Power transmission tower bolt looseness detection method and system based on correlation coefficient

Abstract

The invention discloses a power transmission tower bolt looseness detection method and system based on correlation coefficients, two tower materials are selected from tower materials in bolt connection with a power transmission tower as a tower material 1 and a tower material 2, the method comprises the following steps: respectively selecting to-be-detected points on the tower material 1 and the tower material 2, collecting vibration signals of the to-be-detected points, and calculating the vibration signals of the to-be-detected points according to the vibration signals of the to-be-detected points; at least one point to be measured is selected for each tower material; acquiring a time domain image and a frequency domain image of the vibration signal of each to-be-detected point; solving correlation coefficients of each to-be-measured point of the tower material 1 and each to-be-measured point of the tower material 2 in a time domain and a frequency domain; the bolt looseness condition is detected according to the change of the correlation coefficient, and when the increase proportion of the correlation coefficient is larger than a set threshold value, it is judged that the bolt is loosened; the system comprises a signal acquisition module, an image acquisition module, a correlation coefficient solving module and a judgment module, the power transmission tower bolt loosening condition is detected through a correlation coefficient analysis method, the influence of noise can be eliminated conveniently, operation is easy, rapid and effective, and judgment is more accurate.

Description

technical field [0001] The invention relates to the technical field of bolt loosening detection, in particular to a method for detecting bolt loosening of a transmission tower based on a correlation coefficient. Background technique [0002] The working environment of the transmission tower is complex, and it is repeatedly acted by external loads all year round, which reduces the pre-tightening force of the bolted connection or even loosens, which leads to the decrease of the overall rigidity of the transmission tower. In severe cases, the transmission tower may collapse. Therefore, it is imperative to study a fast and effective method to detect the looseness of the bolted connection structure of the transmission tower. [0003] Many scholars have done a lot of simulation and experimental research on the loosening of bolted structures. In the detection method, Zhou Jing et al. applied the principle of machine vision to the measurement of the bolt loosening rotation angle, a...

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Problems solved by technology

In terms of detection methods, Zhou Jing et al. used the principle of machine vision to measure the bolt loosening rotation angle, and then judge the bolt state. This method has good accuracy, but the height of the transmission tower and the distribution of bolts will affect the acquisition of its visual signal; Li Lubing The ultrasonic nondestructive testing method is used for bolt flaw detection. This method has the characteristics of strong anti-interference ability and high resolution, but the method has strict requirements on experimental instruments; Jiang Wenqiang et al. judge the bolt looseness by observing the strain process of the bolt under lateral load This method can accurately measure the axial force of the bolt to judge the state of the bolt. However, in engineering practice, bolt loosening is a long-term process, and it is not realistic to use strain gauges to monitor it in real time.

[0004] At present, the most widely used method is the detection method based on vibration response, but because the field test will be affected by various noises, in terms of signal processing, Zhou Wenqiang et al. used empirical mode decomposition (EMD) for the vibration signal of the bolted connection structure. In terms of processing, there are many problems in the EMD algorithm, such as low efficiency, mode aliasing, and endpoint effects; Li Qiyue et al. applied the EEMD algorithm to the noise reduction of the blasting vibration signal, although the EEMD decomposition can well solve the problem of the EMD algorithm. The problem of state aliasing, but it will affect the noise reduction effect

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