The infrared thermal wave imaging detection of micro-crack defects in Ti-Al alloy plate

Abstract

The Ti-Al alloy has good physical, chemical and mechanical properties, and it is the preferred material in aerospace and other special fields. The laser spots array is used for thermal excitation of the Ti-Al alloy specimen. Based on the fractional differential equation and Fourier heat conduction equation, the fractional heat transfer model of Ti-Al alloy plate specimen ex-cited by short pulse laser spots array is established, and the infrared thermal imaging simulation analysis is carried out by finite element method. The effects of crack width, crack depth and the distance between the crack and its nearest laser spot center on temperature abrupt jump is analyzed. With the increase of crack width and depth, the temperature abrupt jump increases, but the trend gradually slows down. The distance between the crack and its nearest laser spot center has a significant effect on the temperature abrupt jump. With the increase of the distance, the temperature abrupt jump first increases and then decreases. When the distance equals the laser spot radius, that is, the crack is tangent to the spot, the temperature abrupt jump reaches its maximum.