A theoretical study on vertical finite cracks detection using pulsed laser spot thermography (PLST)

A theoretical study on vertical finite cracks detection in low carbon steel (A36) blocks using pulsed laser spot thermography (PLST) was carried out in this paper. The basic principle of PLST was described. The 3D heat conduction model of flux transfer under pulsed laser spot excitation was established and calculated using finite element method (FEM). The effect of laser-crack distance to temperature abrupt jump across the vertical finite cracks was analyzed, and results show that the optimum laser-crack distance is the radius of laser spot. The relationship between geometric parameters of cracks and temperature abrupt jump was studied, and results show larger geometric size of cracks leads to greater peak values of temperature abrupt jump, and tends to stable values at certain size.