Computer simulation of metal surface micro-crack inspection using pulsed laser thermography

Surface micro cracks are easy to produce in the preparation and service process of metal material, which impacts on the safe operation of metal components. Pulsed laser spot excitation and infrared thermal imaging technology are combined to detect metal surface micro-cracks. The working principle of laser infrared thermal imaging detection technology was described. The three dimensional heat conduction model of pulsed laser excitation flux transfer in metal plate was established, and calculated using finite element method (FEM). The results showed that, thermal flow in the image is a “D” shape. There are temperature differences between the sound regions and defective regions, and the defects experiences the process of obscure, gradually clear, and gradually obscure. Pulsed infrared thermography sequence was processed by polynomial fitting method, and the coefficient images effectively improve the contrast between defective and non-defective areas, which is beneficial to the determination and of recognition micro cracks. © 2016 SERSC.