Theory And Prediction Of Aerospace Aluminum Alloy Arc-Shaped Frame Distortion Induced By Shot Peening

Shot peening is a surface strengthening method to significantly improve fatigue resistance of the peened part,which is widely used in surface treatment of arc-shaped aluminum alloy frame.The distortion of arc-shaped aluminum alloy frame in shot peening process is a serious issue in aviation industry.Focusing on distortion in shot peening of arc-shaped frame,a theoretical model that relating peening parameters to deformation of arc-shaped frame is established.And the method of parameter optimization of shot peening is discussed.The main methods and results are as follows:(1)The shot peening process of 7075-T651 aluminum alloy with multiple randomly distributed shots is simulated by the finite element code ABAQUS.The effects of different sets of peening parameters on shot peeing residual stress are studied.The simulation results show that the depth of the residual stress layer and maximum residual stress increase with shot peening pressure and incident angle.(2)The induced stresses are used to calculate the arc height of 7075-T651 aluminum alloy strip,which is compared with experimental results.Experimental results are in good agreement with the theoretical results,which certifies the validness of the induced stress given in this paper.(3)According to the theory of elastic mechanics,the mechanical model of stress and deformation of arc-shaped frame is introduced.Based on the model,the equations of induced stress and deformation are established,and the calculation of maximum bending deflection of the component is completed.The finite element model is adopted to validate the theoretical method.Results show that the theoretical method can predict the deformation of arc shaped frame after shot peening process under the condition of known induced stress and structure parameters.The characterization of deformation of different shot peening process for arc-shaped frame is studied.It is found that:(a)The deformation of arc-shaped frame increase with shot peening pressure and incident angle.(b)The arc-shaped frame under shot peening process on the web will shrink in the radial directions.(c)The arc-shaped frame under shot peening process on the rib will extend in the radial directions.(4)The shot peeing experiment was conducted to verify the correctness and effectiveness of the proposed theoretical model.The comparison between the theoretical results and experimental results shows that the theoretical model can predict the deformation of arc-shaped frame caused by shot peening within certain range.(5)Basing on the mechanical model of deformation of arc-shaped frame in shot peening process,an optimization method of shot peening parameters was established,and a set of shot peening parameters under engineering conditions is obtained.Experiments prove that using this set of shot peening parameters,the deformation of arc-shaped frame can meet the requirements of the test error,thus the effectiveness of parameter optimization has been verified.