Foam-filled lightweight braided-textile reinforced and nested tubular structures for energy absorption applications

Composite tubular structures have excellent energy absorption (EA) and can be widely applied in lightweight energy absorbers. Made up of thin-walled braided-textile tubes and polyurethane (PU) foams, a hybrid carbon fiber-reinforced composite (CFRC) tubular structure with a simple making process and low cost was designed, made, and tested in this research. Through axial compression tests, the crushing mode, the EA, the specific energy absorption (SEA), the mean crushing force (MCF), the peak force (PF), and the peak force loss rate (PFLR) of the tubes were revealed. The experimental results indicate that filling PU foam can effectively improve the EA of thin-walled braided-textile reinforced tubes. The crushing mode changes from local buckling and diamond crushing mode to progressive annular crushing mode. The nesting of braided-textile tubes with different inner diameters can effectively increase the EA, the MCF, and the PF, but the SEA of some samples will decrease. Filling PU foam can effectively reduce the PFLR. The PLFR of the nested composite structure is negative, indicating that the MCF is greater than the PF within the effective crushing distance (ECD).