基于振动疲劳耦合分析的含裂纹结构寿命预测

It is reported that the complex vibration and structural fatigue caused by the vibration are greatly increasing in the fields of aviation and aerospace in recently years, which endangered the safety and reliability of the aircraft's structure seriously. This project starting from the coupling analysis of structural vibration fatigue, testing of structural vibration fatigue is to be employed to study the prediction method of the fatigue life for cracked structures. Firstly, based on the continuous dynamics, tribology and theory of energy dissipation, it is to establish the stiffness model which is changed with vibration magnitude, damping model of energy dissipation and structural cracked model, and to form a dynamical coupling analytical model of cracked structures. Then, the nonlinear mechanism of structural dynamics and fatigue crack growth that caused by the contacting of crack interface is to be revealed. Thereafter, based on the calculation method of fatigue crack growth, the integrating strategy of coupling analysis and life prediction is to be studied together with the optimization technology. And a whole prediction method for vibration fatigue damage of cracked structures is going to be proposed. Finally, it is to innovate the experimental method of vibration fatigue for cracked structures. After that, a large number of testing for typical structure is to be done to discovery the dynamical nature of vibration fatigue coupling, and a serials of repeated modal experiments and vibration fatigue testing and case studies are going to be done for some typical structures so as to verify the reasonable of the theoretical analysis and prediction model. It could be expected that the research results will enrich and develop the vibration fatigue prediction method furthermore, and could provide a new theory for the vibration fatigue design of aircraft structures.

近年来，航空航天领域内复杂振动及其引致的结构疲劳问题剧增，严重危及飞行器的安全可靠性。本项目拟从结构振动疲劳耦合分析入手，借助结构振动疲劳试验分析，着力研究含裂纹结构的疲劳寿命预测方法。首先，基于连续介质动力学、摩擦学和能量耗散理论，建立随振幅变化的刚度模型、能量耗散阻尼模型和结构裂纹模型，联合构造含裂纹结构耦合动力学模型；在此基础上，揭示裂纹界面间接触引发的结构动力学与疲劳裂纹扩展非线性机制。然后，基于疲劳裂纹扩展计算方法，协同优化技术实现耦合分析与寿命预测的有效融合，创造一套完整的含裂纹结构寿命预测技术。最后，依托典型试验件的动力学与疲劳试验分析，从动态断裂层面探索振动疲劳耦合的动力学本质；同时，通过反复的结构振动模态测试、结构疲劳寿命实验与数值仿真计算，验证耦合理论与预测模型的合理性。研究成果有望推动含裂纹结构振动疲劳寿命预测方法的新发展，并形成飞行器结构抗振动疲劳设计技术的新理论。

随着动力机械的发展，结构零部件的振动疲劳现象日益增多，成为制约机械发展的关键问题。因此，项目组对含裂纹构件的振动疲劳耦合理论、基于振动特性的裂纹识别技术、复杂结构件的抗振动疲劳设计方法等问题进行了深入的研究。基于断裂力学和能量原理，推导了结构裂纹局部柔度矩阵，研究了裂纹呼吸行为，建立了呼吸式裂纹梁的非线性刚度和摩擦阻尼模型。从缺口梁和加筋构件的振动疲劳试验入手，研究了频带激励共振疲劳试验技术，揭示了结构振动与裂纹扩展的耦合行为，建立了基于模态频率的缺口梁裂纹扩展速率模型和剩余寿命预测模型，提出了考虑裂纹扩展的振动疲劳寿命计算方法，提高了振动疲劳寿命预测精度。基于局部柔度理论和Galerkin方法，推导了含裂纹梁的模态频率方程和非线性单自由度模型，研究了裂纹萌生和裂纹扩展对弹性梁模态频率与振动响应的作用机制。结合裂纹扩展方程，提出了振动疲劳耦合计算同步分析法，研究了弹性梁的裂纹扩展行为，揭示了裂纹呼吸行为引致的非线性刚度和摩擦阻尼对振动疲劳裂纹扩展的影响。在此基础上，提出了考虑裂纹效应的弹性板动力学建模策略，推导了弹性板振动疲劳耦合模型，研究了含裂纹弹性板的非线性响应。利用振动行为与裂纹扩展的耦合关系，提出了基于模态频率误差函数的含裂纹构件损伤识别方法，研究了基于模态应变能的含裂纹构件损伤识别技术。围绕复杂结构的抗振动疲劳动力学设计，建立了齿轮机构的啮合刚度模型，研究了裂纹对齿轮副模态频率的影响；开发了螺栓连接结构的参数化模型，研究了不确定参数对螺栓连接结构模态频率的影响；推导了功能梯度圆柱薄壳的动力学模型，揭示了热环境对功能梯度圆柱壳模态频率的影响。本项目完成了预设的研究任务和预期的研究目标，总共发表学术论文二十五篇，出版专著一部，实用新型专利授权三项，培养硕士生八名（已毕业六名），实现了振动疲劳理论、计算与试验技术的发展，对于推动结构抗振动疲劳设计技术的进步与工程应用具有重要的意义。