Electro-thermography technique for nondestructive testing (NDT) applications

In this paper, Electro-Thermography is introduced in nondestructive testing applications. Electro-Thermography is one of the novel active thermography techniques for nondestructive testing. It gains the advantages from the optical and electromagnetic properties in full-field, non-contact, high inspection speed, and sensitivity in geometry variation. It is mostly applicable to all kind of ferrous-metal, some composites materials. A fundamental difference among electro-thermography and other active thermography techniques are the excitation mechanism. Electro-Thermography is a combination of the electromagnetic induction and surface thermal radiation measuring technique; it used the induction method to excite the object, and then it used the radiation properties to measure the distribution of surface temperature of the object. It detects flaws by the flaw's anomalous heating and heat transfer response. The method of excitation is also different from others irradiation excitation. Electro-Thermography needs an electromagnetic coil to generate eddy current through induction to change the surface and subsurface temperature. Electro-Thermography can detect surface and sub-surface flaws, unless the flaw is too remote and tiny from the surface. Some experiments in flaw detections and other types of inspections are demonstrated.