Study on detection and quantitative evaluation of fatigue cracks using surface SH waves

The surface SH waves technique has been used to evaluate the fatigue cracks at the surface of mild steel specimens. I5y adjusting incident angle of SH wave transducer, surface SH waves passing through the surface region of materials are received. In this study, the diffraction of surface SH waves received by double-probe technique was used. Firstly, the specimens introduced surface slit were inspected. With the results that the amplitude decreased and the propagation time increased with the slit depth. Secondly, the shapes of the fatigue cracks, which initiated at a small drill hole by rotating-bending fatigue, were evaluated with the difference between the propagation time of the inspected plate with crack. Obtained results showed that the evaluated values of crack length and crack depth were good agreement with the measured values. Furthermore, this technique was applied to evaluating the crack growth behavior.The surface SH waves technique has been used to evaluate the fatigue cracks at the surface of mild steel specimens. I5y adjusting incident angle of SH wave transducer, surface SH waves passing through the surface region of materials are received. In this study, the diffraction of surface SH waves received by double-probe technique was used. Firstly, the specimens introduced surface slit were inspected. With the results that the amplitude decreased and the propagation time increased with the slit depth. Secondly, the shapes of the fatigue cracks, which initiated at a small drill hole by rotating-bending fatigue, were evaluated with the difference between the propagation time of the inspected plate with crack. Obtained results showed that the evaluated values of crack length and crack depth were good agreement with the measured values. Furthermore, this technique was applied to evaluating the crack growth behavior.