Inductive Shearography Techniques for Non-Destructive Testing and Evaluation (NDT&E)

Shearography has received considerable industrial acceptance for non-destructive testing & evaluation (NDT&E). It is an interferometric optical technique which measures surface deformation (displacement and displacement derivatives), and it reveals flaws by looking for flaw-induced deformation anomalies when the specimen is loaded. Conventional loading methods for shearography include pressurization, mechanical stressing, acoustic and vibration. Most of these stressing techniques are favorably applied in laboratory. However, they may be difficult to apply under harsh industrial environment. In this paper, we propose an inductive shearography for convenient nondestructive evaluation. Inductive shearography uses a low power electromagnetic induction field to excite the specimen and detects the deformation anomalies using shearography setup. It gains the advantages from both optical and electromagnetic properties in full-field, non-contact, high inspection speed and high sensitivity in geometry variation for inspecting ferrous-metals and some composite materials. Consequently, inductive shearography can detect surface and subsurface flaws, unless the flaw is too remote and tiny from the surface. Some experimental demonstrations in flaws detection and other types of inspections are demonstrated.