Non-destructive inspection and quantification of defects in plywood using a portable digital holographic camera

Abstract

The demand for plywood products for the interior and exterior construction has grown significantly over the years. Therefore, detection of defects present in the plywood is of prime importance to maintain good quality of construction. In this study, qualitative and quantitative analyses of defects in plywood using digital holographic interferometric technique are presented. In this process, thermal and mechanical loads are applied to the test sample of plywood to generate interferometric fringes by comparing the normal and stressed states of the test sample. A portable digital holographic camera developed for non-destructive testing applications is employed for detection of cracks, delamination, edge defects, and layer opening in the plywood. The defects in the plywood sample are identified by observing discontinuities in the interferometric fringes. Quantitative analysis of defects is performed by plotting their 2-D and 3-D phase profiles from the digital holographic interferometric results. The obtained results of defects on plywood are validated by a mechanical profiler.