Dependence of the longitudinal velocity of sound in constructional ceramic materials on pressure and damage rate

The effect of porosity and concentration of planar microcracks on the velocity of elastic waves in polycrystalline ceramic materials on the basis of SiC, Al$_2$O$_3$, B$_4$C, and ZrO$_2$ is numerically studied. The mechanical behavior of ceramics is described using the model of a damaged medium. Various dependences that describe the relationship between the effective moduli of elasticity of the medium material and the relative volume of damages are analyzed as applied to predicting wave dynamics. For porosities up to 20%, a satisfactory prediction of the velocity of longitudinal waves in ceramics is ensured by the use of exponential and linear dependences. Within this range of porosities, the velocity of elastic waves decreases linearly with increasing relative volume of damages. The influence of the pulse amplitude on the velocity of elastic waves is analyzed. It is shown that the velocity of elastic waves in constructional ceramics increases in proportion to pressure up to 5% within the range of pulse amplitudes that do not exceed the Hugoniot limit of elasticity. Numerical values of coefficients in the relation between the velocity of the longitudinal elastic wave and the velocity of material particles are determined for ceramic materials considered. As the Hugoniot limit of elasticity is exceeded, the values of the coefficients decrease by 10–30% for different ceramic materials. The resultant values of the coefficients are in good agreement with experimental data found in the literature.