Bolt looseness and structure crack composite fault detection method and system, equipment and medium

Abstract

The invention relates to the technical field of nuclear power equipment detection, in particular to a bolt looseness and structure crack composite fault detection method and system, equipment and a medium, the structure provided by the invention is adopted, and the method mainly comprises the following steps: acquiring an acquired monitoring signal and a reference signal which does not generate bolt looseness and crack; and a difference signal between the monitoring signal and the reference signal is calculated, an amplitude judgment threshold value is set, whether the current bolt is abnormal or not is output according to the amplitude judgment threshold value, the difference signal and the transmission time, and the abnormity comprises a second signal that the bolt is loosened, or cracked, or both loosened and cracked. According to the method, a symmetrical piezoelectric sensor arrangement form is designed, the difference between the bolt looseness and the structure crack on the guided wave signal is combined, the difference signal between the reference signal and the monitoring signal is calculated, and the difference signal is compared with the amplitude discrimination threshold value, so that the bolt looseness and structure crack composite fault is distinguished.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power equipment detection, and in particular to a method, system, equipment and medium for detecting a combined fault of bolt loosening and structural cracks. Background Art

[0002] Bolts, as the most basic connecting parts, are widely used in various fields, such as nuclear capacitor pipeline flange sealing bolt connection structure, aircraft ear structure, wind turbine blade root pitch bearing bolt connection structure, railway switch locking bolt connection structure, etc., one is to play the role of connection and tightening, the other is to play the role of force transmission, etc. During long-term use, they are prone to loosening due to alternating loads and vibration; on the other hand, at the bolt connection part, due to the action of the bolt pre-tightening force, stress concentration occurs locally in the structure, resulting in fatigue cracks in the structure during long-term service due to the action of alternating loads.

[0003] However, in the existing technology, generally only the bolt failure signal is detected, but it is not possible to distinguish whether the bolt is loose or has a fault. The operation and maintenance personnel cannot obtain the current bolt problem in a timely and accurate manner. Therefore, there is an urgent need for an effective monitoring method to realize the monitoring and differentiation of the combined failure of bolt loosening and structural cracks, and provide accurate maintenance strategies for the operation and maintenance personnel. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system, equipment and medium for detecting a combined fault of bolt loosening and structural cracks, so as to solve the above-mentioned problems in the prior art.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for detecting and distinguishing a combined fault of bolt loosening and structural cracks comprises:

[0007] Obtain the collected monitoring signal and a reference signal without bolt loosening and cracking, and calculate the relative energy change index based on the monitoring signal and the reference signal;

[0008] Setting a first judgment threshold, and reacquiring the monitoring signal if the energy change index does not exceed the first judgment threshold;

[0009] If the energy change index exceeds the first judgment threshold, the group velocity of the guided wave propagation and the position of the reflected signal wave packet generated by the bolt hole reflection are obtained, and the transmission time is obtained through the group velocity and the position of the reflected signal wave packet;

[0010] Calculate the difference signal between the monitoring signal and the reference signal, set the amplitude discrimination threshold, and output whether the current bolt has an abnormality or not based on the amplitude discrimination threshold, the difference signal and the transmission time. The abnormality includes looseness, cracks, or a second signal with both looseness and cracks.

[0011] Preferably, the second signal outputting, according to the amplitude discrimination threshold, the difference signal and the transmission time, indicating that the current bolt is loose, cracked, or both loose and cracked, comprises:

[0012] If there is a wave packet with an amplitude greater than the amplitude discrimination threshold among the difference signals, and the generation time corresponding to the amplitude is the same as the transmission time, then the result that the current bolt is only loose is output;

[0013] If there is one or more wave packets with amplitudes greater than the amplitude discrimination threshold in the difference signals, and the generation time and transmission time corresponding to the amplitude are different, then the result that only cracks have occurred in the current bolt is output;

[0014] If there is more than one wave packet with an amplitude greater than the amplitude discrimination threshold in the difference signals, and the generation time corresponding to one of the amplitudes is the same as the transmission time, then the result of the current bolt being loose or cracked is output;

[0015] If the amplitudes of the difference signals are all less than the wave packet of the amplitude discrimination threshold, the result indicating that the current bolt has no abnormality is output.

[0016] Preferably, the calculating the relative energy change index by monitoring the signal and the reference signal comprises:

[0017] D1=(E(D(t))-E(H(t))) / E(H(t))

[0018] Where D1 is the relative energy change index, E(H(t)) is the signal energy of the reference signal at time t, and E(D(t)) is the signal energy of the monitoring signal at time t.

[0019] Preferably, obtaining the transmission time by using the group velocity and the position of the reflected signal wave packet includes:

[0020]

[0021] Where, t d0 is the transmission time, d is the position of the reflected signal wave packet, that is, the distance from the bolt hole to the sensor, v g is the group velocity.

[0022] Preferably, the calculating the difference signal between the monitoring signal and the reference signal comprises:

[0023] Δd(t)=D(t)-H(t)

[0024] Where Δd(t) is the difference signal at time t, D(t) is the monitoring signal at time t, and H(t) is the reference signal at time t.

[0025] In a second aspect, the present invention provides a bolt loosening and structural crack combined fault detection system, comprising:

[0026] The user management module is used to obtain the user's username and password, and send the username and password to the server for verification. If the verification is correct, a permission signal is sent to read the data. If the verification is wrong, no action is taken;

[0027] Monitoring parameter setting module, used to set excitation parameters and acquisition parameters;

[0028] Signal acquisition module, used for collecting reference signals and monitoring signals;

[0029] A fault diagnosis module, configured to execute the above-mentioned method for detecting a combined fault of loose bolts and structural cracks;

[0030] The data display module is used to display the diagnosis results of the fault diagnosis module and the signals collected by the signal acquisition module;

[0031] The data management module is used to save the diagnosis results of the fault diagnosis module and the signals collected by the signal acquisition module.

[0032] In a third aspect, the present invention further provides a device for detecting a combined fault of loose bolts and structural cracks, comprising a first sensor, a second sensor, and the above-mentioned combined fault detection system of loose bolts and structural cracks;

[0033] The first sensor and the second sensor are respectively arranged on the structure to be measured, and the signal output ends of the first sensor and the second sensor are connected to the detection system.

[0034] Preferably, including:

[0035] The first sensor is used to generate an excitation signal;

[0036] The second sensor is used to collect the signal transmitted back by the bolt after the excitation signal generated by the first sensor, as a reference signal.

[0037] Preferably, the structure to be measured includes two connecting plates and bolts, and the two connecting plates are connected by bolts.

[0038] In a fourth aspect, the present invention further provides a computer-readable storage medium storing a computer program, which implements the above-mentioned method for detecting a combined fault of bolt loosening and structural cracks when executed by a processor.

[0039] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0040] The structure provided by the present invention mainly includes obtaining the collected monitoring signal and the reference signal without bolt loosening and cracking, calculating the difference signal between the monitoring signal and the reference signal, and setting the amplitude discrimination threshold. According to the amplitude discrimination threshold, the difference signal and the transmission time, the second signal indicating whether the current bolt has an abnormality or not is output, wherein the abnormality includes looseness, cracking, or both looseness and cracking. Through the above method, the piezoelectric sensor and the monitoring system are used to excite and respond to the guided wave signal in the structure to obtain the monitoring signal for detecting bolt loosening and structural cracking; the signal energy change is used to preliminarily identify whether there is a fault in the structure; a symmetrical piezoelectric sensor arrangement is designed, and the difference signal between the reference and monitoring signals is calculated in combination with the different effects of bolt loosening and structural cracking on the guided wave signal, and the difference signal is compared with the amplitude discrimination threshold to achieve the distinction between the combined fault of bolt loosening and structural cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 It is a control flow diagram of the present invention;

[0043] Figure 2 Schematic diagram of the device structure of the present invention;

[0044] Figure 3 This is intended to illustrate the impact of structural cracks on monitoring signals in the present invention. DETAILED DESCRIPTION

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0046] The terms "first," "second," and so on, in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The naming or numbering of steps in this application does not necessarily imply that the steps in the method flow must be executed in the chronological or logical order indicated by the naming or numbering. Named or numbered process steps may be executed in a different order based on the desired technical objectives, as long as the same or similar technical effects are achieved.

[0047] Please refer to Figure 1-Figure 3 A method for detecting and distinguishing a combined fault of bolt loosening and structural cracks, comprising:

[0048] S101: Obtaining the collected monitoring signal and a reference signal in which no bolt loosening or cracking occurs, and calculating a relative energy change index based on the monitoring signal and the reference signal;

[0049] In the present invention, the reference signal is the signal received by the second sensor after the excitation signal is applied to the first sensor under the condition that the structure has no loose bolts and cracks. The monitoring signal is the signal received by the current detection. Through the relative energy change between the monitoring signal and the reference signal, it is possible to preliminarily obtain the current state of the bolt and whether an abnormality has occurred.

[0050] S102: setting a first judgment threshold, and reacquiring a monitoring signal if the energy change index does not exceed the first judgment threshold;

[0051] When the value exceeds the first judgment threshold, it can be confirmed that the bolt has an abnormality. If the value does not exceed the first judgment threshold, it means that the bolt has no abnormality at this time, and the monitoring signal continues to be collected and the work cycle continues.

[0052] If either loose bolts or cracks occur in the structure, or both occur simultaneously, the relative energy change index will undergo a sudden change. By setting a reasonable discrimination threshold, if the relative energy change index exceeds the discrimination threshold, it is identified that loose bolts, cracks, or both occur in the structure.

[0053] S103: If the energy variation index exceeds a first judgment threshold, the group velocity of the guided wave propagation and the position of the reflected signal wave packet generated by the bolt hole reflection are obtained, and the transmission time is obtained based on the group velocity and the position of the reflected signal wave packet;

[0054] The reflected signal wave packet refers to the wave packet formed when part of the signal energy is reflected back to the source end due to encountering an impedance mismatch interface or obstacle during the signal propagation process.

[0055] S104: Calculate the difference signal between the monitoring signal and the reference signal, and set the amplitude discrimination threshold, and output whether the current bolt has an abnormality or not according to the amplitude discrimination threshold, the difference signal and the transmission time, wherein the abnormality includes looseness, cracks, or a second signal in which both looseness and cracks exist.

[0056] The structure provided by the present invention mainly includes obtaining the collected monitoring signal and the reference signal of no bolt loosening and cracking, calculating the difference signal between the monitoring signal and the reference signal, and setting the amplitude discrimination threshold, and outputting whether the current bolt has an abnormality or not according to the amplitude discrimination threshold, the difference signal and the transmission time, wherein the abnormality includes loosening, or cracking, or a second signal of both loosening and cracking. Through the above method, piezoelectric sensors and monitoring systems are used to excite and respond to guided wave signals in the structure to obtain monitoring signals for detecting bolt loosening and structural cracks; signal energy changes are used to preliminarily identify whether there is a fault in the structure; a symmetrical piezoelectric sensor arrangement is designed, and the difference signal between the reference and monitoring signals is calculated in combination with the different effects of bolt loosening and structural cracks on the guided wave signal, and the difference signal is compared with the amplitude discrimination threshold to achieve the distinction between the combined faults of bolt loosening and structural cracks.

[0057] In an exemplary embodiment of the present invention, the second signal indicating that the current bolt is loose, cracked, or both loose and cracked is output based on the amplitude discrimination threshold, the difference signal, and the transmission time includes:

[0058] When loose bolts or cracks are identified in the structure, the two faults can be distinguished based on the differences in signal feature changes caused by loose bolts and cracks.

[0059] When the bolts loosen, the contact area between the upper and lower connectors decreases, resulting in a decrease in the energy of the guided wave signal, which is reflected in a decrease in the amplitude of the signal. When a crack appears in the structure, the guided wave propagates to the crack location and scatters due to the change in boundary conditions caused by the crack, generating scattered waves. These are also detected by the sensor, resulting in a strong scattered waveband in the signal. Based on the impact of the two aforementioned faults on guided waves, combined with the sensor layout and signal analysis method, fault differentiation can be achieved. The specific implementation process is as follows:

[0060] If there is a wave packet with an amplitude greater than the amplitude discrimination threshold among the difference signals, and the generation time corresponding to the amplitude is the same as the transmission time, then the result that the current bolt is only loose is output;

[0061] If there is one or more wave packets with amplitudes greater than the amplitude discrimination threshold in the difference signals, and the generation time and transmission time corresponding to the amplitude are different, then the result that only cracks have occurred in the current bolt is output;

[0062] If there is more than one wave packet with an amplitude greater than the amplitude discrimination threshold in the difference signals, and the generation time corresponding to one of the amplitudes is the same as the transmission time, then the result of the current bolt being loose or cracked is output;

[0063] If the amplitudes of the difference signals are all less than the wave packet of the amplitude discrimination threshold, the result indicating that the current bolt has no abnormality is output.

[0064] Specifically, calculating the relative energy change index using the monitoring signal and the reference signal includes:

[0065] D1=(E(D(t))-E(H(t))) / E(H(t))

[0066] Where D1 is the relative energy change index, E(H(t)) is the signal energy of the reference signal at time t, and E(D(t)) is the signal energy of the monitoring signal at time t.

[0067] Secondly, obtaining the transmission time by using the group velocity and the position of the reflected signal wave packet includes:

[0068]

[0069] Where, t d0 is the transmission time, d is the position of the reflected signal wave packet, that is, the distance from the bolt hole to the sensor, v g is the group velocity.

[0070] Preferably, the calculating the difference signal between the monitoring signal and the reference signal comprises:

[0071] Δd(t)=D(t)-H(t)

[0072] Where Δd(t) is the difference signal at time t, D(t) is the monitoring signal at time t, and H(t) is the reference signal at time t.

[0073] In a second aspect, the present invention provides a bolt loosening and structural crack combined fault detection system, comprising:

[0074] The user management module is used to obtain the user's username and password, and send the username and password to the server for verification. If the verification is correct, a permission signal to read the data is sent. If the verification is incorrect, no action is taken. It also includes querying usernames and permissions; adding users; viewing historical login users, including users, entry time, and exit time, and users can modify their usernames and passwords.

[0075] Monitoring parameter setting module, used to set excitation parameters and acquisition parameters. Excitation parameters include excitation frequency, excitation delay, excitation signal length, excitation channel, etc. Acquisition parameters include sampling frequency, sampling length, amplification factor, averaging times, etc. Signal acquisition module, used to collect reference signals and monitoring signals;

[0076] A fault diagnosis module, configured to execute the above-mentioned method for detecting a combined fault of loose bolts and structural cracks;

[0077] The data display module is used to display the diagnosis results of the fault diagnosis module and the signals collected by the signal acquisition module;

[0078] The data management module is used to save the diagnosis results of the fault diagnosis module and the signals collected by the signal acquisition module.

[0079] In a third aspect, the present invention further provides a device for detecting a combined fault of loose bolts and structural cracks, comprising a first sensor, a second sensor, and the above-mentioned combined fault detection system of loose bolts and structural cracks;

[0080] The first sensor and the second sensor are respectively arranged on the structure to be measured, and the signal output ends of the first sensor and the second sensor are connected to the detection system.

[0081] Specifically, both the first and second sensors are piezoelectric sensors, coupled to the structure via adhesive and welded to a coaxial cable, which is then connected to the monitoring system. The first sensor is located on the upper surface of the connector, while the second sensor is located on the lower surface, symmetrically with the first sensor. The distance between the first sensor and the bolt hole is measured and recorded.

[0082] During the monitoring process, first, after confirming that there are no loose bolts or cracks in the structure, an excitation signal is applied to the first sensor, and the response signal of the second sensor is collected and stored as a reference signal; after loose bolts and cracks occur in the structure, the above steps are repeated to collect and store the monitoring signal.

[0083] The first sensor is used to generate an excitation signal;

[0084] The second sensor is used to collect the signal transmitted back by the bolt after the excitation signal generated by the first sensor, as a reference signal.

[0085] Preferably, the structure to be measured includes two connecting plates and bolts, and the two connecting plates are connected by bolts.

[0086] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0087] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. The computer software product is stored in a storage medium and includes a number of instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the various embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, optical disks, and other media that can store program code.

[0088] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for detecting and distinguishing a combined fault of loose bolts and structural cracks, characterized in that: include: Obtain the collected monitoring signal and a reference signal without bolt loosening and cracking, and calculate the relative energy change index based on the monitoring signal and the reference signal; Setting a first judgment threshold, and reacquiring the monitoring signal if the energy change index does not exceed the first judgment threshold; If the energy change index exceeds the first judgment threshold, the group velocity of the guided wave propagation and the position of the reflected signal wave packet generated by the bolt hole reflection are obtained, and the transmission time is obtained through the group velocity and the position of the reflected signal wave packet; Calculate the difference signal between the monitoring signal and the reference signal, set the amplitude discrimination threshold, and output whether the current bolt has an abnormality or not based on the amplitude discrimination threshold, the difference signal and the transmission time. The abnormality includes looseness, cracks, or a second signal with both looseness and cracks.

2. A method for detecting and distinguishing a combined fault of bolt loosening and structural cracks according to claim 1, characterized in that: The second signal outputting, according to the amplitude discrimination threshold, the difference signal and the transmission time, indicating that the current bolt is loose, cracked, or both loose and cracked, includes: If there is a wave packet with an amplitude greater than the amplitude discrimination threshold among the difference signals, and the generation time corresponding to the amplitude is the same as the transmission time, then the result that the current bolt is only loose is output; If there is one or more wave packets with amplitudes greater than the amplitude discrimination threshold in the difference signals, and the generation time and transmission time corresponding to the amplitude are different, then the result that only cracks have occurred in the current bolt is output; If there is more than one wave packet with an amplitude greater than the amplitude discrimination threshold in the difference signals, and the generation time corresponding to one of the amplitudes is the same as the transmission time, then the result of the current bolt being loose or cracked is output; If the amplitudes of the difference signals are all less than the wave packet of the amplitude discrimination threshold, the result indicating that the current bolt has no abnormality is output.

3. The method for detecting and distinguishing a combined fault of bolt loosening and structural cracks according to claim 1, characterized in that: Calculating the relative energy change index by monitoring the signal and the reference signal includes: D1=(E(D(t))-E(H(t))) / E(H(t)) Where D1 is the relative energy change index, E(H(t)) is the signal energy of the reference signal at time t, and E(D(t)) is the signal energy of the monitoring signal at time t.

4. The method for detecting and distinguishing a combined fault of bolt loosening and structural cracks according to claim 1, characterized in that: The method of obtaining the transmission time by using the group velocity and the position of the reflected signal wave packet includes: Where, t d0 is the transmission time, d is the distance from the reflected signal wave packet position to the sensor, v g is the group velocity.

5. The method for detecting and distinguishing a combined fault of bolt loosening and structural cracks according to claim 1, characterized in that: The calculating the difference signal between the monitoring signal and the reference signal comprises: Δd(t)=D(t)-H(t) Where Δd(t) is the difference signal at time t, D(t) is the monitoring signal at time t, and H(t) is the reference signal at time t.

6. A bolt loosening and structural crack combined fault detection system, characterized in that: include: The user management module is used to obtain the user's username and password, and send the username and password to the server for verification. If the verification is correct, a permission signal is sent to read the data. If the verification is wrong, no action is taken; Monitoring parameter setting module, used to set excitation parameters and acquisition parameters; Signal acquisition module, used for collecting reference signals and monitoring signals; A fault diagnosis module, configured to execute the method for detecting a combined fault of loose bolts and structural cracks according to any one of claims 1 to 5; The data display module is used to display the diagnosis results of the fault diagnosis module and the signals collected by the signal acquisition module; The data management module is used to save the diagnosis results of the fault diagnosis module and the signals collected by the signal acquisition module.

7. A device for detecting a combined fault of loose bolts and structural cracks, characterized in that: It comprises a first sensor, a second sensor and a bolt loosening and structural crack composite fault detection system according to claim 6; The first sensor and the second sensor are respectively arranged on the structure to be measured, and the signal output ends of the first sensor and the second sensor are connected to the detection system.

8. The device for detecting a combined fault of bolt loosening and structural cracks according to claim 7, characterized in that: include: The first sensor is used to generate an excitation signal; The second sensor is used to collect the signal transmitted back by the bolt after the excitation signal generated by the first sensor, as a reference signal.

9. The device for detecting a combined fault of bolt loosening and structural cracks according to claim 7, characterized in that: The structure to be tested includes two connecting plates and bolts, and the two connecting plates are connected by bolts.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, a method for detecting a combined fault of bolt loosening and structural cracks according to any one of claims 1 to 5 is implemented.

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