基于压电主动式传感的螺栓联接状态健康监测机理与方法研究

Bolted structures are widely used in industries, and their connection status directly determines the reliability and safety of the related equipment. Bolt loosening is not easy to detect in practice, which sometimes results in massive losses, therefore real-time monitoring of bolts connection status has important practical significance.The mechanism and method of bolt connection status health monitoring based on the peizoelectric active sensing technique will be studied. The local and interface nonlinear dynamic of the typical bolted structure will be analyzed systematically first. For the health monitoring method development , the propagation process and energy loss mechanism of the elastic wave generated by piezoeletric actuator across the interface will be simulated based on the theoretical analysis results. Then the experiments will be carried out with the peizoelectric material as the actuator and sensor. The dynamic information of the local and interface of the bolted structure will extracted from the response signal using time reversal method and piezoelectric impedance technique. Based on the theoratical analysis and experimental research results, the time reversal method and the piezoeletric impedance equivalent parameter method for the health monitoring of bolt connection status will be developed and studied, and the real-time monitoring system will be formed. Combined with active sensing methods such as the time reversal method and piezolectric impedance technique, monitoring method for the loosened bolt position and status of bolt group structure will be studied, and the health monitoring system will be developed. This project provides novel bolt connection status monitoring methods based structural health monitoring approach that is highly efficient, accutate and real time, and will make significant contribution to improve safety level of bolted structure.

针对工程中螺栓联接松动问题，研究基于压电主动式传感的螺栓联接状态健康监测机理和方法。首先从理论上系统地研究螺栓联接结构局部及界面非线性动力学特性，结合计算机仿真技术分析压电材料激励产生的弹性波在界面的传播、损耗机理。采用压电主动式传感，以压电材料产生激励并接收螺栓联接结构响应信号，利用时间反演法、压电阻抗法等方法分析螺栓联接结构局部及联接界面动力学信息，结合理论分析与仿真研究获得联接结构局部及界面动力学模型，指导监测方法的研究；研究时间反演法及压电阻抗等效参数法的螺栓联接状态监测理论及方法，形成实时监测系统；利用时间反演法等压电主动式传感的多种方式，研究可精确定位螺栓组联接中螺栓松动位置及确定松动螺栓状态的监测方法。大量的前期研究工作表明，本项目的完成，可为国民经济生产中关键重要设备的螺栓类联接结构提供实时、准确的状态监测系统及解决方案。

螺栓联接广泛应用于各类设备和结构中，其联接状态(表现为轴向预紧力)直接关系到整个设备可靠性和安全性。针对工程中螺栓联接松动问题，分别采用压电时间反演法和压电阻抗频率法，研究了基于压电主动式传感的螺栓联接状态健康监测机理和方法。主要包括：通过对超声波在螺栓联接界面传播特性的分析，揭示了超声波能量在螺栓联接界面的传递机理；通过对螺栓联接界面表面微观分形特征和接触特性的研究，从接触点弹性变形、弹塑性变形及全塑形变形出发，建立了螺栓联接界面实际接触面积分形模型，确立了螺栓联接界面实际接触面积与预紧力之间的关系；基于压电主动传感方式，采用压电时间反演法，建立了时间反演的聚焦信号峰值(即界面透射波能量)与螺栓预紧力之间的单调变化关系，以时间反演聚焦信号作为表征螺栓联接状态的特征量，确立了基于压电时间反演法的螺栓联接状态监测方法，研制出基于压电时间反演的宏观接触面积可控的螺栓预紧力监测智能垫片；提出了采用压电阻抗技术测量安装在螺栓头部的压电材料的导纳信号，通过分析导纳信号中峰值频率的变化监测螺栓预紧力的方法，建立了螺栓预紧力降低时峰值频率增大的单调变化关系，提出以峰值频率作为表征螺栓预紧力的特征参数，形成基于压电阻抗频率法的螺栓联接状态监测方法，提出将压电材料集成在螺栓头部形成压电智能螺栓；通过所研制的智能垫片与智能螺栓，实现对螺栓组联接状态的检测。.本项目提出的基于压电时间反演法和压电阻抗频率法的主动式传感方式实现对螺栓联接状态的监测，通过监测螺栓预紧力的变化确定螺栓的松紧程度，具有重要的理论意义和工程应用价值。在国内重要刊物发表学术论文20篇，其中SCI收录12篇，按Web of Science JCR分区，SCI-2区及以上7篇，SCI-3区5篇，授权发明专利2项，培养硕士10名，博士3名和青年教师5名。.项目成果可用于解决由于螺栓松动引起的设备问题及重大结构的安全使用问题，对于保证重要设备的正常运作和人民生命财产具有重要的价值。