基于HJC本构模型的煤岩SHPB实验数值模拟

Numerical simulation of SHPB tests for coal by using HJC model

利用有限元软件LS-DYNA,采用岩石的Holmquist-Johnson-Cook(HJC)本构模型,对煤岩霍普金森压杆(SHPB)实验进行数值模拟,再现了煤岩在冲击实验过程中的应力波形、应力波的震荡现象及试件的损伤过程,通过对比发现模拟结果与实验实测结果具有较好的相似性,HJC本构模型可以合理地再现煤岩受冲击破坏的动态过程。研究发现:1)试件均在周边开始破坏,破坏形式以沿轴向方向的劈裂破坏为主;2)当冲击速度为3 m/s左右时,煤岩的破坏受压缩和拉伸共同作用;当冲击速度为9 m/s左右时,煤岩的破坏主要受冲击压缩的作用;3)煤岩的破坏与应力峰值并不同步,当动载较低时,试件的破坏滞后于应力峰值;而动载较高时,试件的破坏超前于应力峰值。

By using the Holmquist-Johnson-Cook（HJC）, the constitutive model, the Φ50 mm split Hopkinson pressure bar（SHPB） tests for coal have been numerically simulated with the finite element analysis software LS-DYNA. The simulation results have reoccurred the stress waves shape, stress variation and the destruction process of coal specimen during the SHPB tests. By contrast, it has been found that the numerical simulation is similar to the experiment results, and that the dynamic destruction process of coal specimen during the SHPB tests can be reoccurred reasonably with HJC constitutive model. The numerical simulation has shown that：1） The coal specimens have been destroyed firstly from around with the destruction mode of splitting failure in the axial direction mainly. 2） When the impact velocity is about 3 m/s, the destruction of the coal is caused by both compression and tensile; When impact velocity is about 9 m/s, the destruction of the coal is caused mainly by compression. 3） The destruction of the coal is out of sync with the peak stress： when the dynamic load is lower, the destruction of coal specimens lags behind the stress peak; when the dynamic load is higher, the destruction of coal specimens is ahead of the stress peak.