薄壁曲面结构多工艺复合加工表面完整性设计与工艺控制

Surface integrity of aero-engine key components plays an important role in service life and reliability. Compressor blades have thin-walled, wide-chord, and bent-bow features. They are typical weak-thin, thin-walled curved structures. The high-cycle fatigue failure is the mainstay of the blade. The control of surface integrity is extremely difficult and complex. Existing control methods are insufficient to ensure protection its service life and reliability. This project is based on titanium alloy compressor blades. Based on precision milling, precision shot peening and ultrasonic impact testing, the project investigates three-dimensional characterization and modeling of surface integrity of thin-walled curved structures, modeling and roughing of precision-milled surface integrity technology domains. The coupling optimization method of the finishing milling process reveals the law of surface integrity reconstruction of multi-process composite machining and the mechanism of high-cycle fatigue influence, establishes a surface integrity design method based on the service load and evolution rules under the environment, and proposes a multi-process composite machining under deformation constraints. Surface integrity robust process control strategies and methods, through processing and fatigue verification, provide new ideas and methods for surface integrity control of compressor blade parts. The research results are of great significance for ensuring efficient, precise and high-quality processing of compressor blade components, meeting service life and reliability development requirements, and providing technical support for guiding the development of anti-fatigue machining technologies for key components of aviation.

航空发动机关键构件表面完整性对服役寿命和可靠性具有重要作用。压气机叶片具有薄壁、宽弦、弯掠特征，属于典型的弱刚性薄壁曲面结构，叶身以高周疲劳失效为主，表面完整性控制极为困难和复杂，现有控制方法不足以保障其服役寿命和可靠性。本项目以钛合金压气机叶片为对象，基于精密铣削、精密喷丸和超声冲击等工艺试验，研究薄壁曲面结构表面完整性三维表征与建模、精密铣削表面完整性工艺域建模及粗-精铣工序耦合优化方法，揭示多工艺复合加工表面完整性重构规律及对高周疲劳影响机制，建立基于服役载荷与环境下演化规律的表面完整性设计方法，提出变形约束下多工艺复合加工表面完整性稳健性工艺控制策略和方法，通过加工与疲劳验证，为压气机叶片类零件表面完整性控制提供新思路和方法。研究成果对保证压气机叶片类零件高效、精密和优质加工，满足服役寿命和可靠性发展需求具有重要意义，同时对引导航空关键构件抗疲劳加工技术方向发展提供技术支撑。

项目以TC17钛合金叶片为对象，开展了薄壁曲面结构多工艺复合加工表面完整性设计与工艺控制研究，主要创新性工作有：(1)完成了精密铣削、喷丸强化、超声冲击强化、精密铣削-精密喷丸和精密铣削-超声冲击等典型工艺的表面完整性特征的参数化表征，在单点位置的显微硬度场、残余应力场和微观组织梯度等基础上，通过对薄壁曲面结构特征在u-v向分区和离散化处理，发展了薄壁曲面结构表面完整性u-v-d三维表征与建模方法。(2)建立了精铣参数对表面状态的影响规律，完成了600MPa叶片高周振动疲劳试验，获得了铣削表面完整性对疲劳寿命的影响规律，提出了基于寿命控制的精铣表面完整性工艺域建模方法，发明了基于损伤层控制的粗铣-半精铣-精铣多工序高效分层加工余量优化方法。(3)获得了精密铣削-精密喷丸和精密铣削-超声冲击加工过程中表面几何形貌特征和表层微结构微力学特征的重构规律，建立了TC17叶片在多工艺复合加工下表面完整性变化及其对高周振动疲劳的影响规律，揭示了对高周振动疲劳的影响机制，提出了依赖表面应力集中、考虑应变硬化和应力敏感性的叶片高周振动疲劳寿命预测模型。(4)研究了基于服役载荷的叶片振动疲劳失效的危险区域确定方法，基于TC17喷丸加工表面形貌、残余应力场和显微硬度场，提出了面向叶片失效危险区域的疲劳强度极限分布设计方法，以及残余应力场反推设计方法。(5)获得了TC17精密铣削、精密喷丸、超声冲击表面完整性基础数据，给出了考虑工艺能力的容差设计分配思路，提出了基于影响规律逆向解析的表面完整性特征的工艺参数域求解方法，以及基于加工变形约束的残余应力控制域反向计算方法，完成了典型薄壁叶片模拟件加工与高周振动疲劳验证。发表学术论文共25篇，授权发明专利5项;已初步应用于两机专项某发动机整体叶盘研制，有力支撑了整体叶盘数控精密铣削和精量化喷丸加工，推广应用于多个型号发动机复杂叶片高效铣削下表面完整性和变形控制;获国防科技进步奖二等奖1项，国防科技发明奖三等奖1项。