Finite Element Modeling of Thermosonic and the Effect of Frequency and Amplitude of Vibration on the Temperature Rise in the Crack Surfaces

Thermosonic (Sonic-IR) is a novel non-destructive testing technique (NDT) capable of detecting surface defects and fatigue cracks in different materials. The component is excited with high-power ultrasonic vibrations or other external source, causing crack surfaces rub together and generate heat. The dissipation of vibration energy and converting to heat at the faces of the crack causes an increase in temperature in the vicinity of the crack, which is imaged by the IR camera. However, the excitation in a thermosonic test is non-reproducible and can lead to cracks being undetected if sufficient vibrational energy is not applied at the crack location. This problem has caused that thermosonic is not considered as a reliable non-destructive testing technique. So, the investigation of parameters which have significant effects on temperature rise in thermosonic test is important. The vibrational energy dissipated as heat at the defect is directly related to the frequency and amplitude of the vibration. So, in this paper, a finite element modeling has been used to simulate thermosonic and the affection of these parameters on the temperature rise in the crack surfaces during sonic infrared imaging has been studied.