Defect Orientation Evaluation in Structural Plates Using Reflective Correlation Indexing

The fundamental shear horizontal (SH0) modes exhibit conversion behaviors to higher mode (SH1) influenced by the symmetric and anti-symmetric defects within a plate. Specifically, reflected SH0 modes remain unaffected by symmetrically oriented defects while transitioning to SH1 mode in the presence of anti-symmetrically oriented defects. This prompts inquiry into the effects when defects lie between symmetric and anti-symmetric positions within the plate thickness. In order to quantify the impact of mode conversion resulting from diverse defect orientations, a thorough analysis has been conducted, and a methodology has been proposed to assess the defect’s position using mode conversion of shear horizontal (SH) guided waves. Particularly, as defects move from symmetric to anti-symmetric positions, the energy of the reflected wave is notably influenced by the defect’s orientation. This indicates that defects located close to symmetric orientations yield minimal reflected energy in the converted SH1 mode, whereas those approaching anti-symmetric orientations exhibit significant reflected energy in the converted SH1 mode. To precisely identify the defect’s position, an assessment of the Reflective Correlation Indexing (RCI) of the converted mode has been conducted. Numerical simulations have been performed to investigate these phenomena and validated with an experimental result using chevron EMAT.