Shear Evolution of Fiberglass Composites Under Compression

Woven composites can offer mechanical improvements over more traditional engineering materials, yet understanding the complex interplay between the fiber-matrix architecture during loading remains a challenge. This paper investigates the evolution of shear failure behavior during the compression of high performance fiberglass composites with varying resin binders at both quasi-static and dynamic strain rates. All samples are comprised of commercially available woven glass cloth with approximately 56 % fiber volume fraction. Laminates with thermosetting resin binders of silicone, melamine, and epoxy were examined. High-speed imaging reveals that failure occurs within a localized shear band region through multiple fiber-weave matrix interface failure with a characteristic macroscopic angle. The shear evolution was spatially mapped using grayscale histograms of the light intensity in the shear regions, and the resulting characteristic angles were measured and analyzed in the context of a Mohr-Coulomb failure criterion. Optical microscopy and high-speed imaging of the shear formation shows initiation appears due to local instabilities from kinking and microbuckling, influenced by the stacking and interlacing regions of tows.