服役载荷诱导下滚压校正应变-应力场演变机制及其对航空结构件疲劳寿命影响

Aluminum alloy aeronautical components often have seriously distortion problems due to various factors in the numerical control machining processes. Rolling correction is an effective means to eliminate manufacturing errors of components to meet the requirement of assembly step. However, the service load of the aircraft is extremely complicated, and the research on the service performance of the corrected components is lacking, which seriously affects the aviation safety. Therefore, the evolution mechanism of rolling strain-stress field and its influence on dimensional stability and fatigue life of aeronautical components under service load are studied. Firstly, the forming mechanism for rolling strain-stress field of aluminium alloy components are studied. The coupling influence of rolling strain-stress field and initial stress as well as machining stress are revealed. And a representation method of the rolling stress filed through characteristic parameters is established. Furthermore, the characteristics of dynamic recovery and stress relaxation under service load are studied. The relationship between the rolling stress field and dimensional stability is clarified, and the coupling evolution mechanism of strain-stress field and dimensional accuracy is revealed. Then, the coupling mechanism of rolling stress field and fatigue life is studied, and the fatigue failure mechanism of rolling-corrected components are revealed. Finally, with the goal of high dimensional stability and fatigue life, an active control strategy of rolling stress field is established. The research results will help improve the reliability of aeronautical components, and provide basic theory and method support for the rolling correction of new generation fighter and large aircraft.

铝合金航空结构件在数控加工过程中受到多种因素影响往往存在严重的铣削变形问题，滚压校正是改善结构件制造精度以满足装配需求的有效手段，但航空器服役载荷极其复杂，校正工件服役性能研究匮乏，严重影响航空安全。因此，开展服役载荷诱导下的航空结构件滚压校正应变-应力场演变机制及其对尺寸稳定性、疲劳寿命影响研究。首先，研究铝合金结构件滚压应变-应力场形成机理及其与毛坯应力、加工应力耦合作用机制，建立滚压应力场特征参量表征体系；进而研究服役载荷诱导下滚压塑性变形动态回复及应力松弛特性，阐明校正工件内应力场与尺寸稳定性之间的关系，揭示应变-应力场与尺寸精度耦合演变机制；然后研究缩尺结构件滚压校正应力场对疲劳寿命影响，揭示滚压校正结构件疲劳破坏机制；最后以高尺寸稳定性及疲劳寿命为目标，建立滚压应力场主动调控策略。研究成果有助于提高航空结构件服役可靠性，为新一代战机及大飞机结构件滚压校正提供基础理论及方法支撑。

铝合金航空结构件在数控加工过程中受到多种因素影响往往存在严重的铣削变形问题，滚压校正是改善结构件制造精度以满足装配需求的有效手段，但航空器服役载荷极其复杂，校正工件服役性能研究匮乏，严重影响航空安全。因此，提出服役载荷诱导下滚压校正应变-应力场演变机制及其对航空结构件疲劳寿命影响研究。.首先，研究了滚压校正过程中材料微观物理力学行为。通过薄壁结构双侧滚压试验，获得了滚压对材料表面完整性影响规律，揭示了滚压应力产生机制。进行了滚压过程数值仿真研究，发现滚压引入的微塑性变形是实现结构件变形校正的决定因素。.其次，开展了初始应力状态对薄壁件滚压的影响规律研究。通过对比分析无初始应力、仅毛坯应力、毛坯应力与加工应力耦合三种初始应力状态下的滚压应力场和零件宏观变形，指出毛坯应力对滚压变形的影响程度约为7.8%，在此基础上加工应力的影响约为9.8%。通过滚压前后应力-应变演变，分析了初始应力与滚压应力场的耦合作用机制。.然后，开展温度载荷对滚压校正结构件影响研究，结果表明滚压应力在温度载荷作用下会发生应力松弛，但不会对校正结构件的宏观变形产生影响，进而揭示了温度载荷对滚压校正结构件质量稳定性的影响机制。设计搭建了航空梁类结构件力载荷试验机，开展了外力载荷作用下的结构件稳定性试验，研究发现校正结构件在外载荷作用下具有较好的稳定性。.最后，综合应用ABAQUS、FE-SAFE软件，搭建了大型结构件加工变形-滚压校正-疲劳分析有限元仿真环境，获得了不同滚压校正工艺下的结构件疲劳性能，揭示了滚压校正应力场对结构件疲劳寿命的影响机制。.项目围绕滚压校正-服役跨过程中的应变、应力、变形等影响结构件服役尺寸稳定性、疲劳寿命的关键因素开展了较为系统的研究，获得了滚压校正结构件服役过程中的关键特性，为滚压校正推广应用提供理论及方法支撑。项目执行期间发表高水平论文2篇，授权发明专利3项，发表会议论文2篇，另有1篇论文已录用、3篇已投稿，3项发明专利已提交。