Effect of inertia and crack propagation on dynamic strength of geologic-type materials
Effect of inertia and crack propagation on dynamic strength of geologic-type materials
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惯性和裂纹扩展对地质型材料动态强度的影响
DOI：
10.1016/j.ijimpeng.2019.103367
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发表时间：
2019
影响因子：
5.1
通讯作者：
Youjie Sun
中科院分区：
文献类型：
--
作者：
Chengzhi Qi;Chen Xia;Xiaozhao Li;Youjie Sun
实验数据表明，惯性诱导的径向约束对地质类材料的动强度有一定的影响。然而，目前尚不清楚骨折过程如何影响惯性效应。在这项研究中，我们提出了一个力学模型来研究惯性对地质类型材料动态强度的影响，并考虑了裂纹扩展和与之相关的材料性能退化。根据所提出的模型，轴向应变加速度将增强试件的约束并延缓裂纹的扩展。因此，在宏观断裂(强度增强)瞬间达到较高的加载水平需要较长的时间。同时，裂纹扩展会引起应力松弛，削弱惯性效应。数值分析结果表明，惯性效应的强度与应变历史有关。对于较弱的动载，当轴向应变加速度较大、总轴向应力较小时，初始阶段的惯性效应明显。但在加载过程中，随着轴向总应力的增大和轴向应变加速度的减小，惯性效应变弱甚至为负。这促进了试件的变形和断裂。只有当动载足够大，试件在应变加速阶段失效时，惯性效应才能显著。
Experimental data indicates that inertia-induced radial confinement has a definite effect on the dynamic strength of geologic-type materials. However, it remains unclear how a fracture process affects the inertia effect. In this study, we propose a mechanical model to investigate the inertia effect on the dynamic strength of geologic-type materials, with the consideration of crack propagation and the related degradation of their material property. According to the proposed model, the axial strain acceleration will enhance the confinement and retard the crack propagation of the sample. Therefore, the loading requires a longer time to reach a higher loading level at the instant of macroscopic fracture (strength enhancement). Concurrently, crack propagation will induce stress relaxation and weaken the inertia effect. The numerical analysis results indicate that the intensity of the inertia effect depends on the strain history. For a weak dynamic loading, the inertia effect is significant during the initial phase, when the axial strain acceleration is high and the total axial stress is low. However, with an increase in the total axial stress and decrease in the axial strain acceleration in the loading process, the inertia effect becomes weaker or even negative. This promotes the deformation and fracture of the specimen. Only when the dynamic loading is sufficiently high that the specimen fails in the strain acceleration stage, can the inertia effect be remarkable.