Wang, XD (reprint author), Nanjing Univ, State Key Lab Modern Acoust, Nanjing 210093, Peoples R China.
We investigated the YAG laser-generated ultrasonic wave in a solid with an array of rectilinear sources in the melting regime. By adapting the melting rectilinear sources, a 31.2 gain factor of amplitude of the excited ultrasound can be obtained for the aluminum (Al) sample in comparison with the ultrasound generated by rectilinear sources in the thermoelastic regime. In the melting regime, the sample surface remains undamaged during the inspection. Calculations and experimental results show that the array characteristics and the detection point will decide the increase of amplitude, center frequency, bandwidth, and directivity pattern of the narrow-band ultrasound signals generated by a melting-source array. Through our research, the array of melting sources is proved to be a useful tool to enhance the generation efficiency and detection sensitivity in nondestructive inspection.