| As one connection technology of high efficiency, reliability and accuracy, laser welding is play an important role in modern industrial manufacturing. A serial of complex physical or chemical processes carried out during laser welding, such as heat transmission, melting of welding materials, structural phase transition, welding stress and deformation etc. If the thermal process can be stimulated numerically by finite element analysis, the laser welding will be imitated via FEA software to decide the best method and design plan for kinds of welding materials and then welding parameter will be effective controlled.This paper, theoretical analysis was executed for the thermal process of lasering welding "different thickness of6005A aluminum alloy", as well as relevant mathematical modeling. Three heat source models were introduced:Gaussian distribution heat source model, double ellipsoid heat source model, and birth-death heat source model.3-D transient finite element analysis was applied to the temperature field of different thickness of6005A aluminum alloy, to investigate the shapes of welding seams, and the heat influence area, on all hear source models. The analysis shows that, the result from "Gaussian distribution heat source model" is at most close to the actual situation after welding. The analysis also proves the numerical simulation reasonable and practical. Consequently, the numerical simulation proposal is provided:"Modeling-loading of dynamic heat source-analysis of temperature field-analysis of stress and strain field-control of welding parameters"Software ANSYS13.0was used for the3D transient finite element analysis of temperature field of6005A aluminum alloy treated with laser welding. Mesh transition is applied to ensure the small size of mesh and improved the efficiency and accuracy of calculation. In the simulation, not only is the thermal physical parameter of6005A aluminum alloy, whose features of non-linearity, body heat radiation, melting latent heat according to temperature change, as well as the influence on temperature field from ion, taken into consideration, but also is the laser welding characteristic of different thickness of6005A aluminum alloy. Gaussian heat source procedure of dynamic loading and movement of power is produced via APDL. The simulation result shows that the nearly ellipsoid temperature field of standard quasi stable state formed after a while of laser welding. The temperature field is not distributed evenly, and the field range, welding pool dimension, melding range is larger than the dimension of plate at the same period.On the basis of temperature field simulation, indirect coupling was adopted to numerical simulation analysis of stress-strain field resulted from laser welding. Bilinear kinematic (BKIN) is adopted as option of plasticity analysis, and certain freedom limitation is added on finite element model. The simulation result shows that the stress-strain field resulted from laser welding different thickness of6005A aluminum alloy is distributed unevenly. On welding seam and its surrounding area, the longitudinal residual stress is tensile stress, and the thick plate has one larger residual stress area than the thin plate, which will become the compression stress gradually as being away from welding seam area.By change the methods parameter such as the power of laser, welding speed and laser spot diameter etc, the influence, resulted from different parameters, on welding temperature field and stress-strain field is analyzed. Accordingly, one optimized welding method, and the best coupling area of this test come into the conclusion. Meanwhile, via executing the research regarding the influence from thickness differences on welding stability and welding beam quality, the conclusion that one thickness difference of less than3mm is favorable, is made. This test bring indeed help and guidance for the improvement of welded point quality, rest result prediction and test work reduction while laser welding different thickness of6005A aluminum alloy. |
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