端面不平行对岩石SHPB测试结果的影响分析

为探讨岩石试件加工端面不平行对岩石材料动力学特性测试结果的影响,采用有限元分析软件LS-DYNA对13种端面不平行度的岩石试件开展SHPB数值模拟,并分析了端面不平行对加载过程应力均匀性的影响。结果表明:随端面不平行度γ的增加,岩石试件动态应力-应变曲线逐渐向右和向下移动,且峰前加载段逐渐延长。当γ1.60%时,动态应力-应变曲线在加载初期出现一个微小的加载-卸载过程,且在升时为120μs的半正弦入射波加载阶段岩石试件达不到应力均匀状态。基于数值模拟结果,建立了端面不平行度与量纲一化的动态单轴抗压强度、平均应变率和峰值应变的定量表达式。

Influence of Non-parallel End-face in Rock SHPB Test

To investigate the influence of non-parallel end-face on test results of dynamic mechanical characteris-tics,the numerical simulation of rock SHPB with 13 kinds of end-face non-parallelism were carried out by finite ele-ment analysis software LS-DYNA,and the effect of non-parallel end-surface on stress uniformity during loading process in rock SHPB test were also analyzed.The results show that with the increase of end-face non-parallelism γ, dynamic stress-strain curves move to the right and down gradually with the extension of loading stage before peak stress.When γ is bigger than 1.60%,a small loading-unloading process presents in the initial stage of dynamic stress-strain curve,and rock specimen cannot achieve stress uniformity for half-sine incident wave with the rising time 120 μs.After dimensional normalization,quantitative expressions for dynamic uniaxial compressive strength,average strain rate and peak strain are proposed for rock SHPB test under various non-parallel end-surface conditions.