Prediction of Mechanical Behavior of Short-Fiber-Reinforced Thermoplastics by Viscoelastic-Viscoplastic Analysis

Abstract

In this study, the mechanical behavior of short-fiber-reinforced thermoplastics is predicted by finite element analysis using various unit cells. Each unit cell contains a single elastic fiber and an elastoplastic or viscoelastic-viscoplastic matrix resin. Additionally, fiber break and interfacial debonding between thermoplastics and fibers are reproduced using the extended finite element method and the cohesive zone model, respectively. The analyses using the unit cells evaluate the stresses for various fiber lengths and fiber orientation angles, and then the macroscopic stress is predicted by the laminate analogy approach. The predicted results are compared with the tensile test results at various temperatures. In the plastic region, the predicted results reveal that the viscoelastic-viscoplastic analysis with fiber break and interfacial debonding is needed to predict the actual stress-strain curve. The tensile test results are within the results predicted by the analyses with assumed interfacial strength and with infinite interfacial strength. Therefore, the mechanical behavior of short-fiber-reinforced thermoplastics could be predicted by the viscoelastic-viscoplastic analysis with fiber break and interfacial debonding using appropriate interfacial strength.