冲击荷载下红砂岩非线性黏弹性损伤本构研究

NONLINEAR VISCOELASTIC DAMAGE CONSTITUTIVE OF RED SANDSTONE UNDER IMPACT LOAD

根据红砂岩在冲击荷载作用下应力曲线表现出的明显的分段特征,以朱王唐本构模型为基础进行改进,建立了一种非线性体、Maxwell体和基于Weibull分布的损伤体并联的本构模型;根据红砂岩动态力学特性,对朱王唐本构模型进行简化,并基于Lemaitre等效应变假设推导出一种率型损伤本构方程。对两种新建本构方程进行试验验证,讨论其适用性并对比分析各参数对试验数据拟合结果的影响,结果表明,基于Weibull分布的非线性黏弹性损伤本构方程能很好地对常温及冻结状态下红砂岩峰前以及整个应力曲线的动态力学性能进行表征,而基于Lemaitre等效应变假设的损伤本构方程只可对红砂岩峰前应力部分进行解答,对整个应力曲线的表征存在一定的局限性。

According to the clear segmental characteristics of the stress curve of red sandstone under impact load,a constitutive model with the nonlinear body,Maxwell body and damaged body in parallel is established based on the Zhu-Wang-Tang(Z-W-T)constitutive model.According to the mechanical properties of red sandstone,the Z-W-T model is simplified,and another rate-type damage constitutive equation is derived based on the Lemaitre equivalent strain hypothesis.The applicability of two new constitutive equations is discussed and the influence of each parameter on the fitting result of the experimental data is compared and analyzed.The results show that the nonlinear viscoelastic damage constitutive equation based on Weibull distribution can well characterize the dynamic mechanical properties of pre-peak stress and the whole stress curves at room temperature and freezing temperature.However,the damage constitutive equation based on Lemaitre’s hypothesis of equivalent strain can only be used to solve the pre-peak stress of red sandstone,and has some limitations in the characterization of the whole stress curves.