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Quantitative Characterization of the A0 Scattered Field Due to Edge Delaminations as a Function of the Through Thickness Position

N. NADARAJAH, B.S. VIEN, L.R.F. ROSE, W.K. CHIU

Abstract


The widespread interest in composite materials for use in structural components demands the development of suitable Structural Health Monitoring (SHM) techniques to detect damage and monitor its growth. Delaminations pose serious challenges for structural integrity management, because even low levels of damage (known as barely visible impact damage, BVID) can cause large reductions in residual compressive strength. This paper presents a comprehensive characterization of wave scattering by an edge delamination focusing on the lowest order flexural Lamb wave mode, A0. This mode can be expected to exhibit the highest sensitivity to delaminations because they lead to a significant reduction in the local value of the flexural stiffness. For simplicity, the case of an isotropic plate is studied first, with the delamination being modelled as a semi-circular crack located parallel to the plate’s midplane. The objectives are to characterize the scattering amplitude as a function of scattering angle, damage size and through thickness position of the laminar defect. This characterization is achieved computationally, using the FE package ABAQUS. Scatter patterns of the various scattered mode are determined for various damage sizes and incidence angles. A quantitative relationship is established between the damage size and the scattering amplitude in the regime where the damage size is small. Information from this study can be used for early damage detection. Further the severity of the damage can be evaluated, by using our results to determine the damage size.

doi: 10.12783/SHM2015/244


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