2019 年 68 巻 9 号 p. 704-711
CFRTP (Carbon Fiber Reinforced Thermoplastics) are expected to be used in the automobile parts due to their properties such as high specific strength and high specific stiffness in order to reduce the weight of car body. However, due to the expensive carbon fiber, the cost of CFRTP is high and its application to automobiles is limited. For mass-produced automobiles, a multi-material concept using a combination of dissimilar materials has been attracting attention. While the multi-material concept is often used to joint dissimilar materials, such as composite materials, high tensile strength steel, Al alloy and so on, the method of combining dissimilar material into one part is also expected. For the development of automotive parts, CAE technology is required and in order to apply multi-material concept to mass-produced automobiles, optimization method of materials and shape is necessary to be developed in the future. In this study, multi-material hat shaped members of CFRTP and aluminum alloy were molded by using hybrid molding method and their bending properties were evaluated. Their FEM analysis was also carried out and the relationship between material cost and mechanical properties were evaluated. When the surface of Al alloy is treated by electrolytic polishing, delaminating between Al alloy and CFRTP was suppressed and high stiffness multi-material hat shaped member can be obtained. The multi-material hat shaped member of CFRTP and Al alloy has superior specific stiffness as compared with molded products using only CFRTP for surface material, although the specific maximum bending load was lower.