Thermoelastic photoacoustic effect near tips of radial cracks in ceramics under external loading

The thermoelastic photoacoustic effect near tips of a vertical crack is investigated with linear approximation of the residual strains and stresses. The influence of external normal and shear stresses on the thermoelasticphotoacoustic signal is also analyzed. The results are applied to the analysis of thermoelastic photoacoustic signal near tips of radial cracks of Vickers indented areas in an Al 2 0 3 -SiC-TiC ceramic composite. The experimental results are shown to be in good agreement with the results predicted by the theoretical model both for normal and for shear stresses. It is shown that the thermoelastic photoacoustic method can be used for the determination of stress intensity factors of cracks both for external and for residual stress fields. The value of the nonlinear thermoelastic parameter for this composite has been estimated.