Abstract:

Conventional ultrasonic inspection of large structures is very time consuming due to the surface scanning necessity. Since they can propagate over long distances, Lamb waves are an attractive solution to this problem. Here, we show the feasibility of using Lamb wave generation using a transducer embedded inside the material and we give two methods to determine the presence of a defect along a propagation line. In a first step, the embedded transducer is used to generate and receive Lamb waves. Then, a method based on the spatial Fourier transform is used to measure their phase velocities. The experimental measurements are in good agreement with a numerical phase velocity computation. In a second step, the determination of the presence of a defect along a propagation line is shown. One method consists in measuring the attenuation of Lamb waves during the propagation. Another one is based on the Hilbert transform, which can be used to determine mode conversions due to the damage. In both cases, the results show the feasibility of determining the presence of a defect.