Simulation And Process Optimization On Aero Engine Case Shell Welding Stress

The structure of case shell on aero engine is complex, the weld process more is more,and involves a variety of welding process, so it is unavoidable that produce welding residual stress. The residual stress can directly affect the rigidity, fatigue strength, size precision and service life of the welded parts. So it is very important to predict the residual stress of the welded structure according to the process conditions, and put forward the corresponding control measures. That has important significance for the safety of the aero engine. This paper is based on the methods of combination of experimental and numerical simulation, it in-depth study the process of scanning electron beam welding and TIG welding on case shell, and study the stress distribution and the method of stress control. The welding process of GH4169 alloy with thickness of 2mm was simulated by finite element software, and demonstrated with experiments.The process of electron beam welding and local heat treatment was simulated by finite element software SYSWELD in case shell on aero engine, the typical welded joints of case shell on aero engine was simulated by finite element software SYSWELD, and the heat source model of scanning electron beam welding and TIG welding was developed, The weld pool morphology, temperature field and stress field of the GH4169 alloy plate with 2mm thickness of the scanning electron beam welding and TIG welding are simulated.The process of scanning electron beam welding was simulated by using the composite heat source model of the double ellipsoid heat source +3D Gauss body heat source model, and the process of TIG welding was simulated by using the double ellipsoid heat source model.The actual process of welding the GH4169 alloy plate with 2mm thickness were carried out by using the simulated welding parameters. The results of weld pool morphology are in good agreement with the experimental results, it proved the correctness of heat source. It measured the residual stress of welding plates by using the method of ultrasonic testing stress, and compared with the simulation results. The residual stress distribution of simulation results andmeasured results are similar, and the error range is within 10%. It proved the correctness of the simulation results, which accord with actual welding conditions.Using the heat source model that was developed and was checked simulate the process of welding case shell parts with different process schemes. The results show that the change of welding direction has no obvious effect on the welding residual stress, and the local heat treatment process can effectively reduce the residual stress and reduce the rate of about 20%.The simulation of the whole structure of case shell on aero engine is carried out under the optimized welding process. The simulation results of the temperature field and the stress field were obtained. The maximum longitudinal residual tensile stress is 657 MPa, which mainly exists in the weld area and the near weld zone, which is also the risk area of the case shell. The maximum deformation amount is 0.0045, which is in accordance with the actual production requirements. The results of simulation provide theoretical basis for the actual production process of case shell on aero engine.