高应变率下计及损伤演化的材料动态本构行为

Dynamic constitutive behavior of materials at high strain rate taking account of damage evolution

材料在高速变形过程中常常伴有不同形式的内部缺陷或微损伤的演化。大量的实验观察表明,损伤演化同时依赖于应变、应变率和温度,而且高应变率和低温之间有某种等价性。由此基于热激活机制,提出了同时依赖于应变率和应变的微损伤演化律,及相应的计及损伤弱化效应的率型本构关系。以聚丙烯/尼龙(PP/PA)共混高聚物为例,具体研究了其计及损伤演化的ZWT本构关系,并区分其率相关的本构响应及率相关的损伤演化响应。

High-velocity deformation process of material is usually accompanied with interior damage evolution in different forms. Experimental observations for different materials show that damage evolution is dependent on strain, strain rate and temperature, and a certain equivalency exists between the strain rate effect and the temperature effect. Thus, based on the thermo-activation mechanism, a strain and strain-rate dependent damage evolution law and the corresponding rate-dependent constitutive relation taking account of damage evolution are proposed. As an example, the ZWT nonlinear viscoelastic constitutive relation taking account of damage-weakening effect is further studied, particularly the constitutive response and the response due to damage evolution can be distinguished.