Evaluation of Thickness Reduction in a Thin Plate Using a Non-Contact Guided Wave Technique

Abstract

Ultrasonic guided waves are widely being studied and successfully applied to various non‐destructive tests with the advantage of a long range inspection. Recently, non‐contact methods are also adopted and combined with the guided wave techniques. In this paper, an advanced technique for the nondestructive detection of thinning defects simulating hidden corrosion in thin plates using non‐contact guided waves is presented. The proposed approach uses EMAT(Electro‐Magnetic Acoustic Transducer) for the non‐contact generation and detection of guided plate waves in aluminum plates. Interesting features of the dispersive behavior in selected wave modes are used for the detection of plate thinning. The experimental results show that the mode cutoff measurements provide a qualitative measurement of thinning defects and change in the mode group velocity can be used as quantitative parameter of thinning depth measurement.