Experimental Evaluation of Mesoscale Crack Propagation Behavior in CF/EP Cross-Ply Laminates by Digital Image Correlation Based on Fiber Cross Section

Abstract

In this study, we performed digital image correlation (DIC) using fiber cross sections as random markers, focusing on damage initiation and propagation in 90º layers in carbon fiber/epoxy cross-ply laminates. By comparing these results with mesoscopic in-situ observations, we confirmed the validity of DIC as a method for evaluating such mesoscale damages. This method is independent of the judgement of the observer. Both the locations and values of strain concentrations measured by DIC analysis showed good agreement with the initial in-situ observation of cracks at 0.54 [%] average nominal strain. In addition, a higher strain distribution was confirmed with DIC before the crack was recognized by in-situ observation. Thus, it is expected that the detection and prediction of damages can be realized by the measurement of mesoscopic strain distributions by DIC using fiber cross sections as random markers, as proposed in this study.