Numerical analysis of joint inspection using electromagnetic acoustic transducers

Engineering use of jointed materials requires quantitative inspection of the joints, though it has not been established yet. Electromagnetic acoustic transducers (EMATs) can generate and detect ultrasonic waves in a conductive specimen by electromagnetic coupling without any contact with a specimen. This feature gives EMATs an advantage over conventional ultrasonic transducers: theoretical modeling and formulation based on elastodynamics and electromagnetics can be obtained. In this research, a process of joint inspection using EMATs was analyzed numerically. Numerical results of the wave propagation explain effects of the joint interface and of a joint failure on the propagation of ultrasonic waves and on the receiver signals, in terms of reflection and diffraction of the waves. Predicted receiver signals agree well with experimental results, which verifies our numerical approach. These results show a possibility of quantitative joint inspection using EMATs.