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在车辆的防撞设计中薄壁管作为耗能构件被广泛采用,轴压力是防撞部位承受的最典型荷载之一。为了减轻重量,薄壁管采用轻质材料诸如高强度钢材、铝和镁制成。然而,这些轻质材料中的大多数与传统的钢材相比更脆且易断裂。由于材料的应力、应变状态通常被作为判断其构造断裂点的依据,故对薄壁管的三轴应力分布和时程及其等效应变进行了有限元模拟。分析结果显示,三轴应力和等效应变沿着管长波动,方形薄壁管的断裂更可能发生在边缘而非其他位置。对于相同的轴压冲击,当初始冲击速度在6～24m/s变化时,方形薄壁管内部的应力、应变变化不大。对影响应力、应变状态的参数,包括横截面角的形状、壁厚和横截面形状分别进行研究。所得结果可为薄壁管的设计及轻质材料力学性能的试验特性研究提供参考。
In the crash design of the vehicle, thin-walled tubes are widely used as energy-dissipating components. Axial pressure is one of the most typical loads to be borne by an anti-collision part. To reduce weight, thin-walled tubes are made of lightweight materials such as high-strength steel, aluminum and magnesium. However, most of these lightweight materials are more brittle and easily broken than conventional steel. Due to the stress and strain of material, the triaxial stress distribution and time-history of the thin-walled tube and its equivalent strain are usually simulated by finite element method. The results of the analysis show that triaxial stresses and equivalent strains fluctuate along the tube length, and the fracture of the square thin-walled tube is more likely to occur at the edge than at other locations. For the same axial pressure impact, when the initial impact velocity varies from 6m / s to 24m / s, the stress and strain inside the square thin-walled tube do not change much. The parameters that affect the stress and strain states, including the shape, wall thickness and cross-sectional shape of the cross-sectional angle, are studied separately. The results obtained for the design of thin-walled tube and light mechanical properties of the experimental characteristics of the study provide a reference.