钢铝合金混合式门架法兰节点抗拉承载性能与设计方法

Tensile bearing capacity and design method for steel-aluminum hybrid gantry flange connections

关键词:  钢铝合金混合式门架  铝合金法兰节点  拉伸试验  力学性能  承载力计算理论

Key words:  steel-aluminum alloy hybrid gantry  aluminum alloy flange joint  tensile test  mechanical properties  bearing capacity theory

摘要:

为探究钢铝合金混合式门架法兰节点抗拉承载性能,考虑法兰板厚度、螺栓数和螺栓边距参数设计了7个足尺法兰试件,首先通过轴向拉伸试验研究法兰节点破坏模式以及承载能力变化规律。随后,基于试验结果建立有限元分析模型,分析加劲板厚度、螺杆直径和圆管壁厚对法兰节点承载性能影响规律。最后,根据试验结果和有限元分析结果,提出铝合金法兰节点承载力计算理论。结果表明:试件破坏形态大致可分为铝合金加劲板与法兰板焊缝断裂,铝法兰板和铝管连接焊缝及热影响区处发生断裂、法兰板轻微变形、铝管脱落和铝合金法兰板出现大变形并进入塑性3类;荷载位移曲线大体上可分为弹性阶段、弹塑性阶段和破坏阶段;法兰板厚度由10 mm增到14 mm和18 mm时,极限荷载增幅分别为66.7%和76%,极限位移降幅分别为14%和15%;螺栓数由4增至6和8时,极限荷载增幅分别为89.4%和124.5%,极限位移降幅分别为38.2%和44.2%;螺栓边距参数由0.75增大至0.875和1.0时,极限荷载增幅分别为10.3%和20.1%,极限位移变化不大。有限元参数分析发现加劲板厚度、螺杆直径和圆管壁厚对节点承载力影响均不显著。考虑铝合金材料焊接热影响区强度衰减提出的铝合金法兰节点设计方法可为钢铝合金混合式门架设计提供参考。

Abstract:

To investigate the tensile bearing capacity of aluminum alloy flange joint of steel-aluminum alloy hybrid gantry, seven full-size flange specimens were designed considering the thickness of flange plate, the number of bolt and the bolt edge distance. Firstly, the failure modes and the variation laws of bearing capacities of flange joints were studied by axial tensile test. Then, based on the test results, a finite element analysis model was established to analyze the effects of stiffened plate thickness, screw diameter and tube wall thickness on the bearing performance of flange joints. Finally, based on the test results and finite element analysis results, the calculation theory of aluminum alloy flange node bearing capacity was proposed. The results of the study show that the damage patterns of the specimens can be roughly classified into three categories: fracture of the weld between the aluminium alloy stiffener plate and the flange plate, fracture at the weld and the heat-affected zone of the joint between the aluminium flange plate and the aluminium tube, slight deformation of the flange plate, dislocation of the aluminium tube, and large deformation of the aluminium alloy flange plate and entry into plasticity. The load-displacement curve can be roughly divided into elastic stage, elastic-plastic stage and damage stage. When the thickness of the flange plate was increased from 10 mm to 14 mm and 18 mm, the ultimate load increase by 66.7% and 76%, respectively, and the ultimate displacement decrease was 14% and 15%, respectively. When the number of bolts was increased from 4 to 6 and 8, the increase in ultimate load was 89.4% and 124.5% and the decrease in ultimate displacement was 38.2% and 44.2% respectively. Increasing the bolt margin parameter from 0.75 to 0.875 and 1.0 resulted in an increase in ultimate load of 10.3% and 20.1%, respectively, with little change in ultimate displacement. The finite element parameter analysis showed that the stiffener plate thickness, bolt diameter and round tube wall thickness had no significant effect on the nodal load capacity. The proposed design method of the aluminium alloy flange node, which takes into account the strength attenuation in the heat-affected zone of the welding of aluminium alloy material, can provide a reference for the design of steel-aluminium alloy hybrid gantry.