Examination of Direct Stress Measurement in Hopkinson Bar Tension Test

Abstract

In order to improve the collision safety of transportation equipment such as automobiles, railway vehicles, and aircraft, and the drop impact strength of various electronic equipment, modern CAE-based designs use precise material models, of which the strain rate dependence is properly considered. Therefore, the stress–strain relationship of materials over a wide range of strain rates is required from the usage environment of various products, and the tension test is the most fundamental one that can obtain the tensile strength, fracture strength and failure strain of materials. Furthermore, high speed tension tests, most of which are carried out by the Hopkinson bar method, become particularly important due to the dificulty in measuring with high accuracy. In this study, direct stress measurement at the specimen in the high speed tension test based on the Hopkinson bar method is studied using strain-gauge and DIC methods for the purpose of examining the accuracy of stress measurement that leads to the improvement of the design of the experimental aparatus and specimen.