Electronic speckle pattern interferometry applied for three-dimensional displacement measurement of a sandwich plate containing a fully potted insert

This study presents the construction and operation of a novel electronic speckle pattern interferometry (ESPI) technique, which was applied earliest to sandwich plates containing a single insert. The proposed ESPI is a full-field and non-destructive test that can measure tiny out-of-plane and in-plane displacements under an elastic loading condition. Experimental construction integrates out-of-plane and in-plane measurements into a single optical system to measure three-dimensional displacement of sandwich plates. The ESPI experimental result indicates that displacement of the sandwich plate decreased as the core thickness increased. This experimental result also suggests that displacement decreased as the insert diameter increased; however, estimated strength increased. For validation purposes, the analytical and finite element method (FEM) were utilized to compare the experimental result with ESPI measurements. Comparison between analytical results, ESPI results, and FEM results revealed that all results were in agreement.