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

摘要

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