ランダム配向型熱可塑性CFRPの3点曲げ衝撃試験における速度依存性・温度依存性の評価と考察

抄録

Strain rate and temperature dependence of carbon fiber reinforced thermoplastic composites (CFRTP) were evaluated. CFRTP composites are superior not only in terms of specific strength and stiffness, but also in terms of formability. They are, therefore, expected to be widely applied in mass production of automobiles, thereby resulting in significant vehicle-weight reduction. To incorporate CFRTP composites in automobile structures, novel techniques in vehicle-structure design must be developed to ensure safety in the event of collision accidents. It is also necessary to clarify impact properties of the structure under various temperature conditions that an automobile may be subjected to. To this end, the 3-point bending impact test on chopped carbon fiber tape reinforced thermoplastics (CTT) was performed at various operating temperatures. Fracture behavior was also observed using a high-speed video camera, along with investigations concerning strain rate and temperature dependence. Using the abovementioned bending test, the strain rate and temperature dependence of CTT were confirmed in terms of flexural strength, and the fracture behavior was categorized into three failure modes based on temperature conditions. Concurrently, the viscoelastic properties of the matrix resin were evaluated, and the strain rate and temperature dependence of the flexural strength of CTT were predicted using the master curve derived based on the time–temperature superposition principle. The prediction results were found to be consistent with those obtained via experiments.