Mechanical properties of aluminium oxide at high loading rates

The accurate evaluation of dynamic mechanical and fracture properties of structural ceramics has become increasingly important for fracture safe design of structural components subjected to impact loadings. The results of compression tests of A1203, A1203+TiC and A1203+ZrO2 at high strain rates and room temperature are presented. The dynamic loads applied to the penny shaped specimens of various thicknesses were produced and measured accurately by the computer operated Hopkinson Split Pressure Bar technique (HSPB). The results indicate the possibility of shock wave formation due to the nonlinear response of the porous body during compaction due to porosity reduction and increase of elastic constants. The influence of stress pulse shape and duration is discussed. Modifying the Grady's theory a simple criterion for fragmentation has been proposed.