Ultrasonic attenuation characteristics of metal materials with cracks and identification of subsurface flaws

A two-dimensional isotropic plate model with an embedded horizontal crack was established. Finite element analysis with absorbing boundary condition was employed to simulate the experimental pulse-echo mode to obtain ultrasonic data. The effect of crack depth on the wave propagation was studied and the spectra of different backwall echoes were further extracted. A relationship was determined between ultrasonic attenuation due to the crack and frequency. Finally, a method was proposed for identifying subsurface cracks based on the spectra of backwall echoes.