Intelligent gasket for monitoring hole edge crack of bolt connection structure

Abstract

The invention discloses an intelligent gasket for monitoring hole edge cracks of a bolt connection structure, and relates to the technical field of structure health monitoring, and the technical scheme is characterized in that the intelligent gasket comprises a metal gasket, and the metal gasket is provided with a plurality of through conductive via holes; one side surface of the metal gasket is an induction side surface, and the other side surface is a pad side surface; the metal gasket is provided with an excitation line and a receiving line on the induction side surface, and a connecting line and a plurality of conductive bonding pads are arranged on the side surfaces of the bonding pads; the receiving line is connected with the connecting line and the different bonding pads on the side faces of the bonding pads through the via holes, and the excitation line is connected with the other bonding pads through the via holes. According to the intelligent gasket, the bearing capacity of a metal gasket and the crack monitoring function of a flexible eddy current sensor are combined, the huge load of the hole edge of a bolt connection structure can be borne, meanwhile, effective monitoring of hole edge cracks is achieved, and the bearing capacity and durability are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of structural health monitoring, and more particularly to an intelligent gasket for monitoring cracks at the edge of a hole in a bolted connection structure. Background Art

[0002] Structural health monitoring technology involves deploying advanced sensors on structures to collect parameters representing the structural health status in real time. Through data collection, data processing, and damage identification, the structural health status is determined, allowing maintenance plans to be developed. Currently, sensors commonly used for structural health monitoring include strain sensors, fiber optic sensors, smart coating sensors, ultrasonic guided wave sensors, and flexible eddy current sensors. In mechanical structures, bolted connections are the most important form of connection for aircraft, high-speed rail, and large lifting machinery. Due to the preload, the hole edge area of ​​bolted connection structures is subject to enormous pressure, reaching up to 700 MPa. However, existing crack monitoring sensors cannot directly withstand such large loads, making them difficult to apply to hole edge crack monitoring in bolted connection structures, and present significant limitations in practical engineering applications.

[0003] Existing flexible eddy current (array) sensors are generally prepared using mature flexible circuit manufacturing processes, and the materials used are generally flexible substrate materials, which cannot withstand the large assembly loads. For example, the existing published Chinese utility model patent, publication number: CN215727889U, is a double-sided reinforced flexible eddy current array sensor for hole edge crack monitoring. Its technical content includes an eddy current array sensor, which includes an induction coil and an excitation coil. The leads at both ends of the excitation coil extend out of the eddy current array sensor, and a hollowed-out circular area is provided inside the excitation coil; the bottom surface of the eddy current array sensor is provided with a flexible substrate, and the top surface of the eddy current array sensor is covered with a protective film. The inner diameter of the hollowed-out circular area matches the bolt hole diameter. A bolt is passed through the bolt hole for fixing the structural member. A reinforcement layer is provided between the eddy current array sensor and the bolt and structural member. The above technical solution can effectively monitor cracks on the edge of the bolt hole without destroying the normal function of the sensor, thereby achieving effective and accurate monitoring of cracks on the edge of the bolt hole.

[0004] While this technical solution proposes that attaching reinforcement sheets to both sides of the flexible eddy current sensor can disperse the load-bearing pressure, the core coil will still bear a certain amount of load, and prolonged pressure, friction, and other loads will still cause the sensor to fail. Therefore, to address the problem that existing structural crack monitoring sensors are unable to withstand the huge loads at the edges of bolted holes, making it difficult to detect cracks at the edges of holes, the present invention provides a gasket that combines the crack monitoring capabilities of a flexible eddy current sensor with the load-bearing capacity of a conventional gasket, significantly improving the sensor's durability and engineering application value. Summary of the Invention

[0005] The purpose of the present invention is to provide an intelligent gasket for monitoring cracks at the edge of a bolted connection structure hole, so as to solve the problem that the existing structural crack monitoring sensor cannot bear the huge load at the edge of the bolted connection structure hole, making it difficult to realize hole edge crack monitoring, and realize effective monitoring of cracks at the edge of the bolted connection structure hole.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: an intelligent gasket for monitoring cracks on the edge of a bolted structure hole, comprising a metal gasket, wherein the metal gasket is provided with a plurality of conductive vias running through the metal gasket; one side of the metal gasket is a sensing side, and the other side is a pad side; the metal gasket is provided with an excitation line and a receiving line on the sensing side, and a connecting line and a plurality of conductive pads on the pad side; the receiving line is connected to the connecting line and different pads on the pad side through the via, and the excitation line is connected to the remaining pads through the via.

[0007] The present invention is further configured as follows: the number of the vias is 6, including via 1, via 2, via 3, via 4, via 5, and via 6; the number of the pads is 4, including pad 1, pad 2, pad 3, and pad 4.

[0008] It is further configured as follows: the receiving line is connected to the connecting line on the side of the pad through via one and via two; the receiving line is connected to pad one and pad four respectively through via three and via six; the excitation line is connected to pad two and pad three respectively through via four and via five.

[0009] The present invention is further configured such that: the pad is connected to a lead of an external device by welding.

[0010] The present invention is further configured as follows: the metal gasket is provided with a plurality of grooves on its surface for installing and placing the excitation line, the receiving line and the connecting line respectively; the paths of the plurality of grooves are respectively the same as the paths of the installed excitation line, the receiving line and the connecting line.

[0011] It is further configured as follows: the width of the groove is 0.25mm-0.35mm, the depth is 0.25mm-0.35mm, and the diameter of the through hole is 0.25mm-0.35mm.

[0012] It is further configured as follows: the width of the groove is 0.3 mm and the depth is 0.3 mm; the diameter of the via hole is 0.3 mm.

[0013] The present invention is further configured as follows: the metal gasket is in sheet shape, and a through hole for the bolt to pass through is provided in the middle thereof.

[0014] The present invention is further configured as follows: the surface of the metal gasket is subjected to insulation treatment to have an insulation layer, and the thickness of the insulation layer is 0.04 mm-0.07 mm, specifically 0.05 mm.

[0015] The present invention is further configured as follows: a layer of polyimide film is first adhered to the surface of the metal gasket, and then a physical vapor deposition process is used to use a laser engraving process to remove only the film on the surface of the groove and via, and a mask is formed on the surface of the metal gasket to block the area except the groove and via.

[0016] The present invention is further configured as follows: depositing copper conductive coils at the grooves and vias, and the thickness of the prepared conductive coils is 0.08 mm to 0.12 mm, specifically 0.1 mm.

[0017] The present invention is further configured to use sealant to isolate and protect the excitation line, the receiving line and the via hole.

[0018] The present invention also provides a method for preparing the above-mentioned smart gasket for monitoring cracks at the edge of a bolted connection structure, comprising the following steps:

[0019] S1: According to the pre-designed position paths of the excitation line, receiving line and connecting line on the metal gasket, a groove is prepared by laser engraving process; the width of the groove is 0.25mm-0.35mm and the depth is 0.25mm-0.35mm;

[0020] S2: preparing via holes on a mechanical drill at the locations of the pre-designed multiple via holes on the metal gasket;

[0021] S3: Insulating the metal gasket using an anodic oxidation process to form an insulating layer with a thickness of 0.04 mm to 0.07 mm;

[0022] S4: First, a layer of polyimide film is adhered to the surface of the metal gasket. Then, a laser engraving process is used to remove only the film on the surface of the groove and via, forming a mask on the surface of the metal gasket; the mask covers the metal gasket area except the groove and via; and a copper conductive coil is deposited in the groove and via on the side of the metal gasket. The thickness of the prepared conductive coil is 0.08mm-0.12mm, thereby forming a conductive excitation line, a receiving line and a via;

[0023] S5: Using a physical vapor deposition process, preparing conductive pads at the locations of the multiple pads pre-designed on the other side of the metal gasket;

[0024] S6: Use sealant to encapsulate, isolate and protect the excitation line, receiving line and vias; solder leads to the pads and connect to external devices.

[0025] In summary, the present invention has the following beneficial effects: the smart gasket for hole edge crack monitoring of the present invention forms a sensor by directly engraving a groove on the surface of the metal gasket and directly preparing a conductive coil in the groove using a PVD process; because the width and depth of the groove are only about 0.3 mm, there is no obvious effect on the load-bearing capacity of the smart gasket; since the conductive coil is located in the groove, it basically does not bear any load during monitoring, thereby significantly improving the load-bearing capacity and durability of the smart gasket of the present invention.

[0026] The intelligent gasket of the present invention combines the load-bearing capacity of a metal gasket and the crack monitoring function of a flexible eddy current sensor. It can withstand the huge load on the hole edge of the bolted connection structure, while effectively monitoring the cracks on the hole edge, thereby improving the durability and engineering application value of the sensor.

[0027] Reasonable structural design, such as the setting of vias, pads, grooves, and the connection methods between various components, ensures stable signal transmission and accurate monitoring.

[0028] Advanced preparation processes such as laser engraving, anodizing, and physical vapor deposition ensure the high precision and high quality of the products and improve their performance and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the side structure of the intelligent gasket sensor in an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the side structure of the smart gasket pad in an embodiment of the present invention;

[0031] Figure 3 Schematic diagram of the position of the smart gasket during monitoring in an embodiment of the present invention.

[0032] In the figure: 1. Receiving line; 2. Excitation line; 3. Via one; 4. Via two; 5. Via three; 6. Via four; 7. Via five; 8. Via six; 9. Connecting line; 10. Pad one; 11. Pad two; 12. Pad three; 13. Pad four; 14. Metal gasket; 15. Smart gasket; 16. Bolt; 17. Metal structure under test. DETAILED DESCRIPTION

[0033] The following is combined with Figure 1-3 The present invention is described in further detail.

[0034] Example: A smart gasket for monitoring cracks on the edge of a bolted structure hole, such as Figure 1 、 Figure 2As shown, the device includes a metal gasket 14 with multiple conductive vias extending through it. One side of the metal gasket 14 is the sensing side, and the other side is the pad side. The metal gasket 14 has an excitation line 2 and a receiving line 1 on the sensing side, and a connection line 9 and multiple conductive pads on the pad side. The receiving line 1 is connected to the connection line 9 and different pads on the pad side through vias, and the excitation line 2 is connected to the remaining pads through vias. There are six vias, including via 1 3, via 2 4, via 3 5, via 4 6, via 5 7, and via 6 8. There are also four pads, including pad 1 10, pad 2 11, pad 3 12, and pad 4 13. Receive line 1 connects to connection line 9 on the side of the pad through via 1 (3) and via 2 (4). Receive line 1 connects to pad 1 (10) and pad 4 (13) through via 3 (5) and via 6 (8), respectively. Excitation line 2 connects to pad 2 (11) and pad 3 (12) through via 4 (6) and via 5 (7), respectively. The pads are connected to leads of external devices by soldering.

[0035] The metal gasket 14 has multiple grooves on its surface for mounting the excitation wire 2, the receiving wire 1, and the connecting wire 9. The grooves follow the same path as the excitation wire 2, the receiving wire 1, and the connecting wire 9. The grooves are 0.25mm-0.35mm wide and 0.25mm-0.35mm deep, and the vias have diameters of 0.25mm-0.35mm. Specifically, the grooves are 0.3mm wide and 0.3mm deep, and the vias have a diameter of 0.3mm.

[0036] The metal gasket 14 is in the form of a sheet, and a through hole is provided in the middle thereof for the bolt 16 to pass through. The surface of the metal gasket 14 has been insulated and has an insulating layer, and the thickness of the insulating layer is 0.04mm-0.07mm, specifically 0.05mm. First, a layer of polyimide film is adhered to the surface of the metal gasket, and then a laser engraving process is used to remove only the film on the surface of the groove and the via, forming a mask on the surface of the metal gasket, and forming a mask on the surface of the metal gasket 14 for shielding. Using a physical vapor deposition process, deposited copper conductive coils are prepared in the grooves and vias, and the thickness of the prepared conductive coils is 0.08mm-0.12mm, specifically 0.1mm. Aviation fuel tank sealant is used to isolate and protect the excitation line 2, the receiving line 1 and the via.

[0037] Furthermore, the present invention also discloses a method for preparing the above-mentioned smart gasket 15, the steps of which are as follows:

[0038] S1: According to the pre-designed position paths of the excitation line 2, the receiving line 1 and the connecting line 9 on the metal gasket 14, a groove is prepared by laser engraving process; the width of the groove is 0.25mm-0.35mm and the depth is 0.25mm-0.35mm;

[0039] S2: preparing via holes on a mechanical drill at the locations of the pre-designed multiple via holes on the metal gasket 14;

[0040] S3: The metal gasket 14 is insulated by an anodic oxidation process to form an insulating layer with a thickness of 0.04 mm to 0.07 mm;

[0041] S4: First, a layer of polyimide film is adhered to the surface of the metal gasket. Then, a physical vapor deposition process and a laser engraving process are used to remove only the film on the surface of the groove and the via, forming a mask on the surface of the metal gasket 14; the mask covers the area of ​​the metal gasket 14 except the groove and the via; and a copper conductive coil is deposited in the groove and the via on the side of the metal gasket 14. The thickness of the prepared conductive coil is 0.08mm-0.12mm, thereby forming a conductive excitation line 2, a receiving line 1 and a via.

[0042] S5: Using a physical vapor deposition process, a conductive pad is prepared at the position of the multiple pads pre-designed on the other side of the metal gasket 14;

[0043] S6: Encapsulate with sealant to isolate and protect the excitation line 2, the receiving line 1 and the vias; solder leads to the pads and connect to external devices.

[0044] When the smart gasket 15 of the present invention is used to monitor the cracks at the edge of the hole of the bolt 16 connection structure, Figure 3 As shown, the smart gasket 15 is installed on the edge of the bolt 16 hole of the metal structure 17 to be measured through the bolt 16, and the sensing side is close to the metal structure 17 to be measured, and the pad is located in the area outside the bolt 16. The crack monitoring function of the smart gasket 15 is realized by the excitation line 2 and the receiving line 1. When a sinusoidal alternating current I0 is passed through the excitation line 2, a sinusoidal alternating magnetic field H1 will be generated in space. An induced current I1 will appear on the surface of the metal structure 17 to be measured in the alternating magnetic field H1, and an alternating magnetic field H2 will also be generated. When a crack appears at the edge of the hole, the distribution of the induced current I1 will change, thereby causing the distribution of H2 to change, and then the voltage signal V1 of the receiving line 11 to change. By monitoring the changes in the voltage signal V1 of the receiving line 1, the cracks in the bolt 16 hole edge structure can be monitored.

[0045] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. An intelligent gasket for monitoring cracks on the edge of a bolted structure hole, characterized by: It includes a metal gasket with multiple conductive vias passing through it; one side of the metal gasket is a sensing side, and the other side is a pad side; the metal gasket is provided with an excitation line and a receiving line on the sensing side, and a connecting line and multiple conductive pads on the pad side; the receiving line is connected to the connecting line and different pads on the pad side through the vias, and the excitation line is connected to the remaining pads through the vias.

2. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 1 is characterized in that: The number of the vias is 6, including via 1, via 2, via 3, via 4, via 5, and via 6; the number of the pads is 4, including pad 1, pad 2, pad 3, and pad 4.

3. The intelligent gasket for monitoring cracks on the edge of a bolted connection structure according to claim 2 is characterized in that: The receiving line is connected to the connecting line on the side of the pad through via 1 and via 2; the receiving line is connected to pad 1 and pad 4 respectively through via 3 and via 6; the excitation line is connected to pad 2 and pad 3 respectively through via 4 and via 5.

4. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 1 is characterized in that: The pad is connected to the lead of the external device by welding.

5. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 1 is characterized in that: The metal gasket is provided with a plurality of grooves on its surface for installing and placing the excitation line, the receiving line and the connecting line respectively; the paths of the plurality of grooves are respectively the same as the paths of the installed excitation line, the receiving line and the connecting line.

6. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 5 is characterized in that: The width of the groove is 0.25mm-0.35mm, the depth is 0.25mm-0.35mm, and the diameter of the through hole is 0.25mm-0.35mm.

7. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 5 is characterized in that: The width of the groove is 0.3 mm and the depth is 0.3 mm; the diameter of the via hole is 0.3 mm.

8. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 1 is characterized in that: The metal gasket is in sheet shape, and a through hole is provided in the middle thereof for the bolt to pass through.

9. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 1 is characterized in that: The surface of the metal gasket is subjected to insulation treatment and has an insulation layer, and the thickness of the insulation layer is 0.04 mm-0.07 mm, specifically 0.05 mm.

10. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 1, wherein: First, a layer of polyimide film is adhered to the surface of the metal gasket, and then a laser engraving process is used to remove only the film on the surface of the groove and via, forming a mask on the surface of the metal gasket to cover the area except the groove and via.

11. The intelligent gasket for monitoring cracks at the edge of a bolted structure according to claim 1, wherein Copper conductive coils are deposited in the grooves and vias, and the thickness of the prepared conductive coils is 0.08 mm to 0.12 mm, specifically 0.1 mm.

12. The intelligent gasket for monitoring cracks at the edge of a bolted connection structure according to claim 1, wherein: Use sealant to isolate and protect the excitation line, receiving line and vias.

13. A method for preparing an intelligent gasket for monitoring cracks at the edge of a bolted connection structure, characterized in that: The steps include: S1: According to the pre-designed position paths of the excitation line, receiving line and connecting line on the metal gasket, a groove is prepared by laser engraving process; the width of the groove is 0.25mm-0.35mm and the depth is 0.25mm-0.35mm; S2: preparing via holes on a mechanical drill at the locations of the pre-designed multiple via holes on the metal gasket; S3: Insulating the metal gasket using an anodic oxidation process to form an insulating layer with a thickness of 0.04 mm to 0.07 mm; S4: firstly, a layer of polyimide film is adhered to the surface of the metal gasket, and then a physical vapor deposition process is used to remove only the film on the surface of the groove and the via hole by a laser engraving process to form a mask on the surface of the metal gasket; A mask is used to cover the metal gasket area except for the grooves and vias. A physical vapor deposition process is used to deposit copper conductive coils in the grooves and vias on the side of the metal gasket. The thickness of the prepared conductive coils is 0.08mm-0.12mm, thereby forming conductive excitation lines, receiving lines and vias. S5: Using a physical vapor deposition process, preparing conductive pads at the locations of the multiple pads pre-designed on the other side of the metal gasket; S6: Use sealant to encapsulate, isolate and protect the excitation line, receiving line and vias; solder leads to the pads and connect to external devices.

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