冲击载荷作用下应变率对砂岩力学性能的影响

Impact of Strain Rate on Mechanical Property of Sandstone under Impact Load

借助于ANSYA/LS-DYNA数值分析软件对SHPB试验进行数值模拟,就不同应变率对砂岩力学性能的影响进行了研究,探讨了不同应变率对砂岩峰值应力、弹性模量、软化模量的影响规律,系统地分析了砂岩在不同应变率作用下的破坏规律。结果表明:随着应变率的增加,峰值应力显著增加,表现出较强的应变率相关性;应变率增大,弹性模量随之增大,但增长速率逐渐减小;应变率越大,软化模量反而降低。应变率ε从632.4 s-1变化到752.5 s-1时,软化模量由-2.98降到-4.18,降低了28.71%;当应变率ε大于752.5 s-1为1757.9时,软化模量仅降低了5%,说明应变率较大时变化趋势较为缓慢。高应变率下砂岩试件的动态压缩破坏主要呈现为轴向劈裂破坏。

Conducting a numerical simulation of the SHPB experimental data through ANSYA/LS - DYNA, the present paper studies the impact of different strain rates on the mechanical property of sandstone and investigates the effect law of different strain rates on the peak stress, elastic modulus and softening modulus of sandstone, offering a systematic analysis of the damage law of sandstone under different strain rates. The findings reveal that the peak stress shows a notable increase as the strain rate increases and that the two exhibit a strong correlation. Experimental data shows that the elastic modulus will increase as the strain rate increases, but the rate of increase will decrease gradually. When the strain rate increases, the softening modulus will actually decrease. Experimental data also shows that when the strain rate ε varies from 632.4 s^ -1 to 752.5 s^ -1 , the softening modulus will decrease from - 2.98 to -4.18, showing a 28.71% decrease while the softening modulus only shows a 5 % decrease when the value of strain rate ε is greater than 752.5 s^ - 1 at 1757.9,which indicates that when the strain rate is comparatively greater,the variation trend will become relatively gentle. The experiment also finds that the dynamic compression fracture of the sample sandstone under high strain rate demonstrates the fashion of an axial splitting fracture.