Strain-rate effects on dynamic strength of brittle materials

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.