Method for detecting hidden defect of iron tower based on vibration acceleration

Abstract

The invention relates to the technical field of iron tower detection, in particular to a method for detecting hidden defects of an iron tower based on vibration acceleration, and the method comprises the steps: building a finite element simulation model of a power transmission tower, carrying out the comparative analysis of modal and vibration response before and after damage, and determining a preliminary point distribution position; performing iron tower damage and health state vibration detection experiments on the experimental power transmission tower, setting damage points, arranging vibration acceleration sensors according to initial point distribution positions, applying unit load, drawing a frequency response curve according to data acquired by the sensors, and analyzing the frequency response curve; and if the analysis result does not meet the requirement on the accuracy of identifying the hidden defect of the power transmission tower, adjusting the point distribution position to obtain a final point distribution position. According to the method, efficient and accurate recognition of the hidden defects of the iron tower is achieved, remote monitoring can be conducted, safety, economical efficiency and operability are achieved, the use cost is lower, reliable technical support is provided for intelligent monitoring of electric power facilities, and the obvious engineering application value is achieved.

Description

Technical Field

[0001] This invention relates to the field of tower inspection technology, and in particular to a method for detecting hidden defects in towers based on vibration acceleration. Background Technology

[0002] Currently, existing tower inspection methods still have limitations. Traditional inspection methods rely on manual operation by line workers: inspectors must climb the towers to the transmission lines, conduct regular inspections and maintenance according to a segmented responsibility model, and record various safety hazards existing above and below the overhead lines. However, many high-voltage lines need to cross rivers and traverse high mountains, which poses a great challenge to the physical and mental strength of the inspectors. The drawbacks of manual inspection of high-voltage towers are very prominent: not only is the labor intensity high, the operation safety low, and the inspection efficiency low, but some sections of the line are difficult to reach due to complex terrain (such as cliffs, deep valleys, etc.), resulting in these areas being long-term blind spots for inspection, which brings great difficulties to the comprehensive maintenance of the line. Traditional tower bolt inspection relies on maintenance personnel for regular inspections: workers must climb the towers to visually inspect each connecting bolt or judge the condition by tapping and listening to the sound. Although this method is simple to operate and can meet basic inspection needs, it has obvious limitations such as large workload, long time consumption, high labor costs, and low overall efficiency. In bolt inspection technology, traditional methods such as torque wrench testing, acoustoelastic signal detection, and piezoresistive impedance testing mainly identify loosening conditions by monitoring bolt stress, torque, and other state parameters. In contrast, bolt inspection based on elastic shock wave technology has a greater advantage: when tower bolts are affected by external or internal factors, elastic shock waves are generated. These waves can form high pressure and strong stress in a short time and propagate through elastic media.

[0003] Existing technologies use vibration sensors to collect and amplify relevant signals, combined with spectral analysis, to detect and locate defective bolts, providing reliable data support for assessing the health status of steel towers. However, traditional elastic shock wave measurement methods require the installation of multiple vibration sensors and signal acquisition devices at different locations on the tower to ensure that abnormal signals can be detected when the tower is damaged at different locations. This method requires the installation of a large number of sensors, resulting in high costs and implementation difficulties, which limits its large-scale application. Furthermore, direct analysis of vibration data collected by vibration sensors suffers from insufficient accuracy and limited applicability. Therefore, there is an urgent need to develop a portable steel tower hidden defect detection system that provides accurate detection results and reduces labor costs and the risks of working at heights. Summary of the Invention

[0004] This invention proposes a method for detecting hidden defects in iron towers based on vibration acceleration, which solves the problems of high cost, difficult implementation, and insufficient detection accuracy associated with traditional methods for detecting hidden defects in iron towers, which require the installation of a large number of vibration sensors and signal acquisition devices on the iron tower for signal acquisition and analysis.

[0005] According to one aspect of the present invention, a method for detecting hidden defects in iron towers based on vibration acceleration is provided, comprising:

[0006] Based on the structural characteristics of the transmission tower, a corresponding finite element simulation model is established. Based on this model, a comparative analysis of the modal and vibration responses of the transmission tower structure before and after damage is conducted. Based on the analysis results, the preliminary locations of the monitoring points for the transmission tower are determined.

[0007] A test transmission tower was selected for vibration detection experiments to assess tower damage and health status. During the experiment, damage points were set, and vibration acceleration sensor measuring points were arranged according to the initial layout. A unit load was applied to the test transmission tower at a predetermined excitation position. Based on the data collected by the vibration acceleration sensors, a normalized frequency response curve of the measuring points as a function of frequency was plotted. The normalized frequency response curve was analyzed to determine whether the accuracy of identifying hidden defects in the transmission tower based on the sensor data after the initial layout met the requirements. If not, the layout was adjusted, and the adjusted layout was determined as the final layout.

[0008] Vibration acceleration sensors are deployed and tested on the transmission tower to be tested based on the final location of the sensors, and hidden defects in the transmission tower are identified based on the test results.

[0009] Preferably, the method for establishing a corresponding finite element simulation model based on the structural characteristics of the transmission tower includes:

[0010] The structural features include, but are not limited to: height, spacing between adjacent tower legs, main structure, main stiffener structure, secondary stiffener structure, cross-sectional shape, and cross-sectional dimensions;

[0011] Based on the structural features, a simulation model of the transmission tower is established, and fixed constraints are applied to the bottom of the model structure to simulate the concrete pouring at the bottom of each leg of the actual transmission tower.

[0012] Preferably, the method for conducting a comparative analysis of the modal and vibration responses of the transmission tower structure before and after damage based on the model, and determining the preliminary locations of monitoring points for the transmission tower based on the analysis results, includes:

[0013] The comparative analysis of modal responses before and after damage to the transmission tower structure includes:

[0014] Two typical damage states were selected, and the mode shape cloud diagrams of the model after damage were obtained. The mode shape cloud diagrams of the model before and after damage were compared to determine the stiffeners that had a predetermined impact on the dynamic performance of the model before and after damage.

[0015] The comparative analysis of vibration response before and after damage to the transmission tower structure includes:

[0016] Assessment points are set on the stiffeners that reach the predetermined level of influence. Before and after the model is damaged, unit load and / or triangular pulse load are applied to the predetermined excitation position of the model structure to obtain vibration acceleration data at each assessment point. Vibration transfer function curves are plotted based on these data.

[0017] The vibration transfer function curve is analyzed to determine the location of the assessment point where the difference in vibration morphology before and after the damage reaches a first predetermined difference or more, which is the initial layout location.

[0018] Preferably, the method for plotting the vibration transfer function curve includes:

[0019] Based on the vibration response spectrum of the model tower collected by the vibration acceleration sensor, an FFT transformation is performed to convert the vibration acceleration into a vibration acceleration level, and the vibration transfer function curve of the vibration acceleration level versus frequency is plotted.

[0020] Preferably, setting the damage points includes:

[0021] Loosen the main frame nuts, oblique frame nuts, and nuts near and far from the measuring point of the experimental transmission tower.

[0022] Preferably, the predetermined excitation location is one-third of the way down the transmission tower structure from the ground.

[0023] And / or,

[0024] The vibration acceleration sensor is a single-channel acceleration sensor, and all data collected by the vibration acceleration sensor is transmitted to the server after being acquired by a multi-channel data acquisition instrument.

[0025] Preferably, the method for applying a unit load includes:

[0026] The transmission tower is struck with a hammer, with the striking force ranging from 5 to 20 N. The force is increased by 5 N each time.

[0027] Preferably, the vibration monitoring experiment for tower damage and health status includes several sets of experimental data. The normalized frequency response curve of the measuring point as a function of frequency is the frequency response curve corresponding to each measuring point after the average value of several sets of experimental data is calculated and the result is normalized.

[0028] Preferably, the method for analyzing the normalized frequency response curve to determine whether the accuracy of identifying hidden defects in transmission towers based on sensor data after sensor placement according to the initial location meets the requirements includes:

[0029] Among all the measuring points, the normalized frequency response curves of the measuring points when the damage point is close to the impact position are analyzed to determine whether the difference in vibration response before and after the transmission tower damage reaches the second predetermined difference. If so, the accuracy of the measuring point identification meets the requirements.

[0030] Among all measuring points, the normalized frequency response curves corresponding to the measuring points when the damage point is far from the impact position are analyzed to determine whether the difference in vibration response before and after the transmission tower damage reaches the third predetermined difference. If so, the accuracy of the measuring point identification meets the requirements.

[0031] Preferably, the normalized frequency response curve of the measuring point as a function of frequency is analyzed to determine the vibration response differences corresponding to damage points at different locations;

[0032] Based on the differences in vibration response corresponding to the damage points, the location of the damage points on the transmission tower to be tested is determined.

[0033] The present invention has at least the following beneficial effects:

[0034] This invention proposes a method for detecting hidden defects in power transmission towers based on vibration acceleration. By performing finite element simulation on the transmission tower, the initial locations of monitoring points are determined. Simultaneously, vibration acceleration sensors are used to conduct vibration detection experiments on the tower's damage and health status. Through the collection and analysis of vibration data, the locations of the monitoring points are adjusted to determine the final placement. This invention achieves efficient and accurate detection and identification of hidden defects in power transmission towers, enabling remote monitoring. It also boasts safety, economy, and operability, with lower operating costs, providing reliable technical support for intelligent monitoring of power facilities and possessing significant engineering application value. Attached Figure Description

[0035] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention and, together with the specification, serve to explain the technical solutions of the present invention.

[0036] Figure 1 A flowchart of the method for detecting hidden defects in iron towers based on vibration acceleration according to the present invention is shown;

[0037] Figure 2 The diagram shows a structural damage diagram of the transmission tower according to the present invention, wherein Figure a shows the damage at the main reinforcing rib structure and Figure b shows the damage at the secondary reinforcing rib structure.

[0038] Figure 3 The diagram shows the first-order vibration mode before and after damage to the overall structure of the transmission tower of the present invention. In the diagram, a is the complete state, b is the damaged state of the main reinforcing rib structure, and c is the damaged state of the secondary reinforcing rib structure.

[0039] Figure 4 The modal vibration cloud diagrams of the main stiffener structure before and after damage are shown, wherein figure a is the complete state and figure b is the damaged state of the main stiffener structure.

[0040] Figure 5 The modal vibration cloud diagrams of the secondary stiffener structure before and after damage are shown in the present invention, wherein, figure a is the complete state and figure b is the damaged state of the secondary stiffener structure.

[0041] Figure 6 This diagram illustrates the distribution of incentive points and assessment points according to the present invention.

[0042] Figure 7 This invention shows a comparison curve of the transfer function at test point 1 before and after damage to the main stiffener structure under a unit load.

[0043] Figure 8 The vibration response cloud diagrams at test point 1 before and after damage to the main stiffener structure when a unit load is applied are shown. In the figure, figure a is the intact state and figure b is the damaged state.

[0044] Figure 9 The figure shows the transfer function comparison curves at two test points before and after damage to the secondary stiffener structure when a unit load is applied according to the present invention.

[0045] Figure 10 The vibration response cloud diagrams at two test points before and after damage to the secondary stiffener structure under the applied unit load of the present invention are shown. In the figure, figure a is the intact state and figure b is the damaged state.

[0046] Figure 11 The graph showing the load variation over time according to the present invention is shown.

[0047] Figure 12 This invention shows a comparison curve of the transfer function at test point 1 before and after damage to the main stiffener structure when a triangular pulse load is applied.

[0048] Figure 13 This invention shows the transfer function comparison curves at two test points before and after damage to the secondary stiffener structure when a triangular pulse load is applied.

[0049] Figure 14 The normalized frequency response curve of measuring point 1 is shown when the loose nut is close to the striking position according to the present invention.

[0050] Figure 15 The normalized frequency response curve of measuring point 2 is shown when the loose nut is close to the striking position according to the present invention;

[0051] Figure 16 The normalized frequency response curve of measuring point 3 is shown when the loose nut is close to the striking position according to the present invention;

[0052] Figure 17 The normalized frequency response curve of measuring point 4 is shown when the loose nut is close to the striking position according to the present invention;

[0053] Figure 18 The normalized frequency response curve of measuring point 1 is shown when the loose nut is far from the striking position according to the present invention;

[0054] Figure 19 The normalized frequency response curve of measuring point 2 is shown when the loose nut is far from the striking position according to the present invention;

[0055] Figure 20 The normalized frequency response curve of measuring point 3 is shown when the loose nut is far from the striking position according to the present invention;

[0056] Figure 21 The normalized frequency response curve of measuring point 4 is shown when the loose nut is far from the striking position according to the present invention;

[0057] Figure 22 The finite element analysis model of the transmission tower of the present invention is shown. Detailed Implementation

[0058] Various exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0059] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0060] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0061] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art will understand that the present invention can be practiced without certain specific details. In some instances, methods, means, elements, and circuits well known to those skilled in the art have not been described in detail in order to highlight the spirit of the invention.

[0062] Figure 1 A flowchart of the method for detecting hidden defects in iron towers based on vibration acceleration according to the present invention is shown. Figure 2 A schematic diagram of the damage to the transmission tower structure of the present invention is shown; Figure 3 The diagram shows the first-order vibration mode of the overall structure of the transmission tower before and after damage, according to the present invention. Figure 4 The modal vibration contour maps of the main stiffener structure before and after damage are shown. Figure 5 The modal shape cloud diagrams of the secondary stiffener structure before and after damage are shown. Figure 6 This diagram illustrates the distribution of incentive points and assessment points according to the present invention. Figure 7 This invention shows a comparison curve of the transfer function at test point 1 before and after damage to the main stiffener structure under a unit load. Figure 8 This invention shows the vibration response cloud diagram at test point 1 before and after damage to the main stiffener structure when a unit load is applied. Figure 9 The figure shows the transfer function comparison curves at two test points before and after damage to the secondary stiffener structure when a unit load is applied according to the present invention. Figure 10 The diagram shows the vibration response cloud maps at two test points before and after damage to the secondary stiffener structure when a unit load is applied according to the present invention. Figure 11 The graph showing the load variation over time according to the present invention is shown. Figure 12 This invention shows a comparison curve of the transfer function at test point 1 before and after damage to the main stiffener structure when a triangular pulse load is applied. Figure 13 This invention shows the transfer function comparison curves at two test points before and after damage to the secondary stiffener structure when a triangular pulse load is applied. Figure 14 The normalized frequency response curve of measuring point 1 is shown when the loose nut is close to the striking position according to the present invention. Figure 15 The normalized frequency response curve of measuring point 2 is shown when the loose nut is close to the striking position according to the present invention; Figure 16 The normalized frequency response curve of measuring point 3 is shown when the loose nut is close to the striking position according to the present invention; Figure 17 The normalized frequency response curve of measuring point 4 is shown when the loose nut is close to the striking position according to the present invention; Figure 18 The normalized frequency response curve of measuring point 1 is shown when the loose nut is far from the striking position according to the present invention; Figure 19 The normalized frequency response curve of measuring point 2 is shown when the loose nut is far from the striking position according to the present invention; Figure 20 The normalized frequency response curve of measuring point 3 is shown when the loose nut is far from the striking position according to the present invention; Figure 21 The normalized frequency response curve of measuring point 4 is shown when the loose nut is far from the striking position according to the present invention; Figure 22 The finite element analysis model of the transmission tower of the present invention is shown. Figure 1-22 As shown, a method for detecting hidden defects in transmission towers based on vibration acceleration includes: Step S01: Based on the structural characteristics of the transmission tower, a corresponding finite element simulation model is established. Based on the model, a comparative analysis of the modal and vibration response before and after structural damage is performed. Based on the analysis results, the preliminary layout of monitoring points on the transmission tower is determined. Step S02: An experimental transmission tower is selected, and a vibration detection experiment of tower damage and healthy state is conducted. During the experiment, damage points are set, and vibration acceleration sensor measuring points are arranged according to the preliminary layout. A unit load is applied to the experimental transmission tower at a predetermined excitation position. Based on the data collected by the vibration acceleration sensor, a normalized frequency response curve of the measuring point changing with frequency is plotted. The normalized frequency response curve is analyzed to determine whether the accuracy of identifying hidden defects in the transmission tower based on the sensor data after the sensor arrangement according to the preliminary layout meets the requirements. If not, the layout is adjusted, and the adjusted layout is determined as the final layout.

[0063] Step S03: Based on the final placement location, arrange and test the vibration acceleration sensors on the transmission tower to be tested, and identify hidden defects in the transmission tower based on the test results.

[0064] The method for detecting hidden defects in iron towers based on vibration acceleration provided in this embodiment of the invention specifically includes the following steps:

[0065] Step S01: Based on the structural characteristics of the transmission tower, establish a corresponding finite element simulation model. Based on the model, conduct a comparative analysis of the modal and vibration responses of the transmission tower structure before and after damage. Based on the analysis results, determine the preliminary locations of the monitoring points for the transmission tower.

[0066] In this invention, the method for establishing a corresponding finite element simulation model based on the structural characteristics of the transmission tower includes: the structural characteristics include, but are not limited to: height, spacing between adjacent tower legs, main structure, main reinforcing rib structure, secondary reinforcing rib structure, cross-sectional shape, and cross-sectional dimensions; establishing a transmission tower simulation model based on the structural characteristics, applying fixed constraints to the bottom of the model structure, and simulating the concrete pouring at the bottom of each tower leg of the actual transmission tower.

[0067] In this embodiment of the invention, based on the structural characteristics of the transmission tower, a system is established as follows: Figure 22The finite element simulation model shown is used to analyze the vibration response changes of the transmission tower under intact and damaged conditions. The established transmission tower simulation model has a height of 20.1m and a distance of 8.16m between adjacent tower legs. The overall tower structure is divided into main structure, main stiffener structure, and secondary stiffener structure, and is built using beam elements. The beam elements are assigned three types of equilateral angle steel section properties. The specific parameters are shown in Table 1 below. The density of the material used in the structure is 7850kg / m³. 3 The elastic modulus is 2.1×10⁵MPa, and the structural damping is 0.01.

[0068] Table 1: Beam Section Properties Table

[0069]

[0070] Fixed constraints, such as stress conditions, riveting, or welding, are applied to the bottom of the structure to simulate the concrete pouring at the bottom of each leg of an actual transmission tower.

[0071] In this invention, the method of performing a comparative analysis of the modal and vibration responses of the transmission tower structure before and after damage based on the model, and determining the preliminary layout of the monitoring points of the transmission tower based on the analysis results, includes: the comparative analysis of the modal responses of the transmission tower structure before and after damage includes: selecting two typical damage states, obtaining the mode shape cloud diagram of the model after damage, comparing the mode shape cloud diagrams of the model before and after damage, and determining the stiffeners that have a predetermined impact on the dynamic performance of the model before and after damage;

[0072] The comparative analysis of vibration response before and after damage to the transmission tower structure includes: setting assessment points on the stiffeners that reach a predetermined level of influence; applying unit load and / or triangular pulse load to predetermined excitation positions of the model structure before and after damage to obtain vibration acceleration data at each assessment point; plotting vibration transfer function curves based on these data; analyzing the vibration transfer function curves to determine the assessment point positions where the difference in vibration morphology before and after damage reaches a first predetermined difference as the initial point placement positions.

[0073] In this embodiment of the invention, two typical damage states are selected. Partial units are deleted from the main reinforcing rib structure and the secondary reinforcing rib structure of the transmission tower simulation model, respectively, to simulate structural damage such as bolt loosening or failure at the main and secondary reinforcing rib structures. Figure 2 As shown, where Figure 2 'a' is a diagram illustrating damage at the main reinforcing rib structure. Figure 2 b is a schematic diagram of damage at the secondary reinforcing rib structure.

[0074] The overall modal analysis results of the transmission tower before and after the overall structural damage are as follows: Figure 3 As shown, where Figure 3 'a' represents the complete state. Figure 3b represents the damage state of the main reinforcing rib structure. Figure 3 c represents the damage state of the secondary stiffener structure. As can be seen from the figure, the damage to the local structure has a weak impact on the overall mode.

[0075] like Figure 4 The image shows the modal shape contour plots of the main stiffener structure before and after damage; for comparison. Figure 4 The two mode shape contour maps in the image, such as Figure 4 As shown in Figure a, in its intact state, i.e., before damage, the transmission tower exhibits a relatively uniform distribution of vibration modes, with coordinated vibration deformation across its various parts, demonstrating good structural integrity and continuity. Figure 4 As shown in b, the overall vibration mode changed significantly under the damaged state of the main stiffener, especially near the damaged area, where the vibration pattern differed significantly from the intact state, indicating that the damage altered the structure's vibration mode. Furthermore, the vibration response in this area intensified after the main stiffener was damaged, making it a weak point in the structure's vibration. The damage caused a redistribution of energy near the damaged area, resulting in more pronounced vibration deformation in this region.

[0076] like Figure 5 As shown, the modal shape contour maps of the secondary stiffener structure before and after damage are displayed. Figure 5 'a' represents the complete state. Figure 5 b represents the damage state of the secondary stiffener structure. Compared to the damage to the primary stiffener structure, the natural frequency is significantly reduced (from 7.19Hz to 6.83Hz). The impact of secondary stiffener damage on the overall natural frequency of the transmission tower is relatively small. For example... Figure 5 As shown in Figure a, in its complete state, the vibration mode distribution of the transmission tower exhibits a certain regularity and symmetry, and the vibration deformation of each part is relatively coordinated. For example... Figure 5 As shown in b, the overall vibration mode is similar to that in the intact state when the secondary stiffener structure is damaged, indicating that the damage to the secondary stiffener structure does not have a significant impact on the main vibration modes of the transmission tower.

[0077] In summary, damage to the main stiffener significantly alters the vibration modes, especially near the damage area where the differences are substantial. Damage to the secondary stiffeners results in less overall change in the vibration modes, with differences only observed in the damaged area. This indicates that damage to the main stiffeners has a more pronounced impact on the structural vibration modes. The increased vibration deformation and response in the damaged area of ​​the main stiffeners are far greater than in the damaged area of ​​the secondary stiffeners, reflecting the more significant impact of damage to the main stiffeners on both the local and overall dynamic performance of the structure.

[0078] Therefore, based on the above analysis results, we can identify the reinforcing ribs that have a significant impact on the model's dynamic performance before and after damage, i.e., those that reach a predetermined level of impact. By placing sensors on these reinforcing ribs, the collected data can more accurately identify the damage status of the tower.

[0079] When conducting vibration response comparative analysis, test points are set on the stiffeners that reach the predetermined level of influence. Unit load and triangular pulse load are applied to the predetermined excitation position of the model structure to obtain vibration acceleration data at each test point before and after tower damage, and vibration transfer function curves are plotted based on them.

[0080] If a unit load is applied, the specific analysis process includes:

[0081] like Figure 6 As shown, an excitation load (unit load) is applied at one-third of the distance from the ground on the transmission tower structure, such as... Figure 6 The middle arrow indicates the location, and two assessment points are selected near the structural damage site on the transmission tower. That is... Figure 6 At positions 1 and 2, the vibration response before and after structural damage is compared and analyzed. After applying a unit load and performing simulation analysis, the vibration transfer function curves at each test point are obtained, as shown below. Figure 7 The figure shows the transfer function curves before and after damage to the main reinforcing rib at assessment point 1.

[0082] from Figure 7 It can be seen that the vibration response curves at test point 1 in the intact state differ significantly from those in the main stiffener structure and the damaged state. Specifically, the peak frequency points shifted between the two states in the frequency ranges of 7-8Hz, 26-28Hz, 51-54Hz, and 73-75Hz. This indicates that damage to the main stiffener structure altered the dynamic characteristics of the transmission tower structure, causing a change in its transfer function curve. Figure 8 As shown, Figure 8 a presents the vibration acceleration response contour map at test point 1 under the complete state with a frequency of 8Hz. Figure 8 b presents the vibration acceleration response contour map of the structure at a frequency of 7Hz after damage to the main stiffener.

[0083] Figure 9 The vibration transfer function curves at test point 2 before and after damage to the secondary stiffener structure are presented. It can be seen that the vibration response curves at test point 2 under the intact state and the damaged secondary stiffener structure exhibit significant differences. Specifically, in the frequency ranges of 22-27Hz, 58-59Hz, and 72-75Hz, the peak frequencies of the vibration responses in the intact state and the damaged secondary stiffener structure shift to some extent. This indicates that damage to the secondary stiffener structure affects the dynamic characteristics of the transmission tower structure, although not as significantly as damage to the main stiffener, it still alters the structure's vibration response. Figure 10 As shown, Figure 10 a presents the acceleration response contour plot for a vibration with a frequency of 27Hz under complete conditions. Figure 10b presents the vibration acceleration response contour map of the structure at a frequency of 22Hz after damage to the secondary stiffener.

[0084] If a triangular pulse load is applied, the specific analysis process includes:

[0085] Applying such at the excitation point Figure 11 The triangular pulse load shown is used to simulate the impact load that may be encountered in actual operation. After simulation analysis, the vibration acceleration at each test point is obtained to analyze the vibration and impact response characteristics of the structure.

[0086] Based on the simulation results and the vibration acceleration data at the test points, vibration acceleration level curves at the test points before and after structural damage were plotted.

[0087] In this invention, the method for plotting the vibration transfer function curve includes: performing an FFT transformation on the vibration response spectrum of the model tower collected by the vibration acceleration sensor to convert the vibration acceleration into a vibration acceleration level, and plotting the vibration transfer function curve of the vibration acceleration level versus frequency.

[0088] In this embodiment of the invention, the vibration acceleration level curve at assessment point 1 is as follows: Figure 12 As shown in the figure, the vibration response curves at test point 1 in the intact state and the damaged state of the main reinforcing rib structure exhibit significant differences. Specifically, the peak vibration frequency points differ between the intact state and the damaged state in the 27-30Hz, 67-70Hz, and 78-88Hz frequency ranges. This indicates that damage to the main reinforcing rib structure significantly alters the dynamic characteristics of the transmission tower structure, causing a noticeable shift in the peak vibration frequency point when subjected to triangular pulse load impact.

[0089] Figure 13 The vibration acceleration level curves at assessment point 2 before and after damage to the secondary stiffener structure are given. From... Figure 13 It can be seen that the vibration response curves at test point 2 in the intact state and the damaged state of the secondary stiffener structure show significant differences. Specifically, the peak vibration frequencies differ between the intact state and the damaged state in the 13-16Hz, 42-49Hz, and 71-77Hz frequency ranges. This indicates that the damage to the secondary stiffener structure has a certain impact on the dynamic characteristics of the transmission tower structure, altering its vibration peak position under impact loads.

[0090] In summary, finite element simulation clearly demonstrates a close correlation between the structural damage state and vibration characteristics of transmission towers, providing a solid analytical basis and feasible technical approach for intelligent monitoring and safety inspection of transmission tower structures. When the structural safety state changes, its vibration characteristics and response inevitably change, and this change is closely related to the location of the monitoring point. Structural damage leads to changes in its natural vibration frequency, vibration transfer function, and vibration impact response, with damage to the main stiffeners having a far greater impact on these characteristics than damage to the secondary stiffeners. Therefore, by monitoring the vibration characteristics of transmission towers, such as their natural vibration frequency, vibration transfer function, and vibration impact response, the damage status and health condition of the structure can be effectively perceived.

[0091] By analyzing the vibration transfer function curves, the differences in vibration morphology before and after damage at each assessment point on the primary and secondary stiffeners can be determined. Assessment points with significant differences, exceeding the first predetermined difference, are selected as initial assessment point locations. If the number of selectable assessment points is limited, a comparative analysis of the modal and vibration responses of the transmission tower structure before and after damage can be conducted again. The assessment point locations can then be readjusted, selecting those where the data accurately identifies the damage and covers a wider range of damaged areas as initial assessment point locations.

[0092] Step S02: Select an experimental transmission tower and conduct vibration detection experiments on its tower damage and health status. During the experiment, damage points are set, and vibration acceleration sensor measuring points are arranged according to the preliminary layout. A unit load is applied to the experimental transmission tower at a predetermined excitation position. Based on the data collected by the vibration acceleration sensors, a normalized frequency response curve of the measuring points as a function of frequency is plotted. The normalized frequency response curve is analyzed to determine whether the accuracy of identifying hidden defects in the transmission tower based on the sensor data after the sensor layout according to the preliminary layout meets the requirements. If not, the layout is adjusted, and the adjusted layout is determined as the final layout.

[0093] In this invention, setting damage points includes loosening the main frame nuts, oblique frame nuts, and nuts near and far from the measuring point of the experimental transmission tower.

[0094] In this embodiment of the invention, the structural vibration response of an actual transmission tower under external excitation is monitored in both a damaged state (due to bolt loosening) and a healthy state, respectively, to obtain the transmission tower vibration response spectrum under different damage states. The obtained transmission tower vibration response spectrum is compared with the spectrum obtained under the healthy state to analyze changes in spectral characteristics, such as peak values ​​and their corresponding frequencies, thereby determining the final deployment locations. This also verifies the correctness of the transmission tower health status monitoring method and provides data support for transmission system stability research.

[0095] In this invention, the predetermined excitation position is: one-third of the way down the transmission tower structure from the ground; and / or, the vibration acceleration sensor is a single-channel acceleration sensor, and all data collected by the vibration acceleration sensor are transmitted to the server after being collected by a multi-channel data acquisition instrument.

[0096] In this embodiment of the invention, the instruments and equipment used in the experiment are shown in Table 2 below.

[0097] Table 2: List of Experimental Instruments

[0098]

[0099] During the experiment, vibration acceleration sensors were fixedly installed on the main structure of the transmission tower using magnetic bases to collect the vibration response at different locations before and after external excitation. The nuts connecting the inclined structure, which were initially tightened, were actively rotated to loosen them, simulating a loosened state in the actual structure, thus setting a damage point. The vibration acceleration sensors collected the structural vibration response at a predetermined excitation location at the bottom of the transmission tower, specifically one-third of the way from the ground, under applied excitation. A Siemens LMS data acquisition system was used for data acquisition and post-processing.

[0100] After completing on-site data collection, the data is analyzed to identify the differences in sensor response signals between healthy and unhealthy states of the power tower (such as when nuts have come loose). This systematic testing method allows for in-depth analysis of the patterns behind these differences, providing a scientific basis for accurately assessing the structural health of the power tower, thereby enabling the timely detection of potential problems and the implementation of appropriate maintenance measures.

[0101] In this invention, the method of applying a unit load includes: striking the transmission tower with a hammer, wherein the striking force ranges from 5 to 20 N, and the force increases sequentially from low to high, increasing by 5 N each time.

[0102] In this embodiment of the invention, nuts and bolts at the lower inclined structure of the experimental transmission tower were detached to simulate different structural damage states. Four vibration acceleration sensors (measuring points 1 to 4) were initially positioned on the main structure of the transmission tower. Vibration responses at different locations under different damage states were collected.

[0103] During this experiment, the vibration response of the tower in a healthy state when it was struck was collected, the vibration response of the nut that fell off near the striking point (damage point) when it was struck was collected, and the vibration response of the nut that fell off far from the striking point (damage point located diagonally opposite the striking point) when it was struck was collected.

[0104] In this invention, the vibration monitoring experiment for tower damage and health status includes several sets of experimental data. The normalized frequency response curve of the measuring point as a function of frequency is the frequency response curve corresponding to each measuring point after the average value of several sets of experimental data is calculated and the result is normalized.

[0105] In this embodiment of the invention, taking the vibration response of a nut that has come loose (damage point) near the impact as an example, the specific analysis process includes:

[0106] Four hammering experiments were conducted on the tower in both healthy and loose nut states. The four sets of experimental data collected under the same conditions were processed and averaged. The results were then normalized and normalized to plot the normalized frequency response curves of measuring points 1 to 4 as a function of frequency.

[0107] In this invention, the method for analyzing the normalized frequency response curve and determining whether the accuracy of identifying hidden defects in transmission towers based on sensor data collected after sensor placement according to the initial location meets the requirements includes: analyzing the normalized frequency response curve corresponding to the measurement point when the damage point is close to the impact position, and determining whether the difference in vibration response before and after the transmission tower damage reaches a second predetermined difference or higher; if so, the accuracy of the measurement point identification meets the requirements; and analyzing the normalized frequency response curve corresponding to the measurement point when the damage point is far from the impact position, and determining whether the difference in vibration response before and after the transmission tower damage reaches a third predetermined difference or higher; if so, the accuracy of the measurement point identification meets the requirements.

[0108] In embodiments of the present invention, such as Figure 14 The figure shows the normalized frequency response curve of measuring point 1 when the damage point is close to the impact location. As can be seen from the figure, the nut falling off causes a change in the vibration response spectrum characteristics at measuring point 1 of the tower. At a frequency of 433Hz, the normalized frequency response of the tower in a healthy state is 0.35, while that in the nut-fallen state is 0.53; at a frequency of 840Hz, the normalized frequency response of the tower in a healthy state is 0.37, while that in the nut-fallen state is 0.52; at a frequency of 948Hz, the normalized frequency response of the tower in a healthy state is 0.28, while that in the nut-fallen state is 0.47. At the three frequency points of 433Hz, 840Hz, and 948Hz, the normalized frequency response in the nut-fallen state is 0.18, 0.15, and 0.19 higher than that in the healthy state, respectively, indicating that the nut falling off causes a more severe vibration response of the tower at these frequencies.

[0109] like Figure 15 The figure shows the normalized frequency response curve of measurement point 2 when the damage point is close to the impact location. Figure 15It can be seen that the nut falling off will cause changes in the vibration response spectrum characteristics at measuring point 2 of the tower. At a frequency of 797Hz, the normalized frequency response of the tower in the healthy state is 0.30, and the normalized frequency response in the nut-fallen state is 0.41. The normalized frequency response in the nut-fallen state is 0.11 higher than that in the healthy state, indicating that the nut falling off makes the vibration response of the tower more severe at these frequencies.

[0110] like Figure 16 The figure shows the normalized frequency response curve of measuring point 3 when the damage point is close to the impact location. As can be seen from the figure, the nut falling off causes a change in the vibration response spectrum characteristics at measuring point 3 of the tower. At a frequency of 422Hz, the normalized frequency response of the tower in a healthy state is 0.10, while that in the nut-fallen state is 0.18; at a frequency of 876Hz, the normalized frequency response of the tower in a healthy state is 0.06, while that in the nut-fallen state is 0.13. At the frequencies of 422Hz and 876Hz, the normalized frequency response in the nut-fallen state is 0.08 and 0.07 higher than that in the healthy state, respectively, indicating that the nut falling off causes a more severe vibration response of the tower at these frequencies.

[0111] like Figure 17 The figure shows the normalized frequency response curve of measuring point 4 when the damage point is close to the impact location. As can be seen from the figure, the nut falling off causes a change in the vibration response spectrum characteristics at measuring point 4 of the tower. At a frequency of 495Hz, the normalized frequency response of the tower in a healthy state is 0.25, while that in the nut-fallen state is 0.36. The normalized frequency response in the nut-fallen state is 0.11 higher than that in the healthy state, indicating that the nut falling off makes the vibration response of the tower more severe at these frequencies.

[0112] In summary, by comparing the vibration responses of measuring points 1 to 4 under healthy and nut-loosening conditions, the accuracy of each measuring point in detecting the health status of the transmission tower can be determined. That is, the health status of the transmission tower can be judged by monitoring the changes in the vibration response spectrum characteristics at the measuring point, providing an effective basis for assessing the structural health status of the transmission tower and for studying the stability of the power transmission system.

[0113] In this embodiment of the invention, the vibration response when a nut falls off (damage point) and is far from the impact location is taken as an example. The specific analysis process includes:

[0114] Four hammering experiments were conducted on the tower in a healthy state and on the nut in a loose state (diagonally opposite the hammering position). The four sets of experimental data collected under the same conditions were processed and averaged. The results were then normalized and normalized frequency response curves of measuring points 1 to 4 as a function of frequency were plotted.

[0115] like Figure 18The figure shows the normalized frequency response curve of measuring point 1 when the damage point is far from the impact location. As can be seen from the figure, the nut falling off causes a change in the vibration response spectrum characteristics at measuring point 1 of the tower. At a frequency of 342 Hz, the normalized frequency response of the tower in a healthy state is 0.44, and the normalized frequency response in the nut-fallen state is 0.58; at a frequency of 392 Hz, the normalized frequency response of the tower in a healthy state is 0.34, and the normalized frequency response in the nut-fallen state is 0.62; at a frequency of 445 Hz, the normalized frequency response of the tower in a healthy state is 0.35, and the normalized frequency response in the nut-fallen state is 0.56; at a frequency of 838 Hz, the normalized frequency response of the tower in a healthy state is 0.37, and the normalized frequency response in the nut-fallen state is 0.60; at a frequency of 964 Hz, the normalized frequency response of the tower in a healthy state is 0.23, and the normalized frequency response in the nut-fallen state is 0.56. At three frequency points of 342Hz, 392Hz, 445Hz, 838Hz and 964Hz, the normalized frequency response under the nut-loosening state is 0.14, 0.28, 0.21, 0.23 and 0.33 higher than that under the healthy state, respectively, indicating that the nut-loosening makes the vibration response of the tower more severe at these frequencies.

[0116] like Figure 19 The figure shows the normalized frequency response curve of measuring point 2 when the damage point is far from the impact location. As can be seen from the figure, the nut falling off causes a change in the vibration response spectrum characteristics at measuring point 2 of the tower. At a frequency of 762Hz, the normalized frequency response of the tower in a healthy state is 0.20, while the normalized frequency response in the nut-fallen state is 0.48. The normalized frequency response in the nut-fallen state is 0.28 higher than that in the healthy state, indicating that the nut falling off makes the vibration response of the tower more severe at these frequencies.

[0117] like Figure 20 The figure shows the normalized frequency response curve of measuring point 3 when the damage point is far from the impact location. As can be seen from the figure, the nut falling off causes a change in the vibration response spectrum characteristics at measuring point 3 of the tower. At a frequency of 560Hz, the normalized frequency response of the tower in a healthy state is 0.05, while the normalized frequency response in the nut-fallen state is 0.10. The normalized frequency response in the nut-fallen state is 0.05 higher than that in the healthy state, indicating that the nut falling off makes the vibration response of the tower more severe at these frequencies.

[0118] like Figure 21The figure shows the normalized frequency response curve of measuring point 4 when the damage point is far from the impact location. As can be seen from the figure, the nut falling off causes a change in the vibration response spectrum characteristics at measuring point 4 of the tower. At a frequency of 525Hz, the normalized frequency response of the tower in a healthy state is 0.13, while that in the nut-fallen state is 0.41. The normalized frequency response in the nut-fallen state is 0.28 higher than that in the healthy state, indicating that the nut falling off makes the vibration response of the tower more severe at these frequencies.

[0119] In summary, by comparing the vibration responses of measuring points 1 to 4 in a healthy state and in a state of nut detachment far from the excitation location, the health status of the transmission tower can also be judged by monitoring the changes in the vibration response spectrum characteristics. This verifies the correctness of the transmission tower health status monitoring method and provides an effective basis for assessing the structural health status of transmission towers and for studying the stability of transmission systems.

[0120] Step S03: Based on the final placement location, arrange and test the vibration acceleration sensors on the transmission tower to be tested, and identify hidden defects in the transmission tower based on the test results.

[0121] In this invention, the normalized frequency response curve of the measuring point as a function of frequency is analyzed to determine the vibration response differences corresponding to damage points at different locations; based on the vibration response differences corresponding to the damage points, the location of the damage points on the transmission tower to be tested is determined.

[0122] In this embodiment of the invention, a hammer is installed at a predetermined excitation position on the transmission tower to be tested, namely one-third of the distance from the bottom of the tower, to periodically emit an excitation signal; vibration acceleration sensors are arranged according to the final placement position to collect specific signals of loose screws; the sensor signals are received by a data acquisition device, and after filtering and denoising the signals, feature extraction (frequency, amplitude, peak, etc.) is performed, and preliminary vibration waveform identification is performed. Based on the above steps S01~S02, the tower condition is initially judged, that is, whether there are common hidden defects, and the data is uploaded to a data cloud platform for further detailed detection; the data cloud platform is used to store data under different working conditions to build a data model to detect the tower condition, and to notify the responsible person of any abnormal results for handling.

[0123] The simulations and actual experiments demonstrated above show that the signals generated by loose bolts in the inclined frame and main structure deviate significantly from the signals in a healthy state, thus verifying the effectiveness of vibration spectrum comparison in detecting hidden defects in towers. Furthermore, the signals from these two abnormal conditions also differ. By training the data model, it is possible not only to determine whether the tower is in a healthy state, but also to locate the type and location or area of ​​defects.

[0124] The process of constructing a data model to detect the tower status includes: establishing a neural network model, inputting information on different damage points during the experiment, data collected by the corresponding vibration acceleration sensors, and a large amount of existing abnormal working condition data and corresponding damage point information into the neural network model for training, and obtaining a hidden defect identification model for the tower.

[0125] The data collected by the sensors from the transmission tower to be inspected is input into the hidden defect identification model of the tower. The model judges and identifies the health status of the tower, that is, predicts the corresponding damage point information, accurately identifies defects and pushes alarms, realizes the closed loop of problem detection, improves operation and maintenance efficiency, reduces failure rate, and promotes the upgrade of operation and maintenance mode to "defect pre-intervention".

[0126] The damage point information includes the defect type, such as bolt loosening, loosening angle, metal corrosion fracture, deformation, coating peeling, foreign matter accumulation, etc., as well as information on the degree and location of the defect.

[0127] Once the model detects an anomaly, the system automatically generates an alarm and dispatches a repair work order to the responsible person to ensure timely handling. The responsible person completes the repair and provides feedback, forming a closed-loop problem resolution process. Continuous model optimization improves defect identification accuracy and operational efficiency.

[0128] It is understood that the various method embodiments mentioned above in this invention can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this invention will not elaborate further.

[0129] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0130] Existing methods for inspecting transmission towers are slow, requiring inspectors to climb to higher elevations for monitoring; subtle defects are difficult to detect with the naked eye, and the probability of detecting slightly loose bolts (e.g., loosening angle less than 5°) or bolts in hidden locations is only about 30%-40%; fault location relies on experience-based judgment, resulting in significant positioning errors, with an average error of ±5 meters; tower climbing inspections pose high safety risks, with statistics showing that 1-2 safety accidents (such as falls from heights, electric shocks, etc.) may occur in every 1000 tower climbing inspections; inspections are almost impossible in severe weather (such as typhoons, heavy rains, snow, etc.), and inspected towers may still have undetected safety hazards after severe weather; manual recording of inspection results leads to scattered data that is difficult to analyze systematically; the accuracy and completeness of the data are difficult to guarantee, and there may be delays from recording to analysis; labor costs are high, and specialized protective equipment is required; special areas (such as uninhabited areas and mining subsidence areas) require additional manpower and resources, making each inspection even more costly.

[0131] This invention offers high detection efficiency. Through 4-8 tapping excitations, it can diagnose defects such as loose bolts and cracks—defects difficult to detect by drones or other visual inspections—in approximately 10 minutes. It can accurately detect bolt loosening; using advanced vibration acceleration sensors and model algorithms, it can detect minute changes in bolt loosening angles of less than 1°, achieving an accuracy rate of over 90%. Utilizing sensor array phase difference analysis, the location of loosening points can be pinpointed with an accuracy within ±1 meter. This reduces close-contact operations such as manual tower climbing, allowing maintenance personnel to view and analyze data primarily in a safe environment, significantly reducing the accident rate and effectively improving the safety and reliability of power facilities while lowering the cost and risk of manual inspections. It achieves automatic data collection and storage, with data uploaded to the cloud for systematic analysis. Data accuracy and completeness are high, with analysis taking only a few minutes from collection. The hardware cost per tower is approximately 5000-8000 RMB, with an estimated service life of 5-8 years. Considering the entire service life, the annual maintenance cost is approximately 1000 RMB.

[0132] This invention reduces manual operation, lowers the risks of working in dangerous environments such as high altitudes and high voltages, ensures the personal safety of inspection personnel, and reduces the occurrence of accidents. Simultaneously, it can detect various hidden defects in towers with precision and comprehensiveness, effectively reducing the probability of tower collapse due to improper maintenance and avoiding huge costs such as line repair, equipment replacement, power outage losses, and potential third-party compensation caused by major accidents like tower collapse. Timely detection and handling of hidden defects ensure the stability of towers and the normal operation of power facilities, reducing the frequency and duration of power outages caused by equipment failures, improving the reliability and stability of power supply, and providing more reliable power security for social production and daily life. It realizes a shift in operation and maintenance mode from post-fault emergency repair to pre-defect intervention, with economic benefits that are both short-term visible and long-term sustainable, and is suitable for large-scale management scenarios of transmission networks.

[0133] The advantages of this invention include at least the following: 1. Replacement of high-frequency inspections: It replaces manual climbing of towers to check bolt conditions, reducing the risks of high-altitude operations and lowering the risk of accidents. 2. Preventative maintenance: Early detection and warning of loose bolts prevents major accidents such as tower collapse and conductor breakage. 3. Precise defect location: It pinpoints specific loose bolts, avoiding blind repairs caused by vague judgments in traditional methods. 4. Timely repair of minor defects prevents structural damage, extending tower life by 5-10 years, and saving 200,000-500,000 yuan in replacement costs per tower. 5. Long-term accumulated vibration spectrum data can be used to establish a tower health database, supporting AI model training and optimizing bolt design standards.

[0134] Compared with traditional inspection methods, this invention has significant advantages in detection sensitivity, accuracy, data management and analysis. It can detect more than 80% of hidden defects that are difficult to find by manual inspection, effectively solves many drawbacks of traditional inspection, and has strong market competitiveness and promotion value.

[0135] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for detecting hidden defects in iron towers based on vibration acceleration, characterized in that, include: Based on the structural characteristics of the transmission tower, a corresponding finite element simulation model is established. Based on this model, a comparative analysis of the modal and vibration responses of the transmission tower structure before and after damage is conducted. Based on the analysis results, the preliminary locations of the monitoring points for the transmission tower are determined. A test transmission tower was selected for vibration detection experiments to assess tower damage and health status. During the experiment, damage points were set, and vibration acceleration sensor measuring points were arranged according to the initial layout. A unit load was applied to the test transmission tower at a predetermined excitation position. Based on the data collected by the vibration acceleration sensors, a normalized frequency response curve of the measuring points as a function of frequency was plotted. The normalized frequency response curve was analyzed to determine whether the accuracy of identifying hidden defects in the transmission tower based on the sensor data after the initial layout met the requirements. If not, the layout was adjusted, and the adjusted layout was determined as the final layout. Vibration acceleration sensors are deployed and tested on the transmission tower to be tested based on the final location of the sensors, and hidden defects in the transmission tower are identified based on the test results.

2. The method for detecting hidden defects in iron towers based on vibration acceleration according to claim 1, characterized in that, The method for establishing a corresponding finite element simulation model based on the structural characteristics of the transmission tower includes: The structural features include, but are not limited to: height, spacing between adjacent tower legs, main structure, main stiffener structure, secondary stiffener structure, cross-sectional shape, and cross-sectional dimensions; Based on the structural features, a simulation model of the transmission tower is established, and fixed constraints are applied to the bottom of the model structure to simulate the concrete pouring at the bottom of each leg of the actual transmission tower.

3. The method for detecting hidden defects in iron towers based on vibration acceleration according to claim 1, characterized in that, The method for comparing the modal and vibration responses of the transmission tower structure before and after damage based on the model, and determining the preliminary locations of monitoring points for the transmission tower based on the analysis results, includes: The comparative analysis of modal responses before and after damage to the transmission tower structure includes: Two typical damage states were selected, and the mode shape cloud diagrams of the model after damage were obtained. The mode shape cloud diagrams of the model before and after damage were compared to determine the stiffeners that had a predetermined impact on the dynamic performance of the model before and after damage. The comparative analysis of vibration response before and after damage to the transmission tower structure includes: Assessment points are set on the stiffeners that reach the predetermined level of influence. Before and after the model is damaged, unit load and / or triangular pulse load are applied to the predetermined excitation position of the model structure to obtain vibration acceleration data at each assessment point. Vibration transfer function curves are plotted based on these data. The vibration transfer function curve is analyzed to determine the location of the assessment point where the difference in vibration morphology before and after the damage reaches a first predetermined difference or more, which is the initial layout location.

4. The method for detecting hidden defects in iron towers based on vibration acceleration according to claim 3, characterized in that, The method for plotting the vibration transfer function curve includes: Based on the vibration response spectrum of the model tower collected by the vibration acceleration sensor, an FFT transformation is performed to convert the vibration acceleration into a vibration acceleration level, and the vibration transfer function curve of the vibration acceleration level versus frequency is plotted.

5. The method for detecting hidden defects in iron towers based on vibration acceleration according to claim 1, characterized in that, Setting damage points includes: Loosen the main frame nuts, oblique frame nuts, and nuts near and far from the measuring point of the experimental transmission tower.

6. The method for detecting hidden defects in iron towers based on vibration acceleration according to claim 1, characterized in that: The predetermined excitation location is: one-third of the way down the transmission tower structure from the ground. And / or, The vibration acceleration sensor is a single-channel acceleration sensor, and all data collected by the vibration acceleration sensor is transmitted to the server after being acquired by a multi-channel data acquisition instrument.

7. The method for detecting hidden defects in iron towers based on vibration acceleration according to claim 1, characterized in that, The method for applying a unit load includes: The transmission tower is struck with a hammer, with the striking force ranging from 5 to 20 N. The force is increased by 5 N each time.

8. The method for detecting hidden defects in iron towers based on vibration acceleration according to claim 1, characterized in that: The vibration monitoring experiment for tower damage and health status includes several sets of experimental data. The normalized frequency response curve of the measuring point as a function of frequency is the frequency response curve corresponding to each measuring point after the average value of several sets of experimental data is calculated and normalized.

9. The method for detecting hidden defects in iron towers based on vibration acceleration according to any one of claims 1-8, characterized in that, The method for analyzing the normalized frequency response curve to determine whether the accuracy of identifying hidden defects in transmission towers based on sensor data collected after sensor placement according to the initial location meets the requirements includes: Among all the measuring points, the normalized frequency response curves of the measuring points when the damage point is close to the impact position are analyzed to determine whether the difference in vibration response before and after the transmission tower damage reaches the second predetermined difference. If so, the accuracy of the measuring point identification meets the requirements. Among all measuring points, the normalized frequency response curves corresponding to the measuring points when the damage point is far from the impact position are analyzed to determine whether the difference in vibration response before and after the transmission tower damage reaches the third predetermined difference. If so, the accuracy of the measuring point identification meets the requirements.

10. The method for detecting hidden defects in iron towers based on vibration acceleration according to claim 9, characterized in that: The normalized frequency response curves of the measuring points as a function of frequency are analyzed to determine the differences in vibration response corresponding to damage points at different locations. Based on the differences in vibration response corresponding to the damage points, the location of the damage points on the transmission tower to be tested is determined.

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