Shearographic Monitoring of Time-Dependent Thermoelastic Deformations

Abstract

The potential for performing quantitative analysis of photothermally induced deformations using electronic shearography is investigated. A temporally modulated laser source is used to heat the surface of a material and the resulting thermoelastic deformations are monitored using shearographic methods. Calculated and experimental results are reported for thermally and elastically thick materials in which the sample dimensions do not affect the recorded response. Additional results are given for thin-plate structures where significant geometric effects related primarily to specimen thickness are noted. Using experimental and calculation-based results, it is shown that the temporal evolution of shearographic fringe patterns may be related to thermal diffusion in the structures investigated. For thin-plate structures, through-thickness thermal diffusion dictates the temporal behavior of the deformations such that the corresponding time-dependent shearographic measurements may be related to the plate thickness.