围压下混凝土动态损伤与能量耗散特征数值分析

Numerical analysis of dynamic damage and energy dissipation characteristics of concrete under confining pressure

为了研究围压对混凝土材料冲击破坏过程中损伤演化和能量耗散的影响,基于ANSYS/LSDYNA有限元软件,模拟不同冲击速度和围压级别下的混凝土SHPB实验.结果表明:在不同的冲击速度下,峰值应力均随着围压的提高线性增大,最大可以达到混凝土静态抗压强度的3~4倍.围压条件下混凝土的破坏形式为压剪破坏,试件的平均损伤度随围压的增大而非线性降低,相较于冲击速度,围压对损伤度的影响更弱.随着围压的提高,混凝土对应力波的透射能力增强,反射波的能量非线性降低,而透射能随着围压的增大近似线性增加,混凝土的耗能随着围压的增大而近似线性降低;在不同的入射能下,反射系数、透射系数和试件耗能的变化趋势是一致的.围压一定时,混凝土的损伤程度随入射能的增加线性增长;入射能一定时,试件损伤度随围压的增加而降低,变化幅度也降低.

In order to study the effect of confining pressure on damage evolution and energy dissipation of the failure process of concrete under impact, the SHPB experiments of concrete under different impact velocities and different level of confining pressures were simulated based on ANSYS/LS-DYNA finite element software.The results show that the peak stress increases linearly with the increase of confining pressure at different impact velocities, which can reach 3 ~4 times of the static compressive strength of concrete. Under the condition of confining pressure, the failure mode of concrete is compression-shear failure, and the average damage degree of the specimen decreases nonlinearly with the increase of confining pressure. Compared with the impact velocity, the influence of confining pressure on the damage degree is weaker. With the increase of confining pressure, the transmission capacity of the concrete is enhanced, and the reflected energy decreases nonlinearly, while the transmitted energy increases linearly. The energy dissipation of the concrete decreases linearly with the increasing of the confining pressure. On the other hand, the change trend of the reflection coefficients, transmission coefficients and the energy consumption of the specimen are consistent under different incident energy. When the incident energy is constant, damage degree of specimen decreases with the increasing of confining pressure, meanwhile, the variation range decreases as well.