Overview of automotive structural composites technology developments in Japan

The recent status of Japan's government-driven project to establish carbon fiber reinforced thermoplastic composites (CFRTP) technology for automotive applications conducted in the National Composites Center (NCC) Japan is introduced first. The baseline technology is discontinuous carbon fiber reinforced thermoplastic composites (C-LFT-D: carbon - long fiber thermoplastic-direct) using press compaction. All the components of the target car chassis made of aluminum alloy are replaced by C-LFT-D components and a 10% weight reduction with the same rigidity has been verified. The basic physics of the fiber length distribution mechanism and the experimental procedures to measure fiber length distributions are proposed. A basic theory to predict the flow behavior of extruded raw material of the mixture of melted resin and thermoplastics is proposed, and sophisticated CAE software to predict the flow patterns of the raw material is established. Measured elastic moduli of processed LFT-D plates show strong dependency on local fiber orientations and strong correlations between bending strengths and bending modulus are found. Hence, prediction of fiber orientation in the press compaction is a key point of the design of LFT-D components. The viscoelastic properties of C-LFT-D materials are characterized by using established theories. Certain important parameters, such as the shift factors, are identified by theory and experiments. The basic concepts of joining technology are also established, where ultrasonic fusion bonding is selected as the primary method. Joining procedures are defined and mechanical properties of the joints are evaluated. The essence of the other project conducted in the University of Tokyo for CFRTP applications to automobiles is also introduced. Several new composites are developed and evaluation technologies are developed.