中文摘要：

针对工程实际中出现的螺栓联接松动问题进行了研究,提出了一种基于压电主动式传感的结构频率跟踪的螺栓联接监测方法。根据赫兹接触理论并结合有限元仿真分析,得出了螺栓联接接触界面法向接触刚度与螺栓预紧力之间的单调函数关系,而螺栓联接结构的频率与法向接触刚度相关,进而建立了基于频率跟踪法的螺栓联接状态监测方法。建立实验装置,在螺栓联接件的非接触面的两侧分别粘贴压电材料,作为驱动器和传感器,分别激发脉冲超声波信号和接收通过螺栓联接界面的超声波响应信号,分析了响应信号的功率谱得到螺栓联接结构的频谱。实验结果表明：螺栓联接结合面的法向接触刚度与预紧力近似成对数函数关系,螺栓联接结构的某阶频率与螺栓预紧力近似成对数函数关系,从而可以通过分析螺栓联接结构的某阶频率变化得到螺栓预紧力状态。仿真结果与实验结果相一致,为螺栓联接松动问题提供了一种监测方法。

英文摘要：

Bolted joints interface characteristic is investigated for the bolt looseness in engineering structures,a monitoring method of the structure frequency tracking based on piezoelectric active sensing is proposed. According to the Hertz contact theory and the finite element contact analysis,the relationship between the contact stiffness and the pre-tightening force of the bolt is deduced and gets a monotone increasing relationship in result; the frequency of the bolted joints structure is related to the normal contact stiffness,a method for monitoring the state of bolted joints based on frequency tracking is established. The experiment system is set up,the piezoelectric materials are respectively pasted on the sides of the structure interface of the bolted joints,as drive and sensor,the driver excited ultrasonic signal which is received by the sensor after across the bolted joints interface,the spectrum of the bolted joints system is obtained by analyzing the power spectrum of the response signal. The experiment results show that the normal contact stiffness of the bolted joints and the pre-tightening force is similar to a logarithmic function curve,the relationship between the frequency of the bolted joints system and the pre-tightening force also have the same relationship,so as to be able to obtain the bolt pre-tightening state by analyzing the change of the order frequency of the bolt connection structure. The results of the experiments are consistent with the finite element simulation analysis,which provides a method for monitoring the looseness of bolts.