Quasi-static crush response of lightweight sandwich composite tubes fabricated via newly designed internal thermal expansion technique.

Different from conventional unidirectional outward-inward forming methods, this study employs a multidirectional internal expansion shaping approach to fabricate lightweight sandwich composite tubes. Integrating carbon fiber reinforced polymer (CFRP), thermal expansion foam and polymethacrylimide (PMI) foam, the sandwich composite tubes demonstrate adaptability in terms of material properties as validated through several experimental trials. The one-step molding process eliminates the requirements for subsequent structural assembly and bonding, while ensuring adhesion between diverse material components. The sandwich composite tubes exhibit superior impact resistance, showcasing a stable progressive crushing failure. The energy absorption mechanism shifts from single CFRP damage to a multi-material composite energy absorption mode. The specific energy absorption (SEA) value of designed sandwich composite tube is up to 102 J/g. The sandwich composite tubes fabricated in this study hold promising applications in advanced vehicle/aerospace lightweighting and crashworthiness safety. [Display omitted] [ABSTRACT FROM AUTHOR]