壁板零件喷丸渐进成形中应力场演化机制及增量预测方法

Peen forming processing is the preferred choice to obtain a complex contour of large integral panel. The panel contour incrementally approaches to a target in the peening process. Difference of the deforming history of local contour constitutes barriers to peening stress total prediction, panel deformation prediction and peening process control. This project aims to the mechanism and prediction method of stress and strain evolution with panel contour incrementally varying in peening process. By studying the description method of peening stress and strain evolution, and the influences of material states involving material hardening, residual stress, dimple topography and so forth on shot impacting effects, measuring parameters for the material states are determined based on micromechanics, elastic-plastic theory and fractal theory, then obtaining equivalent homogenization methods for the nonuniform material states. By studying the coupling influences of the material states on shot impacting effects, the contribution parameters of the material states on the shot impacting effects are obtained based on nonlinear feedback and Lypanov methods. Then an incrementally calculation method for peening stress and strain based on current material states and peening results under specific constraints is proposed. Final, the peening deformations of panels can be precisely predicted with the stress calculation method and equivalent simulation of panel deformation, which will help to precisely control peen forming processing on theory and technology.

喷丸成形是大型整体类壁板零件复杂型面成形的首选工艺，成形过程中零件型面随喷丸应力场演化趋于目标型面，零件局部变形历程差异造成喷丸应力场难以全局预测，导致零件变形预测乃至喷丸成形精确控制存在困难。本项目探索喷丸成形中零件型面渐进变化的变形条件下应力应变场的演化机制及预测方法。在研究喷丸应力应变场演化信息描述方法以及包括材料硬化、残余应力及凹坑形貌等在内的靶材状态对弹丸撞击响应的独立及耦合影响规律的基础上，基于细观力学、弹塑性理论及分形理论确定靶材各状态的量化表征参数，建立靶材各非均匀状态的等效均匀化模型；基于非线性反馈及李雅普诺夫分析等方法解耦或弱化靶材各状态间的耦合性，获得靶材各状态对弹丸撞击效果的贡献函数及综合作用模型。形成基于当前靶材状态并利用典型喷丸演化数据的后续喷丸应力应变场的增量计算模型，实现基于零件喷丸成形等效模拟的零件喷丸变形精确预测，为喷丸成形精确控制提供理论及技术支持。

喷丸成形是大型整体类壁板零件复杂型面成形的首选工艺，成形过程中零件型面随喷丸应力场演化趋于目标型面，零件局部变形历程差异造成喷丸应力场难以全局预测，导致零件变形预测乃至喷丸成形精确控制存在困难。针对壁板类零件喷丸成形过程中零件型面渐进变化导致喷丸应力场及零件变形难以预测的问题，本项目探明了喷丸成形中零件型面渐进变化的变形条件下应力应变场的演化机制并建立了其预测方法。通过研究喷丸成形零件型面渐进变化的变形条件下弹丸流撞击应力应变场分布形式、深度、幅值等的变化特点，针对各类喷丸应力应变场演化模式，建立了满足等效、逼近、简便等要求的喷丸条件及喷丸应力应变场的数学描述方法；针对壁板类零件喷丸成形，利用多种喷丸工艺分析及试验，建立了典型固定约束条件下喷丸参数与喷丸应力应变场之间的映射关系；揭示了零件局部区域靶材残余应力、硬化状态及凹坑形貌等靶材状态组合对后续弹丸撞击响应的独立影响及耦合作用，进而建立了靶材非均匀状态的等效均匀化方法；揭示了零件型面渐进变化对后续弹丸撞击响应的影响规律，形成了喷丸应力应变场演化分析理论；基于当前靶材状态与典型喷丸靶材状态之间的关联途径，建立了利用典型喷丸演化数据的后续喷丸应力应变场的增量计算模型；利用本项目研究成果，实现了飞机机翼壁板零件喷丸变形的精确预测及试验验证。本项目研究为壁板类零件喷丸成形工艺参数的预先规划、验证与优化提供理论和技术支持，对保证其喷丸工艺方案安全可行、提高零件成形精度及可互换性具有重要的理论和应用价值。