Assessment of defects in composites using holographic interferometry

Abstract

The use of double-exposure holography in the assessment of a defective glass fibre reinforced composite plate containing a localized thinned region is described in this investigation. The circular plate is clamped along its periphery and an incremental pressure is applied between two exposures to obtain a hologram. The presence of thickness variation causes a perturbation in the out-of-plane displacement field, which in turn results in localised distortions in the reconstructed fringe pattern. Analysis of the fringe pattern provides qualitative and quantitative evaluations of the severity of the defect.