| Non-destructive testing (NDT) is finding more widespread application in a variety of industries. Well beyond traditional metals, NDT techniques are now considering a number of plastic, ceramic and composite materials. Sonic infrared imaging (SIR) is a recent step towards NDT. The objective of this paper is to discuss crack detection in an aluminum plate by using the SIR technique. The experimental setup of SIR is shown in Figure 1. A short pulse of a low frequency ultrasound transducer is used as a source of excitation for the aluminum plate, which generates vibration and creates lamb waves to cause relative motion between the crack surfaces. This motion generates heat due to friction and increases the temperature of the defected region. The imaging is used for detecting temperature by using an infrared camera. The mechanism of heat generation is caused either by friction or viscoelastic energy dissipation, but the frictional heat is comparatively much higher compared to the viscoelastic effect. In this paper we present finite element modeling for the calculation of generated heat in the corresponding defected aluminum plate. This approach can also be useful for different types of composite defects including delamination, transverse ply crack and through cracks. |
