基于不同材料模型的混凝土SHPB试验数值模拟

Numerical simulation of concrete SHPB test based on different material models

为了分析不同材料模型对混凝土分离式霍普金森压杆(SHPB)试验数值模拟结果的影响,在LS-DYNA软件中分别运用K&C,HJC,CSC三种材料模型对混凝土的SHPB试验进行模拟.利用脉冲整形器对入射波进行整形以减小弥散效应,实现恒应变率加载,并从SHPB试验的基本假定出发验证了有限元模型的准确性.通过数值模拟得到了不同撞击速度下基于3种材料模型的混凝土破坏过程及其应力-应变曲线.结果表明:K&C,HJC,CSC三种模型基本上能够反映混凝土的动态力学特性,且K&C模型和CSC模型的失效模式为核心塌陷,而HJC模型则表现出留核现象;在相同的平均应变率下,HJC模型和K&C模型的动力放大系数大于CSC模型;随着平均应变率的增加,峰值应变增大,CSC模型和HJC模型的割线刚度减小,而K&C模型的割线刚度变化不明显.

To analyze the influence o f the different material models on the numerical simulation results of the concrete split Hopkinson pressure bar(SHPB)test,the concrete SHPB test is simulated by using the K&C(Karagozian and Case),HJC(Holmquist-Johnson-Cook)and CSC(continuous surface cap)models in the LS-DYNA software,respectively.The incident wave is shaped by the pulse shaping device to reduce the dispersion effect,and the constant strain rates o f loading are realized.The accuracy of the finite element simulation is verified based on the basic assumption of the SHPB test.The failure process o f concrete and the corresponding stress-strain curves at different impact velocities based on three different material models are obtained by numerical simulation.The results show that the K&Cmodel,the HJC model and the CSC model can basically reflect the dynamic mechanical properties of concrete.The failure modes o f the K&C model and the CSC model are core collapse,while the HJC model shows the kernel phenomenon.A t the same average strain rate,the dynamic am plification factors of the HJC model and the K&C model are larger than that o f the CSC model.W ith the increase of the average strain rate,the peak strain increases,and the secant stiffnesses o f the CSC model and HJC model decrease,while the stiffness o f the K&C model does not change obviously.