航空发动机机匣电子束焊接变形模拟分析与优化

为了对焊接变形进行预测与控制，建立了焊接接头的弹塑性有限元模型，并对电子束热源模型进行了校核，获得了接头焊接位置的塑性应变区域大小；建立了风扇叶片机匣3D壳单元有限元模型，并采用固有应变法对机匣焊接变形进行了模拟计算，获取了焊接过程的变形分布，通过实测机匣变形量并与仿真结果进行对标，验证了模型的准确性；通过对风扇叶片机匣焊接顺序以及焊接熔池宽度等工艺参数的优化，获得了控制风扇叶片机匣焊后变形的最优方案。结果表明:模拟与实测的平均变形误差仅10.3%，基于固有应变法的中心面3D壳单元有限元模型适用于大型复杂薄壁件的电子束焊接变形预测，该方法已得到应用；风扇叶片机匣焊接熔池宽度的优化能够有效控制焊后变形，焊缝上熔池宽度降低为2.7 mm，焊后平均径向变形量降低30%，能够明显降低机匣径向收缩变形，焊接顺序的优化对变形控制效果较差。 

Simulation analysis and optimization of electron beam welding deformation of aero-engine casing

In order to predict and control the welding deformation, the elastoplastic finite element model of the welded joint was established, and heat source model of the electron beam was checked to obtain the size of the plastic strain area of the welded joint. Then, the 3D shell element finite element model of the fan blade casing was established, and the welding deformation of the casing was simulated by using the inherent strain method, so as to obtain the deformation distribution during the welding process. The accuracy of the model was verified by measuring the deformation of the casing and comparing with the simulation results. Finally, by optimizing the welding sequence and welding pool width, the optimal scheme of controlling welding deformation was obtained through simulation calculation. The results showed that the average deformation error between simulation and actual measurement was only 10.3%. The 3D shell element finite element model of the center plane based on the inherent strain method was suitable for the deformation prediction of electron beam welding of large and complex thin-walled parts. The width of the molten pool on the weld was reduced to 2.7 mm, and the average radial deformation after welding was reduced by 30%. Controlling the weld width can significantly reduce the radial shrinkage and deformation of the casing, but the optimization of welding sequence has poor effect on deformation control.