Structural Design of Hybrid CFRP Using Pitch-Based and PAN-Based Carbon Fibers and Their Mechanical Properties

Abstract

近年,地球温暖化および資源の枯渇などの地球環境 問題が深刻となっており,地球環境問題への取り組み が世界的に行われている.特に航空宇宙および自動車 産業を代表とする輸送機器からの排気ガスが問題と なっており,省エネルギの観点から軽量化が必要とさ れている.そこで,軽量高強度の複合材料が期待され ている.その中でも,カーボン繊維強化プラスチック ス(Carbon Fiber reinforced Plastics: CFRP)は,金属 Abstract: The purpose of this study is to design a hybrid CFRP structure using pitch-based carbon fiber and PAN-based carbon fiber, and to develop an optimal hybrid CFRP structure. Various cross-laminated hybrid CFRP structures were fabricated, and the composition and arrangement of pitch-based and PAN-based carbon fibers were changed. The developed CFRP structures were investigated by bending and impact measurements. As a result, the following findings were obtained. The results of the mechanical properties of three-point bending showed that it was possible to obtain higher bending strength than the individual pitch-based or PAN-based CFRP structure by hybridizing. The hybrid CFRP structure with 20% pitch-based carbon fiber in the outermost layer and 80% PAN-based carbon fiber in the core layer shows higher flexural strength, flexure and fracture initiation energy than PAN-based 100% CFRP. It was confirmed that the reinforcement effect of the hybrid of pitch type and PAN type CFRP was remarkable with the synergistic effect of both carbon fibers. From the dynamic mechanical properties by the impact test, a hybrid CFRP structural material with PAN-based carbon fiber 60% in the outermost layer and pitch-based carbon fiber 40% in the core layer, the residual strength after maximum load and the total absorbed energy are greatly improved. Ultrasonic testing shows that pitch-based carbon fibers are arranged in the outermost layer, which reduces delamination and improves internal damage resistance, and supports the hybrid reinforcing effect of pitch-based and PAN-based CFRP. All of these results indicated it is possible to improve the static and dynamic mechanical performance and optimize the material structure by designing the ratio of the pitch-based carbon fiber and the PAN-based carbon fiber and the arrangement in the thickness direction of CFRP structures, which may help in the future CFRP structural design. (Received 22 March, 2020; Accepted 11 May, 2020)