基于振动信号频域离散特征的螺栓完全松动检测方法研究

Research on complete loosening detection method of transmission tower bolt connection based on vibration signal discrete characteristics of frequency domain

针对输电铁塔等桁架结构螺栓松动故障,提出了一种基于振动信号频域离散特征的螺栓完全松动检测方法。首先,利用有限元软件对桁架结构螺栓连接完全松动前后进行瞬态动力学分析,采用方差和变异系数求解仿真振动信号离散特征以及变化率,得出螺栓完全松动时方差和变异系数变化规律,并指出方差对信号的离散程度更加敏感;然后,实测了输电铁塔螺栓完全松动前后脉冲激振下的振动响应信号,经变分模态分解(VMD)-小波硬阈值降噪处理后,求解得到实测振动信号离散特征和变化率。仿真和实验结果表明:当螺栓完全松动后,振动信号频谱图频率成分增多,离散特征系数增大,离散程度增强。该方法能够有效检测输电铁塔等桁架结构螺栓完全松动趋势,具有一定的工程实用性。

Aiming at the complete loosening fault of the transmission tower bolt,the detection method based on the vibration signal discrete characteristics of the frequency domain is proposed.Firstly,finite element software is used to perform transient dynamic analysis of single-limb bolt structure before and after the bolt is completely loosened.The variance and variable coefficient are used to solve the discrete characteristics and damage index of the simulated vibration signal,and the variance and variable coefficient change law when the bolt is completely loose are obtained,and the variance is more sensitive to the degree of dispersion of the signal.Then,the vibration response signal of the transmission tower is measured by the pulse excitation,the vibration signal before and after the transmission tower bolt completely loosened is gotten,and after the variational mode decomposition(VMD)-wavelet hard threshold noise reduction treatment,the discrete characteristics and damage index of the measured vibration signal are solved.Simulation and experimental results show that when the bolt is completely loosened,the frequency component of the vibration signal spectrogram increases,and discrete characteristics and damage index increase.The method can effectively detect the complete loosening trend of the transmission tower bolt and has certain engineering practicability.