Homogenization-based multiscale analysis for equivalent mechanical properties of nonwoven carbon-fiber fabric composites

Abstract

To improve fuel efficiency in the automotive industry, several researchers have made many attempts to replace heavy materials among the automotive components. Hence, carbon-fiber-reinforced plastic (CFRP) composites have drawn significant interest from the automotive and aerospace industries. Continuous and discontinuous carbon fiber are used as representative reinforcing materials in composite manufacturing. Recently, the use of discontinuous-fiber-reinforced plastics has increased, compared to that of continuous-fiber-reinforced plastics, owing to their cost efficiency, weight reduction, and relatively easy fabrication and handling. For composite materials, it is very important to predict mechanical properties due to their various constituents and manufacturing method. In this study, we performed a numerical analysis using homogenization technique to evaluate the equivalent mechanical properties of composites combining a nonwoven carbon fiber fabric reinforcement and epoxy resin matrix. We then compared these results with the experimental results. To calculate the equivalent mechanical properties of composites, we modeled repeating unit cells (RUCs) for homogenization-based multiscale approach, and performed finite element analysis. At the microscale level, this method was compared with the rule of mixture (ROM) theory, which is a typical homogenization technique. Based on the proven homogenization technique, we modeled RUCs for randomly distributed nonwoven carbon fiber fabric (NW-CFF) composites at the mesoscale level and calculated its equivalent properties. At the macroscale level, at which these properties could be verified, we compared the equivalent mechanical properties calculated with experimental test results, such as those of tensile, shear stiffness and Poisson’s ratio.