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Polygonal damage shape reconstruction in plates using guided Lamb wave

Tomographic reconstruction of the damaged region using guided Lamb waves provides important information about the health condition of structures. Two general types of shape reconstruction techniques are discussed before: transform based methods and algebraic iterative methods. There are some limitations associated with each method such as high sensitivity to noise and incomplete data sets, limitations for damage size and contrast, bulky setup for scanning the damaged region, or low speed of reconstruction. In this paper, the concepts of a novel method for reconstructing the contour of damage based on the Polygon Reconstruction Technique are introduced. First, the projections (Radon transform) of the damaged region are generated from a small number of angles with the aid of beamforming method. Then, the damaged region is modeled by a polygon, which its optimal number of vertices is estimated using the minimum description length (MDL) principle. Finally, using the polygon reconstruction technique, the coordinates of the vertices are determined. As the proposed method is at its preliminary stage, two finite element models of an aluminum plate with two different holes as the damage are designed in ABAQUS to examine the feasibility and performance of the method. Results show that the introduced technique based on polygonal damage shape reconstruction is fast and accurate. Copyright © 2016 John Wiley & Sons, Ltd.