Pulsed photothermoelastic quantitative evaluation of flaws in laminates

A pulsed photothermoelastic technique for nondestructive testing of layered materials is described. A Fourier-transform signal analysis is presented for a quantitative characterization of subsurface defects. Discrepancies between the experimental results and the data obtained from the thin-plate analytical theory are interpreted through a finite-element numerical model. The effect of the vibrational properties of the whole structure is shown to be particularly important on the spectral features of the thermoelastic signal for small defects.