The failure mechanism and energy-absorbing characteristics of composite thin-walled C-channels subject to low-speed axial compression

To analyze the failure mechanism and energy-absorbing characteristics of composite thin-walled C-channels subject to the low-speed axial compression, 12 groups of T700/MTM28 specimens with three different layer numbers and four different layups were fabricated and tested. The failure modes and load–displacement curves were observed, and then the effects of layer numbers and layups on failure mechanism and energy-absorbing characteristics were further analyzed based on the crashworthiness indicators, such as peak crushing force ( F max ), mean crushing force ( F mean ), specific energy absorption ( SEA) and crushing force efficiency ( CFE). The results show that for the C-channels with 0° ply, overall instability occurs, which results in a reduction of SEA. The C-channels with 0°/90° ply, ± 45° ply and 45°/90°/−45°/0° ply exhibit the stable progressive crushing progress with the local buckling failure mode, consisting of local buckling, fiber breakage, matrix cracks, delamination and corner cracking. Besides, the SEA of C-channels with 45°/90°/−45°/0° ply increases with the increasing of layer numbers, and the C-channels with 45°/90°/−45°/0° ply have greater potential for the design and application of energy-absorbing structures.