A structure vibration self-powered cable force gauge based on electrostatic and piezoelectric principles

Abstract

The application discloses a structure vibration self-powered cable force meter based on electrostatic and piezoelectric principles, which comprises a cable force sensor, a wind power energy capturer, a power management module and a sensing signal wireless transmission module. The cable force sensor is installed on a cable and connected with the sensing signal wireless transmission module, and an electric potential difference is generated based on the electrostatic and piezoelectric principles to form an electric current, and the sensing signal wireless transmission module is used to send the sensed signal; the wind power energy capturer is electrically connected with the power management module, and the power management module is electrically connected with the sensing signal wireless transmission module; the wind power energy capturer comprises a support sheet, a blunt body shell, a base, a piezoelectric sheet, a fixed contact plate, a sliding contact plate, a positive friction power generation sheet fixed on the upper surface of the fixed contact plate and a negative friction power generation sheet fixed on the lower surface of the sliding contact plate, and can supply power for the sensing signal wireless transmission module. The device does not need external power supply and a large number of wiring, has high durability and high recognition accuracy.

Description

Technical Field

[0001] This invention relates to the field of electrostatic and piezoelectric power generation, and more specifically to a structural vibration self-powered cable force meter based on electrostatic and piezoelectric principles. Background Technology

[0002] Traditionally, buildings, bridges, and other architectural structures are designed primarily to resist static loads, such as vehicle loads and structural weight. However, in reality, civil engineering structures must withstand not only static loads but also variable dynamic loads from the environment, such as wind loads, seismic loads, wave loads, mechanical vibration loads, and traffic loads. The presence of these dynamic loads often causes continuous vibrations in building structures, which is detrimental to both structural safety and the health and safety of users.

[0003] With the rise of tourism in mountainous areas, the number of scenic bridges in these areas has gradually increased. Adding cable-stayed structures to truss structures can make the overall bridge appearance lighter and simpler, allowing it to blend better into nature and enhancing its aesthetic appeal. However, the usage of cable-stayed bridges over the past century shows that cable replacement is very common and frequent. Therefore, in cable-stayed bridge systems, cable tension is often used as a key parameter to assess whether the cables are functioning properly and whether the bridge's operational status is normal and reasonable, making it extremely important for bridge health monitoring.

[0004] However, traditional monitoring of cables largely relies on manual inspections and routine periodic checks, which are labor-intensive, inefficient, subjective, and costly. Meanwhile, some automated monitoring technologies depend on large-scale contact sensors, which suffer from complex wiring, difficult battery replacement, and the significant impact of sensor quality on the accuracy of short cable identification. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention optimizes and simplifies the structure of traditional contact-type self-powered cable force gauges, providing a structural vibration self-powered cable force gauge based on electrostatic and piezoelectric principles. This invention has the advantages of requiring no external power supply, eliminating the need for extensive wiring, ensuring high durability, achieving high recognition accuracy, simplifying and lightweighting the device, and maximizing space utilization.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles comprises four parts: cable force sensor, wind energy harvester, power management module, and wireless transmission module for sensing signals.

[0008] The cable force sensor is mounted on the cable and connected to the wireless transmission module for sensing signals. It generates a potential difference based on electrostatic and piezoelectric principles to form a current, and the wireless transmission module transmits the sensed signal. The cable force sensor includes a cylindrical shell, a nonlinear mass-spring-damping mechanical system, and a pair of friction pairs located within the cylindrical shell. The friction pairs include an independent friction layer on the outer periphery of the mass and a fixed friction layer on the inner surface of the cylindrical shell. Vibration of the nonlinear mass-spring-damping mechanical system causes a change in the relative area between the friction pairs, generating an electrical signal.

[0009] The wind energy harvester is electrically connected to the power management module, and the power management module is electrically connected to the sensing signal wireless transmission module; the wind energy harvester includes a support plate, a blunt body shell, a base, a piezoelectric plate, and a fixed contact plate, a sliding contact plate, a positive triboelectric generator plate fixed on the upper surface of the fixed contact plate, and a negative triboelectric generator plate fixed on the lower surface of the sliding contact plate located inside the blunt body shell.

[0010] One end of the support plate is fixed to the base, and the other end is fixed to the blunt body shell. The piezoelectric sheet is fixed to the support plate. Under the influence of the vibration, the blunt body shell drives the support plate to vibrate left and right perpendicular to the windward surface. The sliding contact plate slides left and right on the fixed contact plate, so that the positive triboelectric generator on the upper surface of the fixed contact plate and the negative triboelectric generator on the lower surface of the sliding contact plate generate a potential difference. The generated electrical energy powers the wireless transmission module of the sensing signal, realizing self-powered operation.

[0011] Furthermore, a cylindrical guide rail is installed in the middle of the cylindrical shell of the cable force sensor, and a mass block is sleeved on the cylindrical guide rail, and is connected to the cylindrical shell above and below by an upper spring and a lower spring, respectively; the friction pair includes an independent friction layer located on the outer periphery of the mass block, and an upper electrode layer, a lower electrode layer, an upper fixed friction layer attached to the upper electrode layer, and a lower fixed friction layer attached to the lower electrode layer located on the inner surface of the cylindrical shell; the upper electrode layer and the lower electrode layer are spaced apart; the upper fixed friction layer and the lower fixed friction layer have the same polarity and are opposite to the polarity of the independent friction layer.

[0012] Furthermore, both the upper and lower fixed friction layers are polytetrafluoroethylene films, both the upper and lower electrode layers are copper foils, and the independent friction layer is a PA6 nylon film.

[0013] Furthermore, there are multiple fixed contact plates and multiple sliding contact plates, thus forming multiple friction pairs; the positive triboelectric generating plate on the upper surface of the fixed contact plate includes a nylon layer and an aluminum film from top to bottom, with each layer of material fully covering the other; the negative triboelectric generating plate on the lower surface of the sliding contact plate has the same shape as the positive triboelectric generating plate.

[0014] Furthermore, the support plate is made of stainless steel, and the fixed contact plate and the sliding contact plate are made of photosensitive resin material.

[0015] Furthermore, a side opening cover is installed on one side of the blunt body shell, and the blunt body shell has grooves on both sides near the side opening cover and holes at the bottom for leading out the aluminum film of the positive friction generator on the upper surface of the fixed contact plate through wires. The aluminum films of each layer are connected in parallel. The wires pass through the grooves and holes, and after converging, they power the wireless transmission module of the sensing signal.

[0016] Furthermore, the piezoelectric sheet is fixed to the upper end of the support sheet near the blunt body shell.

[0017] Furthermore, the fixed contact plate and the sliding contact plate are arranged in parallel and are both solid structures.

[0018] A method for measuring cable force using a self-powered cable force gauge for structural vibration, characterized by comprising the following steps:

[0019] Step 1: Measure the open-circuit voltage U(t) output by the cable force sensor. n Substituting these values ​​into the following formula yields the acceleration time history information of the cable.

[0020]

[0021] Where ω is the natural angular frequency, ξ is the damping ratio, σ is the surface charge density of the independent friction layer, S represents the area of ​​the independent friction layer, L is the length of the independent friction layer along the sliding direction, and C0 is the capacitance between the upper and lower electrode layers.

[0022] Step 2: Obtain the acceleration time history information of the cable. Perform an FFT Fourier transform to obtain its multiple frequencies f. N Substituting the relationship between the cable force and its natural frequency, we obtain the cable force:

[0023]

[0024] Where ρ is the linear density of the cable; L is the effective length of the cable; f N Let N be the Nth natural frequency of the cable; T be the cable force; and N be the order of the cable's natural frequency.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. The self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles of this invention employs a non-contact, independent-layer electrostatic and piezoelectric principle model for its design, which effectively reduces energy loss compared to traditional structures. A quantitative analytical correlation is satisfied between the electrical output of the cable force gauge's friction pair and its relative sliding distance. Based on this quantitative correlation, intelligent sensing of the structural vibration process can be achieved. The non-contact, independent-layer model reduces energy loss during the friction process of the friction pair and improves recognition accuracy.

[0027] 2. This device requires no external power supply or extensive wiring. It can absorb and convert wind energy through wind energy harvesters installed on the bridge. The wind power generation powers the wireless transmission module connected to the cable force meter. After the control terminal acquires the data, it uses sensing theory and other principles to calculate the cable force of the suspenders and conduct bridge health monitoring.

[0028] 3. Compared with traditional wind energy harvester configurations, this device embeds a TENG energy harvesting unit inside the upper blunt body. During the left-right oscillation of the energy harvester, the TENG energy harvesting unit and the piezoelectric plates on the support plate can simultaneously harvest energy, increasing energy output and improving energy harvesting efficiency. Furthermore, when the energy harvester oscillates, the energy harvesting unit inside the upper blunt body can generate impact force on the sidewall of the blunt body, increasing the deformation of the support plate and further improving the energy output of the piezoelectric plates. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the application scenario of the cable force meter according to an embodiment of the present invention.

[0030] Figure 2 This is a side view of the cable force sensor.

[0031] Figure 3 This is a schematic diagram of the longitudinal section of the cable force sensor.

[0032] Figure 4 The image shows the results of the cable force sensor durability test.

[0033] Figure 5 This is a schematic diagram of a wind power harvester.

[0034] Figure 6 This is a front view and a schematic diagram of the internal structure of a wind energy harvester.

[0035] Figure 7 This is a comparison diagram of the amplitude of the conventional configuration of the wind energy harvester and the configuration of this embodiment.

[0036] Figure 8 This is a comparison diagram of the output voltage of the traditional configuration of the wind energy harvester and the configuration of this embodiment.

[0037] Figure 9 This is a schematic diagram illustrating the working principle of the cable force gauge used for cable force measurement in this embodiment.

[0038] In the figure, there are: cylindrical shell 1, cylindrical guide rail 2, mass block 3, upper spring 4, lower spring 5, upper electrode layer 6, lower electrode layer 7, upper fixed friction layer 8, lower fixed friction layer 9, independent friction layer 10, support plate 11, blunt body shell 12, fixing bolt 13, side opening cover 14, base 15, piezoelectric plate 16, fixed contact plate 17, positive triboelectric generating plate 18, sliding contact plate 19, negative triboelectric generating plate 20, nylon layer 1801, and aluminum film 1802. Detailed Implementation

[0039] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0040] This invention relates to a cable force gauge designed based on electrostatic and piezoelectric principles. It utilizes the quantitative analytical correlation between the electrical output of the friction pair and the relative sliding distance. Based on this quantitative correlation and sensing theory, the cable force of the suspension rod can be calculated, enabling intelligent sensing of structural vibration processes. Furthermore, leveraging the significant performance output of triboelectric nanogenerators in low-frequency vibrating bridge structures, and their suitability for sensing and energy harvesting in low-frequency structures, wind energy is absorbed and converted using wind-powered energy harvesters deployed on the bridge. Based on the principles of vortex-induced vibration and galloping, when wind loads act on the external blunt body and support plates, the airflow separation creates vortices that detach, causing the blunt body to experience alternating positive and negative pressures twice, resulting in left-right swaying of the blunt body structure. The simultaneous use of vortex-induced vibration and galloping increases the vibration amplitude and improves energy harvesting efficiency, powering the wireless signal transmission module connected to the cable force gauge, thus achieving self-powering.

[0041] like Figure 1 As shown, this embodiment of a self-powered cable force gauge based on electrostatic and piezoelectric principles is applied to cable force monitoring of cable-stayed bridges. It comprises four parts: a cable force sensor, a wind energy harvester, a power management module, and a wireless signal transmission module. The cable force sensor, installed on the cable, generates a potential difference based on electrostatic and piezoelectric principles, forming a current. The wireless signal transmission module transmits the signal to a computer. Simultaneously, by utilizing the quantitative analytical correlation between the electrical output of the friction pair and the relative sliding distance, the cable force of the suspenders can be calculated based on this quantitative correlation and sensing theory, achieving intelligent sensing of the structural vibration process. The wind energy harvester, installed on the bridge, absorbs and converts wind energy. The power management module supplies power to the wireless signal transmission module connected to the cable force gauge, enabling wireless signal transmission and reception.

[0042] like Figure 2As shown, the cable force sensor comprises three parts: a cylindrical housing 1, a nonlinear mass block-spring-damping mechanical system located within the cylindrical housing 1, and a pair of friction pairs.

[0043] The cylindrical outer shell 1 is a closed hollow cylinder with a central cylindrical guide rail 2, which is used to fix the sliding direction of the mass block 3. The cylindrical outer shell 1 and the cylindrical guide rail 2 are manufactured using 3D printing technology and high-strength, lightweight materials, which reduces the volume of the force gauge and improves the device's convenience. In this embodiment, the cylindrical outer shell 1 has a wall thickness of 1mm, and the cylindrical guide rail 2 has a diameter D = 1mm, which can withstand a certain amount of external force while reducing the device's weight to a certain extent, achieving a simple and lightweight design.

[0044] The nonlinear mass-spring-damping mechanical system consists of a cylindrical mass 3 and an upper spring 4 and a lower spring 5. The cylindrical mass 3 has a central hole and is connected to the cylindrical shell 1 via the upper spring 4 and lower spring 5. The cylindrical mass 3 is manufactured using 3D printing technology, and the upper spring 4 and lower spring 5 are made of corrosion-resistant material. In this embodiment, the diameter D of the cylindrical mass 3 is 17mm, slightly smaller than the inner diameter of the cylindrical shell 1, allowing the cylindrical mass 3 to slide well on the cylindrical guide rail 2.

[0045] like Figure 3 As shown, the friction pair consists of three parts: an upper electrode layer 6 and a lower electrode layer 7 attached to the inner surface of the cylindrical housing 1; an upper fixed friction layer 8 attached to the upper electrode layer 6; a lower fixed friction layer 9 attached to the lower electrode layer 7; and an independent friction layer 10 attached to the surface of the cylindrical mass block 3. The bottom end of the upper electrode layer 6 and the top end of the lower electrode layer 7 are separated by a certain gap. In this embodiment, the upper electrode layer 6 and the lower electrode layer 7 attached to the inner surface of the cylindrical housing 1 are copper foils with a thickness of d = 30 μm, and a gap of g = 1 mm is maintained between the two copper foils. Meanwhile, the upper fixed friction layer 8 and the lower fixed friction layer 9 attached to the upper electrode layer 6 and the lower electrode layer 7 are polytetrafluoroethylene (PTFE) films with a thickness of d = 50 μm, while the independent friction layer 10 attached to the surface of the cylindrical mass block 3 is a PA6 nylon film with a thickness of d = 30 μm.

[0046] like Figure 4 As shown, this cable force sensor device adopts a non-contact, independent-layer structure, avoiding the frictional loss of traditional TENG structures. Durability tests show that the device output performance remains stable under 40,000 cycles of loading, verifying the stability of the device design and effectively reducing frictional loss while ensuring sensing accuracy.

[0047] like Figure 5As shown, the wind energy harvester consists of a support plate 11, a blunt body shell 12, fixing bolts 13, a side cover 14, a base 15, a piezoelectric plate 16, a fixed contact plate 17, a sliding contact plate 19, a positive triboelectric generator 18 fixed on the upper side of the fixed contact plate 17, and a negative triboelectric generator 20 fixed on the lower side of the sliding contact plate 19. The base 15 is made of a solid material with good weather resistance, easy maintenance, and easy installation. The support plate 11 is a stainless steel sheet with good flexibility, easy installation, and easy maintenance, and can withstand the bending stress generated by the vibration of the blunt body shell. One end of the support plate 11 is fixed to the base 15, and the other end is fixed to the blunt body shell 12. The blunt body shell 12 will drive the support plate 11 to vibrate left and right on the windward side under the influence of galloping. The support plate 11 and the blunt body shell 12 are connected by fixing bolts 13. The piezoelectric plate 16 is mounted on the support plate 11. Preferably, the piezoelectric sheet 16 is fixed to the upper end of the support sheet 11 near the blunt body shell, where the deformation of the support sheet is the largest and the energy harvesting effect is the best. A side opening cover 14 is installed on one side of the blunt body shell 12, and the blunt body shell 12 has grooves on both sides near the side opening cover 14. Both the blunt body shell 12 and the side opening cover 14 are made of high-strength, lightweight 3D-printed materials. The cross-section of the blunt body structure is a combination of rectangular and D-shaped. This is because energy harvesters based on the vortex-induced vibration principle can produce large displacements under specific wind speeds. Once this range is exceeded, the energy harvesting effect will decrease significantly, and their blunt bodies mostly adopt a circular cross-section. On the other hand, energy harvesters based on the galloping principle only have a good energy harvesting effect when the ambient wind speed is higher than the cut-in wind speed, and the energy harvesting effect increases with the increase of wind speed. This embodiment combines the advantages of both, adopting a combination of rectangular and D-shaped shapes to fully utilize the advantages of vortex-induced vibration and galloping in energy harvesting, widening the range of working wind speeds, increasing the vibration amplitude, and improving energy harvesting efficiency.

[0048] Since the response amplitude of a rectangular cross-section varies with different width-to-thickness ratios, within a certain range, the response amplitude increases with the increase of the width-to-thickness ratio. However, an excessively large width-to-thickness ratio will cause the system to exhibit vortex-induced vibration response characteristics, which does not meet the energy capture requirements. Therefore, in this embodiment, the rectangular dimensions of the blunt body shell 12 are 300mm×500mm×750mm, and the semi-cylindrical dimensions are 150×750 (r×h), with a width-to-thickness ratio of 0.46, which can generate a higher vibration frequency and a larger vibration amplitude under galloping action.

[0049] like Figure 6As shown, the fixed contact plate 17 and the sliding contact plate 19 are arranged in parallel inside the blunt body shell 12, and both are solid structures. The positive triboelectric generating plate 18 on the upper surface of the fixed contact plate 17 consists of a nylon layer 1801 and an aluminum film 1802 from top to bottom, and the positive triboelectric generating plate 18 is divided into left and right parts with a certain gap in between. The negative triboelectric generating plate 20 fixed on the lower surface of the sliding contact plate 19 has the same shape as the positive triboelectric generating plate 18, and the layers of materials completely cover each other. The negative triboelectric generating plate 20 is slightly smaller than the positive triboelectric generating plate 18, so that the sliding contact plate 19 can make full contact with it during sliding, and the two are parallel to each other in space. The TENG unit of this device adopts an independent layer structure. When the sliding contact plate 19 slides left and right, due to the principle of electrostatic induction, an equal amount of negative charge is induced on the positive triboelectric generator 18. When the negative charges on the two aluminum films are not equal, a potential difference is generated, causing electrons to transfer through the external circuit to balance the potential difference, thereby forming a current. When the sliding contact plate 19 reciprocates, an alternating current is generated between the two aluminum films, outputting energy. Furthermore, two wires are led out from the left and right sides of each corresponding aluminum film. The two wires of each layer are led out from the grooves on the left and right sides respectively. The layers are connected in parallel. After the wires are led out, they converge at the holes reserved at the bottom of the blunt body shell 12 to power the signal wireless transmission module connected to the force gauge, realizing self-powering.

[0050] In this embodiment, the friction pairs within the cable force sensor device are pre-charged. When the cylindrical shell 1 is under a certain acceleration, the mass block 3 moves up and down. Since the friction layers on the surfaces of the cylindrical shell 1 and the mass block 3 have opposite polarities, and the sliding distance of the independent friction layer 10 on the mass block surface is much greater than the interval between the upper fixed friction layer 8 and the lower fixed friction layer 9, the relative area between the friction pairs changes due to the sliding of the mass block 3. This generates oppositely polarized charges on the surfaces of the friction pairs, causing periodic charge transfer in the metal film to generate an electrical signal. Simultaneously, the cable force sensor is considered a single-degree-of-freedom forced vibration system. Based on the principle of forced vibration, a correspondence between the vibration displacement of the mass block and the vibration displacement of the object under test is constructed. By incorporating the Duhamel integral and introducing irregular external loads, the device can successfully sense the acceleration value of the object under any load. Then, using sensing theory and other principles, the tension of the suspender is calculated, achieving intelligent sensing of the structural vibration process and conducting bridge health monitoring. This cable force sensor device adopts a non-contact, independent-layer structure, which effectively reduces energy loss compared to traditional structures. This device leverages the significant performance output of triboelectric nanogenerators in low-frequency vibrating bridge structures, making it suitable for sensing and capturing energy in low-frequency structures. It absorbs and converts wind energy through wind-powered energy harvesters deployed on the bridge, supplying power to the wireless signal transmission module connected to the cable force gauge, thus achieving self-powering. The specific working principle is as follows: Figure 9 As shown.

[0051] like Figure 6 As shown, the positive triboelectric generator 18 has dimensions of 48mm × 28mm, and the negative triboelectric generator 20 has dimensions of 30mm × 20mm. The fixed contact plate 17 is 2mm thick, and the sliding contact plate 19 is 2mm thick. The nylon layer 1801 and aluminum film 1802 of the positive triboelectric generator 18 are 0.03mm and 0.05mm thick, respectively. The negative triboelectric generator 20 is made of PTFE material and is 0.05mm thick. The fixed contact plate 17 and the sliding contact plate 19 are made of photosensitive resin material. During the vibration of the blunt body shell 12, the negative triboelectric generator 20, being smaller than the positive triboelectric generator 18, reciprocates and makes complete contact with the positive triboelectric generator 18 under the action of inertia, thereby improving the power generation efficiency.

[0052] like Figure 7 As shown, compared to the conventional configuration of wind energy harvesters, the conventional configuration has a solid upper bluff body, while this device embeds a TENG energy harvesting unit inside the bluff body. During the left-right swinging of the energy harvester, the energy harvesting unit can generate an impact force on the side wall of the bluff body, increasing the deformation of the support plate and thus increasing the amplitude. Figure 8 As shown, in 10 6 Comparative experiments conducted with an external resistance of Ω show that the amplitude of this device configuration is greater than that of the traditional configuration. Furthermore, comparative experiments were conducted with the traditional PZT configuration, the PZT configuration of this device, and the PZT+TENG configuration of this device. It can be seen that the voltage output magnitude is: PZT of the traditional configuration < PZT of this device configuration < PZT+TENG of this device configuration. This indicates that the amplitude of this device configuration is greater than that of the traditional configuration, the PZT output is greater than that of the traditional configuration, and the combined energy capture by TENG and PZT increases the energy output and improves the energy capture efficiency.

[0053] The cable force measurement method of the self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles of the present invention is as follows:

[0054] (1) Based on previous research on independent layer triboelectric nanogenerator technology, the output open-circuit voltage U(t) of conductor-conductor F-TENG can be obtained. n ) and the sliding distance x(t) of the independent friction layer n The expressions between ) are as follows:

[0055]

[0056] In the formula, σ is the surface charge density of the independent friction layer, S represents the area of ​​the independent friction layer, L is the length of the independent friction layer along the sliding direction, and C0 is the capacitance value between the metal layers.

[0057] (2) Therefore, we can obtain information about x(t) n The expression for ) is:

[0058]

[0059] (3) When the sampling time interval of the measured scatter signal is sufficiently small, according to equation (2), we can obtain:

[0060]

[0061]

[0062] We can then obtain:

[0063]

[0064] (4) Combined with external excitation acceleration and Relationship

[0065]

[0066] Substituting into (5), we get:

[0067]

[0068] In the formula, ω is the natural angular frequency and ξ is the damping ratio.

[0069] (5) Using the obtained acceleration time history information Perform an FFT Fourier transform to obtain its multiple frequencies f. N When the influence of the cable's lateral bending stiffness on the suspender cable force test is not considered, the cable force proportionality coefficient calibration formula and the cable force calculation formula are based on string vibration theory. According to string vibration theory, the explicit relationship between the cable force and its natural frequency is:

[0070]

[0071] In the formula, ρ is the linear density of the cable; L is the effective length of the cable; f N Let N be the Nth natural frequency of the cable; T be the cable force; and N be the order of the cable's natural frequency.

[0072] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles, characterized in that, It consists of four parts: cable force sensor, wind energy harvester, power management module, and wireless transmission module for sensing signals; The cable force sensor is mounted on the cable and connected to the wireless transmission module for sensing signals. It generates a potential difference based on electrostatic and piezoelectric principles to form a current, and the wireless transmission module transmits the sensed signal. The cable force sensor includes a cylindrical shell, a nonlinear mass-spring-damping mechanical system, and a pair of friction pairs located within the cylindrical shell. The friction pairs include an independent friction layer on the outer periphery of the mass and a fixed friction layer on the inner surface of the cylindrical shell. Vibration of the nonlinear mass-spring-damping mechanical system causes a change in the relative area between the friction pairs, generating an electrical signal. The wind energy harvester is electrically connected to the power management module, and the power management module is electrically connected to the sensing signal wireless transmission module; the wind energy harvester includes a support plate, a blunt body shell, a base, a piezoelectric plate, and a fixed contact plate, a sliding contact plate, a positive triboelectric generator plate fixed on the upper surface of the fixed contact plate, and a negative triboelectric generator plate fixed on the lower surface of the sliding contact plate located inside the blunt body shell. One end of the support plate is fixed to the base, and the other end is fixed to the blunt body shell. The piezoelectric sheet is fixed to the support plate. Under the influence of the vibration, the blunt body shell drives the support plate to vibrate left and right perpendicular to the windward surface. The sliding contact plate slides left and right on the fixed contact plate, so that the positive triboelectric generator on the upper surface of the fixed contact plate and the negative triboelectric generator on the lower surface of the sliding contact plate generate a potential difference. The generated electrical energy powers the wireless transmission module of the sensing signal, realizing self-powered operation.

2. The self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles according to claim 1, characterized in that, The cylindrical guide rail is installed in the middle of the cylindrical shell of the cable force sensor. The mass block is sleeved on the cylindrical guide rail and connected to the cylindrical shell at the top and bottom by an upper spring and a lower spring, respectively. The friction pair includes an independent friction layer located on the outer periphery of the mass block, and an upper electrode layer, a lower electrode layer, an upper fixed friction layer attached to the upper electrode layer, and a lower fixed friction layer attached to the lower electrode layer located on the inner surface of the cylindrical shell. The upper electrode layer and the lower electrode layer are spaced apart. The upper fixed friction layer and the lower fixed friction layer have the same polarity and are opposite to the polarity of the independent friction layer.

3. The self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles according to claim 2, characterized in that, Both the upper and lower fixed friction layers are polytetrafluoroethylene films, both the upper and lower electrode layers are copper foils, and the independent friction layer is a PA6 nylon film.

4. The self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles according to claim 1, characterized in that, There are multiple fixed contact plates and multiple sliding contact plates, thus forming multiple friction pairs; the positive triboelectric generating plate on the upper surface of the fixed contact plate includes a nylon layer and an aluminum film from top to bottom, and each layer of material completely covers the other; the negative triboelectric generating plate on the lower surface of the sliding contact plate has the same shape as the positive triboelectric generating plate.

5. The self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles according to claim 4, characterized in that, The support plate is made of stainless steel, and the fixed contact plate and the sliding contact plate are made of photosensitive resin material.

6. The self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles according to claim 4, characterized in that, A side opening is installed on one side of the blunt body shell, and the blunt body shell has grooves on both sides near the side opening and holes at the bottom for leading out the aluminum film of the positive friction generator on the upper surface of the fixed contact plate through wires. The aluminum films of each layer are connected in parallel. The wires pass through the grooves and holes, and after converging, they power the wireless transmission module of the sensing signal.

7. The self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles according to claim 1, characterized in that, The piezoelectric element is fixed to the upper end of the support plate near the blunt body shell.

8. The self-powered cable force gauge for structural vibration based on electrostatic and piezoelectric principles according to claim 1, characterized in that, The fixed contact plate and the sliding contact plate are arranged in parallel and are both solid structures.

9. A method for measuring cable force based on a self-powered cable force gauge for structural vibration according to any one of claims 1 to 8, characterized in that, Includes the following steps: Step 1: Measure the open-circuit voltage U(t) output by the cable force sensor. n Substituting these values ​​into the following formula yields the acceleration time history information of the cable. Where ω is the natural angular frequency, ξ is the damping ratio, σ is the surface charge density of the independent friction layer, S represents the area of ​​the independent friction layer, L is the length of the independent friction layer along the sliding direction, and C0 is the capacitance between the upper and lower electrode layers. Step 2: Obtain the acceleration time history information of the cable. Perform an FFT Fourier transform to obtain its multiple frequencies f. N Substituting the relationship between the cable force and its natural frequency, we obtain the cable force: Where ρ is the linear density of the cable; L is the effective length of the cable; f N Let N be the Nth natural frequency of the cable; T be the cable force; and N be the order of the cable's natural frequency.

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