Numerical simulation of laser-EMAT testing depth of surface crack technology

Laser-EMAT (electromagnetic acoustic transducer) technology has the advantages of laser induced ultrasound and EMAT simultaneously. This paper introduced a novel simulation about laser-EMAT testing the surface crack with various depth in the aluminum block. A finite element model of laser-EMAT detection was set up for investigating the influence of groove-type crack on ultrasonic propagation in the way of numerical simulation. Then, the response curve of voltage in time domain was obtained by the testing coil in EMAT, which is proposed to determine the depth of crack above. Good coupling could be found between voltage of signal received by EMAT coil and amplitude of ultrasound generated by the laser. In addition, the snapshot of ultrasound field at different time demonstrates mode conversion occurs when the surface wave propagated through the crack. The simulation results show the relative error of determining crack depth by the proposed method is less than 6.5%.