铝合金薄板超声辅助渐进成形工艺及其形性协同控制机理研究

Flexible sheet forming technologies, oriented to complex thin-wall metallic components featured with high performance, low-batch and short delivery time, are the key approach to advance the manufacturing level and capacity of aerospace industry. Considering the shortage of current incremental sheet forming technology in terms of low part accuracy and poor surface finish, a novel ultrasonic-assisted incremental sheet forming technology is proposed. First, both analytical and computational models in multi-physics and multiscale for the plastic deformation process will be developed. The effects of ultrasonic vibration on plastic deformation and mechanism of material flow during the forming process will also be investigated. Then, the effects of ultrasonic vibration and process parameters on forming force, transient status of stress and strain and residual stress will be studied. The generation and evolution rule of crystal dislocation, sub-grain, low-angle boundary will be explored and strategies to regulate the microstructure will also be presented. After this, the mapping relation between process parameters,ultrasonic vibration, microstructure and mechanical properties of the formed parts in ultrasonic-assisted forming process will be established and the optimal process window will also be provided. Through this research, a new sheet forming strategy is proposed which is expected to solve the key scientific problems regarding to the dissatisfied surface finish and geometric accuracy in the current sheet forming process. This will also significantly promote both the basic theory and process capability of incremental sheet forming technology.

面向高性能、变批量、交货期短的复杂形状薄壁板材件柔性成形技术，是提升航空航天工业制造水平和研发能力的重要途径。针对现有渐进成形技术成形精度差及易褶皱、破裂等关键质量问题，本项目提出一种超声辅助渐进成形新工艺理论和方法。首先建立超声振动下材料塑性成形过程多物理量、多尺度解析与数值计算模型，探究超声振动对材料塑性变形及流变驱动影响的微观机理；进而研究超声振动与工艺参数对成形力、瞬态应变及残余应力的影响机制，实现对宏观变形精度的有效控制；揭示超声场下晶体位错、亚结构、小角度晶界等现象的产生与演变规律，探索微观组织及材料性能的调控机制；构建超声振动渐进成形工艺参数-超声场-材料组织结构-物理力学性能之间的映射关系，建立多目标优化工艺窗口。通过上述研究，提供一种新的薄壁板材成形方法，解决当前渐进成形中表面质量、精度及成形能力不足所涉及的关键科学问题，显著提升板材渐进成形技术的基础理论及工艺能力。

航空航天等领域对高性能、轻量化、变批量复杂形状薄壁板材构件的交货期和产品质量要求不断提高，使现有的成形技术受到挑战。本项目在传统渐进成形工艺的基础上提出一种超声辅助渐进成形新工艺方法，探索了超声振动对金属板材渐进成形中塑性变形、微观组织结构及宏观物理力学性能的影响及作用机理，基于晶体塑性理论建立了描述金属塑性变形过程中应力-应变关系的理论模型，通过调整位错密度演化和热激活过程体现了超声施加后的声软化效应。建立了表面材料塑性流动模型，分析不同工艺参数的影响作用，揭示了表面材料流动变形机理。探明了超声辅助渐进成形塑性软化机理，并获得不同机理所占比例，揭示了超声对板材渐进成形中材料的位错滑移特征、微观组织演变及成形件物理力学性能的影响机理。考虑超声振动引入的高频脉冲摩擦接触状态，探明超声振动在渐进成形工艺中表面效应的作用效果，分析了表面硬度以及表面形貌的变化规律。研究了不同振幅、不同工艺参数下成形力、摩擦力的传递规律，分析了渐进成形工件在超声作用下成形极限、板材厚度、几何精度、表面残余应力以及拉伸断口的影响。最后，开展了渐进成形能耗分析以及工艺参数优化，实现了对成形件的形性协同控制。该研究为关键金属薄壁板材零件的柔性渐进成形制造提供了理论、方法和技术保障。. 项目研究成果在JCP、IJMS、JMR&T、IJAMT等本领域权威期刊以及学术会议发表论文19篇，其中SCI论文13 篇；申请相关发明专利15项，其中授权5项。