System and method for testing and measuring electrical breakdown ignition characteristics of ignition source of composite fuel tank fastener of airplane

Abstract

The invention discloses a system and a method for testing and measuring electrical breakdown ignition characteristics of an ignition source of a fastener of a composite fuel tank of an airplane. Comprising a pulse electric breakdown test power supply, a fastener carbon fiber composite material laminated plate, an electric breakdown injection clamping mechanism, an adjusting unit, an electric breakdown test control, measurement and analysis unit and an electric breakdown spark monitoring unit, according to test data of electric breakdown and electric spark state characteristics of a fastener composite material laminated plate under the action of pulse voltage, correlation between electric breakdown and ignition source characteristics of a fastener-composite material interface and factors such as fastener-composite material interface sample moisture content, fastener structure and pulse voltage electrical parameters is obtained; the association rule of the ignition source characteristics of the typical fastener structure of the fuel tank, the lightning stroke electrical parameters, the action conditions and the flight environment characteristics is obtained, and a foundation is laid for quantitative prediction and safety evaluation research of the ignition source of the fastener of the fuel tank of a large aircraft.

Description

Technical Field

[0001] The invention relates to the field of composite material testing, in particular to a testing method for fastener carbon fiber composite material properties, and in particular to a testing and measuring system and method for the electrical breakdown ignition properties of an ignition source of an aircraft composite fuel tank fastener. Background Art

[0002] Carbon fiber composite materials have the characteristics of low density, high strength, high modulus, high temperature resistance, chemical corrosion resistance, etc., and have the softness and processability of textile fibers. They are widely used in various fields such as aerospace, military and civilian industries. With the improvement of aircraft design and the advancement of carbon fiber composite material technology, the use of carbon fiber reinforced polymer composite materials CFRP (Carbon Fiber Reinforced Polymers) in large civil aircraft, military aircraft, drones and stealth aircraft is growing. At present, 50% of the main wing, tail, fuselage, floor and other structures of Boeing B787 are made of CFRP materials, the proportion of CFRP materials on Airbus A350XWA reaches 53%, the proportion of CFRP materials on China C919 is 12%, and the use of CFRP materials on the second-generation C929 will reach 50%, and composite fuel tanks will be used.

[0003] Lightning is a multiple continuous time-series discharge process that includes high-voltage shock waves, magnetic field forces and Joule heating effects caused by large currents. The strong current, strong magnetic field and accompanying strong shock waves generated by lightning cause the combustion, melting and explosion of the fuselage materials, which will cause the deformation of the fuselage structure and the reduction of strength, posing a serious threat to the safe operation of the aircraft. The fuel tank is an important component of the complex system of the aircraft, responsible for storing fuel, adjusting the center of gravity and cooling equipment. In the past 50 years, there have been 18 fuel tank explosion accidents in civil transport aircraft worldwide, resulting in 542 deaths. The fuel system composed of the entire fuselage or wing fuel tank is the most vulnerable system in the aircraft. The fuel tank explosion has become one of the main threats to civil aviation safety and has attracted serious attention from airworthiness management authorities around the world.

[0004] In order to fully reduce the probability of civil aircraft fuel tank explosion accidents, the Federal Aviation Administration of the United States, the European Aviation Safety Agency, and the Civil Aviation Administration of China have clearly specified the test methods and airworthiness requirements for aircraft fuel tank ignition sources. Aircraft fuel tank ignition sources include filament heating caused by heat under the current carrying capacity of the wire, static breakdown, lightning hot spots, friction heating, edge corona, and arcs / sparks. The ignition mechanism can be summarized as "electrical ignition" and "thermal ignition".

[0005] In the new carbon fiber composite aircraft fuel tank structure, the assembly structure and interface characteristics of the fasteners themselves are the main factors leading to electric field breakdown and current conduction hotspots. The sparks, temperature rise, and airflow jets caused at the structural interface become the source of fuel tank ignition.

[0006] The existing ignition source of large aircraft fuel tanks is mainly tested by the gas method using a spark source with a certain energy in a predetermined concentration of combustible gas. The energy of the spark discharge is obtained by calculating the energy of each component in the discharge circuit, such as the inductor and resistor. However, the judgment result is a digital quantity with only two results: "burning" and "non-burning", which makes it impossible to achieve quantitative prediction and safety assessment of the ignition source. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention aims to provide a test and measurement system and method for the electrical breakdown ignition characteristics of an aircraft composite fuel tank fastener ignition source, thereby laying a foundation for the structural design and risk assessment of a lightning fuel tank ignition source.

[0008] The present invention is achieved through the following technical solutions:

[0009] A test and measurement system for the electric breakdown ignition characteristics of an aircraft composite fuel tank fastener ignition source, comprising a pulse electric breakdown test power supply, a fastener carbon fiber composite laminate, an electric breakdown injection clamping mechanism and an adjustment unit, an electric breakdown test control and its measurement and analysis unit, and an electric breakdown spark monitoring unit;

[0010] The pulsed electric breakdown test power supply is used to generate a pulse voltage wave with an adjustable rise time, including an adjustable high-voltage DC charging power supply and an adjustable rise time pulse voltage generating unit. The charging voltage of the adjustable rise time pulse voltage generating unit is monitored online by a charging voltage monitoring sensor, and the charging voltage analog quantity is transmitted to the control unit of the control and measurement analysis unit of the electric breakdown ignition test;

[0011] The sample fastener carbon fiber composite material laminate is clamped by an electric breakdown injection clamping mechanism and an adjustment unit, and a pulse voltage is conducted and injected into the sample fastener carbon fiber composite material laminate;

[0012] The electric breakdown injection clamping mechanism and the adjustment unit are used to complete the clamping of the sample fastener carbon fiber composite laminate, and to achieve the application of the pulse voltage to the sample fastener carbon fiber composite laminate;

[0013] The control and measurement and analysis unit of the electric breakdown ignition test is used to realize the control of the ignition source ignition characteristic test of the fastener carbon fiber composite material laminate and the measurement and analysis of the electric breakdown pulse parameters, and includes a control unit and an electric breakdown measurement and analysis unit;

[0014] The electric breakdown spark monitoring unit is used to observe the occurrence and development process of the electric spark of the carbon fiber ignition source of the fastener, and obtain the electric spark process of the carbon fiber ignition source of the fastener;

[0015] The fastener carbon fiber composite laminate is clamped by the electric breakdown injection clamping mechanism and the adjustment unit, and a pulse voltage is applied to the sample by a pulse electric breakdown test power supply. The occurrence and development process of the electric spark of the fastener carbon fiber ignition source is obtained by the electric breakdown spark monitoring unit. The control and measurement analysis unit of the electric breakdown ignition test controls the ignition characteristic test of the fastener carbon fiber composite laminate ignition source and measures and analyzes the electric breakdown pulse parameters. Finally, a database of the correlation between the electric breakdown and electric spark characteristics of the fastener carbon fiber composite laminate and the fastener-composite matching structure, temperature and humidity, and pulse voltage electrical parameters is obtained, forming a database of the electric breakdown and ignition source characteristics of the composite fuel tank fastener ignition source simulating the flight environment of large aircraft.

[0016] Furthermore, the adjustable high-voltage DC charging power supply is composed of an electronically controlled voltage regulator T1, a transformer T2, a rectifier silicon stack D and a current-limiting resistor Rc;

[0017] The adjustable rise time pulse voltage generating unit is composed of a main pulse energy storage capacitor C1, a high voltage discharge switch G, an adjustable waveform forming resistor R1, an adjustable waveform forming resistor R2 and a forming capacitor C2. The fastener carbon fiber composite laminate is injected into the clamping mechanism and the adjustment unit through electrical breakdown and is connected to the output end of the adjustable rise time pulse voltage generating unit.

[0018] Furthermore, the electric breakdown injection clamping mechanism and the adjustment unit are installed on the insulating plate in a double-sided structural fixture with adjustable locking position. The double-sided structural fixture consists of two insulating baffles connected by bolts, and a plate-shaped high-voltage injection electrode HV and a low-voltage return electrode LV are respectively installed on the inner side of the double-sided insulating baffles. The high-voltage end of the pulse electric breakdown test power supply is connected to the high-voltage injection electrode HV, and the low-voltage end is connected to the low-voltage return electrode LV of the electrode structure.

[0019] Furthermore, the control unit includes a charging voltage monitoring circuit and a programmable controller; the charging voltage monitoring circuit of the control unit receives the signal transmitted by the charging voltage monitoring sensor, and after being processed by the programmable controller, performs discharge control on the high-voltage discharge switch G of the pulse voltage generating unit with adjustable rise time;

[0020] The programmable controller is also combined with the industrial control computer of the electrical breakdown measurement and analysis unit to control the connection / disconnection, high voltage increase / decrease and conduction of the high voltage discharge switch G during the charging process of the fastener carbon fiber composite laminate ignition source ignition characteristics test, so as to realize automatic control of the fastener carbon fiber composite laminate ignition source ignition characteristics test process.

[0021] Further, the electrical breakdown measurement and analysis unit includes a pulse voltage sensor, a digital oscilloscope and an industrial control computer;

[0022] The pulse voltage sensor is combined with an array digital oscilloscope to measure the pulse voltage between the high-voltage injection point and the low-voltage return point of the fastener carbon fiber composite laminate; the industrial control computer processes and analyzes the pulse voltage signal measured by the digital oscilloscope to obtain the electrical breakdown voltage U under the fastener assembly method and environmental temperature and humidity parameters.

[0023] Furthermore, the electric breakdown spark monitoring unit includes a high-speed camera monitoring instrument and a high-speed camera control computer; the high-speed camera monitoring instrument observes the occurrence and development process of the electric spark of the fastener carbon fiber ignition source, and its camera process is controlled by the high-speed camera control computer.

[0024] The test and measurement method for the electrical breakdown ignition characteristics of the ignition source of aircraft composite fuel tank fasteners includes the following steps:

[0025] 1) Sample selection and processing: Select multiple fastener composite laminate samples and subject them to temperature and humidity treatment to simulate the actual flight environment of large aircraft;

[0026] 2) installing the first fastener composite laminate specimens with different humidity levels in the electrical breakdown injection clamping mechanism and adjustment unit, and connecting the high voltage injection electrode HV and the low voltage return electrode LV of the electrical breakdown injection clamping mechanism and adjustment unit to the high voltage and low voltage output ports of the adjustable rise time pulse voltage generating unit;

[0027] 3) Applying lightning voltage pulses to the fastener composite laminates, changing the pulse voltage time while keeping the pulse voltage peak constant, obtaining the breakdown characteristics and electrical breakdown ignition characteristics of the fastener carbon fiber composite laminates under different humidity conditions, and using a pulse voltage sensor and an electrical breakdown spark monitoring unit to detect the breakdown spark characteristics;

[0028] 4) While keeping the pulse voltage rise time constant, change the peak value of the pulse voltage to obtain the breakdown characteristics and electrical breakdown ignition characteristics of the fastener carbon fiber composite laminate under different humidity conditions, and use a pulse voltage sensor and an electrical breakdown spark monitoring unit to detect the breakdown spark characteristics;

[0029] 5) Repeating process 2) to process 4) with fastener carbon fiber composite laminates of different humidity, temperature, and assembly methods, to obtain a database of associations between the breakdown voltage and breakdown spark characteristics of the fastener carbon fiber composite laminates and the sample temperature and humidity, pulse voltage rise rate, duration, peak value, and assembly method;

[0030] 6) Perform multi-factor regression statistical analysis on all lightning test results to obtain the correlation between the ignition source characteristics of typical fastener structures of fuel tanks and lightning electrical parameters, temperature and humidity flight environment characteristics, and assembly structure.

[0031] Furthermore, the assembly method includes adjusting the distance between the bilateral insulating baffles to achieve clearance fit, interference fit, and filling insulating materials with different dielectric constants between the high-voltage injection electrode HV and the low-voltage return electrode LV and the carbon fiber composite material.

[0032] The present invention has the following beneficial effects:

[0033] The invention establishes an electric breakdown and spark characteristic test system for a fastener-composite material interface, proposes a test method for the ignition source characteristic of a fastener-composite material interface, and finally obtains the correlation between the electric breakdown and spark state characteristics of a fastener-composite material laminate under the action of a pulse voltage and the observation results of an electric breakdown and spark process monitoring unit, and the electric breakdown and spark state characteristics of the fastener-composite material interface and the moisture content of the fastener-composite material interface sample, the fastener structure, the pulse voltage electrical parameters and other factors, forms an electric breakdown and spark characteristic database of the ignition source characteristics of a fuel tank simulating the flight environment of a large aircraft, obtains the correlation law between the ignition source characteristics of a typical fastener structure of the fuel tank and the lightning electrical parameters, the action conditions and the flight environment characteristics, and lays a foundation for the quantitative prediction and safety assessment research of the ignition source of the fasteners of the large aircraft fuel tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural block diagram of the ignition source ignition characteristic test system of the composite material fastener of the present invention;

[0035] Figure 2 This is a circuit principle block diagram of the ignition source ignition characteristic test system for composite material fasteners of the present invention;

[0036] Figure 3 It is a schematic diagram of the clamping structure for the ignition source ignition characteristic test of the composite material fastener of the present invention;

[0037] Figure 4 Flow chart of the test and analysis method for the ignition source ignition characteristics of fastener composite materials. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0039] join Figure 1 , Figure 2The test and measurement system of the electric breakdown ignition characteristics of the aircraft composite fuel tank fastener ignition source of the present invention is composed of a pulse electric breakdown test power supply 1, a fastener carbon fiber composite laminate 2, an electric breakdown injection clamping mechanism and an adjustment unit, an electric breakdown test control and its measurement and analysis unit 3 and an electric breakdown spark monitoring unit 4.

[0040] The pulse electric breakdown test power supply 1 is mainly composed of an adjustable high-voltage DC charging power supply 1-1 and an adjustable rise time pulse voltage generating unit 1-2, which is used to generate a pulse voltage wave with an adjustable rise time. During the actual test, the charging voltage of the adjustable high-voltage DC charging power supply 1-1 to the adjustable rise time pulse voltage generating unit 1-2 is monitored online by the charging voltage monitoring sensor 1-3, and the charging voltage analog quantity is transmitted to the control unit 31 of the control and measurement analysis unit 3 of the electric breakdown ignition test. The function of the adjustable rise time pulse voltage generating unit 1-2 is to generate a pulse voltage wave with an adjustable rise time.

[0041] See also Figure 2 , which is the principle circuit of the pulse electric breakdown test power supply 1 for the electric spark characteristic test of the carbon fiber ignition source of the fastener of the present invention, mainly contains the circuit principle of two parts: an adjustable high-voltage DC charging power supply 1-1 and an adjustable rise time pulse voltage generating unit 1-2.

[0042] The adjustable high-voltage DC charging power supply 1-1 is mainly composed of an electronically controlled voltage regulator T1, a transformer T2, a rectifier silicon stack D and a current limiting resistor Rc.

[0043] The adjustable rise time pulse voltage generating unit 1-2 is mainly composed of a main pulse energy storage capacitor C1, a high voltage discharge switch G, adjustable waveform forming resistors R1 and R2, and a forming capacitor C2, which are electrically connected in series and parallel, and the sample fastener carbon fiber composite laminate 2 and its connecting clamp are connected in parallel to the output end of the adjustable rise time pulse voltage generating unit 1-2.

[0044] The function of the control and measurement and analysis unit 3 of the electric breakdown ignition test is to realize the control of the ignition characteristic test of the ignition source of the fastener carbon fiber composite material and the measurement and analysis of the electric breakdown pulse parameters. It is mainly composed of a control unit 31 and an electric breakdown measurement and analysis unit 32. Among them, the control unit 31 is mainly composed of a charging voltage monitoring circuit 31-1 and a programmable controller 31-2. The charging voltage monitoring circuit 31-1 of the control unit 31 receives the signal transmitted by the charging voltage monitoring sensor 1-3, and after the measurement and processing of the programmable controller 31-2, the high-voltage discharge switch G of the pulse voltage generating unit 1-2 with adjustable rise time is discharged. In addition, the programmable controller 31-2 is also combined with the industrial control computer 32-4 of the electric breakdown measurement and analysis unit 32 to control the connection / disconnection, high voltage rise / drop and conduction of the high-voltage discharge switch G of the ignition characteristic test of the ignition source of the fastener carbon fiber composite material, so as to realize the automatic control of the ignition characteristic test process of the ignition source of the fastener carbon fiber composite material.

[0045] The function of the electrical breakdown measurement and analysis unit 32 is to realize the control of the ignition characteristic test of the carbon fiber ignition source of the fastener and the measurement and analysis of the electrical breakdown pulse parameters, and to realize the process control of the ignition characteristic test of the ignition source of the fastener carbon fiber composite material and the measurement and analysis of the electrical breakdown pulse parameters. The electrical breakdown measurement and analysis unit 32 is mainly composed of a pulse voltage sensor 32-1, a digital oscilloscope 32-3 and an industrial control computer 32-4. The pulse voltage sensor 32-1 is combined with the array digital oscilloscope 32-3 to measure the pulse voltage between the high-voltage injection point and the low-voltage return point of the fastener carbon fiber composite material; the industrial control computer 32-4 processes and analyzes the pulse voltage signal measured by the digital oscilloscope 32-3, thereby obtaining the electrical breakdown voltage U under parameters including the fastener assembly method, ambient temperature and humidity, etc.

[0046] The electric breakdown spark monitoring unit 4 observes the occurrence and development process of the electric spark of the carbon fiber ignition source of the fastener, and is mainly composed of a high-speed camera monitoring instrument 41-1 and a high-speed camera control computer 41-2. The main function of the high-speed camera monitoring instrument 41-1 is to observe the occurrence and development process of the electric spark of the carbon fiber ignition source of the fastener, and its camera process is controlled by the high-speed camera control computer 41-2, and the electric spark process of the carbon fiber ignition source of the fastener is obtained through the electric breakdown spark monitoring unit 4.

[0047] The sample fastener carbon fiber composite material 2 is clamped by an electric breakdown injection clamping mechanism and an adjustment unit, and a pulse voltage is conducted and injected into the sample fastener carbon fiber composite material 2 .

[0048] See also Figure 3As shown, the electric breakdown injection clamping mechanism and adjustment unit are used to complete the clamping of the sample fastener carbon fiber composite laminate, and realize the application of pulse voltage to the sample fastener carbon fiber composite laminate. The electric breakdown injection clamping mechanism and adjustment unit is a bilateral structural fixture A2 installed on the insulating plate A1, with an adjustable locking position. The bilateral structural fixture A2 is composed of two insulating baffles connected by bolts. The installation position of the insulating baffle is adjusted by nuts A3 and screws A4 to realize the clamping of different sample fastener carbon fiber composite laminates 2. A high-voltage injection electrode HV and a low-voltage return electrode LV are installed on the inner side of the bilateral insulating baffles, and the high-voltage injection electrode HV and the low-voltage return electrode LV are installed on the insulating plate. Its function is to connect the fastener carbon fiber composite laminate sample to the pulse electric breakdown test power supply circuit, wherein the high-voltage end of the pulse electric breakdown test power supply is connected to the high-voltage injection electrode HV of the electric breakdown injection clamping mechanism and adjustment unit, and the high-voltage injection electrode HV is a plate-shaped electrode with a certain thickness. The low voltage end of the pulse electric breakdown test power supply is connected to the low voltage return electrode of the electrode structure.

[0049] See also Figure 4 , the ignition source ignition characteristics test and measurement method of fastener carbon fiber composite materials, the specific test and analysis process is as follows:

[0050] 1) Sample selection and processing: Select fastener composite laminate samples and process the samples, mainly including temperature and humidity, to simulate the actual flight environment of large aircraft. The sample temperature and humidity conditions have at least 5 points, denoted as S m1 To S m5 .

[0051] 2) Install the first fastener composite laminate sample with different humidity in the electrical breakdown injection clamping mechanism and adjustment unit, and connect the high-voltage injection electrode HV and the low-voltage return electrode LV of the electrical breakdown injection clamping mechanism and adjustment unit to the high-voltage and low-voltage output ports of the adjustable rise time pulse voltage generating unit 2.

[0052] 3) For the lightning voltage pulse of the fastener composite laminate 2, while keeping the pulse voltage peak value constant, change the pulse voltage time to obtain the breakdown characteristics and electrical breakdown ignition characteristics of the fastener carbon fiber composite laminate 2 under different humidity conditions, and use the pulse voltage sensor 32-1 and the electrical breakdown spark monitoring unit 4 to detect the breakdown spark characteristics.

[0053] 4) While maintaining the pulse voltage rise time at a certain level, the peak value of the pulse voltage is changed to obtain the breakdown characteristics and electrical breakdown ignition characteristics of the fastener carbon fiber composite laminate under different humidity conditions, and the pulse voltage sensor 32-1 and the electrical breakdown spark monitoring unit 4 are used to detect the breakdown spark characteristics.

[0054] 5) Changing the humidity of the fastener carbon fiber composite material, repeating process 2) to process 4), obtaining a correlation database between the breakdown voltage and breakdown spark characteristics of the fastener carbon fiber composite material and multiple factors such as sample temperature and humidity, pulse voltage rise rate, duration, peak value, and assembly structure.

[0055] 6) Similarly, the influencing factors of the fastener electric spark characteristics may also include the assembly method of the fastener and the carbon fiber composite material, including clearance fit, interference fit, and filling of insulating materials with different dielectric constants between the high-voltage injection electrode HV and the low-voltage return electrode LV and the carbon fiber composite material, etc.

[0056] 7) Perform multi-factor regression statistical analysis on all lightning test results to obtain the correlation between the ignition source characteristics of typical fastener structures of fuel tanks and the lightning electrical parameters and temperature and humidity flight environment characteristics.

[0057] 8) Statistical analysis of the electrical breakdown and spark characteristics test structure, including the study of the electrical breakdown and spark characteristics and influencing factors of carbon fiber composite materials for fasteners, mainly including two aspects:

[0058] First, adjust the temperature and humidity of the fastener carbon fiber composite laminate to simulate the different flight electrical environments of large aircraft, and apply pulse voltage waves with different rising rates and different intensities, and obtain the electrical breakdown characteristics and electrical breakdown ignition characteristics of the fastener carbon fiber composite laminate through the pulse voltage sensor and the electrical breakdown spark monitoring unit; as well as the attachment area of ​​lightning on the end face of the sample forest standing tree;

[0059] Secondly, the characteristics of the electric breakdown ignition source of the fastener carbon fiber composite laminate are analyzed. Through experiments, a correlation database between the electric breakdown of the fastener carbon fiber composite laminate, the electric breakdown ignition source and other multiple factors is established, and a multi-factor regression method is used to obtain the correlation regularity between the ignition source characteristics of typical fastener structures and lightning electrical parameters, temperature and humidity flight environment characteristics, and the ignition source characteristics evaluation method.

Claims

1. A test and measurement system for the electrical breakdown ignition characteristics of an aircraft composite fuel tank fastener ignition source, characterized in that: It comprises a pulse electric breakdown test power supply (1), a fastener carbon fiber composite material laminate (2), an electric breakdown injection clamping mechanism and an adjustment unit, an electric breakdown test control and its measurement and analysis unit (3) and an electric breakdown spark monitoring unit (4); The pulse electric breakdown test power supply (1) is used to generate a pulse voltage wave with an adjustable rise time, and comprises an adjustable high-voltage direct current charging power supply (1-1) and an adjustable rise time pulse voltage generating unit (1-2); the adjustable high-voltage direct current charging power supply (1-1) monitors the charging voltage of the adjustable rise time pulse voltage generating unit (1-2) online via a charging voltage monitoring sensor (1-3), and transmits the charging voltage analog quantity to a control unit (31) of a control and measurement analysis unit (3) of an electric breakdown ignition test; The sample fastener carbon fiber composite material laminate (2) is clamped by an electric breakdown injection clamping mechanism and an adjustment unit, and a pulse voltage is conducted and injected into the sample fastener carbon fiber composite material laminate (2); The electric breakdown injection clamping mechanism and the adjustment unit are used to complete the clamping of the sample fastener carbon fiber composite material laminate (2) and to achieve the application of pulse voltage to the sample fastener carbon fiber composite material laminate; The control and measurement and analysis unit (3) of the electric breakdown ignition test is used to control the ignition source ignition characteristic test of the fastener carbon fiber composite material laminate and measure and analyze the electric breakdown pulse parameters, and comprises a control unit (31) and an electric breakdown measurement and analysis unit (32); The electric breakdown spark monitoring unit (4) is used to observe the occurrence and development process of the electric spark of the carbon fiber ignition source of the fastener, and obtain the electric spark process of the carbon fiber ignition source of the fastener; The fastener carbon fiber composite laminate (2) is clamped by an electric breakdown injection clamping mechanism and an adjustment unit, and a pulse voltage is applied to the sample by a pulse electric breakdown test power supply (1). The occurrence and development process of the electric spark of the fastener carbon fiber ignition source is obtained by an electric breakdown spark monitoring unit (4). The control and measurement analysis unit (3) of the electric breakdown ignition test controls the ignition characteristic test of the fastener carbon fiber composite laminate ignition source and measures and analyzes the electric breakdown pulse parameters. Finally, a database of the association between the electric breakdown and electric spark characteristics of the fastener carbon fiber composite laminate and the fastener-composite matching structure, temperature and humidity, and pulse voltage electrical parameters is obtained, forming a database of the electric breakdown and ignition source characteristics of the composite fuel tank fastener ignition source simulating the flight environment of a large aircraft.

2. The test and measurement system for the electrical breakdown ignition characteristics of the aircraft composite fuel tank fastener ignition source according to claim 1 is characterized by: The adjustable high-voltage direct current charging power supply (1-1) is composed of an electronically controlled voltage regulator T1, a transformer T2, a rectifier silicon stack D and a current limiting resistor Rc; The adjustable rise time pulse voltage generating unit (1-2) is composed of a main pulse energy storage capacitor C1, a high voltage discharge switch G, an adjustable waveform forming resistor R1, an adjustable waveform forming resistor R2 and a forming capacitor C2. The fastener carbon fiber composite material laminate (2) is injected into the clamping mechanism and the adjustment unit through electrical breakdown and is connected to the output end of the adjustable rise time pulse voltage generating unit (1-2).

3. The test and measurement system for the electrical breakdown ignition characteristics of the aircraft composite fuel tank fastener ignition source according to claim 1 is characterized by: The electric breakdown injection clamping mechanism and the adjustment unit are installed on a double-sided structural clamp (A2) with adjustable locking position on an insulating plate (A1). The double-sided structural clamp (A2) is composed of two insulating baffles connected by bolts. A plate-shaped high-voltage injection electrode HV and a low-voltage return electrode LV are respectively installed on the inner side of the double-sided insulating baffles. The high-voltage end of the pulse electric breakdown test power supply (1) is connected to the high-voltage injection electrode HV, and the low-voltage end is connected to the low-voltage return electrode LV of the electrode structure.

4. The test and measurement system for the electrical breakdown ignition characteristics of the aircraft composite fuel tank fastener ignition source according to claim 2, characterized in that: The control unit (31) comprises a charging voltage monitoring circuit (31-1) and a programmable controller (31-2); the charging voltage monitoring circuit (31-1) of the control unit (31) receives a signal transmitted by a charging voltage monitoring sensor (1-3), and after being processed by the programmable controller (31-2), performs discharge control on a high-voltage discharge switch G of a pulse voltage generating unit (1-2) with adjustable rise time; The programmable controller (31-2) is also combined with the industrial control computer (32-4) of the electrical breakdown measurement and analysis unit (32) to control the on / off, high voltage increase / decrease and conduction of the high voltage discharge switch G during the charging process of the fastener carbon fiber composite material laminate ignition source ignition characteristic test, thereby realizing automatic control of the fastener carbon fiber composite material laminate ignition source ignition characteristic test process.

5. The test and measurement system for the electrical breakdown ignition characteristics of the aircraft composite fuel tank fastener ignition source according to claim 2, characterized in that: The electrical breakdown measurement and analysis unit (32) comprises a pulse voltage sensor (32-1), a digital oscilloscope (32-3) and an industrial control computer (32-4); The pulse voltage sensor (32-1) is combined with an array digital oscilloscope (32-3) to measure the pulse voltage between the high-voltage injection point and the low-voltage return point of the fastener carbon fiber composite laminate; the industrial control computer (32-4) processes and analyzes the pulse voltage signal measured by the digital oscilloscope (32-3), thereby obtaining the electrical breakdown voltage U under the fastener assembly method and environmental temperature and humidity parameters.

6. The test and measurement system for the electrical breakdown ignition characteristics of the aircraft composite fuel tank fastener ignition source according to claim 4 or 5, characterized in that: The electric breakdown spark monitoring unit (4) comprises a high-speed camera monitoring instrument (41-1) and a high-speed camera control computer (41-2); the high-speed camera monitoring instrument (41-1) observes the occurrence and development process of the electric spark of the carbon fiber ignition source of the fastener, and its camera process is controlled by the high-speed camera control computer (41-2).

7. A method for testing and measuring the electrical breakdown ignition characteristics of an aircraft composite fuel tank fastener based on the test system of claim 6, characterized in that The steps include: 1) Sample selection and processing: Select multiple fastener composite laminate samples and subject them to temperature and humidity treatment to simulate the actual flight environment of large aircraft; 2) installing the first fastener composite laminate sample with different humidity in the electric breakdown injection clamping mechanism and adjustment unit, and connecting the high voltage injection electrode HV and the low voltage return electrode LV of the electric breakdown injection clamping mechanism and adjustment unit to the high voltage and low voltage output ports of the adjustable rise time pulse voltage generating unit (1-2); 3) applying a lightning voltage pulse to the fastener composite laminate (2), changing the pulse voltage time while maintaining a constant pulse voltage peak value, obtaining the breakdown characteristics and electrical breakdown ignition characteristics of the fastener carbon fiber composite laminate (2) under different humidity conditions, and using a pulse voltage sensor (32-1) and an electrical breakdown spark monitoring unit (4) to detect the breakdown spark characteristics; 4) while maintaining a certain pulse voltage rise time, changing the peak value of the pulse voltage, obtaining the breakdown characteristics and electrical breakdown ignition characteristics of the fastener carbon fiber composite laminate under different humidity conditions, and using a pulse voltage sensor (32-1) and an electrical breakdown spark monitoring unit (4) to detect the breakdown spark characteristics; 5) Repeating process 2) to process 4) with fastener carbon fiber composite laminates of different humidity, temperature, and assembly methods, to obtain a database of associations between the breakdown voltage and breakdown spark characteristics of the fastener carbon fiber composite laminates and the sample temperature and humidity, pulse voltage rise rate, duration, peak value, and assembly method; 6) Perform multi-factor regression statistical analysis on all lightning test results to obtain the correlation between the ignition source characteristics of typical fastener structures of fuel tanks and lightning electrical parameters, temperature and humidity flight environment characteristics, and assembly structure.

8. The test and measurement method of the electrical breakdown ignition characteristics of the ignition source of the aircraft composite fuel tank fastener according to the test system of claim 7, characterized in that: The assembly method includes adjusting the distance between the bilateral insulating baffles to achieve clearance fit, interference fit, and filling insulating materials with different dielectric constants between the high-voltage injection electrode HV and the low-voltage return electrode LV and the carbon fiber composite material.

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