Study of the effect of crack closure in Sonic Infrared Imaging

Sonic infrared (SIR) imaging is a novel hybrid technology that employs ultrasonic excitation and infrared imaging to detect defects in materials. There are several parameters can affect the detectability of a defect in Sonic IR. One is the closure status of a defect, say a crack in a material. We have studied the relationship between the heating in a crack and crack closure. The crack closure was realized by applying a variety of clamping forces on the crack. In this paper, we provide quantitative results of the study on infrared signal levels at different status of crack closure. The temperature profile of a fixed point at the crack during the excitation period was presented. The thermal energy transformed from the kinetic movement was analysed over a fixed region for all clamping cases. Meanwhile, the crack energy at two fixed points crossing the crack was also studied.