Crashworthiness design and multi-objective optimization of 3D-printed carbon fiber-reinforced nylon nested tubes

This study presents a novel variable thickness nested tube consisting of circular tube and origami tube (VTCO) designed to reduce the initial peak crushing force (PCF) under axial loading while maintaining high energy absorption. The core of this design is to achieve progressive and controlled energy absorption and to reduce peak forces as well as accelerations that can lead to passenger injuries. Nested tube structures were fabricated using short carbon fiber-reinforced nylon composites through 3D printing technology, and quasi-static axial compression tests were performed. The results show that equal-thickness nested tubes consisting of circular tubes and origami tubes (ETCO) perform better in terms of energy absorption and deformation stability compared to circular and origami tubes individually. The further improved VTCO reduced the PCF by 53% and significantly improved the crash force efficiency (CFE) by 54%. The VTCO structure was parametrically investigated by means of a validated finite element model and optimized using the Non-Symmetric Dominance Sorting Genetic Algorithm II (NSGA-II). The optimization results provide a feasible way to adjust the structural crashworthiness to meet different engineering requirements. This study provides valuable insights into the energy-absorbing properties of VTCO structures and is an important guide for the application and material development of novel VTCO structures. Highlights ETCO offers better energy absorption and stability than circular and origami tubes individually. VTCO is superior to ETCO in reducing PCF and increasing CFE. Multi-objective optimization using NSGA-II to balance conflicting crashworthiness indicators.