Study On Mechanical Properties Of Aluminum Alloy Box Section Cross-shaped Welded Joints

The existing aluminum alloy structural design specifications haven’t been updated for a long time.Therefore,in the practical application of engineering,there is a lack of some normative guidance for aluminium alloy new materials and joints.Because aluminium alloy structure has been widely used in many fields,and the welded joints of aluminium alloy structure have more complex characteristics,the further study of aluminium alloy joints has better engineering value and theoretical significance.In this paper,the mechanical properties of aluminium alloy cross-welded joints with box section are studied by means of experimental research and finite element simulation,including the following contents:(1)The physical and mechanical properties and stress-strain curves of 12 aluminium alloys 6061-T6 were obtained by unidirectional tensile tests.Then unidirectional tensile tests were carried out on the welded specimens of aluminium alloys,and the effects of aluminium alloy welding on welding materials and welds were analyzed.The results show that the tensile strength of the welded specimens will be reduced by about 20% compared with the base metal.And MIG has better characteristics.(2)Static loading tests were carried out on four cross-section welded joints of aluminium alloy box section.The destructive behavior and load-displacement curves of the joints were obtained,and the influence of stiffening ribs on the bearing capacity of the joints was studied.The conclusions are as follows: the welded joints of cross joints are weak and easy to be damaged.When vertical ribs are added,the ribs will be damaged first.From this,it can be seen that adding stiffeners in vertical direction and adding stiffeners in horizontal direction can obviously improve the bearing capacity of the test specimens.(3)Comparing the numerical simulation results with the experimental results using ABAQUS,it shows that the numerical simulation is consistent with the experimental results.On this basis,the thickness of the column section,the length of the vertical ribbed plate,the length of the cover plate,the position of the cover plate and the addition of horizontal ribbed plate are analyzed by finite element method.It is concluded that the load-bearing capacity of the specimens increases gradually with the increase of the column wall thickness,but it can be found that the increase is not obvious;the loadbearing capacity of the specimens also keeps positive with the length of the cover plate.However,after the length of the cover plate is 150 mm,the increase is slight;the loadbearing capacity of the specimens increases with the increase of the vertical rib plate’s extension length,and the increase effect is obvious;after adding horizontal rib plate to the test component,it can be found that the yield strength of the component is obviously improved.(4)The hysteretic behavior of aluminium alloy specimens under reciprocating loads is simulated by ABAQUS,and the hysteretic curves of joints are obtained.The results show that the hysteretic curves of all specimens are full,which indicates that the seismic capacity and energy dissipation capacity of the specimens are better;the change of column wall thickness has little effect on the mechanical properties of the specimens,while the improvement of the mechanical properties of the vertical and horizontal ribbed plates is obvious.