Digital volumetric speckle photography: a powerful experimental technique capable of quantifying interior deformation fields of composite materials

Abstract

Due to the heterogeneity at different length scales, composite materials have a complex mechanical behavior. While many studies have been devoted to understanding their failure mechanism, much remain unknown. One of the main reasons is the lack of an effective experimental tool to monitor, in situ, the internal stress/strain field as the deformation progresses leading to failure. By taking advantage of the volumetric imaging capability of an X-ray CT (computed tomography), we have developed a new tool called digital volumetric speckle photography, whereby we can map quantitatively the interior deformation of almost any opaque material. In this paper, we described in detail the theory of this technique and its application to mapping the internal deformation fields of two different types of composites: fiberglass-reinforced woven composite and sandwich composite made of a polymeric foam core and two fiberglass face sheets.