Defect Detection in a Plate Loaded with Water on a Single Surface using Quasi-Scholte Wave

Ultrasonic guided waves achieve non ︲ destructive inspection of thin plates. However, issues such as large energy leakage and attenuation often plague guided wave inspection of storage tanks and pipes filled with fluid. This study experimentally investigated the non ︲ destructive testing of a water ︲ loaded flat aluminum alloy plate through the application of a quasi ︲ Scholte （ QS ） wave that propagated along the fluid ︲ plate interface without experiencing attenuation due to leakage. A QS wave was confirmed as having been generated and propagated in a plate loaded with water on the bottom surface using ultrasonic incidence and detection at the top water ︲ free surface. Two ︲ dimensional Fourier transform images of the waveforms revealed reflection of the QS wave from a defect as well as a forward incident QS wave. The visualization results experimentally confirmed — via measurements of waves in water using a laser Doppler vibrometer — that QS waves propagated along a plate surface, while scattered waves were generated by defects.