Two-dimensional damage mapping of a glass-epoxy composite test sample by optical transmission analysis

Under mechanical stress, the optical transmission coefficient of a translucent composite material changes. In this study, the optical response, defined as transmitted luminous flux function of the stress, is used to characterize the opto-mechanical behavior. Tensile tests were carried out on composite specimens made of glass fibers and epoxy resin. A visible imaging instrument has been developed to characterize this opto-mechanical response. The used camera has permitted to map the two-dimensional behavior, resulting from the heterogeneous stress field. Monotonic tests have been conducted as well as fatigue tests, to analyze de damage state along the material cycle life. In this study, both the principle and the experimental setup of this contactless method are described.