Numerical simulation research on welded residual stress and distortion of aero-engine afterburner lobe mixer with different welding sequences

Abstract

Most thin-walled parts of aero-engines with intricate surfaces, such as lobe mixer, are welded using tungsten inert gas (TIG), which will certainly induce stress and distortion, causing a serious influence on assembly accuracy. The objective of this study was to establish a finite element model to optimize TIG wire filler welding sequence for an aero-engine lobe mixer composed of GH3044 nickel–based superalloy at the thickness of 2 mm. A new method for optimizing residual stress and distortion in the welding of large-size components was proposed. We carried out a 2-mm-thickness plate TIG wire filler welding experiment to obtain the ideal process parameters and validate the heat source model and thermal boundary condition, and also designed a set of frock clamp. The stress and distortion of the lobed mixer were analyzed under various welding sequences based on the established finite element model. The results showed that the peak residual stress difference of the lobe mixer is smaller using such a fixture. But different welding sequences affected the stress uniformity throughout the structural member. Only the symmetrical welding of single weld was a better process, with a peak distortion of 0.54 mm and more uniform stress distribution.