Effects of the Rate Dependency of a Matrix Material on the Tensile Response of Plain Weave Carbon Fabric Reinforced Epoxy Composites

Textile composites are extensively used in structures subjected to both static and dynamic loads. However, research on how loading rates influence performance remains limited. A better understanding of how the rate dependency of matrix materials affects the mechanical behavior of textile composites could facilitate more accurate performance predictions and the efficient selection of components based on loading rates. This study investigates the effect of the rate dependency of epoxy on the overall rate dependency of a plain weave carbon fabric-reinforced epoxy composite. Specimens were prepared using only epoxy resin, and tensile tests were conducted at four loading rates (5 mm/min, 50 mm/min, 200 mm/min, and 800 mm/min) to evaluate changes in the tensile properties of epoxy with varying loading rates. Composite specimens were fabricated using the same epoxy, and tensile tests were performed under identical conditions. The results demonstrated that both materials became more brittle at higher loading rates while their stiffness remained largely unaffected. Furthermore, the failure process of the composite at different loading rates was analyzed through micro-scale finite element analysis. The analysis revealed that the onset of failure in textile composites shifted owing to the rate-dependent brittleness of epoxy. To mitigate the high computational cost of explicit simulations accounting for time dependency, a modified Johnson–Cook model and an acceleration model were newly developed and incorporated into the analysis.