Thermal stressing techniques for flaw characterization with shearography

Controlled heating of a test specimen with a laser source provides several advantages for flaw detection using shearographic detection. This stressing method is non-contacting, can be localized, and allows defect information to be obtained while heating. In addition, the beam profile can be tailored to aid in the detection of different defect types. This paper presents results of simultaneous observations of material response to an applied thermal load using both TRIR and shearographic detection methods. Of particular importance is the demonstration that the depth of a defect can be determined by measuring the time-dependence of the shearographic fringe development during heating.