不同铺层角度复合材料 Ω 形柱的吸能特性

Ω-shaped composite tubes have certain application potential in terms of collision energy absorption and lightweight. To study the effects of ply orientation and loading rate on the energy absorption characteristics of the Ω-shaped composite tubes, quasi-static and dynamic axial compression experiments were carried out on carbon-fiber-reinforced composite Ω-shaped tubes by using an electronic universal testing machine and a high-speed hydraulic servo testing machine, respectively. In addition, the failure modes and evaluation index relevant to energy absorption were analyzed based on the crushing load-displacement curves and failure morphologies. In the experiments, the Ω-shaped tubes with three ply orientations, namely [0/90]_3s, [0/45/90/−45]₃ and [±45]_3s, were compressed under quasi-static and dynamic loading rates. Under quasi-static loading, the specimens with [0/90]_3s and [0/45/90/−45]₃ ply orientations both showed progressive failure, while the specimens with [±45]_3s ply orientation showed a catastrophic failure mode. The specific energy absorption (SEA) of the specimens with [±45]_3s ply orientation is about half of those of the other two specimens due to different failure modes. Under the dynamic loading, the Ω-shaped tubes with three ply orientations, where the SEA almost remains the same, were all featured by the progressive crushing. Moreover, the SEAs of the specimens with [0/90]_3s and [0/45/90/−45]₃ ply orientations under dynamic loading are reduced by 29.70% and 20.97%, respectively, compared with those under quasi-static loading. However, the SEA of the specimens with [±45]_3s ply orientation is 46.10% higher than that under quasi-static loading. The change of failure modes is the main reason for the increase of the SEA. Under quasi-static loading, the ply orientation has a certain effect on the SEA of the Ω-shaped tube, while under dynamic loading, its influence is relatively weak. The main reasons are as follows. Under a low loading rate, buckling fracture and interlaminar delamination of fiber and matrix gradually occur, resulting in a global response of the structure. On the other hand, under a higher loading rate, the contact time between the Ω-shaped tubes and the indenter is short, leading to a localized response, which is dominated by the loading rate, while the failure mode is less affected by the ply orientations.