions in SHB technique.