SHPB试验中岩石试件的端面不平行修正

为研究短圆柱体岩石试件端面不平行对岩石动力学特性测试结果的影响，采用有限元分析软件LS-DYNA对9种端面不平行度和5种杨氏模量的岩石试件开展SHPB(split Hopkinson pressure bar)试验数值模拟，对岩石选用HJC(Holmquist-Johnson-Cook)本构模型。数值模拟结果表明，当端面不平行度在0.40%以内时，端面不平行对动态应力测试结果的影响可忽略不计；但对动态应变测试结果的影响较大。当杨氏模量一定时，平均应变率测试误差和峰值应变测试误差随端面不平行度增大呈线性增大；当端面不平行度一定时，平均应变率测试误差和峰值应变测试误差随杨氏模量增大也呈线性增大。对数值模拟得到的平均应变率测试误差和峰值应变测试误差实施二元线性回归分析，提出了SHPB试验中端面不平行岩石试件平均应变率和峰值应变的修正公式。

Correction of non-parallel end-faces of rock specimens in SHPB tests

To investigate the influence of a non-parallel end-face for a short cylinder rock specimen on dynamic mechanical test results,we carried out numerical simulation of the SHPB test for rock material in 9 non-parallelisms and 5 Young's moduli using the finite element analysis software LS-DYNA,with the HJC constitutive model chosen for the rock material.The numerical simulation results show that when the non-parallelism of the rock specimen end-face is below 0.40％,the influence of the non-parallel end-face on the dynamic stress test results is negligible,while the influence of the non-parallel end-face on the dynamic strain test results is much bigger.When the Young's modulus remains the same,there is an approximately linear relation between the test error of the average strain rate and the non-parallelism or between the test error of the peak strain and the non-parallelism.When the non-parallelism remains the same,there is also an approximately linear relation between the test error of the average strain rate and the Young's modulus or between the test error of the peak strain and the Young's modulus.After conducting the binary linear regression analysis for the test error of the average strain rate and the test error of the peak strain obtained from numerical simulation,a correction formula for the average strain rate and the peak strain is proposed for the SHPB test of non-parallel end-face rock specimens.