| Induction heating is commonly used in engineering applications.Typical applications include welding,heat treatment,plate bending and corrected shape.However,induction heating is a complex process involving electromagnetic field,temperature field and structural field.Therefore,multiphysics coupling method is often used to effectively assist in simulating the process.The magneto-thermo-structural coupling does not consider the interactions among electromagnetic field,thermal field and structural field and cannot meet the requirements of the induction heating applications.It is also noted that the magneto-thermo-structural coupling is not suitable for the calculation of the model with large-scale mesh division due to the harsh requirements of the grid.Therefore,an equivalent heat source(EHS)is needed to simplify the magneto-thermo-structural coupling analysis.This dissertation proposes a fully coupled magneto-thermo-structural model.Meanwhile,a construction method of equivalent heat source(CMEHS)is also proposed for the large-scale of FEM model.The main research contents of this dissertation are as follow:(1)Development of a fully coupled magneto-thermo-structural numerical simulation method.In order to consider the influence of a structural analysis on an electromagnetic analysis,a fully coupling magneto-thermo-structural model is constructed with the morphing technique: Based on the magneto-thermal two-way coupling model,the node displacement generated by structural analysis is retained in the general coupling database using mesh morphing,and the deformation can be then transferred to the magnetic analysis.To verify the proposed fully coupled model,this model and the conventional segregated model are applied to simulate induction heating process of plate bending.The fully coupling model provides a novel tool for the numerical calculation of induction heating process in engineering.(2)Study on construction method of equivalent heat source for induction heating based on magneto-thermo-structural couplingDue to demanding meshing requirements of magnetic analysis,two-way coupling and relative movement of components,magneto-thermo-structural coupled analysis is time-consuming and cannot meet the requirements of factory on-site calculations when computing large-scale of FEM model.Based on magneto-thermo-structural coupled method,the induction heating simulation is carried out on the local but precise coupling model to study the mechanism and influencing factors of induction heating.It is found that the actual heat source of induction heating can be simplified to the equivalent surface heat source.Therefore,based on magneto-thermo-structural coupled model,a method of constructing an equivalent heat source for induction heating is developed.(3)Study on numerical simulation of plate bending with induction heatingFor the commonly used inductors of the "IHIMU-?" automatic induction heating bending system,the relation between the equivalent heat source and heating parameters is studied using proposed CMESH.By introducing four dimensionless variables,the relational mathematical model between the equivalent heat source and the heating parameters is obtained;the equivalent heat sources under the test conditions are calculated by the relational model;the simulation of the induction heating bending process is carried out by the thermo-structural coupling method with equivalent heat source.The computed results are in good agreement with the experimental data,while the elapse time is significantly reduced compared with the conventional magnetothermo-structural coupling method.(4)Study on numerical simulation of thermal fatigue analysis of aluminum alloy piston with induction heatingThermal fatigue test platform of the aluminum alloy piston with induction heating is researched.The equivalent heat source(EHS)is determined by proposed CMESH to perform finite element analysis on the piston.The results of the thermal analysis are compared with the experimental data obtained from the established thermal fatigue test platform of piston.It is found that the calculated results using the EHS are in good agreement with the experimental results.Subsequently,the thermo-structural coupling analysis is carried out to obtain the constraint rate of the throat of the piston that is prone to thermal fatigue cracking.Based on the established thermal fatigue test platform and the proposed method for calculating the constraint rate,the equipment and data support are provided for the use of constraint rate-fatigue life model. |
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