Evaluation of mechanical properties of CFRP modeled by FDM

Knee joint diseases have been increasing in recent years due to the aging of society and the increase in the sports population. Knee braces used in treatment play a role in immobilizing and stabilizing the knee joint and reducing the direct burden on the knee joint. Therefore, the development of knee braces using CFRP material by fused deposition modeling (FDM), one of the additive manufacturing (AM) methods, is expected. The application and development of CFRP for knee orthoses requires safe design that considers the weakest points in terms of the shape of the various parts used in the orthoses and the walking motion. However, the mechanical properties of CFRP materials using FDM have not been clarified. In this study, the effects of carbon fiber content and orientation on the flexural strength of FDM-molded CFRP were investigated. 4-point flexural strength tests revealed that the carbon fiber layer was distributed throughout the entire structure, and that the higher the fiber content, the higher the strength. Therefore, it is suggested that an even arrangement of the fiber and resin layers increases the bending strength.