Research On Mechanical Properties Of Welded Joint Of Box Aluminum Alloy

Aluminum alloy structure has been widely used in domestic and foreign buildings.Compared with steel structure,aluminum alloy has many advantages,such as light weight,high specific strength,good corrosion resistance and short construction period and so on.Nodes as the force transfer hub of structure has an important role in the overall structure of the bearing capacity.At present,there are few researches on welding joints of aluminum alloy at home and abroad,hindering the development and application of aluminum alloy structures.Therefore,the welding joints of aluminum alloy structures are studied by experiment and finite element numerical simulation in this paper.The monotonous tensile test of domestic aluminum alloy 6061-T6 and its weld joint is carried out.The influence of the type of welding wire,the thickness of welding piece and the welding process on the tensile strength of the test piece is analyzed.The test results show that the tensile strength of 5356 welding wire specimen is obviously higher than that of the 4043 welding wire specimen.With the increase of the thickness of the weldment,the tensile strength of the specimen decreases.Under the same conditions,the tensile strength of the specimen by MIG welding is greater than TIG welding specimen.Four box-type aluminum alloy welded specimens are designed to carry out the static loading test.The force transmission members of the joints include vertical ribs and capping plates.The results show that the vertical rib can effectively increase the bearing capacity and ductility of the joint,and the increase of the vertical rib elongation also has a significant improvement on the bearing capacity of the welded joint.At the same time,the finite element analysis software ABAQUS is used to conduct non-linear analysis of the specimens.The yield load,displacement and failure mode obtained by numerical simulation are in good agreement with the experimental results,which verifies the correctness of the FEM modeling method.Based on the correct finite element model,the influence of column wall thickness,cover length,vertical rib extension and horizontal ribs on the mechanical properties of aluminum alloy welded joints is analyzed.The results show that with the increase of column wall thickness,the yield load of the test piece increases gradually,but the increase is small.With the increase of the cover length,the yield load gradually increases,but when the cover length reaches 150 mm,the increase is small;With the extension of the vertical rib increases,the yield load also increases gradually,the increase rate is obvious;The yield strength significantly increases when horizontal ribs is welded.Finally,the finite element analysis of the member subjected to low-cycle reciprocating cyclic loading obtains the hysteresis curve.The curve shows a fuller spindle shape with no pinch-in phenomenon and large hysteresis loop area,but the bearing capacity of the column increases slightly when column wall thickness is increased.When the cover plate is increased by 150 mm,the bearing capacity is slightly increased.Adding vertical and horizontal ribs significantly increases the bearing capacity,and as the length of the extension of the vertical ribs increases,the bearing capacity is also significantly increased.The skeleton curves and hysteresis curves show consistent characteristics,which shows that adding vertical and horizontal ribs are two better methods of node reinforcement.