脆性材料动态强度应变率效应

Strain-rate effects on dynamic strength of brittle materials

通过求解波动方程,结合有限结构-时间破坏准则,得到了动态载荷下脆性材料单轴拉伸强度应变率效应的解析表达式。分析结果表明:材料动态强度的应变率效应具有明显的结构响应特征,即材料动态强度除与应变率和静态参数相关外,还显著地依赖于外载荷结构及其与材料间的相互作用,因而动态强度不是表征材料动态破坏的内禀材料性质;此外,由于在不同的外载荷条件下材料将表现出不同的动态强度,这是导致实验结果离散性大的内在因素。

An explicit expression for the strain-rate effect on the uniaxial tensile strength of brittle materials under dynamic loadings was derived by solving the wave equation together with the so-called finite structural-time failure criterion.It is shown that there is an obvious structural response characteristic for the dynamic strength;that is,apart from on the strain rate and the static material constants,it depends remarkably on the loading as well as the interaction between the loading features and the material,and thus the dynamic strength cannot be one of the intrinsic material properties.Moreover,it is also found that the previous experimental data should have intrinsically high discreteness because the dynamic strengths of material attain different values under different loadings.