Experimental-Computational Characterization of Fiber-to-Fiber Interactions in Glass Macro Fiber Composites

Abstract

Effects of inter-fiber distance and angular orientation on the fiber-matrix interface debonding are investigated using a hybrid experimental-computational approach. Model composite samples are fabricated using two glass macro fibers embedded in a clear epoxy resin and then subjected to remote tensile loads. The distance and angular position between the two fibers in the epoxy are varied systematically to cover a wide range of inter-fiber distances and orientations. Specifically, the model composites are designed to include fiber-to-fiber angles ranging from 0° to 90° in 15° increments. Displacement and strain fields developed in the vicinity of the fiber-matrix interface are measured by high-magnification digital image correlation (DIC). The initiation and propagation of debonding at the fiber-matrix interface are characterized as a function of far-field stress, inter-fiber distance and angle. A finite element simulation framework is established and calibrated by the experimental measurements first. Correlations between local and global stress-strain fields are then identified from the experimental measurements supplemented by finite element simulations. Results obtained herein indicate that the spacing and angular orientation between adjacent fibers affect the interface debonding initiation and propagation. However, the interfiber distance has a more consequential effect on the debonding process, i.e., the smaller the distance the larger the fields intensity. The results obtained from the hybrid approach here are further analyzed to identify the sources of uncertainty quantification. The hybrid approach proposed and discussed in this work provides a systematic methodology for the quantitative analysis of fiber-matrix interface debonding mechanisms leading to transverse cracking in unidirectional composites.