Numerical Simulation For The Welding Deformation Of Aluminum Alloy’s Frame

Welding distortion prediction is one of the research focuses in materialprocessing field, especially for aluminum alloy frame. Due to the large thermalexpansion coefficient, aluminum alloy component will generate lager residualdeformation than other materials after welding. If there isn’t proper control measure,the welding deformation affects its carrying capacity and service life. In the paper, thealuminum alloy frame’s welding deformation and the influence of different weldingprocesses on the final distortion were researched with numerical analysis method.The inherent strain method consider that the residual plastic strain mainly exist inrelative small zone which is near the weld bead, while the rest of the whole structure’sdeformation is regarded as elastic deformation. Based on the inherent strain method,the residual plastic strain of welding joint was separated from the whole structural.Local plastic strain of the welding joint was calculated precisely considering theinfluence of temperature, metallurgy and mechanics. Then, the plastic strain’s resultof the local model was inserted into the global model, and deformation of the globalstructure was obtained. In this way, the overall deformation was predicted, and thecalculation process was simplified.In the assembly welding process of aluminum alloy frame, there are three typicaljoints, butt joint, T joint and cross joint. They were studied respectively. Thedistribution of stress and strain during the welding process was obtained. Theinfluence of welding speed, the presence of groove on welding residual stress anddeformation were analyzed. The residual strain is mainly concentrated on the zonenear welding bead. But it is almost zero in the zone away from the welding bead.Under the condition of constant welding voltage and current, the increase of weldingspeed can improve welding productivity; if the welding speed is too fast, however, theresidual stress will increase, and the defects of incomplete fusion will occur. Large stress concentration, which exist in weld toe of T joint and Cross joint, can besuppressed by groove welding.Utilizing the above results, the overall deformation of aluminum alloyframework was analyzed. The influence of different welding sequences on the finaldeformation was studied. The results showed that the symmetrical welding sequencedecrease the overall deformation.Two welding assembly methods, the normal assembly process and the reverseassembly in the assembly of large aluminum alloy frame, were researched by thefinite element analyses and experiments. In the reverse assembly process, clampswere used to fix and weld the sub-blocks, and then the blocks were welded together.The simulation results showed that the reverse assembly technology can greatlydecrease the overall frame’s welding deformation.