Content of research

Advanced composites (carbon fiber composites, carbon fiber reinforced plastics (CFRP)) are widely used as structural materials due to their high specific strength and stiffness. The development of fiber orientation technology has made it possible to arrange fibers not only in straight but also curved lines. Compared with straight fibers, design flexibility is greatly improved, and it is thus possible to produce CFRP components for specific part shapes and uses. In our laboratory, we have been producing composite specimens with curved fibers using a fiber stitching machine (Fig. 1), which is based on embroidery machine technology, to evaluate the mechanical properties of specimens and develop a unique method to optimize fiber shapes. For example, Figure 2 shows the optimum fiber shape to reduce the strain concentration around the holes in a wing model with multiple circular holes, and the strain distribution is shown in Fig. 3. It has been found that the strain concentration is reduced more than with straight fibers.

Potential for social implementation

• ・Optimal fiber placement considering the shape after molding (e.g., press molding of thermoplastic composites in association with optimal fiber placement)
• ・Strengthening of optimal parts used for unique shapes such as stepped parts and those used around holes

Appealing points to industry and local governments

Our laboratory has been focusing on research of the optimal design of curvilinear fibers since an early stage in the world. In addition to curved fibers, we have built a track record of conducting research on the optimal design of composite materials. We have participated in the national SIP program and have a wealth of experience in joint research with companies, public research institutes, and overseas researchers.