Advances in control of unequal deformation by locally loading and theories related to precision plastic forming
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Research on control of unequal deformation and theories related to precision plastic forming is not only one of the key and challenging subjects in frontiers of advanced plastic forming,but also the urgently needs of the development of aero-space high technology.In this project,beginning with realizing in-plane bending under local unequal loading,which is difficult to form using conventional methods,the theory and technology is developed for realizing precision plastic forming processes by controlling unequal deformation,which provides an important inspiration for solving difficult problems of forming and manufacturing large-scale complex integral components of titanium alloy.Numerical models are established for predicting wrinkling onset,springback,cross section distortion,and for analyzing and determining forming limit in NC thin-walled tube bending processes,and methods are developed for process simulation and optimization design;effect laws of key factors on the process are revealed.3D-FE process simulation models are established for multi-pass conventional spinning,curved thin-walled shell spinning,power spinning with hoop inner rib.Methods are proposed for solving complex forming defects produced by unequal deformation and roller-trace optimization design.The effects of temperature and velocity and their controls under coupled thermo-mechanical effects with multi-factors and multi-physical fields are solved in isothermal extrusion processes for large-size aluminium profiles,which are important and difficult problems to be urgently solved in the research and development of advanced isothermal extrusion theory and technology.3D-FE simulation models are developed for complex cold ring rolling process,and an analytic-numerical method for ascertaining the critical friction coefficient for stable rolling process;three kinds of plastic deformation behaviors during cold ring rolling process and effects of multi-factors on the process are found;a robust integration algorithm for implementing rate dependent crystal plasticity into explicit FEM are proposed and Macro-deformation are described by Micro-reflect in cold ring rolling process.The achievements of this study are of significance to developing advanced theory and technology of precision plastic forming for thin-walled and large-scale complex components.