高应变率条件下山西黑花岗岩的动态力学性能研究

Research on dynamic characteristics of Shanxi black granite under high strain rates

采用分离式Hopkinson压杆试验技术,对山西黑花岗岩进行了一系列不同应变率(315.53/s^1 349.87/s)的动态压缩试验。试验结果表明:山西黑花岗岩在高应变率条件下,动态抗压强度表现出突变特性:应变率从460.09/s上升到860.20/s的时候,山西黑花岗岩的动态抗压强度从272.33 MPa提高到371.78 MPa;在高应变率条件下,山西黑花岗岩材料的破碎机理为在初始冲击波作用区先产生体积破碎,而后在试样后半部分产生赫兹破碎;山西黑花岗岩在高应变率下的弹塑性变形能随应变率的增大而减小,高应变率条件下材料失效和裂纹扩展消耗更多能量,对应更加严重的材料破碎。

A series of dynamic compression tests of Shanxi black granite under different strain rates （315.53/s - 1 349.87/s） has been carried out with Split-Hopkinson pressure bar. The dynamic compressive strength of Shanxi black granite increased from 272.33 MPa to 371.78 MPa when the strain rate increased from 460.09/s to 860.20/s. The fracture mechanism of Shanxi black granite with high strain rates is volume fracture in the initial impact region of the shockwave and Hertzian fracture in the second half of the cylinder sample. The elastic-plastic deformation energy per unit volume of Shanxi black granite decreased as strain rate increases. Material failure and crack propagation absorb more energy during the impact with higher strain rate, which results in severer fracture of the granite material.