Flexible triboelectricity-piezoelectricity expansion joint monitoring device based on rubber waterstop

Abstract

The invention discloses a flexible frictional electricity-piezoelectric expansion joint monitoring device based on a rubber waterstop. The flexible frictional electricity-piezoelectric expansion joint monitoring device comprises an acquisition module buried in the rubber waterstop and used for acquiring an expansion joint vibration signal, and a processing module for processing an electric signal collected by the acquisition module, the collecting module comprises a flexible contact layer, a rigid cone, a PVDF electrostatic spinning film and a metal electrode, wherein the flexible contact layer extends upwards from the bottom and is provided with a plurality of hollow pyramid-shaped protruding parts; the rigid cone is located at the lower end of the flexible contact layer and is matched with the hollow pyramid-shaped protruding parts; the PVDF electrostatic spinning film is located at the lower end of the rigid cone; and the flexible packaging bottom layer is located at the bottom end. According to the flexible triboelectric-piezoelectric expansion joint monitoring device, based on the cooperation of the acquisition module and the processing module, vibration signals generated on the PVDF electrostatic spinning film are acquired through the acquisition module, the vibration signals and a normal vibration curve are compared and analyzed through the processing module, and then whether a bridge expansion joint is damaged or not can be monitored in real time.

Description

Technical Field

[0001] The invention belongs to the field of expansion joint monitoring devices, and in particular relates to a flexible triboelectric-piezoelectric expansion joint monitoring device based on a rubber waterstop. Background Art

[0002] Bridges with larger plane dimensions will deform due to thermal expansion and contraction under the action of temperature difference. In order to adapt to the expansion and deformation of the structure under temperature changes and avoid cracks in the structure caused by deformation, expansion joints are usually set every few holes in the bridge. Among them, the main types of expansion joints are butt joint type, steel plate type, combined shear type, modular support type and seamless type. Except for seamless expansion joints, other expansion joints contain rubber waterstops to prevent moisture, debris, etc. from penetrating into the interior of the bridge through the expansion joints.

[0003] Increased traffic volume, overloading, speeding, and unqualified construction often lead to damage to bridge expansion joints. Due to the particularity of bridge engineering, expansion joint damage is generally not discovered in time, and regular inspections are also very difficult. In addition, bridges have many and long expansion joints, which is time-consuming and laborious for workers to inspect, and manual inspections may not be able to accurately detect damage to expansion joints. Damage to expansion joints may cause height differences between bridge decks, and this unevenness of the bridge deck will affect the safety and comfort of vehicle driving. If the expansion joint fails, it may even cause it to be unable to provide the expected expansion and contraction capacity, causing stress concentration in the bridge structure and accelerating the destruction of the bridge structure.

[0004] Most of the existing monitoring devices are rigid devices, which are connected to the expansion joints and may be damaged as the expansion joints are damaged. Monitoring devices are generally exposed to the air and will oxidize with use, especially some metal parts, which will oxidize after long-term exposure to the air, thus affecting the performance of the sensor. The shell material of the sensor may be sensitive to light, and the material will age under the influence of long-term sun and wind. At the same time, bridges often span over water with high humidity. When working in a high humidity environment, corrosion or short circuit may occur inside the monitoring device. There are also pollutants in the air, such as dust, chemicals, etc., which may be deposited on the surface of the monitoring device or enter the inside of the device, causing the monitoring device to be damaged before the expansion joint is damaged. In addition, existing monitoring devices often require internal or external power supply, regular maintenance, battery replacement, etc., and there is a risk of running out of power and failing to work.

[0005] Electrospinning is an advanced fiber manufacturing process that can produce polymer fibers with nanometer diameters. The PVDF fiber polymer film manufactured by electrospinning can transform most of the crystals of the PVDF fiber material from the α crystal form to the β crystal form to obtain piezoelectric properties, making it have excellent triboelectric and piezoelectric properties. However, when using PVDF for signal acquisition, its triboelectricity and piezoelectricity cannot be acquired at the same time, but are acquired separately according to different vibration frequencies. For example, when the PVDF electrospun film is under low acceleration and low vibration frequency, the spinning fibers contact and rub against each other, mainly producing triboelectric effect and triboelectric potential difference; when it is under high acceleration and high frequency, the spinning fibers themselves are squeezed and deformed, mainly producing piezoelectric effect and piezoelectric potential difference. That is, although the film can generate electrical signals regardless of low or high frequency vibration, it is impossible to simultaneously collect triboelectric and piezoelectric properties based on one frequency. Summary of the invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to provide a flexible triboelectric-piezoelectric expansion joint monitoring device based on a rubber waterstop, which can simultaneously obtain triboelectric and piezoelectric properties at the same frequency.

[0007] Technical solution: The flexible triboelectric-piezoelectric expansion joint monitoring device based on the rubber waterstop of the present invention is characterized in that the monitoring device comprises a collection module buried in the rubber waterstop for collecting the vibration signal of the expansion joint, and a processing module for processing the vibration signal collected by the collection module;

[0008] The collection module includes a flexible contact layer extending from bottom to top and provided with a plurality of hollow pyramid-shaped protrusions, a rigid cone located at the lower end of the flexible contact layer and matching the plurality of hollow pyramid-shaped protrusions, a PVDF electrospinning film arranged at the lower end of the rigid cone, a metal electrode arranged at one end of the PVDF electrospinning film, and a flexible packaging bottom layer arranged at the bottom.

[0009] The present invention is based on a flexible contact layer, on which a plurality of hollow pyramid-mounted protrusions extending from the bottom to the top are arranged, and a rigid cone-shaped body is correspondingly arranged to be embedded with the plurality of hollow pyramid-mounted protrusions. Based on the cooperation of the two, when the rigid cone-shaped body is squeezed by the rubber of the waterstop belt, the pressure will be transmitted to the PVDF electrospinning film, so that the fibers at the bottom of the cone-shaped body are compressed and the surrounding fibers are stretched, thereby generating triboelectric and piezoelectric effects at the same time, that is, no matter the vibration frequency is low or high, the triboelectric and piezoelectric properties can be monitored at the same time, and the processing module will record the transmitted vibration curve. By comparing it with the normal vibration curve, the state of the expansion joint can be judged, thereby improving the accuracy of monitoring.

[0010] Furthermore, the processing module performs gain amplification on the vibration signal collected from the acquisition module, and draws a vibration curve to be analyzed, and judges the state of the expansion joint by comparing the vibration curve to be analyzed with the normal vibration curve. Preferably, when the vibration curve to be analyzed and the normal vibration curve are compared and analyzed, if the similarity between the two is less than a preset similarity threshold, it is judged to be normal, otherwise it is abnormal.

[0011] Furthermore, the PVDF electrospun films of the monitoring device are divided into two groups, which are arranged between the flexible packaging bottom layer and the rigid cone in a horizontal and vertical cross manner.

[0012] The two layers of PVDF electrostatic spinning films with different orientations of the present invention can output two different signals simultaneously during extrusion and conduct them through metal electrodes.

[0013] Correspondingly, there are two groups of metal electrodes, which are arranged at both ends of the PVDF electrospinning film in a horizontal and vertical cross manner and are consistent with the setting direction of the PVDF electrospinning film.

[0014] Furthermore, the rigid cone of the monitoring device is embedded in the hollow pyramid-shaped protrusion of the flexible contact layer.

[0015] Furthermore, the flexible contact layer of the monitoring device is a PDMS flexible contact layer, the flexible packaging bottom layer is a PDMS flexible packaging bottom layer, and the rigid cone is an epoxy resin rigid cone.

[0016] Furthermore, the number of the collecting devices of the monitoring device is no less than four, and the flexible contact layer is provided with nine hollow pyramid-shaped protrusions in the middle, which are arranged in a 3×3 matrix.

[0017] Beneficial effect: Compared with the prior art, the significant advantages of the present invention are: the flexible triboelectric-piezoelectric expansion joint monitoring device, based on the cooperation of the acquisition module and the processing module, collects the triboelectric and piezoelectric effects generated on the PVDF electrospinning film through the acquisition module, and compares and analyzes the normal vibration curve through the processing module, thereby providing real-time monitoring of whether the bridge expansion joint is damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The diagram is a schematic diagram of the distribution of the acquisition modules of the present invention and their connection with the processing modules;

[0019] Figure 2 This is a schematic diagram of the installation position of the acquisition module of the present invention in the expansion joint;

[0020] Figure 3 This is a schematic diagram of the installation position of the collection module of the present invention in the water stop belt, that is, Figure 2 Enlarged view of part A in the middle;

[0021] Figure 4 It is a structural diagram of the acquisition module of the present invention, that is, Figure 3 Enlarged view of part B in the middle. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0023] like Figures 1 to 3 As shown, the flexible triboelectric-piezoelectric expansion joint monitoring device of the present invention is used to monitor whether the bridge expansion joint combination is damaged. It includes a collection module and a processing module for processing the signal collected by the collection module. The number of collection modules is not less than four.

[0024] The collection module is a flexible collection device, buried in the rubber waterstop, bonded to the rubber stiffening layer, and deformed with the deformation of the rubber waterstop to collect the vibration signal of the expansion joint. That is, if the expansion joint of the bridge is damaged, when a vehicle passes by, the frequency and amplitude of its vibration will change, especially when the fastening bolts of the expansion joint are loose or fall off, the change will become more obvious. This vibration change will also be transmitted to the rubber waterstop of the expansion joint. By monitoring the vibration of the rubber waterstop, the expansion joint can be monitored.

[0025] The processing module is electrically connected to the acquisition module, which collects the electrical signal from the acquisition module for gain amplification and draws the vibration curve to be analyzed of the electrical signal. By comparing the vibration curve to be analyzed with the normal vibration curve, the state of the expansion joint is judged. When comparing and analyzing the vibration curve to be analyzed and the normal vibration curve, if the similarity between the two is less than the preset similarity threshold, it is judged as normal, otherwise it is abnormal.

[0026] The collection device adopts a layered stacking structure, including a flexible contact layer 3 extending from the bottom to the top and provided with a plurality of hollow pyramid-shaped protrusions, a rigid cone 4 located at the lower end of the flexible contact layer 3 and matching the plurality of hollow pyramid-shaped protrusions, a PVDF electrospinning film 5 located at the lower end of the rigid cone 4, a metal electrode 6 located at one end of the PVDF electrospinning film 5, and a flexible packaging bottom layer 7 located at the bottom. In order to further improve the accuracy of monitoring, the PVDF electrospinning film 5 located at the lower end of the rigid cone 4 of the monitoring device can be arranged in two groups to achieve arrangements with different orientations. Figure 4 As shown, a PVDF electrospinning film staggered horizontally and vertically can be set at the lower end of the rigid cone, and two groups of metal electrodes staggered horizontally and vertically can be set at both ends of the PVDF electrospinning film staggered horizontally and vertically. The metal electrodes staggered horizontally and vertically are separated by the PVDF electrospinning film, so that different orientation signals can be collected.

[0027] In addition, the flexible contact layer 3 of the present invention can be a PDMS flexible contact layer, and the rigid cone 4 can be an epoxy resin rigid cone. When preparing it, a pit mold and a column mold with a 3×3 pit in the shape of a truncated pyramid are first printed by a 3D printer, and a mixture of a PDMS solution in a mass ratio of 10:1 is poured into the pit mold, and then the column mold is placed on the solution. After curing at 70°C for 12 hours, it is heated in an oven to obtain a PDMS flexible contact layer. The rigid cone 4 is embedded in the PDMS flexible contact layer by pouring the epoxy resin material into the convex part of the PDMS hollow pyramid, curing it at 25°C for 24 hours, so that the epoxy resin rigid cone is embedded in the upper PDMS flexible contact layer.

[0028] The longitudinal PVDF electrostatic spinning film and the transverse PVDF electrostatic spinning film of the middle layer of the present invention can be directly pasted on the PDMS flexible contact layer. The PVDF electrostatic spinning film is made by electrostatic spinning, and the material used for spinning is PVDF powder, which is fully stirred and dissolved in a DMF (dimethylformamide) solution by a magnetic stirrer to prepare a 15wt% PVDF solution. Its surface is covered with longitudinal metal electrodes and transverse metal electrodes. The PVDF electrostatic spinning film is cut into a square, and the longitudinal metal electrode and the transverse metal electrode are cut into a rectangle with a long side longer than the side length of the spinning membrane and a short side shorter than the side length of the spinning membrane. The extended part is convenient for connection with the wire. The size of the PVDF electrostatic spinning film is slightly larger than the metal electrode to prevent short circuits caused by direct contact between the electrodes. The flexible encapsulation bottom layer 7 can be a PDMS flexible encapsulation bottom layer, which can be directly encapsulated on the above-mentioned PVDF electrostatic spinning film 5.

[0029] That is, the flexible triboelectric-piezoelectric expansion joint monitoring device of the present invention is based on the cooperation of the acquisition module and the processing module. The triboelectric and piezoelectric effects generated on the PVDF electrospinning film are collected by the acquisition module, and compared and analyzed with the normal vibration curve by the processing module, thereby providing real-time monitoring of whether the expansion joint of the bridge is damaged.

Claims

1. A flexible triboelectric-piezoelectric expansion joint monitoring device based on a rubber waterstop, characterized in that: The monitoring device comprises a collection module buried in the rubber water stop and used to collect vibration signals of the expansion joint, and a processing module (2) for processing the vibration signals collected by the collection module (1); The collection module (1) comprises a flexible contact layer (3) extending from the bottom to the top and provided with a plurality of hollow pyramid-shaped protrusions, a rigid cone (4) located at the lower end of the flexible contact layer (3) and matching the plurality of hollow pyramid-shaped protrusions, a PVDF electrostatic spinning film (5) arranged at the lower end of the rigid cone (4), a metal electrode (6) arranged at one end of the PVDF electrostatic spinning film (5), and a flexible packaging bottom layer (7) arranged at the bottom.

2. The flexible triboelectric-piezoelectric expansion joint monitoring device based on rubber waterstop according to claim 1 is characterized in that: The processing module (2) performs gain amplification on the vibration signal collected from the acquisition module, draws a vibration curve to be analyzed, and determines the state of the expansion joint by comparing the vibration curve to be analyzed with a normal vibration curve.

3. According to claim 2, the flexible triboelectric-piezoelectric expansion joint monitoring device based on rubber waterstop is characterized in that: When comparing and analyzing the vibration curve to be analyzed with the normal vibration curve, if the similarity between the two is less than a preset similarity threshold, it is judged to be normal, otherwise it is abnormal.

4. The flexible triboelectric-piezoelectric expansion joint monitoring device based on rubber waterstop according to claim 1 is characterized in that: The PVDF electrostatic spinning films (5) are divided into two groups, which are respectively arranged between the flexible packaging bottom layer (7) and the rigid cone (4) in a horizontal and vertical cross manner.

5. The flexible triboelectric-piezoelectric expansion joint monitoring device based on rubber waterstop according to claim 4 is characterized in that: The metal electrodes (6) are divided into two groups, which are arranged at intervals at both ends of the PVDF electrostatic spinning film (5) in a horizontal and vertical crossing manner, and are consistent with the setting direction of the PVDF electrostatic spinning film (5).

6. The flexible triboelectric-piezoelectric expansion joint monitoring device based on rubber waterstop according to claim 1 is characterized in that: The rigid cone (4) is embedded in the hollow pyramid-shaped protrusion of the flexible contact layer (3).

7. The flexible triboelectric-piezoelectric expansion joint monitoring device based on rubber waterstop according to claim 1 is characterized in that: The flexible contact layer (3) is a PDMS flexible contact layer, the flexible packaging bottom layer (7) is a PDMS flexible packaging bottom layer, and the rigid cone (4) is an epoxy resin rigid cone.

8. The flexible triboelectric-piezoelectric expansion joint monitoring device based on rubber waterstop according to claim 1 is characterized in that: The number of the collecting devices (1) is not less than four, and the flexible contact layer (3) is provided with nine hollow pyramid-shaped protrusions in the middle, arranged in a 3×3 matrix.

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