A Study of Pre-Stress Effect on Dynamic Failure of Transparent Brittle Materials
Final technical rept. 1 Mar 2006-1 Mar 2007
RUSSIAN ACADEMY OF SCIENCES MOSCOW INST FOR HIGH ENERGY DENSITIES
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The report presents results of studying the pre-stress effect on dynamic failure of K8 crown glass, K14 crown glass, fused quartz and sapphire crystals. A technology of radial pre-compression of glass samples has been worked out. Controlled confinement pressure on the specimen in a range of 150 MPa to 550 MPa was provided by installing a shrink-fit metal sleeve on the lateral surface of the glass specimen disk. Results of measurements of the particle velocity histories of sock-loaded free and pre-stressed glasses confirm our expectation of influence of transversal stress upon the failure wave propagation and the failure threshold for all pre-stressed glasses we observed earlier break of the failure wave propagation at unloading from shock-compressed state. However, sensitivity of the failure threshold to the confinement stress value is not as high as it could be expected. Large heterogeneity of inelastic deformation and scatter in the Hugoniot elastic limit of sapphire have not allowed us to determine an influence of pre-stressing on the HEL value of this material. However, the experiments unambiguously demonstrate growth of viscosity of inelastic compression of the sapphire as a result of pre-stressing.
- Ceramics, Refractories and Glass