Fatigue test method and system based on fatigue load spectrum of landing gear

Abstract

The invention belongs to the technical field of aircraft design, and particularly relates to a fatigue test method and system based on a fatigue load spectrum of a landing gear. The method comprises the following steps: step S1, acquiring stop loads of a main landing gear and a nose landing gear of an aircraft in different test modes; s2, acquiring buffer strokes of a main landing gear and a front landing gear of the aircraft under different load conditions; step S3, acquiring undercarriage loading modes of each load condition and frequencies and specifications of different undercarriage loading modes; s4, for different undercarriage loading modes, calculating design loads of the main undercarriage and the front undercarriage in all directions according to specifications and shutdown loads, and forming a fatigue load spectrum; and S5, carrying out a fatigue load test on the landing gear according to the fatigue load spectrum and the stroke of the buffer. The service life of the landing gear of the aircraft can be predicted, and the working capacity and reliability of the landing gear can be verified.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft design, and in particular relates to a fatigue test method and system based on a fatigue load spectrum of a landing gear. Background Art

[0002] High-altitude long-flight UAVs can provide 24-hour uninterrupted monitoring capabilities for distant targets, and can use their high flight altitude and long endurance advantages as a research platform for high-altitude atmospheric research to conduct long-term tracking research on some special phenomena in the high-altitude atmosphere, providing a reliable and low-cost research method for high-altitude atmospheric and meteorological research. High-altitude long-flight UAVs have put forward many new requirements for aircraft fatigue design.

[0003] The fatigue life of the landing gear plays a vital role in whether the high-altitude long-flight UAV can complete the scheduled mission well. At the same time, the quality of the fatigue life assessment scheme also directly affects the landing performance of the high-altitude long-flight UAV. During the design process, the fatigue life assessment scheme must be accurately evaluated to meet the requirements of the life design index. For this reason, it is necessary to develop a landing gear fatigue load spectrum to evaluate the life of the landing gear of the high-altitude long-flight UAV. Summary of the invention

[0004] In order to solve the above problems, the present application provides a fatigue test method and system based on the fatigue load spectrum of the landing gear to solve the problem of life assessment of the landing gear of high-altitude and long-flight UAVs.

[0005] The first aspect of the present application provides a fatigue test method based on a landing gear fatigue load spectrum, which mainly includes: Step S1, obtaining the parking loads of the main landing gear and the front landing gear of the aircraft in different test modes; Step S2, obtaining the buffer travel of the main landing gear and the front landing gear of the aircraft under different load conditions; Step S3, obtaining the landing gear loading mode of each load condition, and the frequency and specifications of different landing gear loading modes; Step S4: for different landing gear loading modes, the design loads of the main landing gear and the front landing gear in various directions are calculated according to the specifications and the parking load to form a fatigue load spectrum; Step S5: Perform a fatigue load test on the landing gear according to the fatigue load spectrum and the buffer stroke.

[0006] Preferably, in step S1, the test modes include an aircraft takeoff test mode, an aircraft landing test mode and an aircraft landing impact test mode.

[0007] Preferably, in step S2, the load conditions include landing, taxiing, braking, test running, turning, towing, and touchdown.

[0008] Preferably, in step S3, the specifications include but are not limited to overload factor and load percentage.

[0009] Preferably, in step S4, the directions of the main landing gear and the front landing gear include vertical, heading and lateral directions.

[0010] The second aspect of the present application provides a fatigue test system based on a landing gear fatigue load spectrum, mainly comprising: A parking load acquisition module is used to obtain the parking loads of the main landing gear and the front landing gear of the aircraft in different test modes; A buffer travel acquisition module is used to acquire the buffer travels of the main landing gear and the front landing gear of the aircraft under different load conditions; A landing gear loading mode acquisition module is used to obtain the landing gear loading mode of each load condition, and the frequency and specifications of different landing gear loading modes; The design load calculation module is used to calculate the design loads in all directions of the main landing gear and the nose landing gear according to the specifications and parking loads for different landing gear loading modes, and form a fatigue load spectrum; The fatigue load spectrum test module is used to perform fatigue load tests on landing gear according to the fatigue load spectrum and buffer stroke.

[0011] This application conducts fatigue load tests based on the fatigue load spectrum of high-altitude and long-flight UAVs, which can not only predict the life of the aircraft's landing gear, but also verify the working ability and reliability of the landing gear. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a flow chart of a preferred embodiment of the fatigue test method of the present application based on the fatigue load spectrum of the landing gear. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0014] The first aspect of the present application provides a fatigue test method based on a fatigue load spectrum of a landing gear, such as Figure 1 As shown, it mainly includes: Step S1, obtaining the parking loads of the main landing gear and the front landing gear of the aircraft in different test modes.

[0015] In some optional implementations, in step S1, the test modes include an aircraft takeoff test mode, an aircraft landing test mode, and an aircraft landing impact test mode.

[0016] For example, the aircraft takeoff test mode is used to reflect the normal takeoff of the aircraft. At this time, the main landing gear parking load is 6500kg and the front landing gear parking load is 800kg. The aircraft landing test mode is used to reflect the normal landing of the aircraft. At this time, the main landing gear parking load is 5000kg and the front landing gear parking load is 600kg. The aircraft landing impact test mode is used to reflect the situation where the aircraft hits the ground due to other factors during the landing process. At this time, the main landing gear parking load is 6000kg and the front landing gear parking load is 1000kg.

[0017] Step S2: Obtain the buffer travels of the main landing gear and the front landing gear of the aircraft under different load conditions.

[0018] In some optional embodiments, in step S2, the load conditions include landing, taxiing, braking, test running, turning, towing, and touchdown.

[0019] Table 1 gives the calculation method of the landing gear buffer stroke under various load conditions, where Smax is the maximum stroke of the landing gear buffer.

[0020] Table 1 Stroke specification table of drop frame buffer Load conditions Nose landing gear buffer travel Main landing gear buffer travel Landing (0.1~0.2)Smax (0.1~0.2)Smax slide (0.55~0.65)Smax (0.5~0.7)Smax brake (0.55~0.65)Smax (0.35~0.45)Smax Test Drive Determined by the buffer static pressure curve based on the vertical load Determined by the buffer static pressure curve based on the vertical load Turning (0.4~0.5)Smax (0.35~0.4)Smax Traction (0.35~0.45)Smax (0.35~0.45)Smax Grounding 0.2 Smax 0.2 Smax

[0021] According to Table 1 and the maximum stroke of the landing gear buffer, the stroke of the landing gear buffer under various load conditions can be calculated. For example, when the landing gear is subjected to traction load, the stroke of the front landing gear buffer is 100 mm.

[0022] Step S3: Obtain the landing gear loading mode of each load condition, and the frequency and specifications of different landing gear loading modes.

[0023] It is understandable that for different load conditions, there may be multiple landing gear loading modes. For example, for traction, it may be forward traction or backward traction, or it may be traction with a certain angle of wheel deflection or traction without wheel deflection. Different traction modes correspond to different frequencies. For example, each flight requires one forward traction and one backward traction. Different traction modes correspond to different specifications. In some optional embodiments, in step S3, the specifications include but are not limited to overload coefficients and load percentages. For example, the vertical overload coefficient during traction is 1, which means that the vertical load design is performed according to one times the parking load in step S1.

[0024] Table 2 gives the specific landing gear loading mode, frequency and specifications.

[0025] Table 2 Landing gear loading method

[0026] It should also be noted that the above Table 2 also gives the order of load application. The load test is performed according to the serial number in the first column of Table 2. If the landing gear is a multi-wheel coaxial landing gear, the load distribution ratio is set to 0.45:0.55 when the load distribution of the two wheels is not much different during take-off and landing.

[0027] Step S4: for different landing gear loading modes, the design loads in various directions of the main landing gear and the front landing gear are calculated according to the specifications and the parking load to form a fatigue load spectrum.

[0028] In some optional embodiments, in step S4, the directions of the main landing gear and the front landing gear include vertical, heading and lateral.

[0029] As shown in Table 3 or Table 4, Pymax is the maximum vertical load, Pymin is the minimum vertical load, Px is the heading load, positive and negative indicate the direction, and Fz is the lateral load, positive and negative indicate the direction. For example, for the landing gear loading mode numbered 0101 in Table 2, for the front landing gear, two detailed landing gear loading modes of 80% right deflection angle traction and 80% left deflection angle traction are formed in Table 3. For the landing gear loading mode of 80% right deflection angle traction, since the aircraft is in a parking attitude, according to the front landing gear parking load of 800kg given in the aircraft takeoff test mode of step S1, according to the vertical overload coefficient of 1.0 given in Table 2, it is determined that the maximum vertical load Pymax and the minimum vertical load Pymin of the landing gear of 80% right deflection angle traction are both 800kg.

[0030] Table 3 Design load spectrum of front landing gear

[0031] Table 4 Main landing gear design load spectrum

[0032] Step S5: Perform a fatigue load test on the landing gear according to the fatigue load spectrum and the buffer stroke.

[0033] The second aspect of the present application provides a fatigue test system based on a landing gear fatigue load spectrum corresponding to the above method, mainly comprising: A parking load acquisition module is used to obtain the parking loads of the main landing gear and the front landing gear of the aircraft in different test modes; A buffer travel acquisition module is used to acquire the buffer travels of the main landing gear and the front landing gear of the aircraft under different load conditions; A landing gear loading mode acquisition module is used to obtain the landing gear loading mode of each load condition, and the frequency and specifications of different landing gear loading modes; The design load calculation module is used to calculate the design loads in all directions of the main landing gear and the nose landing gear according to the specifications and parking loads for different landing gear loading modes, and form a fatigue load spectrum; The fatigue load spectrum test module is used to perform fatigue load tests on landing gear according to the fatigue load spectrum and buffer stroke.

[0034] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A fatigue test method based on a landing gear fatigue load spectrum, characterized in that: include: Step S1, obtaining the parking loads of the main landing gear and the front landing gear of the aircraft in different test modes; Step S2, obtaining the buffer travel of the main landing gear and the front landing gear of the aircraft under different load conditions; Step S3, obtaining the landing gear loading mode of each load condition, and the frequency and specifications of different landing gear loading modes; Step S4: for different landing gear loading modes, the design loads of the main landing gear and the front landing gear in various directions are calculated according to the specifications and the parking load to form a fatigue load spectrum; Step S5: Perform a fatigue load test on the landing gear according to the fatigue load spectrum and the buffer stroke.

2. The fatigue test method based on the landing gear fatigue load spectrum according to claim 1, characterized in that: In step S1, the test modes include an aircraft takeoff test mode, an aircraft landing test mode and an aircraft landing impact test mode.

3. The fatigue test method based on the landing gear fatigue load spectrum according to claim 1, characterized in that: In step S2, the load conditions include landing, taxiing, braking, test running, turning, towing, and touchdown.

4. The fatigue test method based on the landing gear fatigue load spectrum according to claim 1, characterized in that: In step S3, the specifications include but are not limited to overload factor and load percentage.

5. The fatigue test method based on the landing gear fatigue load spectrum according to claim 1, characterized in that: In step S4, the directions of the main landing gear and the front landing gear include vertical, heading and lateral directions.

6. A fatigue test system based on the fatigue load spectrum of landing gear, characterized in that: include: A parking load acquisition module is used to obtain the parking loads of the main landing gear and the front landing gear of the aircraft in different test modes; A buffer travel acquisition module is used to acquire the buffer travels of the main landing gear and the front landing gear of the aircraft under different load conditions; A landing gear loading mode acquisition module is used to obtain the landing gear loading mode of each load condition, and the frequency and specifications of different landing gear loading modes; The design load calculation module is used to calculate the design loads in all directions of the main landing gear and the nose landing gear according to the specifications and parking loads for different landing gear loading modes, and form a fatigue load spectrum; The fatigue load spectrum test module is used to perform fatigue load tests on landing gear according to the fatigue load spectrum and buffer stroke.

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