TIME-RESOLVED SHEAROGRAPHIC AND THERMOGRAPHIC NDE METHODS FOR GRAPHITE EPOXY HONEYCOMB COMPOSITE/

Results are presented showing the application of both time resolved th ermography and time resolved shearography to specimens of graphite epo xy/honeycomb composites containing delaminations. Of particular import ance is the demonstration that the depth of a defect can be determined by measuring the time dependence of the shearographic fringe developm ent during heating. Upon application of a noncontacting heating source , large thermoelastic deformation in the heated region occurs over del amination regions in a specimen. The bending stresses in the material above the delamination decrease characteristically when the diffusing temperature field interacts with the delamination and the temperature gradient through the intact material decreases. As a result, both the presence of the delamination and its depth can be measured simultaneou sly.