Research Of Stressing Ultrasonic Peening Forming Technology In Stiffened Plate

Stiffened panels have many advantages,such as good structural integrity,good sealing performance,small number of parts,small amount of connection and assembly,strong stiffness which is a common lightweight structures in engineering field and is widely used in aerospace.when the stiffened plate is formed by mechanical shot peening technology,there is a problem that it can not meet the complex hyperbolic shape and the deformation of the area is insufficient.It is urgent to develop the new shot peening process of stiffened plate.Ultrasonic shot peening(UPF),as a new kind of shot peening technology,can get a larger and deeper residual compressive field than conventional shot peening,which can greatly increase the bending forming deformation of the stiffened plate and improve the comprehensive properties of materials after forming.however,UPF has prone to occur spherical deformation and the deformation of the area is insufficient in free state.The stress shot peening can reduce the spherical deformation trend and increase the forming deformation.In this study,combined with the forming advantages of UPF and stress shot peening,the forming process of stress ultrasonic shot peening on stiffened plate was studied and tested.the main research work is as follows:1.Based on the theory of Hertz collision,the deformation and stress of the sheet in the ultrasonic shot peening process are studied.The size of pit diameter,pit depth,impact force,residual stress before and after springback is studied.The generation process of residual stress in free state and stress state,and the relationship between the bending deformation and the residual stress field of the plate are analyzed.2.the influence of the non-stiffened plate and stiffened plate on the radius of curvature of spanwise and chordwise were studied in spanwise shot peening;Secondly,the influence of pre bending radius of curvature on the radius of curvature of stiffened plate were studied;Finally,study the effects of shot velocity,offset distance,peening areas and other parameters on the radius of curvature of spanwise and chordwise in the free state and the stress rate,Ry/Rx was introduced to compare the influence of the shot peening process parameters under prestress on reducing the spherical deformation trend.3.On the basis of the SUPF test,studied the surface performance of forming samples.Analyzed the effects of different process parameters on surface topography,surface roughness,microhardness and residual stress field.4.the numerical analysis model of stiffened plate bystress ultrasonic peening forming was established by ABAQUS software.The effects of different peening parameters on the radius of curvature and the residual stress field of the stiffened plate were studied finite element method.The results of numerical analysis are compared with the experimental results.The data error of the two results is very small,which verifies the accuracy of the finite element model and provides theoretical and technological data references for the development of stress ultrasonic peening forming process of large deformation wing panel.