Research Of Ultrasonic Peening Forming Technology In Stiffened Plate

Stiffened plate is a common lightweight structure in engineering field,which can not only reduce the structure weight but also meet the structural strength and rigidity requirements.It is widely used in aerospace and other industrial fields.At present,when the stiffened plate is formed by mechanical shot peening technology,there is a problem that the bending deformation of ribbed plate is insufficient,and it is urgent to carry out research on the new shot peening forming process of stiffened plate.Ultrasonic peening technology,as a new kind of shot peening technology,can obtain larger and deeper residual compressive stress field than conventional mechanical shot peening technology,which can greatly increase the bending forming deformation of the stiffened plate.Meanwhile,the surface quality and the comprehensive performance after ultrasonic peening forming are superior to the traditional mechanical shot peening forming,which provides a new forming way for the stiffening plate.Based on the theoretical analysis of ultrasonic peening forming,the forming amount,forming characteristics and surface properties of stiffened plate were studied by using ultrasonic peening forming process.Besides the numerical simulation method was used to simulate the process of the ultrasonic peening forming.The main research work is as follows:1.The process of ultrasonic peening forming was analyzed theoretically.Based on the theory of Hertz collision,the deformation and stress of the plate during ultrasonic peening forming were studied.The size of pits,the depth of pits and the impact force before and after the elastic-plastic deformation were discussed and the residual stress along the depth direction after springback was also discussed.The generation process of residual compressive stress field and the relationship between the compressive residual stress field and the bending deformation of plate were analyzed,and the formulas for calculating the relationship between the radius of curvature and residual compressive stress are derived2.Ultrasonic peening forming tests were carried out on the non-reinforced wall panels.The effect of different peening forming track on the radius of curvature of the non-reinforced wall was analyzed.It was found that the spanwise peening trajectory could increase the degree of chordal deformation and reduce the degree of spanwise deformation of the wall panel so as to can improve the spherical deformation tendency of the wall panel.Based on the spanwise peening trajectory,ultrasonic peening forming tests was carried out on the stiffened plate.The effects of main peening parameters on the forming curvature radius of stiffened plate were studied and the basic bending deformation rule of the stiffened plate was analyzed.The results show that the ratio of spanwise curvature radius andchordwise curvature radius of stiffened plate is more than 11 times under the spanwise peening trajectory.At this time,the spanwise deformation of the stiffened plate is very small so as to can be neglected,the stiffened plate approximately render single curvature spanwise deformation featureAt the same time,the comparatively excellent forming parameters of the stiffened plate were obtained.3.The surface properties of the stiffened plate specimen by ultrasonic peening forming were studied.The effects of different peening parameters on the surface morphology,surface roughness,microhardness and residual stress field of the specimens were analyzed.The results show that,compared with the raw material specimen,the surface roughness and hardness of specimens by ultrasonic peening forming increases and the " √ " shape of residual compressive stress field is distributed in the surface layer of the material,which indicates that the ultrasonic peening forming technology is a new process that concentrates plastic forming and impact strengthening.At the same time,the comparatively excellent surface performance parameters of the stiffened plate were obtained.4.By means of dynamic simulation and static simulation,the numerical analysis model of stiffened plate by ultrasonic peening forming was established.The effects of different peening parameters on the radius of curvature and the residual stress field of the stiffened plate were studied by using 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 reliability of the finite element model and provides theoretical and data references for the development of ultrasonic peening forming process of large deformation wing panel.