Research Of Temperature Field Simulation System For Typical Welding Joints Of The Aero Engine

With the increasing requirements for design and manufacturing of aero engine,high-performance materials and welded structures have played an important role in reducing the weight and ensuring the performance of aero engine.During the study of welding process,the finite element simulation method is widely used to predict the size and residual stress,optimize the welding parameters,and improve the reliability of the welded joints.The calculation of the welding thermal process is the basis of the calculation of residual stress.The domestic simulation researches of welding thermal process are based on the foreign commercial finite element software.The users have to spend much time learning about the software.The cost of the researches is becoming higher and higher.Therefore,the inevitable trend of the development of domestic simulation research is developing the finite element simulation software with independent intellectual property rights.In this paper,a finite element simulation system of welding temperature field with friendly interactive interface was developed for typical joints of aero engine.The system has important practical value for engineering application.Firstly,the overall framework of the simulation system was designed,the development platform was determined,and the implementation methods of system functions was selected.The framework of the system was built based on C++ / MFC on the Visual Studio platform.The interface of the system was divided into three areas: menu area,dialog area,and graphics area.The system was divided into three modules according to the functions: pre-processing,solving,and post-processing.Then,the implementation of the core solver with Fortran program was studied.The differential equation of the three-dimensional transient heat conduction model,which describes the heat transfer problem of the welding process,was converted to non-linear equations with Galerkin weighted residual method.The matrixes contained in the equations were obtained by generating the element stiffness matrixes and assembling the total stiffness matrix.Finally,the direct iterative method was used to solve the equations to obtain the node temperature.The program realized the establishment of geometric and grid models for different joint forms such as flat butt joints and T-type joints.The program also provided a double ellipsoid heat source model to simulate the heat effect of the most widely used welding method in aero engine: tungsten inert gas welding.The functions of pre-processing were established with the MFC tree control.The thermo-physical property library,containing the parameters of key materials of aero engine: titanium alloy and nickel-based alloy,was established.The welding process parameters library,containing the parameters for tungsten inert gas welding,was also established.In addition,through the dynamic link library DLL,the mixed programming of C++ interface program and Fortran solver program was realized.With the Open GL technology,the temperature results were visualized during the post-process.The system provided the display of the three-dimensional model,temperature field cloud map,surface isotherm map,molten pool cross-section view,thermal cycle curves,and temperature path curves.It also provided the functions of translation,rotation,and scaling of the model.Finally,the steps of welding analysis of flat butt joints and T-type joints with this system were introduced.The results were compared with experimental results and those calculated by commercial finite element software,which verified the computing ability of this system and the feasibility of post-processing.The temperature simulation system designed and developed in this paper has a friendly operation interface,excellent calculation ability,and good graphic display functions.It has a good application prospect in the finite element analysis of typical welded joints of aero engines.It lays the foundation for further development of the relevant stress analysis system.