Analysis Of Residual Stress And Deformation For Side Beam On Bogie

The residual stress field is an equilibrium the stress field inside the structure, it is retained when deformation or phase change happen in materials plastic at high temperature then cool off, the peak of the residual stress often reach or exceed the yield strength of material. When welded components put into use, they suffered the overlay of work stress caused by load and its internal welding residual stresses, which will lead to secondary deformation and welding residual stress re-distribution, thereby reducing the rigidity and dimensional stability of the welded component and causing significant impact on the normal use of the mechanical structure.Take the side beam of bogie as subject of study, establish finite element model for typical joints on side beam, with the help of SYSWELD, numerical simulation for welding process of different element size T-joint finite element models were performed, determine the proper element size suit the software, and determine that the element size should between2-2.5mm so than can assure accuracy and efficiency at the same time, besides, study the relationship between simulation time and scale of nodes, it is exponential increase. Two types of typical structures of side beam were simulated; distribution and change discipline of residual stress and deformation on these two typical structures was analyzed, providing reference for numerical simulation of the whole side beam.With the current welding procedure, the major welding lines were simulated in three different finite models. Results indicates that the peak of residual stress occur in the long direction of the welding line, the value can reach420MPa close to the yield limit of the material, while the peak value of residual stress in the vertical direction of welding line is about300MPa. It can be seen from the simulated results that the residual stress exists in welding bead area, along the welding line the residual stress concentrate in the area the box beam and spring strut joined together, the distribution at spring strut is irregular while it is regular at the box beam area.The effects of heat input, welding speed and clamping condition were studied, results indicate that residual stress decline with the increase of heat input and raise with the increase of welding speed, but the changing range value is less than50MPa. The simulated results uncovered that the clamping can not assure the least deformation, because the results showed that the full clamping at the middle of side beam got smaller deformation, and this can be used in factory practice.Nondestructive method X-ray diffraction method was adopted; residual stress at typical areas and key points on side beam of bogie was measured, results of measurement were compared with that of numerical simulation, though there is difference between them, the changing trend is consistent, the obvious difference would be the simulated value is higher than measured value on the whole and the fluctuation of the simulated results is much less than that for measured results. The effectiveness and accuracy of SYS WELD for simulating residual stress was conformed.