A bolt loosening monitoring washer and a monitoring method

Abstract

This invention relates to a bolt loosening monitoring washer and monitoring method. The washer includes a washer assembly (1), a triboelectric ring structure (2), and a connecting wire (3). The washer assembly (1) includes a large washer (101) and a small washer (102). The triboelectric ring structure (2) is disposed around the small washer (102), and the large washer (101) is located on both sides of the triboelectric ring structure (2) and the small washer (102). The triboelectric ring structure (2) includes a positive electrode layer, a rubber dielectric layer, and a negative electrode layer. The connecting wire (3) is connected to the positive electrode layer and the negative electrode layer of the triboelectric ring structure (2) respectively, for transmitting the signal of the potential difference on the electrode surface. Compared with the prior art, the washer of this invention has strong applicability and simple construction, providing a convenient and practical method for health monitoring of bolted connection components in engineering.

Description

Technical Field

[0001] This invention relates to the field of bolt connection condition monitoring technology, and in particular to a bolt loosening monitoring washer and monitoring method. Background Technology

[0002] Bolts are crucial connecting components in construction, machinery, and transportation engineering, and their fastening quality directly impacts the safety and reliability of structures. With the rapid pace of industrialization, the application of bolts is becoming increasingly widespread, especially in high-load, high-vibration, and harsh environments, where bolt loosening is a common and serious hazard. Therefore, online monitoring of bolt loosening is particularly important, enabling real-time early warning and reducing equipment failures or safety accidents caused by loosening.

[0003] Traditional methods for detecting bolt loosening primarily rely on physical sensors, such as strain gauges, vibration sensors, or force sensors. While each method has its own advantages and disadvantages, they all generally suffer from some limitations:

[0004] Strain gauge monitoring method: Strain gauges determine the degree of looseness by measuring the deformation of bolts, typically requiring the installation of strain sensors on the bolts or connecting components. The disadvantages of this method are the complexity of the installation process and the susceptibility of the sensors to environmental interference, such as changes in temperature and humidity, leading to unstable measurements. Furthermore, the electrical noise of the sensor itself and the transmission distance can also affect accuracy.

[0005] Vibration monitoring method: This method uses vibration sensors to monitor vibration signals generated by loose bolts during equipment operation. It is commonly used for monitoring large equipment, but the acquisition of vibration signals is greatly affected by factors such as equipment type and working environment, and it cannot immediately provide quantitative analysis of the specific degree of loosening. The vibration method often only provides indirect information about loosening and cannot accurately reflect minute changes in bolt loosening.

[0006] Force sensor monitoring method: This method uses force sensors to measure the force on bolted connections to determine if the bolts are loose. However, this method requires installing a force sensor at each bolt location, increasing cost and complexity. Furthermore, force sensors are sensitive to changes in the external environment (such as temperature and pressure), are easily affected by interference, and long-term use may lead to a decrease in measurement accuracy.

[0007] Visual inspection method: This method uses video surveillance and image processing technology to determine the looseness of bolts by observing their surface condition. While effective for detecting surface looseness in simple scenarios, it struggles to respond promptly to hidden locations or minute changes in looseness, and typically requires manual intervention, making real-time monitoring impossible.

[0008] In summary, traditional bolt loosening monitoring methods have several drawbacks, such as complex installation, high cost, susceptibility to environmental interference, and low accuracy. These problems make it difficult for traditional monitoring methods to meet the demands for high accuracy, real-time performance, and long-term stability. Especially in high-risk areas and harsh environments, traditional technologies often fail to provide sufficient safety guarantees.

[0009] To overcome these shortcomings, passive sensing technology based on the triboelectric effect has received widespread attention in recent years. The triboelectric effect generates electric charge and creates a potential difference when objects come into contact or move relative to each other; this phenomenon exhibits high sensitivity and accuracy in practical applications. Compared to traditional methods, triboelectric effect sensors offer advantages such as no external power supply required, high sensitivity, fast response speed, simple structure, and low cost. Therefore, intelligent bolt loosening monitoring systems based on the triboelectric effect have become a solution with great potential.

[0010] CN108775978A discloses a static prestress monitoring device and method based on PZT. The device collects the voltage signal of the equivalent circuit of the PZT smart washer through a lower-level computer module and transmits it to a higher-level computer for data analysis to monitor static prestress. The prestress is calculated using the correspondence between the signal oscillation period and the static prestress. However, the smart washer in CN108775978A involves pulse signal excitation. Since the working mechanism of the PZT sensor itself requires an external excitation signal, the system still needs a power supply. Compared with passive triboelectric sensors, this increases the system's complexity and power consumption.

[0011] CN118462702A discloses a smart washer and method for monitoring bolt loosening based on a triboelectric origami superstructure. The smart washer includes a washer, a spring, and the triboelectric origami superstructure. In use, the smart washer is installed between the bolt and the bolted connection component: if the bolt is not loose, the preload of the bolt compresses the spring, and the triboelectric origami superstructure has no deformation space; therefore, no electrical signal is output when a load is applied to the bolted connection component. If the bolt loosens, the spring rebounds, and the triboelectric origami superstructure has deformation space. The bolted connection component displaces under load, causing the spring to compress again, which in turn deforms the triboelectric origami superstructure, resulting in friction between the triboelectric pairs and generating an electrical signal output. After receiving the signal, the signal receiver can determine the degree of bolt loosening. However, the problem with the smart washer in CN118462702A in practical applications is that, on the one hand, the ordinary spring, which is the main load-bearing component, has insufficient load-bearing capacity, making it unable to withstand the bolt preload and prone to irreversible plastic deformation or even fracture. On the other hand, the smart washer system requires a large deformable space to work properly. However, in practical applications, when the space between the nut and the component is large enough, it often means that the nut has completely separated from the washer, and the bolt preload is close to zero, making the design unable to function in many practical scenarios.

[0012] Therefore, there is an urgent need for a smart gasket that can operate passively and respond to minute deformations. Summary of the Invention

[0013] The purpose of this invention is to provide a bolt loosening monitoring washer and monitoring method that can operate passively and respond to minute deformations.

[0014] The objective of this invention can be achieved through the following technical solution: a bolt loosening monitoring washer, comprising a washer assembly, a triboelectric ring structure, and a connecting wire;

[0015] The gasket assembly includes a large gasket and a small gasket, with a triboelectric ring structure disposed around the small gasket and the large gasket located on both sides of the triboelectric ring structure and the small gasket.

[0016] The triboelectric ring structure includes a positive electrode layer, a rubber dielectric layer, and a negative electrode layer. Connecting wires are connected to the positive electrode layer and the negative electrode layer of the triboelectric ring structure, respectively, to transmit the signal of the potential difference on the electrode surface.

[0017] In this invention, the rubber dielectric layer alters the electrode spacing through elastic rebound, thereby causing a change in potential difference and effectively reflecting the degree of bolt loosening. If the bolt is not loose, the bolt's preload compresses the triboelectric ring structure, compressing the rubber dielectric layer and reducing the electrode spacing. This results in a relatively high surface induced charge density and a large potential difference between the electrodes. Conversely, if the bolt loosens, the rebound of the rubber dielectric layer increases the electrode spacing, thus decreasing the surface induced charge density and reducing the potential difference between the electrodes.

[0018] Preferably, the outer diameter of the small pad does not exceed the inner diameter of the triboelectric ring structure.

[0019] More preferably, the outer diameter of the small pad is smaller than the inner diameter of the triboelectric ring structure.

[0020] Preferably, the inner diameters of the large and small gaskets in the gasket assembly should match each other to ensure that the bolts can pass through the gasket assembly and be secured to the bolt connection member.

[0021] Preferably, the large and small gaskets in the gasket assembly are made of stainless steel.

[0022] More preferably, the large gasket and the small gasket in the gasket assembly are made of 304 stainless steel.

[0023] Preferably, the positive electrode layer is composed of an insulating layer, a metal electrode layer and an electron-losing material layer stacked in sequence, and the negative electrode layer is composed of an electron-gaining material layer, a metal electrode layer and an insulating layer stacked in sequence, with the electron-losing material layer and the electron-gaining material layer facing each other.

[0024] More preferably, the insulating layer is a polyimide film layer.

[0025] More preferably, the metal electrode layer is an aluminum foil layer.

[0026] More preferably, the metal electrode layer is connected to a connecting wire.

[0027] More preferably, the electron-depleting material layer is a paper layer.

[0028] More preferably, the electron-generating material layer is a polytetrafluoroethylene thin film layer.

[0029] More preferably, the layers of the positive electrode layer are bonded together by adhesive.

[0030] More preferably, the layers of the negative electrode layer are bonded together by adhesive.

[0031] More preferably, the rubber dielectric layer and the electron-depleting material layer are bonded together by adhesive.

[0032] More preferably, the rubber dielectric layer and the electron-gaining material layer are bonded together by adhesive.

[0033] More preferably, each of the positive electrode layer and the negative electrode layer has a circular annular plate structure.

[0034] In this invention, a high-strength adhesive bonding process is used between the layers to ensure that delamination or detachment will not occur during long-term use.

[0035] Preferably, the rubber medium layer comprises a rubber material and a cavity;

[0036] The rubber material has a circular ring structure with a cavity.

[0037] In this invention, the rubber material has high pressure resistance, wear resistance and aging resistance, and the surface can maintain lubrication for a long time, ensuring the stability and monitoring accuracy of the gasket during long-term use.

[0038] More preferably, the rubber material has multiple cavities spaced apart circumferentially, and the cavities penetrate the rubber material along the axial direction.

[0039] More preferably, the positive electrode layer and / or negative electrode layer have a protruding structure on the side facing the rubber dielectric layer.

[0040] Preferably, the protrusion structure corresponds to the position of the cavity.

[0041] Preferably, the total thickness of the protrusion structure does not exceed the thickness of the rubber material under normal conditions.

[0042] Preferably, the connecting wire is connected to the signal receiving component.

[0043] More preferably, the signal receiving component includes a digital multimeter, and the potential difference between the positive and negative electrodes can be effectively transmitted to the digital multimeter.

[0044] More preferably, the digital multimeter is connected to a host computer, which receives and analyzes voltage signals to achieve high-precision monitoring of bolt loosening.

[0045] In this invention, changes in potential difference can be monitored in real time using a digital multimeter, thereby determining the degree of bolt loosening. Based on the magnitude of the potential difference change, the loosening of the bolt can be accurately assessed, and corresponding early warning signals can be provided.

[0046] A method for detecting bolt loosening, using the aforementioned bolt loosening detection washer, includes the following steps:

[0047] The bolt loosening monitoring washer is installed between the bolt and the bolt connection component, and the positive electrode layer and negative electrode layer of the triboelectric ring structure are respectively connected to the signal receiving component by connecting wires;

[0048] When the bolts loosen, the triboelectric ring structure generates a potential difference during deformation, which is transmitted to the signal receiving component via the connecting wire.

[0049] Preferably, the bolt loosening monitoring method specifically includes the following steps:

[0050] (a) Install the bolt loosening monitoring washer between the bolt and the bolt connection component;

[0051] (b) Connect the positive electrode layer and negative electrode layer of the triboelectric ring structure to a digital multimeter via connecting wires, and connect the digital multimeter to a host computer.

[0052] (c) When the bolt is loose, the triboelectric ring structure generates a potential difference due to the accumulation of induced charge during the deformation process. This potential difference is transmitted to a digital multimeter and received and analyzed by the host computer, which then issues an alarm and displays the degree of looseness, thereby achieving high-precision monitoring of bolt loosening.

[0053] (d) The alarm signals and loose data obtained from the analysis of the host computer are transmitted to the cloud platform through the wireless transmission module, thereby realizing remote monitoring and multi-point monitoring, and improving the coverage and real-time performance of monitoring.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] 1. The gasket of the present invention can operate passively and can respond to minute deformations.

[0056] 2. Compared with the intelligent washer for monitoring bolt loosening based on triboelectric origami superstructure, the present invention can generate a potential difference change within a tiny deformation space (i.e., a tiny displacement after the bolt loosens), and can respond to tiny deformations.

[0057] 3. This invention enables real-time monitoring of bolt loosening using a simple device, without requiring an external power source.

[0058] 4. The triboelectric ring structure of this invention, through the synergistic operation of the triboelectric ring structure and the small washer, can generate a potential difference change within a very small deformation space (i.e., the tiny displacement after bolt loosening). Traditional bolt loosening monitoring systems require a large deformation space to accurately respond to bolt loosening, at which point the bolt preload is often significantly reduced, or even zero, making it difficult for traditional monitoring systems to accurately detect the loosening state in the initial stage. In contrast, this invention uses the principle of triboelectric effect, which can accurately detect bolt loosening even with a small loss of preload, avoiding the shortcomings of traditional systems that cannot work effectively when space is insufficient or preload is reduced, and has better adaptability in a wider range of application scenarios.

[0059] 5. This invention addresses the limitations of existing bolt loosening monitoring technologies, which typically rely on external excitation signals and power supplies to maintain sensor operation. It proposes a smart washer and method for bolt loosening monitoring based on the triboelectric effect. The bolt loosening monitoring system derived from this invention requires no external power supply or excitation signal. The triboelectric effect generates charge through physical contact and friction. Changes in preload affect the distribution of induced charge on the electrode surface, leading to changes in potential difference, thereby achieving accurate monitoring of bolt loosening status. This design greatly simplifies the system structure, making it suitable for applications where continuous power is difficult to provide, such as offshore platforms and high-pressure vessels. This innovative design significantly improves the system's energy efficiency while reducing long-term costs and complexity.

[0060] 6. This invention establishes a quantitative relationship between the degree of bolt loosening and the potential difference through the design of a triboelectric ring structure. It can accurately capture changes in the potential difference between the electrodes during bolt loosening. These signals are transmitted and further processed and analyzed via a digital multimeter connected to a host computer, thus achieving high-precision monitoring of the bolt loosening state. Especially in the early stages of bolt loosening, even very small displacement changes can be quickly detected by the monitoring system, which promptly issues an alarm and displays the specific degree of loosening. Through this high-precision monitoring and real-time alarm function, this invention effectively improves equipment safety, ensuring timely intervention before bolt loosening reaches a dangerous level, thus preventing accidents. Simultaneously, this precise monitoring method provides more efficient decision support for equipment maintenance and management, and has significant application value, particularly in large-scale industrial equipment and important engineering structures.

[0061] 7. The gasket of this invention has strong applicability and simple structure, providing a convenient and practical method for health monitoring of bolted connection components in engineering.

[0062] 8. This invention integrates triboelectric effect sensing technology, which can be used to monitor the looseness of bolted connections with high precision, and can be widely used in online detection and fault early warning of bolted connections in industries, machinery, construction and other fields.

[0063] 9. The triboelectric ring structure of the present invention is based on the triboelectric effect, requires low-cost raw materials with a wide range of choices, and has a simple preparation method. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the bolt loosening monitoring washer of the present invention;

[0065] Figure 2 This is a schematic diagram of the exploded structure of a triboelectric ring structure according to the present invention;

[0066] Figure 3 This is a schematic diagram of the working principle of the cross-section of a triboelectric ring structure according to the present invention;

[0067] Figure 4 This is a schematic diagram of the bolt loosening monitoring system based on washers according to the present invention;

[0068] Figure 5 This is a schematic diagram of the exploded structure of another triboelectric ring structure of the present invention;

[0069] Figure 6 This is a schematic diagram of the working principle of another triboelectric ring structure cross-section of the present invention;

[0070] In the diagram: 1. Gasket assembly; 2. Triboelectric ring structure; 3. Connecting wire; 4. Digital multimeter; 5. Host computer; 6. Wireless transmission module; 7. Cloud platform; 101. Large gasket; 102. Small gasket; 201. Polyimide film layer; 202. Aluminum foil layer; 203. Paper layer; 204. Polytetrafluoroethylene film layer; 205. Rubber material; 206. Cavity. Detailed Implementation

[0071] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0072] Example 1

[0073] A bolt loosening monitoring washer, such as Figure 1 As shown, it includes a gasket assembly 1, a triboelectric ring structure 2, and a connecting wire 3.

[0074] The gasket assembly 1 consists of two large gaskets 101 and one small gasket 102. The large gaskets 101 are located on both sides of the triboelectric annular structure 2 and the small gasket 102. The three are stacked axially to form a layered structure of "large gasket - (triboelectric annular structure + small gasket) - large gasket". The triboelectric annular structure 2 is located around the small gasket 102.

[0075] Furthermore, the triboelectric ring structure 2 includes a positive electrode layer, a rubber dielectric layer, and a negative electrode layer arranged sequentially. The connecting wire 3 is connected to the positive electrode layer and the negative electrode layer of the triboelectric ring structure 2 respectively, and is used to transmit the signal of the potential difference on the electrode surface.

[0076] Example 2

[0077] A bolt loosening monitoring washer, wherein the positive electrode layer is composed of an insulating layer, a metal electrode layer and an electron-depleting material layer stacked in sequence, and the negative electrode layer is composed of an electron-gaining material layer, a metal electrode layer and an insulating layer stacked in sequence.

[0078] In this embodiment, as Figure 2 As shown, the insulating layer is a polyimide film layer 201, the metal electrode layer is an aluminum foil layer 202, the electron-losing material layer is a paper layer 203, and the electron-gaining material layer is a polytetrafluoroethylene film layer 204. The rubber dielectric layer includes a rubber material 205 and a cavity 206 disposed on the rubber material. The rest is the same as in Example 1.

[0079] Example 3

[0080] A smart washer for monitoring bolt loosening based on triboelectric effect, the smart washer comprising a washer assembly 1, a triboelectric ring structure 2, and a connecting wire 3.

[0081] The gasket assembly 1 consists of two large gaskets 101 and one small gasket 102, which together form the load-bearing body of the smart gasket. The large gaskets 101 are located on both sides of the triboelectric ring structure 2 and the small gasket 102. The three are stacked axially to form a layered structure of "large gasket - (triboelectric ring structure + small gasket) - large gasket". The triboelectric ring structure 2 is disposed around the small gasket 102 as the functional body of the smart gasket. The triboelectric ring structure 2 includes a positive electrode layer, a rubber dielectric layer, and a negative electrode layer. The connecting wires 3 are connected to the positive electrode layer and the negative electrode layer of the triboelectric ring structure 2 respectively through aluminum foil tape, and are used to transmit the signal of potential difference on the electrode surface.

[0082] The triboelectric ring structure 2 and the small washer 102 together form a structure system similar to a parallel spring. The triboelectric ring structure 2 acts as a soft spring, bearing minor pressure, while the small washer 102 acts as a hard spring, bearing the main preload. When the bolt is tightened, the small washer 102 bears almost all of the preload, while the triboelectric ring structure 2 remains in an elastic state and responds sensitively to minor deformations caused by bolt loosening.

[0083] by Figure 3 The working principle of the triboelectric ring structure is explained using the example shown. When the bolt is not loose, the preload of the bolt keeps the triboelectric ring structure 2 in a compressed state; when the bolt loosens, the preload of the bolt decreases, causing the triboelectric ring structure 2 to spring back.

[0084] The triboelectric ring structure 2 includes a positive electrode layer, a rubber dielectric layer, and a negative electrode layer arranged sequentially from top to bottom. The electrode spacing and surface charge density vary with the degree of bolt loosening. The positive electrode layer is composed of an insulating layer, a metal electrode layer, and an electron-losing material layer stacked in sequence; the negative electrode layer is composed of an electron-gaining material layer, a metal electrode layer, and an insulating layer stacked in sequence. Specifically, the insulating layer is a polyimide film layer 201, the metal electrode layer is an aluminum foil layer 202, the electron-losing material layer is a paper layer 203, and the electron-gaining material layer is a polytetrafluoroethylene film layer 204. The rubber dielectric layer includes a rubber material 205 and a cavity 206. During bolt loosening, the rubber material 205 not only acts as an elastomer to respond to applied pressure but also, together with its internal cavity, serves as a dielectric material, significantly improving the efficiency of charge accumulation and separation.

[0085] The bonding process between the layers of the triboelectric ring structure 2 employs high-strength adhesive; in this embodiment, acrylic pressure-sensitive adhesive is used to ensure that delamination or detachment does not occur during long-term use. The aluminum foil layer 202 and paper layer 203 are bonded along their four edges; the aluminum foil layer 202 and polytetrafluoroethylene film layer 204 are bonded along their four edges to achieve charge transfer; the polyimide film layer 201 and aluminum foil layer 202 are bonded to each other; the paper layer 203 and rubber material 205 are bonded to each other; and the polytetrafluoroethylene film layer 204 and rubber material 205 are bonded to each other.

[0086] In this embodiment, the paper layer 203 and the polytetrafluoroethylene film layer 204 are first rubbed with opposite charges, and then respectively installed on both sides of the rubber material 205. When the bolt is not loosened, the rubber dielectric layer in the triboelectric ring structure 2 is compressed under the bolt preload, causing the friction electrodes to approach and maintain a high charge density, thereby generating a large potential difference between the electrodes; when the bolt is loosened, the rubber dielectric layer in the triboelectric ring structure 2 rebounds and causes the friction electrodes to separate, the charge density decreases, and the potential difference between the electrodes decreases as the compression of the rubber dielectric layer decreases.

[0087] by Figure 4The following example illustrates the working principle of a bolt loosening monitoring system based on smart washers. This system also includes a digital multimeter 4, a host computer 5, a wireless transmission module 6, and a cloud platform 7. The two aluminum foil layers 202 of the triboelectric ring structure 2 are connected to the digital multimeter 4 via connecting wires 3 to ensure that the potential difference between the positive and negative electrodes is effectively transmitted to the digital multimeter 4. The digital multimeter 4 is connected to the host computer 5 to receive and analyze the potential difference signal. Specifically, the host computer 5 contains a signal analysis and processing program. First, it analyzes the timing and amplitude of the signal to extract characteristic parameters related to bolt loosening. For example, it analyzes the fluctuation range, trend, and frequency characteristics of the potential difference to determine the specific situation of bolt loosening. Second, it uses artificial intelligence algorithms (such as support vector machines, neural networks, random forests, etc.) to train and test based on the characteristic information to measure the loss of bolt preload and monitor the degree of bolt loosening. In this embodiment, a neural network is used as an example: First, the data is labeled based on the collected potential difference signal. Labels can be based on different bolt loosening states (e.g., 90 / 70 / 50 / 30 / 10% of the initial preload). Second, the dataset is divided into a training set and a test set. Typically, 80%–90% of the data is used to train the model, and the remaining 10%–20% is used to validate and test the model's performance. The training set is used for the algorithm's learning process, and the test set is used to evaluate the model's actual performance. Next, model parameters are initialized, including the number of network layers, the number of neurons per layer, and the learning rate. Then, a suitable loss function is selected to optimize the model's performance; mean squared error (MSE) is commonly used in bolt loosening monitoring. Based on the training set data, optimization algorithms (such as gradient descent) are used to adjust the model parameters to minimize the loss function value. During this process, the algorithm iterates continuously to adjust the model's parameters to better fit the training data. Finally, the adjusted model is validated using the test set to evaluate its generalization ability on unseen data. By comparing the errors between predicted and actual values, metrics such as accuracy, precision, and recall of the model are calculated. If the validation results indicate that the model performs poorly, hyperparameters can be further adjusted, the algorithm optimized, or the model architecture improved.

[0088] To enable remote monitoring and intelligent decision support, all processed and analyzed data is transmitted to the cloud platform 7 via wireless transmission module 6. On the cloud platform, the data is stored long-term and further analyzed. Through the cloud server, the system can achieve centralized management and analysis of data from multiple monitoring points.

[0089] Leveraging the computing power of the cloud platform, the system can monitor a large number of devices in real time, analyze data trends, generate reports, and provide predictive maintenance suggestions. The cloud platform can also perform remote device diagnostics, automatically issuing early warnings based on predicted bolt loosening to help maintenance personnel take timely action. Once bolt loosening is detected to reach a preset threshold, the system automatically triggers an alarm signal, which is transmitted to the host computer 5 or relevant terminals via wireless transmission module 6. Maintenance personnel can monitor the system in real time via mobile devices, PCs, etc., ensuring rapid response to potential equipment safety risks.

[0090] Furthermore, the smart washer is designed to be universal and can be customized to meet the needs of different users by different bolt specifications and usage scenarios.

[0091] Example 4

[0092] A smart washer for monitoring bolt loosening based on triboelectric effect, such as Figures 5-6 As shown, the paper layer 203 has a raised structure of the same material on the side facing the rubber medium layer, and the polytetrafluoroethylene film layer 204 has a raised structure of the same material on the side facing the rubber medium layer. The raised structures of the paper layer 203 and the polytetrafluoroethylene film layer 204 correspond to the positions of the cavity 206. The rest is the same as in Example 3.

[0093] When the raised structures of the paper layer 203 and the raised structures of the polytetrafluoroethylene film layer 204 come into contact with each other, they generate surface charges of opposite signs on the contact surface. In this embodiment, it is not necessary to rub the paper layer 203 and the polytetrafluoroethylene film layer 204 with opposite signs before installation, making the operation simpler.

[0094] This invention utilizes a triboelectric ring structure to sense changes in charge through the triboelectric effect, thereby reflecting the degree of bolt loosening. During use, a smart washer is installed between the bolt and the bolt-connecting component. If the bolt is not loose, the preload of the bolt compresses the triboelectric ring structure, compressing the rubber dielectric layer within it, reducing the distance between the triboelectric electrodes, and resulting in a relatively high surface charge density and a large potential difference between the electrodes. If the bolt loosens, the rebound effect of the rubber dielectric layer increases the electrode distance, thus reducing the surface charge density and decreasing the potential difference between the electrodes. This change in potential difference can be monitored in real time using a digital multimeter to determine the degree of bolt loosening. Based on the magnitude of the potential difference change, the loosening of the bolt can be accurately assessed, and corresponding early warning signals can be provided.

[0095] To overcome the limitations of existing bolt loosening monitoring methods—namely, the need for external excitation signals and power supply, insufficient load-bearing capacity, and the requirement for large deformation space for normal operation—this invention provides a smart washer and method for bolt loosening monitoring based on the triboelectric effect. This smart washer, through a uniquely designed triboelectric ring structure, causes the potential difference between the positive and negative electrodes to change with the degree of bolt loosening. This potential difference signal is transmitted to a host computer via a digital multimeter for real-time analysis, thereby achieving high-precision monitoring of the bolt loosening state. This system can issue alarms promptly and accurately, and display the specific degree of loosening, significantly improving the accuracy and reliability of bolt loosening monitoring.

[0096] It should be noted that the orientations or positional relationships indicated by terms such as "front," "rear," "left," "right," "up," "down," "inner," and "outer" in this application are based on the orientations or positional relationships indicated in the accompanying drawings. They are used for the purpose of making the description of this application more concise and clear, and do not imply that the device or component must have a definite orientation limitation. Therefore, they should not be considered as limitations on this application. Furthermore, the embodiments described in this application are only a part of the embodiments of the present invention and cannot represent all embodiments. Other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this invention.

[0097] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0098] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0099] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A bolt loosening monitoring washer, characterized in that, It includes a gasket assembly (1), a triboelectric ring structure (2), and a connecting wire (3); The gasket assembly (1) includes a large gasket (101) and a small gasket (102), a triboelectric ring structure (2) is disposed around the small gasket (102), and the large gasket (101) is located on both sides of the triboelectric ring structure (2) and the small gasket (102); The large gasket (101) and small gasket (102) in the gasket assembly (1) are made of stainless steel; The triboelectric ring structure (2) includes a positive electrode layer, a rubber dielectric layer and a negative electrode layer. The connecting wire (3) is connected to the positive electrode layer and the negative electrode layer of the triboelectric ring structure (2) respectively, and is used to transmit the signal of the potential difference on the electrode surface. The rubber medium layer includes a rubber material (205) and a cavity (206); The rubber material (205) has a circular ring structure with a cavity (206) on it; The rubber material (205) is provided with a plurality of cavities (206) spaced apart along the circumferential direction, and the cavities (206) penetrate the rubber material (205) along the axial direction; The positive electrode layer and / or negative electrode layer have a protruding structure on the side facing the rubber dielectric layer, and the protruding structure corresponds to the position of the cavity (206); The total thickness of the protrusion structure does not exceed the thickness of the rubber material (205) under normal conditions.

2. The bolt loosening monitoring washer according to claim 1, characterized in that, The inner diameters of the large gasket (101) and the small gasket (102) in the gasket assembly (1) are matched, and the bolt can pass through the gasket assembly (1) and be fixed to the bolt connection member.

3. The bolt loosening monitoring washer according to claim 1, characterized in that, The positive electrode layer is composed of an insulating layer, a metal electrode layer, and an electron-depleting material layer stacked in sequence, and the negative electrode layer is composed of an electron-gaining material layer, a metal electrode layer, and an insulating layer stacked in sequence, with the electron-depleting material layer and the electron-gaining material layer facing each other.

4. The bolt loosening monitoring washer according to claim 3, characterized in that, The insulating layer is a polyimide film layer (201); The metal electrode layer is an aluminum foil layer (202); The electron-depleting material layer is a paper layer (203); The electron-generating material layer is a polytetrafluoroethylene thin film layer (204).

5. The bolt loosening monitoring washer according to claim 3, characterized in that, The layers of the positive electrode layer are bonded together by adhesive, the layers of the negative electrode layer are bonded together by adhesive, and the rubber dielectric layer is bonded together with the electron-losing material layer and the electron-gaining material layer by adhesive.

6. A method for monitoring bolt loosening, characterized in that, Using the bolt loosening monitoring washer according to any one of claims 1-5, the procedure includes the following steps: The bolt loosening monitoring washer is installed between the bolt and the bolt connection component, and the positive electrode layer and negative electrode layer of the triboelectric ring structure (2) are respectively connected to the signal receiving component by the connecting wire (3); When the bolts loosen, the triboelectric ring structure (2) generates a potential difference during deformation, which is transmitted to the signal receiving component via the connecting wire (3).

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