Experimental And Numerical Research Of Stressing Ultrasonic Peening Forming On Thin Plate

Ultrasonic peen forming(UPF)technology has widely application prospect in many fields of aerospace,national defense,ship and automotive,construction for its many advantages such as simple equipment,easy operation,non-pollution,low energy consumption and good comprehensive performance after forming,and so on.However,the ultrasonic peen forming is also prone to spherical deformation in free state,and the actual needs of the parts shape is not always required to be spherical.It is very difficult to eliminate or change in the event of spherical deformation.Stress peen forming can not only improve the curvature of components,but also reduce the spherical deformation tendency to a certain extent.In this study,combined with UPF and stress peen forming to systematic investigate the forming mechanism,forming characteristics and surface performance by stressing ultrasonic peen forming(SUPF)based on the theory analysis of UPF and used numerical analysis method simulated the process of SUPF,the main research work is as follows:(1)The process of ultrasonic peen forming was analyzed theoretically.Based on the theory of collision,the mechanical state of the sheet was analyzed.The critical velocity of the impactor,the diameter and depth of the pit,the magnitude of the impact force and the distribution of the residual stress during elastic deformation and elastic-plastic deformation were deduced.The calculation formula of residual stress in prestressed state was deduced and the radius of curvature of the free state and prestress state was compared.(2)Experimental study on 2024-T351 aluminum alloy thin plate by SUPF.The effects of pre-bending curvature,forming trajectory,pin speed,offset distance and plate thickness on the radius of forming curvature are analyzed.The results show that SUPF can greatly increase spanwise(the direction of prebending)forming curvature and decrease chordwise forming curvature.With the increase of the pre-bending curvature,the effect of increase and decrease is gradually increasing,which greatly reduces the trend of spherical deformation.(3)The surface layer properties of the samples by SUPF were studied.The effects of different process parameters on the surface morphology,surface roughness,microhardness and residual stress field were analyzed.Compared with the free state,the surface roughness value of the forming part slightly reduced,the surface hardness increased,and the surface layer of the material produced a larger and deeper residual compressive stress field showing a typical “?”shape distribution in the prestressed state,which indicates that SUPF can achieve better surface layer properties.(4)The numerical analysis model of SUPF was established by using ABAQUS software.The influence of different parameters on the forming curvature and residual stress field of the plate was analyzed.Compared numerical results with experimental results,and the data error of the two was very small,which verifies the reliability of the model of SUPF and provides the theory and data reference for the development of UPF process.