An analysis of angled surface-breaking crack detection by dual-laser source generated ultrasound

The propagation and scattering of ultrasound generated in a cracked specimen detected by an evaluating system with a dual-laser source has been studied by using finite element method (FEM). The various ultrasonic modes are analyzed in detail, and a method for calculating the crack-orientation angle is presented by employing the propagating times of scattered ultrasonic modes. Corresponding experimental system is then built. The arrival time of scattered ultrasonic modes propagating in two cracked aluminium specimens are measured by using the method provided and crack-orientation angles are calculated. Results from numerical simulation and experiment are compared, the accuracy of the method is proved accordingly.