A testing device for bolted laminated plates

Abstract

This application discloses a detection device for a bolted laminated plate. The device includes: a first piezoelectric thin-film sensor mounted on the first end of the bolt; a second piezoelectric thin-film sensor mounted on the second end of the bolt; a first sensor washer assembly including a first mounting washer and a first thin-film piezoelectric sensor array formed by a plurality of thin-film piezoelectric sensor units arranged in a ring at intervals on the sensing washer, the first mounting washer being fitted around the outer periphery of the first end of the bolt; and a second sensor washer assembly including a second mounting washer and a second thin-film piezoelectric sensor array formed by a plurality of thin-film piezoelectric sensor units arranged in a ring at intervals on the sensing washer, the second mounting washer being fitted around the outer periphery of the second end of the bolt. This application combines bolt preload detection technology with perforated plate hole periphery damage monitoring technology to achieve real-time monitoring of the health of perforated plates and their bolted connections, providing a new approach for safety monitoring of wing-body connection structures in aircraft.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laminated plate monitoring, and particularly relates to a detection device for a laminated plate with a bolt. BACKGROUND

[0002] Fiber-reinforced composites have been widely used in aerospace, shipbuilding, automobile, building and other fields due to their high modulus, high strength, low density, small thermal expansion coefficient and other performances. Therefore, the structural safety of the composite material is an important factor to ensure the normal operation of the entire system. A slight damage can potentially develop and cause a catastrophic accident. The connection structure of the composite laminated plate is a key part of the wing-body connection structure of the aircraft, and is also the most prone to failure position. However, there are few studies on the damage detection of the wing-body connection structure at home and abroad, especially the real-time monitoring method for the damage around the hole of the hole plate is relatively backward. Usually, the structure needs to be disassembled for offline testing. The testing method is time-consuming and depends on human participation, such as acoustic emission, X-ray and thermal imaging. Therefore, real-time health monitoring of the laminated plate and its bolt connection structure is beneficial to improve the overall safety.

[0003] The current industry and academia are actively developing new methods for structural health monitoring and damage analysis. Compared with traditional methods, the requirements for new monitoring and analysis methods are: 1) integrate the monitoring system into the structure (become an intelligent structure); 2) make online monitoring of the structure possible; 3) the data analysis algorithm should be simple; 4) have the ability to identify, locate and quantify damage, and even predict the weaker areas. Commonly used sensors include optical fiber sensors, piezoelectric sensors, microchip sensors and eddy current sensors. For example, ultrasonic time-of-flight method is considered to be a promising bolt pre-tightening force monitoring technology. First, a wear-resistant and high-temperature-resistant nano-composite piezoelectric coating is prepared by direct current magnetron sputtering technology and plasma etching technology. Ultrasonic waves are generated by the vibration of the piezoelectric material and propagate along the bolt axis. The pre-tightening force of the bolt is calculated by the time difference between the signal generation and signal reception. The intelligent bolt is not only suitable for high-temperature environments, but also improves the detection accuracy of the pre-tightening force. In addition, there is also a kind of eddy current film sensor. The distribution and flow path of the eddy current will be affected by the position change of the damage around the hole in the horizontal direction and the thickness direction, thereby realizing the ability to detect the damage around the hole. SUMMARY

[0004] Therefore, the detection device for a laminated plate with a bolt provided by the present application not only has the ability to detect the change of the bolt pre-tightening force, but also has the ability to monitor the size and position of the damage around the hole of the hole plate.

[0005] The application provides a bolted laminated plate detection device suitable for detecting bolt pre-tightening force and damage around bolt holes of a bolted laminated plate, the bolted laminated plate comprising a laminated plate with threaded holes and bolt members screwed into the threaded holes, and the detection device comprising:

[0006] a first piezoelectric film sensor mounted on a first end of the bolt member;

[0007] a second piezoelectric film sensor mounted on a second end of the bolt member;

[0008] a first sensor washer assembly comprising a first mounting washer and a first piezoelectric film sensor array formed by a plurality of piezoelectric film sensor units arranged in a ring shape and spaced apart, the first mounting washer being sleeved on the outer periphery of the first end of the bolt member;

[0009] a second sensor washer assembly comprising a second mounting washer and a second piezoelectric film sensor array formed by a plurality of piezoelectric film sensor units arranged in a ring shape and spaced apart, the second mounting washer being sleeved on the outer periphery of the second end of the bolt member;

[0010] wherein the first piezoelectric film sensor is configured as an active excitation sensor to excite a pulse voltage signal, the pulse voltage signal is conducted through the bolt member to generate a vibration signal, the second piezoelectric film sensor is configured as a signal receiving sensor to receive the vibration signal, and the time difference between the excitation signal and the received signal is collected by an external data collection device to obtain the flight time of the vibration signal inside the bolt member, and then the bolt pre-tightening force is obtained;

[0011] wherein the first piezoelectric film sensor array is used to excite a pulse voltage signal, the pulse voltage signal is conducted through the outer periphery of the threaded hole of the laminated plate to form a Lamb wave signal, and the second piezoelectric film sensor array is used to receive the Lamb wave signal, and the damage condition around the threaded hole is detected by an external detection chip.

[0012] Optionally, the first piezoelectric film sensor array and the second piezoelectric film sensor array are electrically connected with a ring-shaped electrode as an anode, and the first mounting washer and the second mounting washer are configured as a cathode.

[0013] Optionally, the ring-shaped electrode comprises a polyimide film substrate and a copper wire plated on the polyimide film substrate.

[0014] Optionally, the thickness of the polyimide film substrate is 100 microns, and the thickness of the copper wire is 10 microns.

[0015] Optionally, the detection chip is an ADG708 chip.

[0016] Optionally, the first piezoelectric thin film sensor, the second piezoelectric thin film sensor, the first thin film piezoelectric sensor array, and the second thin film piezoelectric sensor array include, from the inside out, a stacked AlCr alloy bonding layer, an AlCrN / AlScN nanopiezoelectric coating, and an AlCr alloy electrode. The AlCrN / AlScN nanopiezoelectric coating is prepared using a combination of DC magnetron sputtering and plasma etching techniques, and is formed by alternating deposition of monolayer AlCrN thin films and monolayer AlScN thin films.

[0017] Optionally, the thickness of the monolayer AlCrN film and the monolayer AlScN film is 5-20 nanometers, and the thickness of the AlCrN / AlScN nanopiezoelectric coating is 5-50 micrometers.

[0018] Optionally, protective washers are provided on the surfaces of the first thin-film piezoelectric sensor array away from the first mounting washer and on the surfaces of the second thin-film piezoelectric sensor array away from the second mounting washer.

[0019] Optionally, the protective gasket is surface polished until its surface roughness is less than 0.32 micrometers.

[0020] Optionally, the detection chip is electrically connected to a microcontroller output pin, which is used to form high and low level states.

[0021] This application has the following beneficial effects:

[0022] 1. The bolt preload monitoring method proposed in this application has a simple structure and low cost. The use of piezoelectric thin-film sensors at both ends avoids the reuse of the same sensor, reducing signal interference. Signal acquisition and data processing are simple, and when combined with a multi-channel data acquisition device, signal detection of bolt arrays can be achieved.

[0023] 2. The nanoscale piezoelectric thin film prepared in this application has the advantages of mature preparation process, wear resistance and high temperature resistance, and adjustable piezoelectric properties.

[0024] 3. The perforation damage detection method for perforated plates proposed in this application can not only monitor the structural health around the perforation in real time, but also detect and locate cracks or matrix fractures.

[0025] This application combines bolt preload monitoring with perihole structure health monitoring to achieve overall health monitoring of perforated plate connection structures. The method proposed in this application can also be combined with intelligent skin or intelligent sandwich structures to achieve overall health monitoring of composite laminate structures. Attached Figure Description

[0026] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0027] Figure 1 This is a schematic diagram of the health monitoring structure of the perforated plate and its bolted connection structure disclosed in the embodiments of this application;

[0028] Figure 2 This is a schematic diagram of the structure of the nanoscale piezoelectric coating disclosed in the embodiments of this application;

[0029] Figure 3 This is a schematic diagram of the structure of the mounting gasket disclosed in the embodiments of this application;

[0030] Figure 4 This is a schematic diagram of the structure of the ring electrode disclosed in the embodiments of this application.

[0031] The components in the diagram are labeled as follows:

[0032] 1-First piezoelectric thin film sensor, 2-Bolt, 3-First protective washer, 4-First piezoelectric thin film sensor array, 5-First mounting washer, 6-First adhesive layer, 7-Laminated board, 8-Second adhesive layer, 9-Second mounting washer, 10-Second piezoelectric thin film sensor array, 11-Second protective washer, 12-Nut, 13-Second piezoelectric thin film sensor, 14-Polyimide substrate, 15-Copper wire, 16-Ring electrode, 101-AlCr alloy electrode, 102-AlCrN / AlScN nano-piezoelectric coating, 103-AlCr alloy bonding layer. Detailed Implementation

[0033] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0036] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0037] Please refer to Figure 1 , Figure 2 The detection device for bolted laminates disclosed in this application is suitable for detecting the bolt preload and / or damage around the bolt holes of the bolted laminate 7. The bolted laminate 7 includes a laminate 7 with threaded holes and bolts 2 screwed into the threaded holes.

[0038] It should be added that the practical significance of the bolt preload and thread hole perimeter damage detection performed by this testing device is that, by monitoring the perimeter health of each bolted component 2 in real time, the locations of stress concentration in bolted connection structures (such as the wing-body connection structure of an aircraft) can be analyzed. By optimizing the structure at stress concentration points (such as changing the size, number, or distribution of bolts), the safety and service life of bolted laminates can be improved.

[0039] The above-mentioned detection device includes:

[0040] The first piezoelectric thin film sensor 1 is mounted on the first end of the bolt 2;

[0041] The second piezoelectric thin film sensor 13 is mounted on the second end of the bolt 2;

[0042] The first sensor washer assembly includes a first mounting washer 5 and a first piezoelectric thin film sensor array 4 formed by a plurality of thin film piezoelectric sensor units arranged in a ring at intervals on the aforementioned sensor washer. The first mounting washer 5 is sleeved on the outer periphery of the first end of the bolt member 2.

[0043] The second sensor washer assembly includes a second mounting washer 9 and a second piezoelectric thin film sensor array 10 formed by a plurality of thin film piezoelectric sensor units arranged in a ring at intervals on the aforementioned sensor washer. The second mounting washer 9 is sleeved on the outer periphery of the second end of the bolt member 2.

[0044] The first piezoelectric thin film sensor 1 is configured as an active excitation sensor to excite a pulse voltage signal. The pulse voltage signal is transmitted through the bolt 2 to generate a vibration signal. The second piezoelectric thin film sensor 13 is configured as a signal receiving sensor to receive the vibration signal. The time difference between the excitation signal and the received signal is collected by an external data acquisition device to obtain the flight time of the vibration signal inside the bolt 2, and then the magnitude of the bolt preload is obtained, for example, F = k·(Δt-Δt0), where Δt is the signal sound time difference between the active excitation end and the signal receiving end, and F is the bolt preload.

[0045] The first piezoelectric thin film sensor array 4 is used to excite a pulse voltage signal. The pulse voltage signal is conducted around the threaded hole of the laminate 7 to form a Lamb wave signal. The second piezoelectric thin film sensor array 10 is used to receive the Lamb wave signal so that the damage condition around the threaded hole can be detected by an external detection chip.

[0046] The first piezoelectric thin film sensor 1 can be mounted on the first end of the bolt member 2 through the first adhesive layer 6, and the second piezoelectric thin film sensor 13 can be mounted on the second end of the bolt member 2 through the second adhesive layer 8.

[0047] It is easy to imagine that, since the first mounting washer 5 is fitted onto the outer periphery of the first end of the bolt 2, the first mounting washer 5 is pressed tightly against the first end of the laminate 7 by the bolt 2. Since the second mounting washer 9 is fitted onto the outer periphery of the second end of the bolt 2, the second mounting washer 9 is pressed tightly against the second end of the laminate 7 by the bolt 2.

[0048] As for bolt 2, it can be formed by assembling a screw and nut 12.

[0049] As previously stated, "the first piezoelectric thin-film sensor array 4 is formed by several thin-film piezoelectric sensor units arranged in a ring at intervals," and "the second piezoelectric thin-film sensor array 10 is formed by several thin-film piezoelectric sensor units arranged in a ring at intervals." Therefore, the thin-film piezoelectric sensor units are generally fan-shaped. The number of thin-film piezoelectric sensor units can be six or other numbers. Considering the need to improve the accuracy of damage localization while generating more signal data, those skilled in the art can increase the number of fan-shaped areas, further subdividing the periphery of the hole into more detection areas.

[0050] It is easy to understand that each thin-film piezoelectric sensor unit constituting the first piezoelectric thin-film sensor array 4 is paired with each thin-film piezoelectric sensor unit constituting the second piezoelectric thin-film sensor array 10. That is, when a thin-film piezoelectric sensor unit in the first piezoelectric thin-film sensor array 4 generates an excitation pulse voltage signal, there must be a thin-film piezoelectric sensor unit in the second piezoelectric thin-film sensor array 10 to receive the pulse voltage signal.

[0051] In order to accommodate the electrical connection between the first piezoelectric thin film sensor array 4, the second piezoelectric thin film sensor array 10 and the external detection component, the first piezoelectric thin film sensor array 4 and the second piezoelectric thin film sensor array 10 are electrically connected with an annular electrode 16 as the positive electrode, and the first mounting washer 5 and the second mounting washer 9 are configured as the negative electrode.

[0052] It is easy to imagine that the shape of the ring electrode 16 is composed of multiple electrode units arranged in a ring, and each electrode unit is simultaneously electrically connected to each thin film piezoelectric sensor unit of the first piezoelectric thin film sensor array 4 and each thin film piezoelectric sensor unit of the second piezoelectric thin film sensor array 10, for example, through independent leads.

[0053] As an exemplary example, the aforementioned annular electrode 16 includes a polyimide substrate 14 and an electroplated copper wire 15 disposed on the polyimide substrate 14.

[0054] Here, the polyimide substrate 14 has a thickness of 100 micrometers, and the copper wire 15 has a thickness of 10 micrometers. One end of the copper wire 15 is made into a disk shape to increase the contact area with the piezoelectric thin film sensor. The size of the disk should be contained within a single fan-shaped area to prevent contact with the gasket substrate and cause a short circuit. The other end of the copper wire 15 is made into standard, equally spaced leads for easy connection to a flexible printed circuit board.

[0055] The electrical signals of each sector area can be obtained simultaneously through a multi-channel data acquisition device. To prevent mutual interference between adjacent areas, the detection chip mentioned above is the ADG708 chip.

[0056] The specific operating method is as follows:

[0057] 1. The high-frequency pulse signal generated by the signal generator is selected by the ADG708 chip to apply a pulse signal to a single piezoelectric sensor in the piezoelectric thin film sensor array. The multi-channel data acquisition device detects the voltage change of the corresponding piezoelectric sensor on the signal receiving washer.

[0058] 2. The selection state of the ADG708 chip is controlled by using the high and low level states of the microcontroller's output pins. A program is written for the microcontroller to cyclically select six regions and detect the Lamb wave signal within each region.

[0059] 3. To prevent the Lamb wave signal generated by the previous sensor from interfering with the signal measurement of the next sensor, the time interval for switching channels of the ADG708 chip should be appropriately increased. When the Lamb wave signal generated by the previous sensor has attenuated to almost zero, the channel of the next signal excitation and signal receiving sensor should be turned on.

[0060] As an example, the first piezoelectric thin film sensor 1, the second piezoelectric thin film sensor 13, the first piezoelectric thin film sensor array 4, and the second piezoelectric thin film sensor array 10 include, from the inside out, sequentially stacked AlCr alloy bonding layer 103, AlCrN / AlScN nanopiezoelectric coating 102, and AlCr alloy electrode 101. The AlCrN / AlScN nanopiezoelectric coating 102 is prepared using a combination of DC magnetron sputtering and plasma etching techniques, and is formed by alternating deposition of monolayer AlCrN thin films and monolayer AlScN thin films.

[0061] As one implementation method, the thickness of the monolayer AlCrN film and the monolayer AlScN film is 5-20 nanometers, and the thickness of the AlCrN / AlScN nanopiezoelectric coating 102 is 5-50 micrometers.

[0062] Before fabricating the piezoelectric thin film sensor, plasma etching technology is used to etch the upper and lower end faces of the bolt to reduce surface roughness and improve the adhesion of the piezoelectric thin film sensor.

[0063] It is important to note that adjusting the total thickness and average thickness of the piezoelectric functional layer can improve its piezoelectric performance. An AlCr alloy electrode 101 is deposited on the outer surface of the nanoscale piezoelectric coating, establishing a good conductive path between it and the annular electrode 16, thus preventing open circuits.

[0064] In a typical implementation, protective washers are provided on the surface of the first piezoelectric thin film sensor array 4 away from the first mounting washer 5 and on the surface of the second piezoelectric thin film sensor array 10 away from the second mounting washer.

[0065] Therefore, by setting a protective washer, on the one hand, the wear of the bolt (or nut 12) on the annular electrode 16 can be reduced, thus improving its service life. On the other hand, after tightening the nut 12, the annular electrode 16 can be fully connected to the outer electrode of the piezoelectric thin film sensor array, preventing open circuit phenomena.

[0066] The aforementioned protective gaskets undergo surface polishing treatment until their surface roughness is less than 0.32 micrometers.

[0067] Therefore, polishing reduces wear on the annular electrode 16, thereby protecting it. The polishing process can be performed using plasma technology.

[0068] The operational process of this application's testing will now be described in several common application scenarios. It should be noted that these common implementation schemes should not be used as the basis for determining the essential features for understanding the technical problem claimed to be solved by this application; they are merely examples.

[0069] Example 1

[0070] Please see Figure 1 This testing device is used to test the preload of bolts, specifically as follows:

[0071] The threaded holes of the laminate 7 with threaded holes are fitted with bolts 2. The bottom end of the bolts is fitted with nuts 2. The bolts 2 and nuts 12 with the first piezoelectric film sensor 1 are attached to both ends.

[0072] A 10MHz high-frequency pulse signal is applied to the first piezoelectric film sensor 1 at the upper end of the bolt 2 by a signal generator. Due to the inverse piezoelectric effect of the piezoelectric material, a vibration signal is generated inside the bolt 2. The vibration signal propagates in the form of ultrasound. When it reaches the bottom of the bolt 2, due to the direct piezoelectric effect of the piezoelectric material, the second piezoelectric film sensor 13 at the bottom of the bolt 2 will generate a voltage change. The electrical signal is detected by a data acquisition device. By comparing and analyzing the acoustic time difference between the input pulse signal and the acquired electrical signal, the flight time of the vibration signal along the axial direction of the second piezoelectric film sensor can be obtained, thereby determining the magnitude of the axial load on the bolt 2, which is usually the magnitude of the preload. Using the first piezoelectric film sensor 1 and the second piezoelectric film sensor 13 separately avoids the input and output ends sharing a single sensor, reducing mutual interference between signals. The signal acquisition device only needs to collect the voltage signal, eliminating the need for an ultrasonic detection device, making data acquisition simpler.

[0073] Example 2

[0074] Please see Figures 1-4 This testing device is used for detecting periphery damage in laminated plates as follows:

[0075] The laminate 7 with threaded holes has bolts 2 installed in the threaded holes. Each bolt 2 has a first piezoelectric thin-film sensor 1 at both ends. One end has a first mounting washer 5 for a first piezoelectric thin-film sensor array 4. There is also a first protective washer 11 without the sensor, an annular electrode 16, and a nut 12. The inner side of the first mounting washer 5 is adhered to the laminate 7, and a piezoelectric thin-film sensor array 4 is fabricated on the outer side, using the same method as the first piezoelectric thin-film sensor 1 on the bolt 2.

[0076] Using a combination of plasma etching and magnetron sputtering techniques, a ring-shaped piezoelectric thin-film sensor is first fabricated at one end of the mounting gasket. Then, an etching process is used to cut the ring-shaped sensor into six identical fan-shaped regions, forming a circumferentially distributed first piezoelectric thin-film sensor array 4 and a second piezoelectric thin-film sensor array 10. Figure 3 As shown.

[0077] The first mounting washer 5 and the second mounting washer 9 are further divided into signal excitation washers and signal receiving washers. The six sector-shaped areas of the signal excitation washer and the signal receiving washer correspond one-to-one, dividing the perimeter of the hole into six regions. The outer side of the first mounting washer is connected to the annular electrode 16, which serves as the positive electrode for the six sector-shaped areas, while the washer base is the common negative electrode. When the nut 12 is tightened, the annular electrode 16 is tightly fitted to the first piezoelectric thin-film sensor array, preventing open circuits.

[0078] The annular electrode 16 is a flexible electrode, with a copper wire 15 electroplated on a polyimide film 14 substrate. To reduce wear between the bolt 2 (or nut 12) and the annular electrode 16 and improve their service life, this application adds a first protective washer 3 and a second protective washer 11 between the annular electrode 16 and the bolt 2 (or nut 12). The end faces of the first protective washer 3 and the second protective washer 11 are treated with plasma etching technology, which greatly reduces surface roughness and reduces wear on the annular electrode. The high and low level states of the microcontroller output pins control the selection state of the ADG708 chip, detecting the Lamb wave signals in six regions respectively, thereby realizing the ability to monitor and locate hole periphery damage in real time.

[0079] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A testing device for a bolted laminated plate, characterized in that, The application relates to a bolt pre-tightening force and bolt hole damage detection device for a bolted laminated plate, which comprises a laminated plate provided with a threaded hole and a bolt member screwed into the threaded hole, and the detection device comprises: a first piezoelectric film sensor installed at a first end of the bolt member; a second piezoelectric film sensor installed at a second end of the bolt member; a first sensor gasket assembly comprising a first installation gasket and a first piezoelectric film sensor array formed by a plurality of piezoelectric film sensor units arranged in a ring shape on the first installation gasket, the first installation gasket being sleeved on the outer periphery of the first end of the bolt member; a second sensor gasket assembly comprising a second installation gasket and a second piezoelectric film sensor array formed by a plurality of piezoelectric film sensor units arranged in a ring shape on the second installation gasket, the second installation gasket being sleeved on the outer periphery of the second end of the bolt member; wherein the first piezoelectric film sensor is configured as an active excitation sensor for exciting a pulse voltage signal, the pulse voltage signal is conducted through the bolt member to generate a vibration signal, the second piezoelectric film sensor is configured as a signal receiving sensor for receiving the vibration signal, and the time difference between the excitation signal and the receiving signal is collected by an external data collection device to obtain the flight time of the vibration signal in the bolt member, and then the bolt pre-tightening force is obtained; wherein the first piezoelectric film sensor array is used to excite a pulse voltage signal, the pulse voltage signal is conducted through the periphery of the threaded hole of the laminated plate to form a Lamb wave signal, the second piezoelectric film sensor array is used to receive the Lamb wave signal, and the damage condition around the threaded hole is detected by an external detection chip according to the received Lamb wave signal; the first piezoelectric film sensor and the second piezoelectric film sensor are used separately to reduce mutual interference between signals.

2. The bolted-laminate panel inspection apparatus of claim 1, wherein The first piezoelectric film sensor array and the second piezoelectric film sensor array are electrically connected with a ring-shaped electrode as an anode, and the first installation gasket and the second installation gasket are configured as a cathode.

3. The bolted-laminate panel inspection apparatus of claim 2, wherein The ring-shaped electrode comprises a polyimide film substrate and a copper wire plated on the polyimide film substrate.

4. The bolted-laminate panel inspection apparatus of claim 3, wherein The thickness of the polyimide film substrate is 100 microns, and the thickness of the copper wire is 10 microns.

5. The bolted-laminate panel inspection apparatus of claim 1, wherein The detection chip is an ADG708 chip.

6. The bolted-laminate panel inspection apparatus of claim 1, wherein The first piezoelectric film sensor, the second piezoelectric film sensor, the first piezoelectric film sensor array and the second piezoelectric film sensor array comprise an AlCr alloy bonding layer, an AlCrN / AlScN nano piezoelectric coating and an AlCr alloy electrode which are stacked in sequence from inside to outside, the AlCrN / AlScN nano piezoelectric coating is prepared by combining a direct current magnetron sputtering technology with a plasma etching technology, and the AlCrN / AlScN nano piezoelectric coating is formed by alternately depositing a single-layer AlCrN film and a single-layer AlScN film.

7. The bolted-laminate panel inspection apparatus of claim 6, wherein The thickness of the single-layer AlCrN film and the single-layer AlScN film is 5-20 nanometers, and the thickness of the AlCrN / AlScN nano piezoelectric coating is 5-50 microns.

8. The apparatus of claim 1, wherein The first thin film piezoelectric sensor array is provided with a protective washer away from the surface of the first mounting washer, and the second thin film piezoelectric sensor array is provided with a protective washer away from the surface of the second mounting washer.

9. The detection device for bolted laminated plates according to claim 8, characterized in that, The protective washer is subjected to surface polishing treatment until the surface roughness is less than 0.32 microns.

10. The apparatus of claim 1, wherein The detection chip is electrically connected with an output pin of a single-chip microcomputer, and the output pin is used to form high and low level states.

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