Computational study of the A0 scattered field due to an edge delamination

Delamination detection presents a pertinent problem for SHM (structural health monitoring), as in most cases, there may be no visible signs of the damage on the surface of the structure. This study investigates the scattering of a zeroth-order anti-symmetric (A0) Lamb wave mode by an edge delamination using the commercial FE (finite element) package ABAQUS. The A0 Lamb mode is chosen because the corresponding stress distribution is more sensitive to delamination than is the case for symmetric modes. The paper presents results for the scatter field for various angles of incidence, and for varying defect sizes. The regime of small defect size relative to the incident wavelength is of particular interest for SHM as it corresponds to early damage detection. It is shown that, in this regime the scattered field appears to originate from a point source at the origin of the delamination, and the corresponding amplitude is linearly proportional to area of the delamination. These results can be used to guide the use of Lamb waves to detect and quantify edge delamination in plate-like structures.