Bolt connection structure health monitoring method

Abstract

The invention provides a bolt connection structure health monitoring method. The method comprises the steps that S1, at least two piezoelectric sensors are arranged on the two sides of a to-be-monitored bolt connection face respectively; s2, a guided wave signal is emitted through a first piezoelectric sensor, and a second piezoelectric sensor receives the signal and records original waveform data; s3, analyzing the energy loss change of the received signal, and judging the bolt connection state; s4, calculating a loose area based on a root-mean-square difference algorithm, and generating an alarm signal; and S5, uploading the data to a cloud platform through remote data transmission for intelligent diagnosis. A small number of piezoelectric sensors are arranged on key parts of a power transmission and transformation line tower, guided wave signals are excited through voltage, bolt looseness alarm is achieved by analyzing the propagation change of guided waves on the surface of a structure, a remote data transmission system is constructed, and bolt looseness is deeply analyzed through the big data technology. Positioning and theorem analysis of bolt loosening are achieved, and support is provided for operation and maintenance of an iron tower.

Description

Technical Field

[0001] The present invention belongs to the field of monitoring technology, and in particular relates to a health monitoring method for a bolt connection structure. Background Art

[0002] The main structure of a power transmission tower is a steel frame connected by a large number of bolts. Therefore, the effectiveness of bolt tightening is directly related to the tower's safety. Currently, maintenance personnel regularly visit the tower site to visually inspect the bolts for abnormalities. However, due to the large number and widespread distribution of power transmission towers, this operation and maintenance method is extremely labor-intensive. Inspections in remote locations also pose safety risks. Visual inspections cannot detect problems such as loose bolts in the early stages. Traditional bolt detection relies on manual inspections or offline equipment, resulting in low efficiency, incomplete coverage, and the inability to provide real-time warnings. Therefore, there is an urgent need to develop online monitoring and intelligent diagnosis technologies for loosening key bolts on power transmission towers to achieve digital transformation of operation and maintenance and improve the efficiency and intelligence level of power transmission tower operation and maintenance in my country. Summary of the Invention

[0003] The present invention provides a method for monitoring the health of a bolted connection structure, wherein the method comprises:

[0004] S1: Arrange at least two piezoelectric sensors on both sides of the bolt connection surface to be monitored;

[0005] S2: The first piezoelectric sensor transmits the guided wave signal, and the second piezoelectric sensor receives the signal and records the original waveform data;

[0006] S3: Analyze the energy loss change of the received signal and determine the bolt connection status;

[0007] S4: Calculate the loose area based on the root mean square difference algorithm and generate an alarm signal;

[0008] S5: Upload data to the cloud platform through remote data transmission for intelligent diagnosis.

[0009] Furthermore, the waveguide signal includes an ultrasonic pulse signal with a frequency range of 50kHz-2MHz, and a signal transmission interval of 0.1-5 seconds.

[0010] Furthermore, the waveguide signal includes

[0011] The Lamb wave in the first frequency band of 50-100kHz is used to detect macroscopic structural deformation;

[0012] The second frequency band of 300-500kHz shear waves is used to capture microscopic contact surface changes;

[0013] The third frequency band of 1-2 MHz ultrasonic surface waves is used to evaluate the surface stress distribution.

[0014] Furthermore, the S3 includes

[0015] Under normal preload conditions, the original waveform data propagation matrix H0 is established, and the dynamic propagation matrix H is obtained during real-time monitoring. (t) , calculate the difference matrix ΔH (t) =H (t) -H0; for ΔH (t) Singular value decomposition is performed to extract the main modal change characteristics and determine the bolt connection status.

[0016] Furthermore, step S4 includes training the historical looseness data of the loose area based on the machine learning model, optimizing the root mean square difference threshold and positioning accuracy, and performing looseness determination on the loose area.

[0017] Furthermore, the root mean square difference algorithm includes:

[0018] The root mean square value of the energy difference between the un-loosened state and the current state signal is calculated, and when the root mean square difference exceeds a preset threshold, it is determined to be loose.

[0019] Furthermore, the position and distance of the loosened bolt are determined based on the signal attenuation gradient between the piezoelectric sensors.

[0020] Furthermore, when severe looseness is detected, an alarm signal is generated, automatically triggering a shutdown command or notifying maintenance personnel.

[0021] Furthermore, step S5 includes linking the monitoring data with the wind turbine system, automatically generating an operation and maintenance work order through remote data transmission in the wind turbine system, and pushing it to the cloud platform for intelligent diagnosis.

[0022] Furthermore, the piezoelectric sensor is placed in an external waterproof housing, and the waterproof housing is made of aviation aluminum and coated with a salt spray-proof coating on the surface.

[0023] Beneficial effects:

[0024] This invention deploys a small number of piezoelectric sensors on key components of power transmission towers, using voltage to stimulate guided wave signals. By analyzing the changes in guided wave propagation along the structure's surface, it generates bolt loosening alarms, establishes a remote data transmission system, and leverages big data technology to conduct in-depth analysis of bolt loosening, enabling location and theoretical analysis of loose bolts, thus supporting tower operation and maintenance. This technology achieves comprehensive coverage and online monitoring of power transmission tower bolts at a low cost, demonstrating both technological advancement and strong application value.

[0025] It should be understood that the above general description and the following detailed description are only exemplary and illustrative and do not limit the scope of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for health monitoring of a bolted connection structure according to the present invention;

[0027] It should be understood that the drawings are not necessarily drawn to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the present disclosure. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes will be determined in part by the particular intended application and use environment.

[0028] In the drawings, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION

[0029] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. Although the present invention will be described in conjunction with exemplary embodiments of the present invention, it should be understood that this description is not intended to limit the present invention to those exemplary embodiments. On the other hand, the present invention is intended to cover not only the exemplary embodiments of the present invention, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the present invention as defined by the appended claims.

[0030] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The specific structures and functions described in the exemplary embodiments of the present invention are for illustrative purposes only. The embodiments according to the concepts of the present invention may be implemented in various forms, and it should be understood that they should not be interpreted as being limited to the exemplary embodiments described in the exemplary embodiments, but include all modifications, equivalents or alternatives included in the spirit and scope of the present invention.

[0031] Throughout the specification, the technical terms used herein are for the purpose of describing various exemplary embodiments only and are not intended to be limiting. It will be further understood that the terms "comprises," "comprising," "having," etc., when used in exemplary embodiments, specifically refer to the presence of the stated parts, steps, operations, or elements, but do not preclude the presence or addition of one or more other parts, steps, operations, or elements.

[0032] like Figure 1 As shown, the present invention arranges piezoelectric sensors on the bolt connection surface to transmit and receive guided wave signals, and combines the root mean square difference algorithm and big data analysis to achieve real-time monitoring, positioning and early warning of bolt loosening; the present invention has the characteristics of low cost, full coverage, high reliability, etc., which significantly improves operation and maintenance efficiency and safety.

[0033] In an exemplary embodiment, a bolt connection structure health monitoring method is provided based on an embodiment of the present application, the method comprising:

[0034] S1: Arrange at least one pair of piezoelectric sensors on both sides of the bolt connection surface to be monitored;

[0035] At least two piezoelectric sensors are arranged on the surface of the flange connected by bolts to be monitored, wherein the first sensor acts as an excitation end to transmit a guided wave signal, and the second sensor acts as a receiving end to collect a guided wave response signal;

[0036] For example, six piezoelectric sensors are installed on the flange of the bolt connection structure of the wind turbine tower. Each group contains three piezoelectric plates arranged in a herringbone pattern. Adjacent units are spaced 90 degrees apart, and each unit covers a 45-degree sector area. Each sensor covers 12 bolts.

[0037] Among them, the piezoelectric sensor uses flexible packaging materials, which can conform to irregular surfaces and the installation error is less than ±1mm; the piezoelectric sensor is fixed with epoxy resin glue, and the reference signal is calibrated after installation.

[0038] S2: The first piezoelectric sensor transmits the guided wave signal, and the second piezoelectric sensor receives the signal and records the original waveform data;

[0039] The first piezoelectric sensor generates a sinusoidal swept frequency excitation signal with an adjustable frequency band, which is converted into a multi-band guided wave signal, and receives the signal collected by the second piezoelectric sensor at the working frequency point of the bolt connection interface and records the original waveform data;

[0040] The waveguide signal includes an ultrasonic pulse signal with a frequency range of 50kHz-2MHz, and a signal transmission interval of 0.1-5 seconds.

[0041] The Lamb wave in the first frequency band of 50-100kHz is used to detect macroscopic structural deformation;

[0042] The second frequency band of 300-500kHz shear waves is used to capture microscopic contact surface changes;

[0043] The third frequency band of 1-2 MHz ultrasonic surface waves is used to evaluate the surface stress distribution.

[0044] Among them, after collecting the reference original waveform data signal, a waveguide transmission is performed once every 1 second, the sampling rate is not less than 10MS / s, and the resolution is 16bit; the preset threshold is 10%-20% of the amplitude of the reference original waveform data signal, and the threshold is dynamically adjusted to adapt to the environmental noise.

[0045] S3: Analyze the energy loss change of the received signal and determine the bolt connection status;

[0046] Under normal preload conditions, the original waveform data propagation matrix H0 is established, and the dynamic propagation matrix H is obtained during real-time monitoring. (t) , calculate the difference matrix ΔH (t) =H (t) -H0; for ΔH (t) Singular value decomposition is performed to extract the main modal change characteristics and determine the bolt connection status.

[0047] S4: Calculate the loose area based on the root mean square difference algorithm and generate an alarm signal;

[0048] Based on the machine learning model, the historical loosening data of the loose area is trained, the root mean square difference threshold and positioning accuracy are optimized, and the looseness of the loose area is judged.

[0049] The root mean square value of the energy difference between the un-loosened state and the current state signal is calculated, and when the root mean square difference exceeds a preset threshold, it is determined to be loose.

[0050] The loose area is calculated using the root mean square difference algorithm (RMSD algorithm). The RMSD formula is:

[0051]

[0052] Among them, S ref is the reference signal, S current is a real-time signal. i is the current acquisition signal, y i Reference original waveform data signal, N is the number of sampling points.

[0053] The location and distance of the loosened bolt are determined based on the signal attenuation gradient between the piezoelectric sensors.

[0054] When severe looseness is detected, an alarm signal is generated, automatically triggering a shutdown command or notifying maintenance personnel.

[0055] In the above technical solution, after a bolt is manually loosened, the system will alarm within 3 seconds, and the positioning error is less than ±2 bolts.

[0056] S5: Upload data to the cloud platform through remote data transmission for intelligent diagnosis.

[0057] The monitoring data is linked with the fan system, and through remote data transmission in the fan system, operation and maintenance work orders are automatically generated and pushed to the cloud platform for intelligent diagnosis.

[0058] The remote data transmission supports CAN bus, Ethernet or wireless communication protocols, and is configured with a forward isolation device to ensure data security.

[0059] For example, if the difference exceeds 15%, the system marks the loose area and uploads the data to the cloud platform via remote data transmission for intelligent diagnosis.

[0060] In the above technical solution, the piezoelectric sensor is placed in an external waterproof shell, the waterproof shell is made of aviation aluminum, the surface is coated with a salt spray-proof coating, and the waterproof grade is IP67.

[0061] The above-mentioned embodiments of the present application can be implemented in various hardware, software coding, or a combination of the two. For example, the embodiments of the present application can also represent program code for executing the above-mentioned method in a digital signal processor. The present application can also relate to various functions performed by a computer processor, a digital signal processor, a microprocessor, or a field programmable gate array. The above-mentioned processor can be configured according to the present application to perform specific tasks, which are completed by executing machine-readable software code or firmware code that defines the specific methods disclosed in the present application. The software code or firmware code can be developed to represent different programming languages ​​and different formats or forms. It can also represent different target platform compiled software codes. However, the different code styles, types, and languages ​​of the software code for performing tasks according to the present application and other types of configuration code do not depart from the spirit and scope of the present application.

[0062] The foregoing description of specific exemplary embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to exclude or limit the invention to the precise form disclosed, and it is apparent that many modifications and variations are possible in light of the above teachings. The exemplary embodiments have been selected and described to explain certain principles of the present invention and their practical application so as to enable others skilled in the art to make or utilize the various exemplary embodiments of the present invention, and various alternatives and modifications thereof. It is intended that the scope of the present invention be defined by the claims appended hereto and their equivalents.

[0063] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for monitoring the health of a bolted connection structure, characterized in that: The method comprises S1: Arrange at least two piezoelectric sensors on both sides of the bolt connection surface to be monitored; S2: The first piezoelectric sensor transmits the guided wave signal, and the second piezoelectric sensor receives the signal and records the original waveform data; S3: Analyze the energy loss change of the received signal and determine the bolt connection status; S4: Calculate the loose area based on the root mean square difference algorithm and generate an alarm signal; S5: Upload data to the cloud platform through remote data transmission for intelligent diagnosis.

2. A method for health monitoring of a bolted connection structure according to claim 1, characterized in that: The waveguide signal includes an ultrasonic pulse signal with a frequency range of 50kHz-2MHz, and a signal transmission interval of 0.1-5 seconds.

3. A method for health monitoring of a bolted connection structure according to claim 2, characterized in that: The waveguide signal includes The Lamb wave in the first frequency band of 50-100kHz is used to detect macroscopic structural deformation; The second frequency band of 300-500kHz shear waves is used to capture microscopic contact surface changes; The third frequency band of 1-2 MHz ultrasonic surface waves is used to evaluate the surface stress distribution.

4. A method for health monitoring of a bolted connection structure according to claim 1, characterized in that: The S3 includes Under normal preload conditions, the original waveform data propagation matrix H0 is established, and the dynamic propagation matrix H is obtained during real-time monitoring. (t) , calculate the difference matrix ΔH (t) =H (t) -H0; for ΔH (t) Singular value decomposition is performed to extract the main modal change characteristics and determine the bolt connection status.

5. The method for health monitoring of a bolted connection structure according to claim 1, characterized in that: The step S4 includes training the historical looseness data of the loose area based on the machine learning model, optimizing the root mean square difference threshold and positioning accuracy, and performing looseness determination on the loose area.

6. A method for health monitoring of a bolted connection structure according to claim 5, characterized in that: The root mean square difference algorithm includes: The root mean square value of the energy difference between the un-loosened state and the current state signal is calculated, and when the root mean square difference exceeds a preset threshold, it is determined to be loose.

7. A method for health monitoring of a bolted connection structure according to claim 6, characterized in that: The location and distance of the loosened bolt are determined based on the signal attenuation gradient between the piezoelectric sensors.

8. The method for health monitoring of a bolted connection structure according to claim 7, characterized in that: When severe looseness is detected, an alarm signal is generated, automatically triggering a shutdown command or notifying maintenance personnel.

9. The method for health monitoring of a bolted connection structure according to claim 1, characterized in that: The step S5 includes linking the monitoring data with the wind turbine system, automatically generating an operation and maintenance work order through remote data transmission in the wind turbine system, and pushing the work order to the cloud platform for intelligent diagnosis.

10. The method for health monitoring of a bolted connection structure according to claim 1, characterized in that: The piezoelectric sensor is externally provided with a waterproof housing, which is made of aviation aluminum and coated with a salt spray-proof coating on the surface.

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