飞机受损件在线激光喷丸修复方法及机理研究

In view of the currently common used off-line repair methods that disassembled the damaged component firstly and then strengthening by shot peening to extend the fatigue life of the repaired component of the aircraft, propose a kind of online repair method by laser peening based on surface nano-crystallization, and study the laser energy absorption coating and coating materials to meet the demands of economy and speediness of the repairing processes, and improve the aviation safety of the repaired component. Aiming at the damaged aircraft components of the rib or beam with notch after grinding, combining with the finite element numerical simulation and experimental research method, explore the influence of processing parameters, such as the laser incident angles, beam energy, spot size, etc., on the residual stress field and grain structure during laser shot peening; establish the interactive influence of the stress strengthening (the residual stress field) and structure strengthening (grain size and grain distribution) on fatigue life of the peened components; point out the interactive strengthening mechanisms, and obtain the optimal processing parameter of laser peening. Therefore, to obtain the optimal fatigue performance of the repaired aircraft components during the actual flight. Develop a portable CNC laser peening experimental device to realize the online laser peening repair of the damaged aircraft component. The research of this project has both the important theoretical value and practical significant on the development of laser peening and repair of aircraft damaged component.

针对当前对各类飞机受损件常采取的先拆卸再喷丸强化以延长其疲劳寿命的离线修复方法，项目首次提出一种可适用于在线修复并可以实现表面纳米化的激光喷丸强化方法，并对激光能量吸收涂层及涂层材料进行研究以满足飞机受损件经济、快捷的修复要求及有效提高修复后构件的航空安全性。针对经打磨后带缺口形貌的梁肋类损伤件，采用有限元数值模拟及试验研究相结合的方法，获得激光入射角度、光束能量、光斑尺寸等喷丸工艺参数对构件残余应力场和晶粒结构的影响规律；研究应力强化（残余应力场）及组织强化（晶粒尺寸、晶粒分布情况）对受喷构件疲劳寿命的交互影响，探索出在线激光喷丸复合强化机理，并获得优化的激光喷丸工艺参数，使得经损伤修复后的构件在实际服役时疲劳性能最优；研制出相应的便携式数控激光喷丸试验装置，以实现飞机受损件的在线喷丸修复。本项目的研究对于激光喷丸工艺的发展及飞机受损件的修复具有重要的理论价值及实践意义。

老龄飞机结构件腐蚀损伤问题严重降低结构件强度和疲劳寿命，威胁飞机飞行安全。因此需要对腐蚀损伤结构件进行表面强化以获得足够强度和疲劳寿命。为避免离线修理造成的拆装成本及时间成本，项目提出采用激光喷丸工艺实现飞机受损件在线修复新方法，并对激光喷丸强化的基本方法与强化效果展开了研究。构建出激光喷丸在线修复装置，首次提出采用环氧树脂约束层、单面胶带和双面胶带吸收层作为激光喷丸在线修复的复合覆盖层。建立了BP神经网络结合遗传算法的优化模型，实现了激光喷丸覆盖层材料参数的分析与优化。构建了7075-T6铝合金激光喷丸有限元模型，解决冲击波压力模型、网格划分等问题，实现激光喷丸强化过程的模拟研究。分析了激光喷丸材料表层残余应力分布特点，获得了激光喷丸参数、试样表面形状（曲率半径及平均曲率）对残余应力分布的影响规律。基于试验研究，获得激光喷丸参数对7075-T6铝合金激光喷丸后冲击区域完整性的影响规律。首次提出用于描述激光喷丸过程中出现的残余应力洞现象的量化指标，并分析了激光喷丸参数对于该量化指标的影响规律，探索了残余应力洞优化和控制方法。分析了不同激光喷丸参数下试样疲劳寿命分布情况，为获得最佳疲劳寿命提供参数选择指导意见。首次分析了边缘效应对激光喷丸的影响机理，获得不同激光喷丸参数下边缘效应对残余应力分布的影响规律。本项目的完成，实现了飞机受损件在线激光喷丸修理工艺，对推动飞机结构件维修、强化等技术的发展和激光喷丸强化理论的完善具有重大的科学意义和应用价值。