Investigation And Application On Numerical Simulation Of Welding Deformation In Bogie Frame

High speed of locomotive is becoming a strategic direction of the development ofrailway transportation in China. Bogie frame is a very important part for high-speed train,we must make sure that it’s sufficient strength and stiffness for the bogie to make the trainsafe enough; also, the bogie should have appropriate elasticity, good impact resistance andfatigue resistance. Therefore, optimizing welding technology and improving welding qualitywill be of great application value and significance.This thesis is based on the research of numerical simulation of welding deformation inbogie frame by Key Technologies R&D Program of Changchun (no.10KZ03). The thesisintensively investigates the modeling method and theory of welding in bogie frame.Themain work includes:First, this thesis is based on the research of transition piece of gs trbine cmbustoroptimization design by National High-Tech R&D Program of China (863Program). Thethesis intensively investigates the modeling method and theory of impingement cooling, aswell as the smplified transition piece model. This thesis focuses on the cooling technologyof a transition piece of this kind of combustion chamber and established equations ofmathematical physics. This project also studies the objective low, by multi physical fieldscoupling analysis of CFD (computational fluid dynamics), of the distribution and interactionof the multi physical coupling fields such as flow field/thermal field/stress field in conditionof compound impinging cooling. Based on the heat-mass transfer analogy, the results ofthese experiments prove that the distribution of wall temperature and the effectiveness ofcooling could be achieved through increasing inclination of coolant holes and coolant flow orientation. Morever，this thesis proposes to introduce discrete phase mist into airflow fieldto a traditional impinging cooling way for improving the heat transfer effect and enhancingthe turbulent of the flow field. Numerical simulation was performed to study the heattransfer of mist/air impingement via FLUENT code. The results of this paper can provideguidance for corresponding experiments and serve as the qualification reference for futuremore complicated studies with convex surface cooling.Second, heat source model is an important aspect in numerical simulation of weldingprocesses. The chapter briefly introduces several heat source models in numericalsimulation, including Rosenthal model, Gaussian distribution, double-ellipsoid andself-adaption cut-off temperature technique. Adopting the sequential coupling analysis, wedesigned a self-adaption cut-off technique for different materials and structures. Basing onthe material properties of S355J2G3, we made the threshold optimization of cuttingtemperature and established the evaluation method for simulation performance. The resultsshow that using this method can obtain the optimal cut-off temperature. In this paper, thesimulation results are almost identical with experiment. The self-adaption cut-offtemperature technique is ascertained the validity of evaluation method, which improves theaccuracy of the displacement solution and decreases the computation time. By using thismethod in the welding numerical simulation, it could realize the efficiency and accuracy.Accordingly, the self-adaption cut-off temperature technique has significance for thewelding numerical simulation.Third, there were many problems in producing and stress analysis of the bogie frameof railway passenger cars. It is really difficult to establish the dynamic welding heat sourcemodel and performance the processing. To solve the problems, the authors researched thetheory of space welding path and defined the welding heat source coordinate mobile mode.Then, the authors completed the curve path dynamic welding heat source model by inputingparameters and operating in the Ansys. The authors designed a loading method of the planecurve path, space curve path and bogie frame of railway passenger cars model. In this paper,the authors used numerical simulation to performance the moving heat source model and welding curve path method. During the researching, the authors could deeply understandingof welding process and well control the residual stress and deformation by choosingreasonable process and deformation. The welding process simulation can be realizedefficiently and exactly. Therefore, the theory proposed has an important significance intheory research and engineering application.Four, it is amajor issue to reduce and control the welding deformation in the process ofmanufacturing the bogie frame of the high-speed locomotive. In this paper, heat-elastic-plasticmechanicswas proposed to establish heating-elastic-plastic simulation model of the weldbeam based on heating-mechanical coupling algorithm. The welding deformation withdifferentwelding sequences for innerwelds andmainwelds were investigated with ANSYS.The results of finite element compution was applied to reducewelding deformation andquality control in manufacturing the bogie frame of the high-speed locomotive. The responsesurface models was established by adopting design of experiment (DOE) and approximatemodeling method. The simulation results show that the optimum design proposal werereduced by residual deformation and residual stress than the initial results while the coolingeffectiveness investigated between the optimum impinging cooling and injection orientationand the initial scheme. To avoid the problem of low efficiency in such large complicatedsimulation model, the following strategies were taken in establishing the simulation model,such as the subsection moving string heat source model, parallel treatment calculationtechnique and so on, which could catch the main relationship in the most complicated weldingprocess simulation so that the conclusions were able to be applicable in the real engineeringproblems.Finally, the main content is summarized and prospects for the futher work is predicted.