Study On Shot Peening Strengthening Method Of Corrosion Damaged Civil Aircraft Structural Parts

Corrosion damage often occurs in civil aircraft structural parts because they works inspecial condition. In order to extend the life of the parts, shot peening is necessary. Complexsurfaces like inclined and circular surface will be formed after the damaged parts were clearedup and polished. It is of vital importance to investigate the shot peening method for such partswith complex surface topography.The research subject is supported by Collaborative Fund of National Natural ScienceFoundation of China and Civil Aviation Administration of China (61179051). In this paper,corrosion damaged and polished civil aircraft structural parts were the object of research. Thefinite element model of the shot peening of parts was created and simulation was carried out.The influence of process parameters, shot peening mode and surface morphology of the parton surface residual stress field and roughness was obtained. The result was verified byexperiment at last. In this paper, the following works were carried out:Firstly, the evolution of shot peening finite model was analyzed. Based on the surfacemorphology of polished parts, abstractive geometric models were created and zoned,mechanical model of the shots and parts were put forward, constraint and contact model andload were exerted.Secondly, random distribution model of shots and mathematical model of coveragecalculation based on set were put forward. The influence of shot peening process parametersand surface morphology on coverage and number of shots needed for full coverage wasstudied. Simplified model of multiple analysis step was brought about. Results show that thecalculation method in this paper is more accurate than the method based on strain. The modelin which shots were randomly distributed is closer to reality compared with the one in whichshots were regularly distributed.Thirdly, simulation of shot peening process with different process parameter, shotpeening mode and surface morphology was carried out. The influence of shot velocity, shotdiameter, coverage, shot peening mode, radius of transition circular surface and slopeinclination of transition ramp on residual stress field and roughness was studied. Results showthat increase of shot velocity and coverage will lead to increase of surface residual stress,maximum compressive residual stress, depth of residual compressive stress layer androughness. Increase of slope inclination of transition ramp will cause reduction of its surfaceresidual stress. Application of fixed-angle shot peening mode will lead to a larger surfaceresidual stress and roughness on transition ramp. Lastly, automated transformation of existing simple equipment for shot peening wascarried out. Frequency of shot peening to reach full coverage using different shot peeningmethod was determined. Shot peening experiment of parts with different surface morphologyusing different process parameter and peening mode was carried out. Surface residual stressand roughness of the shot peened part was measured. Results show that the variation ofsurface residual stress and roughness is consistent with that obtained by simulation.