Bolt loosening monitoring method and related device

Abstract

The invention discloses a bolt looseness monitoring method and a related device, and relates to the field of bolt monitoring, and the method comprises the steps: obtaining a current vibration response signal of a bolt, and carrying out the spectrum analysis, and obtaining a first frequency point set; calculating the ratio of each frequency point in the set to form a first ratio set, and establishing a first mapping relation set between each ratio and the generated frequency point pair; and in combination with the second mapping relation set, the second ratio set and the second frequency point set, determining a plurality of frequency point pair combinations, and screening to obtain a target key frequency pair containing the key current frequency point and the key fastening frequency point. And respectively calculating a first damping ratio and a second damping ratio corresponding to the two key frequency points, and determining the loose state of the bolt based on the first damping ratio and the second damping ratio. According to the invention, high-reliability and high-precision automatic monitoring of the loosening state of the bolt is realized.

Description

Technical Field

[0001] This application relates to the field of bolt monitoring, and in particular to a method and related apparatus for monitoring bolt loosening. Background Technology

[0002] Bolted connections are widely used in many engineering fields such as machinery, construction, bridges, and aerospace due to their advantages such as simple structure, low cost, strong load-bearing capacity, and convenient assembly and disassembly. They are one of the most common connection methods in various equipment and structures.

[0003] However, in actual service, bolted connections are often subjected to dynamic effects such as vibration, impact, and alternating loads, which can easily lead to a decrease in preload, resulting in loosening or even detachment, seriously affecting the safety and reliability of the structure. Traditional bolt loosening detection methods, such as the tapping method, are simple to operate, but rely on human experience, are highly subjective, and are difficult to effectively excite complete vibration modes, leading to inaccurate identification of characteristic frequencies and damping ratios, and insufficient reliability of the judgment results.

[0004] Therefore, it is particularly important to develop a monitoring method that can automatically and accurately identify the state of bolt loosening. Summary of the Invention

[0005] The purpose of this application is to provide a method and related device for monitoring bolt loosening, which can achieve accurate, stable and automated determination of bolt loosening status, and effectively overcome the shortcomings of traditional tapping method, which is highly subjective and has inaccurate feature recognition.

[0006] To achieve the above objectives, this application provides the following solution: Firstly, this application provides a method for monitoring bolt loosening, comprising: The vibration response signal of the bolt under the current state is obtained, and the first frequency point set is obtained by performing spectral analysis on the vibration response signal of the bolt under the current state.

[0007] Calculate the ratio of each frequency point in the first set of frequency points to obtain the first set of ratios.

[0008] Each ratio in the first ratio set is associated with a pair of frequency points in the first frequency point set that generate the corresponding ratio, thus obtaining the first mapping relationship set.

[0009] Based on the first mapping relationship set, the first ratio set, the first frequency point set, the second mapping relationship set, the second ratio set, and the second frequency point set, several frequency point pair combinations are determined. The second frequency point set is obtained by performing spectral analysis on the vibration response signal under bolt tightening conditions. The second ratio set is obtained by calculating the ratios of each frequency point in the second frequency point set. The second mapping relationship set is obtained by establishing a correspondence between each ratio in the second ratio set and a pair of frequency points in the second frequency point set that generate the corresponding ratio. The frequency point pair combinations include a first frequency point pair and a second frequency point pair, wherein the first frequency point pair is a pair of frequency points corresponding to a mapping relationship in the first mapping relationship set, and the second frequency point pair is a pair of frequency points corresponding to a mapping relationship in the second mapping relationship set.

[0010] Several frequency point pairs are filtered to obtain target key frequency pairs. Each target key frequency pair includes a key current frequency point and a key fixed frequency point. The key current frequency point is a frequency point from a first set of frequency points within a frequency point pair combination. The key fixed frequency point is a frequency point from a second set of frequency points within the frequency point pair combination containing the key current frequency point.

[0011] Calculate the first damping ratio at the critical current frequency point and the second damping ratio at the critical fastening frequency point, respectively.

[0012] The loosening state of the bolt is determined based on the first damping ratio and the second damping ratio.

[0013] In a second aspect, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the bolt loosening monitoring method described in any one of the above.

[0014] Thirdly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the bolt loosening monitoring method described above.

[0015] Fourthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the bolt loosening monitoring method described above.

[0016] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a method and related device for monitoring bolt loosening. By introducing a frequency ratio correlation and mapping mechanism, it effectively identifies the corresponding characteristic frequency points of the bolt's tightening state and current state, overcoming the problems of inaccurate characteristic frequency identification and unstable damping ratio estimation caused by the traditional tapping method due to its strong subjectivity and insufficient modal excitation. Furthermore, by constructing a frequency ratio mapping relationship and screening corresponding frequency point pairs, it can accurately identify the characteristic frequency changes caused by bolt loosening and eliminate the influence of random tapping factors. Further, by combining damping ratio calculation and comparative analysis at key frequency points, it significantly improves the reliability and sensitivity of loosening judgment, making it particularly suitable for rapid, automated monitoring and safety early warning of bolt connection status in engineering sites. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is an application environment diagram of a bolt loosening monitoring method according to an embodiment of this application; Figure 2 A schematic flowchart illustrating a bolt loosening monitoring method provided in one embodiment of this application; Figure 3 The spectrum of the vibration response signal under bolt tightening conditions; Figure 4 This is a spectrum diagram of the vibration response signal of the bolt under its current state. Figure 5 This is a schematic diagram of the linear decreasing curve of the energy logarithmic sequence of the first filtered signal; Figure 6 A schematic diagram showing the installation of bolted connections and an acceleration sensor; Figure 7 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application.

[0019] Attached image labels: 102 Terminal, 104 Storage Server. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] The bolt loosening monitoring method provided in this application embodiment can be applied to, for example... Figure 1 In the application environment shown, terminal 102 communicates with server 104 via a network. A data storage system can store the data that server 104 needs to process. The data storage system can be set up independently, integrated into server 104, or placed in the cloud or on another server. Terminal 102 can send the vibration response signal of the bolt in its current state to server 104. Server 104 receives the vibration response signal of the bolt in its current state. For the vibration response signal of the bolt in its current state, server 104 performs spectral analysis on the vibration response signal of the bolt in its current state to obtain a first set of frequency points; calculates the ratio of each frequency point in the first set of frequency points to obtain a first set of ratios; establishes a correspondence between each ratio in the first set of ratios and a pair of frequency points in the first set of frequency points that generate the corresponding ratio to obtain a first set of mapping relationships; based on the first set of mapping relationships, the first set of ratios, the first set of frequency points, the second set of mapping relationships, the second set of ratios, and the second set of frequency points, determines several combinations of frequency point pairs; filters the several combinations of frequency point pairs to obtain target key frequency pairs; the target key frequency pairs include key current frequency points and key fastening frequency points; calculates the first damping ratio at the key current frequency point and the second damping ratio at the key fastening frequency point; and determines the loosening state of the bolt based on the first damping ratio and the second damping ratio. Server 104 can feed back the obtained bolt loosening status to terminal 102. Furthermore, in some embodiments, the bolt loosening monitoring method can also be implemented by either server 104 or terminal 102 independently. For example, terminal 102 can directly determine the bolt loosening status based on the vibration response signal of the bolt in its current state, or server 104 can obtain the vibration response signal of the bolt in its current state from the data storage system and determine the bolt loosening status based on the vibration response signal.

[0023] The terminal 102 can be, but is not limited to, various desktop computers, laptops, and IoT devices. The server 104 can be implemented using a standalone server or a server cluster consisting of multiple servers, or it can be a cloud server.

[0024] In one exemplary embodiment, such as Figure 2As shown, a method for monitoring bolt loosening is provided. This method is executed by a computer device, specifically a terminal or server, or both. In this embodiment, the method is applied to... Figure 1 Taking server 104 as an example, the explanation includes the following steps 201 to 207. Wherein: When bolts are in a tightened state, typically after initial tightening and before use, at their maximum tightening torque, an accelerometer is installed on the bolt connection. A hammer is used to tap the side of the nut or bolt head, and the accelerometer collects the vibration response signal detected by the bolt under tightened conditions. Multiple taps are performed, and the signal with the highest characteristic frequency is selected as the vibration response signal for the tightened bolt. After the bolts have been in use for a period of time, typically during periodic inspections, such as every six months, a hammer is used to tap the side of the nut or bolt head, and the accelerometer collects the vibration response signal detected by the bolt under its current state. A schematic diagram of the bolt connection and accelerometer installation is shown below. Figure 6 As shown.

[0025] Step 201: Obtain the vibration response signal of the bolt in its current state, and perform spectral analysis on the vibration response signal to obtain a first set of frequency points. In this step, firstly, find the point with the largest amplitude in the spectrum of the vibration response signal of the bolt in its current state. Set an amplitude threshold based on a preset proportion of the amplitude of the largest amplitude point. In the spectrum of the vibration response signal of the bolt in its current state, find all peak points with amplitudes higher than the amplitude threshold. Use the frequencies corresponding to the peak points as characteristic frequency points in the first set of frequency points. The preset proportion can be 10%.

[0026] Step 202: Calculate the ratio of each frequency point in the first frequency point set. (Assuming the first set of frequency points contains) n Each frequency point, For the first frequency point set, the first i Each frequency point, For the first frequency point set, the first j Each frequency point, i=1,2,3..., j=1,2,3... ,and i>j ), thus obtaining the first set of ratios.

[0027] Step 203: Establish a correspondence between each ratio in the first ratio set and a pair of frequency points in the first frequency point set that generate the corresponding ratio, thereby obtaining a first mapping relationship set.

[0028] Step 204: Based on the first mapping relationship set, the first ratio set, the first frequency point set, the second mapping relationship set, the second ratio set, and the second frequency point set, determine several frequency point pair combinations. The second frequency point set is the set obtained after performing spectral analysis on the vibration response signal under bolt tightening conditions. Corresponding to the first frequency point set, similarly, first find the point with the largest amplitude in the spectrum of the vibration response signal under bolt tightening conditions. Set an amplitude threshold based on a preset proportion of the amplitude of the point with the largest amplitude. In the spectrum of the vibration response signal under bolt tightening conditions, find all peak points with amplitudes higher than the amplitude threshold. Use the frequencies corresponding to the peak points as characteristic frequency points in the second frequency point set. The preset proportion can be 10%.

[0029] The second ratio set is the set obtained by calculating the ratios of each frequency point in the second frequency point set. That is, it involves calculating the ratios of each frequency point in the second frequency point set. （ Assuming the second set of frequency points contains p Each frequency point, The second frequency point set k Each frequency point, The second frequency point set m Each frequency point, k=1,2,3..., m=1,2,3... ,and k>m The obtained ratios are then set together to obtain the second set of ratios.

[0030] The second mapping relationship set is the set obtained by establishing a correspondence between each ratio in the second ratio set and a pair of frequency points in the second frequency point set that generate the corresponding ratio. The frequency point pair combination includes a first frequency point pair and a second frequency point pair, wherein the first frequency point pair is a pair of frequency points corresponding to a mapping relationship in the first mapping relationship set, and the second frequency point pair is a pair of frequency points corresponding to a mapping relationship in the second mapping relationship set.

[0031] Step 205: Filter the several frequency point pair combinations to obtain target key frequency pairs; the target key frequency pairs include a key current frequency point and a key fixed frequency point. The key current frequency point is a frequency point from a first frequency point set in a frequency point pair combination. The key fixed frequency point is a frequency point from a second frequency point set in the frequency point pair combination containing the key current frequency point.

[0032] Step 206: Calculate the first damping ratio at the critical current frequency point and the second damping ratio at the critical fastening frequency point, respectively.

[0033] Step 207: Determine the loosening state of the bolt based on the first damping ratio and the second damping ratio.

[0034] Implementing steps 201 to 207 above, the structural stiffness decreases after the bolts loosen, inevitably causing changes in the excited modes. The characteristic frequency will slightly decrease, while the damping ratio will significantly increase. Therefore, this application determines bolt loosening by first initially identifying the characteristic frequency, then calculating the damping ratio. Compared with existing bolt loosening detection methods, this method eliminates random factors during the tapping process, automatically identifies the characteristic frequency, and provides a more stable damping ratio calculation, making the bolt loosening judgment more accurate. Specifically, by constructing a frequency ratio mapping relationship and filtering corresponding frequency point pairs, the characteristic frequency change caused by bolt loosening can be accurately identified, eliminating the influence of random tapping factors. Furthermore, combining the damping ratio calculation and comparative analysis at key frequency points significantly improves the reliability and sensitivity of loosening judgment, making it particularly suitable for rapid, automated monitoring and safety early warning of bolt connection status in engineering sites.

[0035] In another exemplary embodiment of this application, step 204 is replaced by steps 2041-2042: Step 2041: Traverse all ratios in the first ratio set and the second ratio set, and when any first ratio in the first ratio set and any second ratio in the second ratio set satisfy a preset condition, determine the frequency point pair corresponding to the first ratio and the frequency point pair corresponding to the second ratio based on the first mapping relationship set and the second mapping relationship set.

[0036] Step 2042: Based on the frequency point pairs corresponding to the determined first ratio and the frequency point pairs corresponding to the second ratio, filter from the first frequency point set and the second frequency point set, and combine the filtered frequency point pairs to obtain several frequency point pair combinations, with 4 frequency points in each frequency point pair combination.

[0037] In another exemplary embodiment of this application, the preset conditions in step 2041 specifically include: the absolute value of the difference between the first ratio and the second ratio is less than a preset tolerance threshold; the ratio of one frequency point in the frequency point pair corresponding to the first ratio to one frequency point in the frequency point pair corresponding to the second ratio is in a first preset interval; and the ratio of another frequency point in the frequency point pair corresponding to the first ratio to another frequency point in the frequency point pair corresponding to the second ratio is in a second preset interval.

[0038] In another exemplary embodiment of this application, step 205 is replaced by steps 2051 to 2053: Step 2051: Identify all frequency points from the first frequency point set from all the frequency point pair combinations, and select the frequency point with the largest frequency value as the key current frequency point. f 0 .

[0039] Step 2052: Determine the frequency point pair combination where the key current frequency point is located, and filter the frequency points from the second frequency point set from the frequency point pair combination where the key current frequency point is located, and determine the filtered frequency points as the key fastening frequency points. f 1 .

[0040] Give an example, such as and and (Where i = 1, 2, 3..., j = 1, 2, 3..., i > j and k = 1, 2, 3..., m = 1, 2, 3..., k > m) If the above conditions are met, these four frequency points are determined to be the corresponding characteristic frequency points, and these four frequency points are combined as a set of frequency point pairs.

[0041] Using the same method, several frequency point pair combinations can be obtained, if It happens to be the maximum frequency point from the first set of frequency points, then... As the key current frequency point, and in the combination of frequency points where the key current frequency point is located, and from the second frequency point set and together with Corresponding (in ratios, both are either numerators or denominators) Determined as the critical fastening frequency point f 1 .

[0042] Step 2053: Determine the key fastening frequency point and the key current frequency point as the target key frequency pair.

[0043] In another exemplary embodiment of this application, step 206 is replaced by steps 2061 to 2064: Step 2061: Using the key current frequency point as the center frequency, perform narrowband filtering on the vibration response signal of the bolt in its current state using a first filtering bandwidth to obtain a first filtered signal; the first filtering bandwidth is determined based on the minimum frequency interval between any two different frequency points in the second frequency point set. The formula for calculating the first filtering bandwidth is as follows: ,in The first filter bandwidth, and These represent any two different frequency points in the second set of frequency points.

[0044] Step 2062: Process the first filtered signal to obtain the first damping ratio.

[0045] Step 2063: Using the key fastening frequency point as the center frequency, the vibration response signal under the bolt fastening state is narrowband filtered using the first filtering bandwidth to obtain the second filtered signal.

[0046] Step 2064: Process the second filtered signal to obtain the second damping ratio.

[0047] In another exemplary embodiment of this application, step 2062 is replaced by the following steps: Through formula Calculate the energy logarithm sequence of the first filtered signal; where, The energy logarithmic sequence of the first filtered signal. This is the first filtered signal. The integration length is set to be no less than 4 frequency cycles, i.e. ,in f 0 This is the key current frequency point.

[0048] Extract the linearly decreasing segment of the energy logarithmic sequence of the first filtered signal, such as... Figure 5 As shown, the slope of the linearly decreasing segment of the energy logarithmic sequence of the first filtered signal is obtained by fitting the linearly decreasing segment using the least squares method.

[0049] According to the formula Calculate the first damping ratio, where, For the first damping ratio, Let be the slope of the linearly decreasing segment of the energy logarithmic sequence of the first filtered signal. This is the key current frequency point.

[0050] In another exemplary embodiment of this application, step 2064 is replaced by the following steps: Through formula Calculate the energy logarithm sequence of the second filtered signal; where, The energy logarithmic sequence of the second filtered signal. This is the second filtered signal. The integration length is set to be no less than 4 frequency cycles, i.e. ,in f 1 This is the critical fastening frequency point.

[0051] Extract the linearly decreasing segment of the energy logarithmic sequence of the second filtered signal, and fit the linearly decreasing segment using the least squares method to obtain the slope of the linearly decreasing segment of the energy logarithmic sequence of the second filtered signal.

[0052] According to the formula Calculate the second damping ratio, where, The second damping ratio, Let be the slope of the linearly decreasing segment of the energy logarithmic sequence of the second filtered signal. This is the critical fastening frequency point.

[0053] In another exemplary embodiment of this application, step 207 is replaced by the following steps: when If so, the bolt is determined to be loose. The second damping ratio, This is the first damping ratio.

[0054] In another exemplary embodiment of this application, a specific implementation method is provided: like Figure 3 As shown, the vibration response signal of the bolt under the tightened state was collected using an accelerometer. The preset ratio was set to 10%, and the characteristic points in the second frequency point set were obtained as follows: 14435.4, 14069.6, 9882.01, 8797.02, 8095.36, 7237.51, 6989.12, 6669.85, 6262.67, 5668.22, 5438.67, 4425.93, 3672.06, and 3084.62.

[0055] like Figure 4 As shown, the vibration response signal of the bolt under the current state is collected using an accelerometer. The preset ratio is set to 10%, and the feature points in the first frequency point set are: 8058.9, 7696.44, 6512.09, 6132.06, 5718.31, 5096.94, 4749.63, 3916.62, and 3634.68.

[0056] Assuming that after determining a preset condition, all suitable frequency point pairs are found, and further, all characteristic frequency points that meet the preset condition are found, as shown in Table 1: Table 1 Comparison of characteristic frequencies under bolt tightened and loosened states.

[0057] Find the maximum value of all characteristic frequency points under the bolt tightened state, i.e., 8095.36, and take 8095.36 as the key tightening frequency point. Find the maximum value of all characteristic frequency points under the current state of the bolt, i.e., 7696.44, and take 7696.44 as the key current frequency point. Calculate the first damping ratio at 7696.44 and the second damping ratio at 8095.36 respectively. Based on the first damping ratio and the second damping ratio, determine the loose state of the bolt.

[0058] This application also provides an application scenario in which the above-described bolt loosening monitoring method is applied. Specifically, the bolt loosening monitoring method provided in this embodiment can be applied in the bolt connection health monitoring and safety early warning scenario. The bolt connection health monitoring and safety early warning scenario includes the initial structural state calibration stage, the periodic detection and data acquisition stage, and the loosening state determination and early warning stage. The bolt loosening monitoring method provided in this embodiment belongs to the loosening state determination and early warning stage.

[0059] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 7 As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs in the non-volatile storage media. The database stores vibration response signals of the bolts in their current state. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network. When executed by the processor, the computer program implements a method for monitoring bolt loosening.

[0060] Those skilled in the art will understand that Figure 7 The structures shown are merely block diagrams of some structures related to the present application and do not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than shown in the figures, or combine certain components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0061] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0062] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0063] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0064] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0065] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0066] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for monitoring bolt loosening, characterized in that, The method for monitoring bolt loosening includes: The vibration response signal of the bolt under the current state is obtained, and the vibration response signal of the bolt under the current state is subjected to spectral analysis to obtain a first set of frequency points; Calculate the ratio of each frequency point in the first set of frequency points to obtain the first set of ratios; Each ratio in the first ratio set is associated with a pair of frequency points in the first frequency point set that generate the corresponding ratio, thus obtaining a first mapping relationship set. Based on the first mapping relationship set, the first ratio set, the first frequency point set, the second mapping relationship set, the second ratio set, and the second frequency point set, several frequency point pair combinations are determined; the second frequency point set is a set obtained after performing spectral analysis on the vibration response signal under bolt tightening conditions; the second ratio set is a set obtained after calculating the ratio of each frequency point in the second frequency point set; the second mapping relationship set is a set obtained after establishing a correspondence between each ratio in the second ratio set and a pair of frequency points in the second frequency point set that generate the corresponding ratio; the frequency point pair combinations include a first frequency point pair and a second frequency point pair, wherein the first frequency point pair is a pair of frequency points corresponding to a mapping relationship in the first mapping relationship set, and the second frequency point pair is a pair of frequency points corresponding to a mapping relationship in the second mapping relationship set; Filtering several frequency point pairs yields target key frequency pairs; each target key frequency pair includes a key current frequency point and a key fastening frequency point; the key current frequency point is a frequency point from a first set of frequency points in a frequency point pair combination; the key fastening frequency point is a frequency point from a second set of frequency points in the frequency point pair combination containing the key current frequency point. Calculate the first damping ratio at the critical current frequency point and the second damping ratio at the critical fastening frequency point, respectively; The loosening state of the bolt is determined based on the first damping ratio and the second damping ratio.

2. The method for monitoring bolt loosening according to claim 1, characterized in that, Based on the first mapping relationship set, the first ratio set, the first frequency point set, the second mapping relationship set, the second ratio set, and the second frequency point set, several frequency point pair combinations are determined, specifically including: Traverse all ratios in the first ratio set and the second ratio set, and when any first ratio in the first ratio set and any second ratio in the second ratio set satisfy a preset condition, determine the frequency point pair corresponding to the first ratio and the frequency point pair corresponding to the second ratio based on the first mapping relationship set and the second mapping relationship set; Based on the frequency point pairs corresponding to the determined first ratio and the frequency point pairs corresponding to the second ratio, a selection is made from the first frequency point set and the second frequency point set, and the selected frequency point pairs are combined to obtain several frequency point pair combinations.

3. The method for monitoring bolt loosening according to claim 2, characterized in that, The preset conditions specifically include: The absolute value of the difference between the first ratio and the second ratio is less than a preset tolerance threshold, the ratio of one frequency point in the frequency point pair corresponding to the first ratio to one frequency point in the frequency point pair corresponding to the second ratio is in a first preset range, and the ratio of another frequency point in the frequency point pair corresponding to the first ratio to another frequency point in the frequency point pair corresponding to the second ratio is in a second preset range.

4. The method for monitoring bolt loosening according to claim 1, characterized in that, By filtering several combinations of the aforementioned frequency points, target key frequency pairs are obtained, specifically including: From all the frequency point pair combinations, identify all frequency points from the first frequency point set, and select the frequency point with the largest frequency value as the key current frequency point; Determine the frequency point pair combination where the key current frequency point is located, and filter the frequency points from the second frequency point set in the frequency point pair combination where the key current frequency point is located, and determine the filtered frequency points as the key fastening frequency points; The key fastening frequency point and the key current frequency point are determined as the target key frequency pair.

5. The method for monitoring bolt loosening according to claim 1, characterized in that, Calculate the first damping ratio at the critical current frequency point and the second damping ratio at the critical fastening frequency point, specifically including: Using the key current frequency point as the center frequency, the vibration response signal of the bolt in its current state is narrowband filtered using the first filtering bandwidth to obtain the first filtered signal; the first filtering bandwidth is determined based on the minimum frequency interval between any two different frequency points in the second frequency point set; The first filtered signal is processed to obtain the first damping ratio; Using the key fastening frequency point as the center frequency, the vibration response signal under the bolt fastening state is narrow-band filtered using the first filtering bandwidth to obtain the second filtered signal. The second filtered signal is processed to obtain the second damping ratio.

6. The method for monitoring bolt loosening according to claim 5, characterized in that, The first filtered signal is processed to obtain the first damping ratio, specifically including: Through formula Calculate the energy logarithm sequence of the first filtered signal; where, The energy logarithm sequence of the first filtered signal. This is the first filtered signal. The length of the integral; Extract the linearly decreasing segment of the energy logarithmic sequence of the first filtered signal, and fit the linearly decreasing segment using the least squares method to obtain the slope of the linearly decreasing segment; According to the formula Calculate the first damping ratio, where, For the first damping ratio, The slope of the linearly descending segment. This is the key current frequency point.

7. The method for monitoring bolt loosening according to claim 1, characterized in that, Based on the first damping ratio and the second damping ratio, the loosening state of the bolt is determined, specifically including: when If so, the bolt is determined to be loose. The second damping ratio, This is the first damping ratio.

8. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that the processor executes the computer program to implement the bolt loosening monitoring method according to any one of claims 1-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the bolt loosening monitoring method according to any one of claims 1-7.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the bolt loosening monitoring method according to any one of claims 1-7.

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