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高强螺栓松动是各种半刚性连接中常见的损伤形式。本文提出了利用非线性振动特性识别半刚性连接螺栓松动的方法。通过改变高强螺栓的预紧力模拟螺栓松动的程度,记录试验梁自由振动加速度信号,经小波软阈值去噪和解析模式分解,从加速度信号中分离出一阶振动分量,再进行希尔伯特变换,得到钢梁的频率与振幅的关系曲线,分析钢梁的非线性振动特性随螺栓松动状态的变化规律。结果表明非线性振动特性对螺栓松动导致的半刚性连接损伤敏感,适用于螺栓松动的损伤检测。
Loose high strength bolts are common forms of damage in a variety of semi-rigid connections. In this paper, a method of identifying the looseness of semi-rigid connecting bolts by using nonlinear vibration characteristics is proposed. By changing the preload of high-strength bolts to simulate the degree of bolt loosening, the free vibration acceleration signal of the test beam is recorded, and the first-order vibration components are separated from the acceleration signal by the wavelet soft threshold denoising and analytical mode decomposition, and then Hilbert The relationship between the frequency and the amplitude of the steel beam is obtained, and the variation of the nonlinear vibration characteristics of the steel beam with the looseness of the bolt is analyzed. The results show that the nonlinear vibration characteristics are sensitive to the semi-rigid connection damage caused by loose bolts, which is suitable for the detection of loose bolts.