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.
