Finite Element Simulation of a Technological Process of Welding

Welding is often applied for jointing structural components with each other, and for increasing joint strength a multilayer weld is to be performed. For example, this technology is used in the turbo-machine engineering for structural component fitting to a shaft. The structural component composed from two parts is fitted to a shaft without a gap, then both parts are coupled with each other, and the multilayer weld is made. In the process of welding, the high temperature differences result in large temperature strains, which affect the distribution of the contact pressure between a structural component and a shaft after cooling of the weld, as a result of which there could occur skewing, and a component would be attached to a shaft improperly. The results of the research of contact interaction between a structural component and a shaft during a manufacturing process of welding and a consequent cooling are presented in the paper. On the basis of the developed mathematical models for a solution of a decoupled quasistatic termo-elasto-plastic problem with account of the contact interaction, the problem was solved in two stages. 1.The first stage included a solution of the transient nonlinear 3D thermal problem, in which model of the welding process is the driving heat source of the appropriate power. The thermal properties of the materials are functions of the temperature. After laying the first joint weld, at the next stage of a solution the members modeling the second joint weld were taken into account. The obtained earlier solution is transferred to a new model and the all process repeats. As a result, the variation of temperature fields during welding is obtained, and the time of the joint weld cooling up to an ambient temperature was found. 2.The second stage included the solution of a series of the quasistatic nonlinear problems of the plasticity theory with account of thermal fields obtained at the previous stage. For simplification of a problem the transferring of metal in to a fluid phase during welding was not considered. For accounting plastic strains, the bilinear model of kinematical hardening was chosen. As a result, the plastic strain localization areas were found out, and it was stated that the contact pressure field is characterized by asymmetrical distribution on the contact surface and stabilizes with time.

View Now