Onboard electronic device bolt fastening detection circuit

Abstract

The bolt fastening detection circuit of the airborne electronic equipment of the present application comprises a bolt clamp, a metal strain wire, a resistance measurement circuit, a conditioning circuit, a microcontroller and a communication network. The bolt clamp and the metal strain wire are connected with the measured bolt, the resistance measurement circuit and the conditioning circuit convert the resistance value of the measured metal strain wire into a digital signal, complete the resistance value collection of the metal strain wire, the microcontroller acquires the resistance value information of the strain wire, processes and calculates the tensile length, and monitors the fastening degree of the bolt. The technical scheme of the present application can detect the loosening phenomenon of the bolt, and report the bolt loosening condition to the pilot or the maintenance personnel through the communication network.

Description

Technical Field

[0001] This invention belongs to the technical field of airborne electronic equipment, and particularly relates to a bolt tightening detection circuit for airborne electronic equipment. Background Technology

[0002] During the service life of an aircraft, the operation of the aircraft engine and the impact of takeoff and landing expose airborne equipment to a constant environment of frequent vibration. Simultaneously, the thermal expansion and contraction of metal materials caused by sudden temperature changes can lead to loosening or even detachment of the fastening bolts of airborne electronic equipment. Therefore, it is essential to regularly check the tightness of the bolts on the aircraft.

[0003] Currently, the inspection of bolt tightness on the aircraft is mainly based on periodic manual inspections during maintenance, which incurs significant manpower costs. In addition, when the installation space for airborne equipment is limited, a single manual inspection often takes a long time, resulting in low efficiency and failing to meet the needs of the next-generation airborne health management system.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a bolt tightness detection circuit for airborne electronic equipment, solving the technical problem of low bolt tightness detection efficiency in existing technologies. The technical solution of this invention has many beneficial effects, as described below:

[0006] A bolt fastening detection circuit for airborne electronic equipment is provided, comprising a bolt clamp assembly, a test metal strain wire, a reference metal strain wire, a resistance measurement circuit, a conditioning circuit, and a microcontroller. The output terminal of the resistance measurement circuit is connected to the conditioning circuit, and the output terminal of the conditioning circuit is connected to the microcontroller, which transmits signals to a communication network.

[0007] One end of the bolt clamp assembly is mounted on the bolt of the product housing, and the other end is used for the test metal strain wire to pass through. The two ends of the test metal strain wire are respectively fixed by the fixing plate and are in a straightened or taut state. Both ends pass through the fixing plate and have protruding ends. One end is grounded and the other end is electrically connected to the resistance measurement circuit.

[0008] The reference metal strain wire is fixed at both ends by the fixing plate and is in a straightened or taut state. Both ends pass through the fixing plate and have protruding ends. One end is grounded and the other end is electrically connected to the resistance measurement circuit.

[0009] The resistance measurement circuit includes adjustable resistors R1 and R2. The output terminal of the reference metal strain wire is electrically connected to the adjustable resistor R1, and the output terminal of the test metal strain wire is electrically connected to the adjustable resistor R2. The adjustable resistors R1 and R2, the test metal strain wire, and the reference metal strain wire form a bridge circuit. In the initial state of the circuit, the bridge circuit is balanced by adjusting the adjustable resistors R1 and R2.

[0010] The conditioning circuit is used to convert the voltage signal output by the resistance measurement circuit into a digital signal and transmit it to the microcontroller. Specifically, when the airborne equipment vibrates or the metal material of the product casing expands and contracts due to heat, the bolts on the product casing may loosen or fall off. As the bolts rotate, the bolt clamp assembly causes the test metal strain wire to undergo tensile deformation, resulting in a change in the resistance value of the test metal strain wire. This causes a change in one input value of the resistance measurement circuit, disrupting the balance of the bridge circuit. The conditioning circuit then transmits the change in the bridge state to the microcontroller.

[0011] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0012] The circuit is used to detect the tightness of bolts, which improves detection efficiency and reduces detection costs. When a bolt is found to be loose, the airborne network will send an alarm to the airborne health management system and maintenance personnel. At the same time, during ground maintenance of the aircraft, the inspection personnel can also check the tightness of the bolts through this circuit. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a metal strain wire structure.

[0015] Figure 2 This is a top view of the bolt clamp structure;

[0016] Figure 3 For reference, see the schematic diagram of the connection layout of the metal strain wire and the test metal strain wire;

[0017] Figure 4 This is a schematic diagram of the resistance measurement circuit.

[0018] Figure 5 This is a schematic diagram illustrating the application of a bolt tightening detection circuit.

[0019] Figure 6 This is the main view of the bolt clamp structure, where:

[0020] 11. Clamp; 12. Fixing clamp; 21. Test metal strain wire; 22. Reference metal strain wire; 3. First hole; 4. Second hole; 5. Fixing plate. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0023] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0024] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that aspects can be practiced without these specific details. To enable those skilled in the art to better understand the invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. 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 indicated technical features. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0025] See Figures 1 to 6 The airborne electronic equipment bolt fastening detection circuit shown includes a bolt clamp assembly, a test metal strain wire 21, a reference metal strain wire 22, a resistance measurement circuit, a conditioning circuit, and a microcontroller. The output terminal of the resistance measurement circuit is connected to the conditioning circuit, and the output terminal of the conditioning circuit is connected to the microcontroller. The microcontroller transmits signals to the communication network.

[0026] like Figure 3 As shown, one end of the bolt clamp assembly is installed on the bolt of the product housing, and the other end is used for the test metal strain wire 21 to pass through. The two ends of the test metal strain wire 21 are fixed by the fixing plate 5 and are in a straight or taut state. Both ends pass through the fixing plate 5 and have protruding ends. One end is grounded and the other end is electrically connected to the resistance measurement circuit.

[0027] The reference metal strain wire 22 is fixed at both ends by the fixing plate 5 and is in a straightened or taut state. Both ends pass through the fixing plate 5 and have protruding ends. One end is grounded and the other end is electrically connected to the resistance measurement circuit.

[0028] The resistance measurement circuit includes adjustable resistors R1 and R2. The output terminal of the reference metal strain wire 22 is electrically connected to the adjustable resistor R1, and the output terminal of the test metal strain wire 21 is electrically connected to the adjustable resistor R2. The adjustable resistors R1 and R2, the test metal strain wire 21, and the reference metal strain wire 22 form a bridge circuit. In the initial state of the circuit, the bridge is balanced by adjusting the adjustable resistors R1 and R2 (the test metal strain wire 21 and the reference metal strain wire 22 are equivalent to strain resistors and can form a bridge circuit with the adjustable resistors R1 and R2).

[0029] The conditioning circuit is used to convert the voltage signal output by the resistance measurement circuit into a digital signal and transmit it to the microcontroller. Specifically, when the airborne equipment vibrates or the metal material of the product casing expands and contracts due to heat, the bolts on the product casing may loosen or fall off. As the bolts rotate, the bolt clamp assembly causes the test metal strain wire 21 to undergo tensile deformation, resulting in a change in the resistance value of the test metal strain wire 21. This causes a change in one input value of the resistance measurement circuit, disrupting the balance of the bridge circuit. The conditioning circuit then transmits the change in the bridge state to the microcontroller.

[0030] The circuit detects and stores the output voltage value of the resistance measurement circuit composed of metal strain wires. The microcontroller uses the measured data and the fastening detection method to detect the tightness of the bolt, so as to promptly report the potential for bolt loosening.

[0031] As a specific implementation method provided in this case, such as Figure 6 As shown, the bolt clamp assembly includes a clamp 11 and a fixed clamp 12. The clamp 11 and the fixed clamp 12 are rotatably connected (e.g., by a rotating shaft, or by a bearing and a rotating shaft, or a miniature flange, or by a groove). When the bolt loosens, it will drive the bolt clamp to rotate, further stretching the metal strain wire 21 for testing.

[0032] The fixing clamp 12 is provided with a first hole 3 in the radial direction for the metal strain wire 21 to pass through, and a second hole 4 with a threaded structure in the vertical direction, and the second hole 4 is offset from the first hole 3.

[0033] The top surface of the chuck 11 is provided with multiple threaded holes at intervals, among which:

[0034] If the test metal strain wire 21 is not in a straight line after passing through the first hole 3, rotate the fixing clamp 12 to make the test metal strain wire 21 in a straight line, and use bolts to pass through the second hole 4 and the threaded hole corresponding to the second hole 4 in sequence to fix the fixing clamp 12 and the clamp 11 into one piece.

[0035] When the airborne equipment vibrates, the clamp 11 rotates with the bolts on the product, causing the test metal strain wire 21 to undergo tensile deformation, resulting in a change in the resistance value of the test metal strain wire 21.

[0036] As a specific implementation provided in this case, the conditioning circuit includes resistors R3 and R4, capacitors C1, C2, and C3, an A / D converter, and an integrated operational amplifier. The integrated operational amplifier is provided with a gain resistor R0, wherein:

[0037] The input terminal of resistor R3 is connected to the input terminal of adjustable resistor R1, and the output terminal of resistor R3 is connected to the input terminal of capacitor C1 and the positive terminal of integrated operational amplifier, respectively.

[0038] The input terminal of resistor R4 is connected to the input terminal of adjustable resistor R2, and the output terminal of resistor R4 is connected to the output terminal of capacitor C1 and the inverting terminal of integrated operational amplifier, respectively.

[0039] Capacitor C1 is used for differential-mode filtering, while capacitors C2 and C3 are used for common-mode filtering.

[0040] When the test metal strain wire 21 is subjected to tensile deformation, the integrated operational amplifier is used to amplify the changing voltage and input it to the A / D converter. The A / D converter is used to convert the voltage signal into a digital signal and transmit it to the microcontroller.

[0041] As a specific implementation method provided in this case, the microcontroller communicates with the host computer via a communication network. The microcontroller acquires the output voltage value of the resistance measurement circuit and calculates at least the resistance change and / or length change information of the test metal strain wire 21. Based on the host computer's detection instructions, it performs a tightening test on the bolt. Specifically, the calculation of the resistance change and / or length change information of the test metal strain wire includes:

[0042] 1) Receive test instructions;

[0043] 2) Acquire the output voltage of the resistance measurement circuit, including:

[0044] The microcontroller acquires the output voltage value U of the resistance measurement circuit through the above circuit and stores it in the microcontroller's internal memory;

[0045] 3) Calculate the change in resistance of the strain gauge wire used for the fastening test, including calculating the change in resistance ΔR of the strain gauge wire using the following steps. x ,in:

[0046] s1) Calculate the current resistance R of the metal strain wire x ,

[0047]

[0048] s2) R x Perform digital filtering to obtain R x1 ;

[0049] Calculate the change in resistance ΔR of the test metal strain wire x :

[0050] ΔR x =R x1 -R x0 In the formula, U SC U is the input voltage value of the resistance measuring circuit; U is the output voltage value of the resistance measuring circuit, which is measured by the resistance measuring circuit; R x R represents the resistance of the metal strain wire used for fastening testing. x1 R is the resistance value of the metal strain wire after digital filtering.x0 R is the initial value of the resistance of the metal strain wire during the tightening test. f The resistance of the metal strain wire used for reference; ΔR x To measure the change in resistance of the metal strain wire during fastening testing;

[0051] 4) Calculate the change in length of the metal strain wire, including calculating the change in length ΔL of the metal strain wire:

[0052]

[0053] ΔL=ε·L, where K0 is the strain sensitivity coefficient of the metal material, ε is the length strain value of the metal material, characterizing the degree of axial deformation of the metal strain wire; and L is the length of the metal strain wire.

[0054] 5) Determine the bolt tightness and send alarm information, including:

[0055] When the calculated change in the length of the test metal strain wire exceeds the bolt loosening maintenance threshold, a loosening alarm message is sent to the airborne health management system or ground maintenance equipment via the microcontroller and communication network to indicate the potential bolt loosening. The bolt loosening alarm signal status is calculated according to the following formula.

[0056] In the formula, Wa is the alarm signal, and L o This is the threshold value for the bolt loosening alarm.

[0057] For example:

[0058] In this embodiment of the invention, the circuit includes a bolt clamp, a metal strain wire, a resistance measurement circuit, a conditioning circuit, a microcontroller, and a communication network. The circuit is powered by ±15V, +5V, and +3.3V power supplies from the airborne electronic equipment. The test and reference metal strain wire consists of a metal core and an insulating outer sheath, such as... Figure 1 As shown. The metal strain core in a metal strain wire is made of a metal material with a large resistance strain sensitivity coefficient, a high elastic limit, and a small temperature coefficient, such as tungsten, gold, silver, or aluminum. The resistance of the metal strain wire changes under mechanical deformation (tension or compression).

[0059] Bolt clamps consist of a clamp head and a retaining clamp, such as... Figure 2 As shown. The clamp can be fixed to the bolt head and connected to it. The strain wire clamp has a strain wire fixing hole and an angle locking screw. When the angle locking screw is loosened, the clamp and the strain wire clamp can rotate relative to each other; when the angle locking screw is tightened, the clamp and the metal strain wire clamp are locked and cannot rotate relative to each other. Optionally, to ensure reliable angle locking, adhesive can be applied to the screw for reinforcement after tightening.

[0060] The metal strain wire passes through the strain wire clamp and is secured by the strain wire fixing hole. After the angle locking screw is tightened, when the bolt loosens, it will cause the bolt clamp to rotate, further stretching the metal strain wire.

[0061] The resistance measurement circuit consists of an adjustable resistor and a metal strain gauge bridge. In the initial state of the circuit, the bridge is balanced by adjusting the adjustable resistor.

[0062] The resistance measurement circuit consists of a test strain gauge wire, a reference strain gauge wire, and a variable resistor bridged together, such as... Figure 4 As shown. The test metal strain wire passes through the bolt clamp, and the reference metal strain wire is placed parallel to the test metal strain wire, and fixed by a fixing device, such as... Figure 3 As shown.

[0063] The conditioning circuit acquires the output voltage of the resistance measurement circuit. It consists of a signal amplification circuit, a filtering circuit, and an analog-to-digital converter chip. After filtering the voltage information, it converts it into a digital signal and transmits it to the microcontroller MCU.

[0064] The microcontroller is the core processing chip of the circuit; in this embodiment, a general-purpose MCU is used. The MCU collects the voltage data output by the resistance measurement circuit, calculates the axial length change of the metal strain wire, and realizes the bolt tightening detection.

[0065] The communication network connects the core processing chip with the airborne health management system and ground maintenance equipment, enabling information communication between them. In this embodiment, RS485 is used as the communication network. The fastening detection circuit obtains the detection operation instructions from the pilot / ground maintenance personnel through the communication network, and simultaneously sends information such as the bolt tightness to the airborne health management system or ground maintenance equipment.

[0066] The above circuit is used to implement a bolt tightness detection method. By acquiring voltage data, measuring the resistance of the resistance measurement circuit, the resistance of the reference metal strain wire, and the strain sensitivity coefficient of the metal material, the bolt tightness is calculated, and a bolt loosening maintenance alarm is output. This is achieved through the following steps:

[0067] 1) The MCU receives operating instructions from the pilot / ground control personnel via the bus.

[0068] 2) The MCU acquires the output voltage information U of the resistance measurement circuit through the above circuit and stores it in the internal memory.

[0069] 3) Based on the voltage value measured in step 2), calculate the change in resistance ΔR of the test metal strain wire according to the following sub-steps. x .

[0070] s1) Calculate the current resistance R of the metal strain wire x :

[0071]

[0072] s2) Take the R obtained in step s1) x Perform digital filtering to obtain R x1 ;

[0073] s3) Calculate the change in resistance ΔR of the test metal strain wire. x :

[0074] ΔR x =R x1 -R x0

[0075] In the formula, U SC R is the input voltage value of the resistance measuring circuit; U is the output voltage value of the resistance measuring circuit, measured by the resistance measuring circuit; R1 and R2 are adjustable resistors on the bridge circuit, and in this embodiment, their values ​​are approximately 100Ω; R x R represents the resistance of the metal strain wire used for fastening testing. x1 The resistance value of the metal strain wire after digital filtering is calculated using the moving average filtering method in this embodiment. x1 ;R x0 R is the initial value of the resistance of the metal strain wire during the tightening test. f For the reference resistance value of the metal strain gauge wire, tungsten wire with a resistance of 5.48 Ω / m is selected as the metal core material in this embodiment; ΔR x This is to measure the change in resistance of the metal strain wire during tightening and testing.

[0076] 4) Using the information calculated in step 3), calculate the change in the length of the metal strain wire according to the following formula:

[0077]

[0078] ΔL=ε·L

[0079] In the formula, K0 is the strain sensitivity coefficient of the metallic material, ε is the length strain value of the tungsten wire, characterizing the degree of axial deformation of the metal strain wire, and its value should be within 0.24 to 0.4; L is the length of the metal strain wire; ΔL is the change in length of the metal strain wire; ΔR x The change in resistance of the metal strain wire is calculated from step 3).

[0080] 5) When the calculated change in the length of the test metal strain wire exceeds the bolt loosening maintenance threshold, the MCU sends a loosening alarm message to the airborne health management system or ground maintenance equipment, indicating a potential bolt loosening hazard. The bolt loosening alarm signal status is calculated according to the following formula.

[0081]

[0082] In the formula, Wa is the alarm signal, and L o This is the threshold value for the bolt loosening alarm.

[0083] The product provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the invention claims.

Claims

1. A bolt tightening detection circuit for airborne electronic equipment, characterized in that, Includes bolt clamp assembly, test metal strain wire, reference metal strain wire, resistance measurement circuit, conditioning circuit and microcontroller; The output of the resistance measurement circuit is connected to the conditioning circuit, and the output of the conditioning circuit is connected to the microcontroller, which transmits signals to the communication network. One end of the bolt clamp assembly is mounted on the bolt of the product housing, and the other end is used for the test metal strain wire to pass through. The two ends of the test metal strain wire are respectively fixed by the fixing plate and are in a straightened or taut state. Both ends pass through the fixing plate and have protruding ends. One end is grounded and the other end is electrically connected to the resistance measurement circuit. The reference metal strain wire is fixed at both ends by the fixing plate and is in a straightened or taut state. Both ends pass through the fixing plate and have protruding ends. One end is grounded and the other end is electrically connected to the resistance measurement circuit. The resistance measurement circuit includes adjustable resistors R1 and R2. The output terminal of the reference metal strain wire is electrically connected to the adjustable resistor R1, and the output terminal of the test metal strain wire is electrically connected to the adjustable resistor R2. The adjustable resistors R1 and R2, the test metal strain wire, and the reference metal strain wire form a bridge circuit. In the initial state of the circuit, the bridge circuit is balanced by adjusting the adjustable resistors R1 and R2. The conditioning circuit is used to convert the voltage signal output by the resistance measurement circuit into a digital signal and transmit it to the microcontroller. Specifically, when the airborne equipment vibrates or the metal material of the product casing expands and contracts due to heat, the bolts on the product casing may loosen or fall off. As the bolts rotate, the bolt clamp assembly causes the test metal strain wire to undergo tensile deformation, resulting in a change in the resistance value of the test metal strain wire. This causes a change in one input value of the resistance measurement circuit, disrupting the balance of the bridge circuit. The conditioning circuit then transmits the change in the bridge state to the microcontroller. The bolt clamp assembly includes a clamp and a fixing clamp, wherein the clamp and the fixing clamp are rotatably connected. The fixing clamp is provided with a first hole in the radial direction for the metal strain wire to pass through, and a second hole with a threaded structure in the vertical direction, and the second hole and the first hole are offset from each other. The top surface of the chuck is provided with multiple threaded holes at intervals; If the test metal strain wire is not in a straight line after passing through the first hole, rotate the fixing clamp to make the test metal strain wire in a straight line, and use bolts to pass through the second hole and the threaded hole corresponding to the second hole in sequence to fix the fixing clamp and the clamp into one piece; When the airborne equipment vibrates, the clamp rotates with the bolts on the product, causing the test metal strain wire to undergo tensile deformation, resulting in a change in the resistance value of the test metal strain wire.

2. The airborne electronic equipment bolt tightening detection circuit according to claim 1, characterized in that, The conditioning circuit includes resistors R3 and R4, capacitors C1, C2, and C3, an A / D converter, and an integrated operational amplifier. The integrated operational amplifier has a gain resistor R0, wherein: The input terminal of resistor R3 is connected to the input terminal of adjustable resistor R1, and the output terminal of resistor R3 is connected to the input terminal of capacitor C1 and the positive terminal of integrated operational amplifier, respectively. The input terminal of resistor R4 is connected to the input terminal of adjustable resistor R2, and the output terminal of resistor R4 is connected to the output terminal of capacitor C1 and the inverting terminal of integrated operational amplifier, respectively. Capacitor C1 is used for differential-mode filtering, while capacitors C2 and C3 are used for common-mode filtering. When the test metal strain wire undergoes tensile deformation, the integrated operational amplifier amplifies the changing voltage and inputs it to the A / D converter, which converts the voltage signal into a digital signal and transmits it to the microcontroller.

3. The airborne electronic equipment bolt tightening detection circuit according to claim 2, characterized in that, The microcontroller communicates with the host computer via a communication network. The microcontroller collects the output voltage value of the resistance measurement circuit, calculates at least the resistance change and / or length change information of the test metal strain wire, and performs bolt tightening detection according to the detection instructions of the host computer.

4. The airborne electronic equipment bolt tightening detection circuit according to claim 3, characterized in that, Calculate the resistance change and / or length change information of the test metal strain wire, including: 1) Receive test instructions; 2) Acquire the output voltage of the resistance measurement circuit, including: The microcontroller acquires the output voltage value U of the resistance measurement circuit through the above circuit and stores it in the microcontroller's internal memory; 3) Calculate the change in resistance of the strain gauge wire used for the fastening test, including the following steps: ,in: s1) Calculate the resistance of the metal strain wire during the current fastening test. , In the formula, U SC Input voltage value for the resistance measurement circuit; U The output voltage value of the resistance measuring circuit is obtained by the resistance measuring circuit. R f The resistance value of the metal strain wire used for reference; s2) will Perform digital filtering to obtain R x1 ; Calculate the change in resistance of the metal strain wire during the fastening test. : In the formula, R x1 The resistance value of the metal strain wire after digital filtering; R x0 The initial value of the resistance of the metal strain wire in the fastening test; 4) Calculate the change in length of the metal strain wire, including calculating the change in length of the metal strain wire. : ； In the formula, The strain sensitivity coefficient of metallic materials, The length strain value of the metallic material characterizes the degree of axial deformation of the metal strain wire; The length of the metal strain wire; 5) Determine the bolt tightness and send alarm information, including: When the calculated change in the length of the test metal strain wire exceeds the bolt loosening maintenance threshold, a loosening alarm message is sent to the airborne health management system or ground maintenance equipment via the microcontroller and communication network, indicating a potential bolt loosening hazard. The bolt loosening alarm signal status is calculated according to the following formula: In the formula, Wa This is an alarm signal. L o This is the threshold value for the bolt loosening alarm.

Images