New criterion for evaluating influences of stress uniformity on results in split Hopkinson bar tests

Abstract

The split Hopkinson bar (SHB) technique has been widely used to determine dynamic behaviours of materials at high strain rates. In this technique, the non‐uniformity of the stress within specimen may lead to errors in test results. In most of the relevant literatures, the relative time duration for stress to approximately equilibrate in specimen was used to evaluate the stress uniformity. But by one‐dimensional simulations, it is found that this criterion is not always true. Therefore, two new indices, the degree of stress uniformity and the relative uniformity strain, are defined to characterise the stress uniformity. Then a new criterion is proposed for evaluating the influences of stress uniformity on test accuracy. This study provides guidelines for SHB test designs and data validations.

Keywords:

• Split Hopkinson bar
• Stress uniformity
• Criterion
• Theory of one‐dimensional stress wave

This work was supported by the Key Project of National Natural Science Foundation of China (grant no. 10932008) and the Programme of Introducing Talents of Discipline to Universities of China, i.e. the 111 Project (grant no. B07050).