振动激励下螺栓连接松动失效的摩擦学机理与控制研究

As important connecting pieces in mechanical equipment, the self-loosening failure of fasteners has become an important factor restricting the development of high-security, high-reliability and long-life for mechanical joining structures. This study mainly focuses on the key and common issues of self-loosening failure of bolted joints in mechanical joining system, which will be investigated systematically by fretting tribological theory. Through simulating the loosening process of bolted joints and changing the additional excitation (loading direction, amplitude and frequency), preload value, loading cycle and other parameters, the microslip and damage between contact threads will be studied quantitatively. Combining analysis of the dynamic response of bolted joints and the contact state between threads using FER/Contact, the interaction and relationship between microslip, thread damage, and degree of self-loosening will be discussed and the self-loosening mechanism will be revealed. In view of the criteria of anti-fretting damage, a new effective anti-loosening method based on the theory of fretting tribology will be presented using the avenues of surface engineering technology and design of new bolted joints based on shape memory alloy. This study will not only provide the theoretical dependence of tribological design for further constructing the mechanical joining system with high reliability, but also have an important guiding role in mitigating the problem on the self-loosening failure of bolted joints.

紧固件作为机械设备中重要的连接部件，其松动失效制约了机械连接结构向高安全、高可靠、长寿命方向发展。本项目针对机械连接系统中螺栓松动的关键共性问题，提出运用微动摩擦学理论对螺栓松动失效进行理论分析和试验研究，通过模拟螺栓的松动过程，从不同外加振动激励（载荷方向、幅值及频率）、螺栓预紧力、循环次数等方面入手，对螺纹接触界面的微滑及损伤等指标进行定量研究，并结合FER/Contact程序对连接结构的动力学响应和界面的接触状态进行分析，探讨界面微滑及损伤与螺栓松动程度之间的相互作用和内在联系，揭示螺栓松动失效机理。本项目根据抗微动损伤的防护准则，通过运用表面工程技术、基于形状记忆合金的新型螺栓连接设计等途径，提出基于微动摩擦学理论的有效防松方案。本研究不仅可以为进一步构建高可靠性的机械连接系统提供摩擦学设计的理论依据，同时对减缓螺栓松动失效的工程应用具有重要指导作用。

紧固件作为机械设备中重要的连接部件，其松动失效制约了机械连接结构向高安全、高可靠、长寿命方向发展。本项目针对机械连接系统中螺栓松动的关键共性问题，提出运用微动摩擦学理论对螺栓松动失效进行理论分析和试验研究，通过模拟螺栓的松动过程，从不同外加振动激励（载荷方向、幅值及频率）、螺栓预紧力、循环次数等方面入手，对螺纹接触界面的微滑及损伤等指标进行定量研究，并利用有限元软件对连接结构的动力学响应和界面的接触状态进行分析，探讨界面微滑及损伤与螺栓松动程度之间的相互作用和内在联系，揭示螺栓松动失效机理。本项目根据抗微动损伤的防护准则，运用表面工程技术对螺栓进行表面处理，提出基于微动摩擦学理论的有效防松方案。结果表明，螺纹表面的主要磨损机制为疲劳磨损，并伴随磨粒磨损、粘着磨损和氧化磨损。剪切载荷作用下，螺栓连接结构的主要松动失效机制为塑性变形、微动磨损和界面相对滑移；偏心载荷作用下，螺栓连接结构的主要松动失效机制为塑性变形和微动磨损；扭转载荷作用下，螺栓连接结构的主要松动失效机制为界面相对滑移，螺栓支撑面与被连接件之间的摩擦力矩对连接结构的松动行为具有重要影响：当该摩擦力矩的两倍大于拧松力矩而小于拧紧力矩时，连接结构易发生松动。DLC涂层、WC/C涂层、TiCN涂层和TiCN-MoS2复合涂层具有优良的耐磨损性能，几种涂层螺栓具有很好的防松性能。在本项目的资助下，研发了螺栓连接结构精确建模软件，实现了螺栓连接结构的参数化建模。此外，基于VDI2230螺栓连接标准，研发了螺栓连接设计软件，实现了螺栓连接设计、强度校核及结构优化设计。本项目研究成果不仅可以为进一步构建高可靠性的机械连接系统提供摩擦学设计的理论依据，同时对减缓螺栓松动失效的工程应用具有重要指导作用。