Numerical Simulation Of Welding Stress And Deformation Of Aeroengine Afterburner Lobed Mixer

In the development trend of aeroengine integration and lightweight,welding technology has been widely used in the field of aeroengine manufacturing.However,due to the complexity of the aeroengine structure and the welding process,the industry people pay great attention to the control method of post-weld residual stress and deformation of aeroengine.As an important component in the afterburner of aeroengine,the lobed mixer has high requirement of post-weld residual stress and deformation in actual production process.In this paper,the dynamic evolution process of welding temperature field,stress field and deformation field of lobed mixer are investigated by the method of the combination of experimental research and numerical simulation,and the welding process of lobed mixer is optimized from different angles.The results provide theoretical support to control the post-weld residual stress and deformation of lobed mixer for the actual welding process.Firstly,the tungsten inert gas(TIG)welding experiment for 2mm thick GH3044 nickel-based superalloy plate was designed and conducted.Comprehensive analysis was made on the influences of different welding process parameters on macro morphology,tensile strength and microhardness.The results show that the welding quality is remarkably improved under the welding parameters with welding current of 95 A,welding voltage of 10 V,welding speed of 3.2mm/s.In addition,the TIG butt welding process of plate was simulated by the thermal elastoplastic finite element method(TEFEM),the results show that the simulated weld cross-section morphology and post-weld residual stress are good agree with the experiment,which verifies the accuracy of the finite element model.Next,the temperature field,stress field and deformation field of TIG welding process of lobed mixer are calculated by the TEFEM according to the actual condition.The results show that the shape of temperature field of lobed mixer is ellipsoid,and it shows obvious trailing phenomenon.The peak stress of the lobed mixer increases continuously while the maximum deformation increases first and then decreases during the welding period.In addition,the clamp release process can reduce the stress effectively near the weld and the area which is constrained by the clamp,but the deformation of the lobed mixer also increases after the clamp is released.In the final state,there is significant inward deformation occurred at the entrance of the inner channel,and large upward deformation occurred at the exit of the outer channel of the lobed mixer.Then,the post-weld residual stress and deformation of the lobed mixer were calculated by the inherent strain finite element method(ISFEM),and the calculation results were compared with the TEFEM.It is found that the distribution characteristics of post-weld stress and deformation of the lobed mixer obtained by the two methods are similar,and the peak stress obtained by the two methods is also very close,but the value of final deformation obtained by the ISFEM is quite different from that obtained by the TEFEM.In addition,the calculation efficiency of the ISFEM is greatly better than that of the TEFEM.Finally,the welding process of the lobed mixer was optimized by the TEFEM.The results show that the post-weld stress and deformation of the lobed mixer can be reduced by the clamp release sequence of release the upper plate first,then the lower fixed plate and the lobed support plate.The welding direction scheme from the lobed mixer exit to the lobed mixer entrance along the seam can also better control the post-weld stress and deformation of the lobed mixer.Meanwhile,using single-seam symmetrical welding can reduce the peak stress and maximum deformation,lower the variance of average weld deformation,and ensure the assembly accuracy at the entrance of the lobed mixer,which is a better welding sequence process scheme.In addition,the electron beam welding(EBW)instead of TIG welding cannot reduce post-weld residual stress of lobed mixer,but it can obviously improve the welding efficiency and reduce the welding deformation.Therefore,it still has great application value in actual welding.The research of this paper reveals the evolution law of the temperature field,stress field and deformation field during the welding process of the lobed mixer,explores the method of optimizing its welding process.Moreover,the study provides a theoretical basis for reducing the stress and deformation of the lobed mixer in actual welding process.