Buckling tolerance design of aircraft fuselage using carbon fiber reinforced thermoplastic (CFRTP)

In the structural design of next-generation aircraft, it is desired to reduce the weight of the aircraft by applying carbon fiber reinforced plastic (CFRP) to the structural material. Conventional aircrafts that use metal materials for its outer skins of fuselage are often designed with buckling tolerance design to reduce weight. However, it is difficult to adopt the buckling tolerance design because general CFRP breaks brittlely. On the other hand, carbon fiber reinforced thermoplastic (CFRTP) uses a thermoplastic resin as the matrix resin and is expected to have toughness. Therefore, there is possibility to adopt buckling tolerance design proactively, and further weight reduction can be expected. In this study, a design tool that analyses post-buckling behavior and optimizes the aircraft fuselage structures using CFRTP was developed. For a validation, three types of general CFRPs were used: T700S/3900-2B, T800S/3900-2B and T1100G/3900-2B. Structural weights were evaluated by performing structural sizing under the same load and constraint conditions. In the fuselages with respective CFRPs, the T1100G-based fuselage was minimized and that weight was the lightest compared to the other composites. T700S/LMPAEK was used as CFRTP and the fuselage with the CFRTP was compared to fuselage with CFRP for evaluation. In comparison of fuselage with T1100G/3900-2B designed by buckling nontolerance design and fuselage with T700S/LMPAEK designed by buckling tolerance design, the fuselage weight with T700S/LMPAEK was lighter than with T1100G/3900-2B although the material properties are lower than T1100G/3900-2B. This result suggests that the buckling tolerance design utilizing CFRTP is effective on fuselage design.