Compilation method of undercarriage landing impact test load spectrum

Abstract

The invention discloses a compilation method of an undercarriage landing impact test load spectrum, which comprises the following steps of: firstly, selecting actually measured overload data of a landing impact task section from undercarriage overload data, and obtaining a vertical overload spectrum, a course overload spectrum (including starting overload, springback overload and oscillation overload) and a lateral overload spectrum through statistical processing; converting the overload spectrums in all directions into standard block spectrums in all directions under set rising and falling times; performing trend fitting on each directional standard block spectrum, rounding an overload value of each directional overload spectrum after trend fitting, and obtaining each directional overload spectrum after rounding through interpolation; performing high-load interception on the rounded overload spectrum in each direction, and performing equal-damage conversion on the overload spectrum in each direction after high-load interception to obtain an equal-damage overload value in each direction with specified rising and falling times; multiplying the equal damage overload value in each direction by the landing gear shutdown load to obtain a test load value in each direction; and finally, combining the loading sequences of the test load values in all directions to obtain an undercarriage landing impact test load spectrum.

Description

Technical Field

[0001] The present invention relates to, but is not limited to, the technical field of aircraft landing gear fatigue test load spectrum compilation, and in particular to a method for compiling a landing gear landing impact test load spectrum. Background Art

[0002] As a key aircraft component, landing gear must undergo fatigue testing to accurately estimate its lifespan. This testing is premised on the development of a fatigue test load spectrum. As a key fatigue test load technology, the landing impact test load spectrum must accurately reflect the loading conditions experienced by the landing gear during a landing impact in order to accurately estimate its lifespan.

[0003] During landing, the landing gear is subject to vertical, axial, and lateral loads. The maximum values ​​of these loads do not occur simultaneously, and the number of loads in different directions caused by the landing impact is also different. The landing gear experiences multiple landing impacts during each landing, but the load values ​​in the second and subsequent impacts are much smaller. The traditional method of compiling load spectra for landing gear landing impact tests simplifies the landing impact loads, focusing on the first large load that occurs during each flight, causing the landing gear load spectrum to deviate from the actual loading conditions. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for compiling a landing gear landing impact test load spectrum to solve the problem that the conventional method for compiling a landing gear landing impact test load spectrum simplifies the landing impact load, resulting in the landing gear load spectrum deviating from the actual loading condition.

[0005] The technical solution of the present invention is: the present invention provides a method for compiling a load spectrum for a landing gear landing impact test, the method comprising: Step 1: Select the measured overload data of multiple landing impact mission segments from the landing gear overload data; Step 2: Statistically process the measured overload data from multiple landing and impact missions to obtain vertical overload spectra, directional overload spectra, and lateral overload spectra. The directional overload spectrum includes the rotational overload spectrum, rebound overload spectrum, and oscillation overload spectrum. Step 3: Convert the directional overload spectrum obtained by the measured overload data into a directional standard block spectrum; wherein the directional overload spectrum refers to the directional overload values ​​and corresponding overload times under the measured take-off and landing times, and the standard block spectrum refers to the directional overload values ​​and corresponding overload times obtained by conversion under the set take-off and landing times; Step 4: Perform trend fitting on the converted isotropic standard block spectrum to make it conform to the Weibull distribution, then round the overload values ​​in the isotropic overload spectrum after trend fitting, and obtain the overload times corresponding to the rounded overload values ​​by interpolation to obtain the rounded isotropic overload spectrum; Step 5: perform high-load interception on the rounded overload spectrum, and perform equal damage conversion on the overload spectrum after high load interception to obtain the equal damage overload value of each direction for the specified number of take-offs and landings. ; Step 6: Set the isotropic damage overload value Multiply it by the landing gear parking load Pg to obtain the test load value in each direction ; Step 7: Test load values ​​in all directions The loading sequence is combined to obtain the load spectrum of the landing gear landing impact test.

[0006] Optionally, in the above-described method for compiling a landing gear landing impact test load spectrum, the measured overload data of the landing gear includes data of a takeoff and taxiing mission segment, an airborne mission segment, a landing impact mission segment, and a landing and taxiing mission segment; and selecting the measured overload data of multiple landing impact mission segments in step 1 includes: The landing impact mission segment starts when the aircraft landing gear compression begins to increase, and ends when the aircraft landing gear directional load becomes significantly larger again. The measured overload data of the landing impact mission segment corresponding to multiple measured takeoffs and landings are determined.

[0007] Optionally, in the method for compiling a landing gear landing impact test load spectrum as described above, step 2 includes: Step 21: Statistically process the measured vertical overload data and lateral overload data of the multiple landing and impact mission segments using the rainflow method to obtain vertical overload spectra and lateral overload spectra. Step 22: For directional overload, the maximum positive overload that occurs once during each takeoff and landing is counted to obtain the takeoff and rotation overload spectrum. The minimum negative overload that occurs once during each takeoff and landing is counted to obtain the rebound overload spectrum. The other directional overload data during the landing and impact mission segment are statistically processed using the rain flow method to obtain the oscillation overload spectrum.

[0008] Optionally, in the method for compiling a landing gear landing impact test load spectrum as described above, step 3 includes: Based on the directional overload spectrum obtained from the measured overload data, the overload times under the measured take-off and landing times in the directional overload spectrum are calculated. Converted into the standard overload number corresponding to the set rise and fall times in the standard block spectrum , the overload value remains unchanged during the transformation process, and the isotropic standard block spectrum is obtained.

[0009] Optionally, in the above-mentioned method for compiling the load spectrum of the landing gear landing impact test, the standard block spectrum is set to include the overload values ​​in all directions under 1000 take-off and landing times and the corresponding standard overload times; in step 3, the method for converting the standard overload times is: ; Where M is the measured number of take-offs and landings, is the number of overloads corresponding to different overload values ​​in the measured isotropic overload spectrum, is the standard overload number corresponding to different overload values ​​in the converted standard block spectrum.

[0010] Optionally, in the above-mentioned method for compiling a landing gear landing impact test load spectrum, step 4 includes: The converted isotropic standard block spectrum is trend fitted to obtain an isotropic overload spectrum that conforms to the Weibull distribution. The overload values ​​in the isotropic overload spectrum that conforms to the Weibull distribution are rounded according to the order difference of 0.1, and the overload times are linearly interpolated to obtain the overload times corresponding to the rounded overload values, that is, the rounded isotropic overload spectrum is obtained.

[0011] Optionally, in the method for compiling a landing gear landing impact test load spectrum as described above, step 5 includes: Step 51, using the overload value at which the rise and fall times occur once in the standard block spectrum of each direction as the cutoff value, and truncating the overload data above the cutoff value to obtain the overload spectrum of each direction after high load truncation; Step 52: perform equal damage conversion on the overload spectrum after high load interception, and convert the overload spectrum corresponding to the overload times of the multi-level overload values ​​in each direction into the overload value of level 1 in each direction corresponding to the specified overload times. .

[0012] Optionally, in the method for compiling the landing gear landing impact test load spectrum as described above, the test load values ​​in each direction obtained in step 6 are include:

[0013] in, F 垂 is the vertical test load value, g 垂 is the vertical equal damage overload value; F 起 is the test load value for starting rotation, g 起 This is the overload value for damage such as starting; F 回 is the test load value of rebound, g 回 This is the overload value for rebound and other damage; F 侧 is the lateral test load value, g 侧 is the lateral damage overload value; F 震 is the test load value of the oscillation, g 震 This is the overload value for damage such as shock.

[0014] Optionally, in the above-mentioned method for compiling a landing gear landing impact test load spectrum, in step 7, the loading order of the test load values ​​in each direction is combined in the following manner: The vertical load, heading load, and lateral load are loaded to their maximum values ​​simultaneously. The maximum heading load is the rotation load. The loading direction of the lateral load alternates left and right with each takeoff and landing, and only occurs once in each takeoff and landing. The vertical load remains at its maximum value, and the heading load and lateral load return to 0 simultaneously. The lateral load remains at 0, and the heading load is loaded from 0 to the rebound load and then back to 0. Then, the heading load is loaded from 0 to the maximum oscillation load and back to the minimum oscillation load. The oscillation load is loaded for two complete takeoffs and landings in each takeoff and landing, and finally the heading load and vertical load return to 0 simultaneously.

[0015] The beneficial effects of the present invention are as follows: the present invention provides a method for compiling a load spectrum for a landing impact test of a landing gear, by statistically processing the measured overload data of the landing impact mission segments corresponding to multiple measured take-offs and landings, obtaining a vertical overload spectrum, a heading overload spectrum and a lateral overload spectrum, wherein the heading overload spectrum includes a rotation overload spectrum, a rebound overload spectrum and an oscillation overload spectrum; converting the directional overload spectrum obtained by the measured overload data into an directional standard block spectrum; performing trend fitting on the converted directional standard block spectrum, rounding the overload values ​​in the directional overload spectrum after trend fitting, and obtaining the overload number corresponding to the rounded overload value by interpolation, thereby obtaining the rounded directional overload spectrum; performing high-load interception and equal-damage conversion on the rounded directional overload spectrum, thereby obtaining the directional equal-damage overload value for a specified number of take-offs and landings. , combined with the landing gear parking load Pg, the test load values ​​in each direction are obtained ; Finally, the test load values ​​in each direction The loading sequence is combined to obtain the load spectrum of the landing gear landing impact test.

[0016] The technical solution provided by the present invention has the following beneficial effects: on the one hand, by proposing the concept of an oscillating overload spectrum, the load borne by the landing gear during a landing impact can be fully described, thereby reducing errors introduced by simplification in the overload spectrum processing process; on the other hand, in the loading of the test load spectrum, the peak and valley arrival times of the vertical load, the heading load, and the lateral load are comprehensively considered, resulting in more rigorous test assessments and ensuring the safety of the landing gear; on the other hand, the landing gear landing impact test load spectrum compiled using the method provided by the present invention is closer to the actual load on the landing gear, and accurately evaluates the impact of the load on the landing gear life during a landing impact; on the other hand, the method provided by the present invention is simple and can accurately and quickly calculate the landing gear landing impact test load spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0018] Figure 1 A schematic flow chart of a method for compiling a load spectrum for a landing gear landing impact test provided by an embodiment of the present invention; Figure 2 Schematic diagram of the measured overload spectrum of the landing gear landing impact mission segment in an embodiment of the present invention; Figure 3 Schematic diagram of the process of converting the measured vertical overload spectrum of the landing gear into the tested vertical overload value in an embodiment of the present invention; Figure 4 Schematic diagram of trend fitting of the actually measured overload spectrum of the landing gear in an embodiment of the present invention; Figure 5 Schematic diagram of the load spectrum of the landing gear landing impact test in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other in any manner.

[0020] The above background technology has explained the importance of fatigue test load spectrum to landing gear fatigue testing, and explained that the traditional method of compiling landing gear landing impact test load spectrum simplifies the landing impact load, causing the landing gear load spectrum to deviate from the actual loading conditions.

[0021] Specifically, in the compilation of landing impact test loads for traditional landing gear fatigue tests, emphasis is usually placed on the first large load occurring in the landing impact of each flight, while some small loads are ignored. Therefore, the landing impact heading load is simplified, focusing on the first large load occurring in each flight.

[0022] In order to accurately evaluate the life of the landing gear and make the load spectrum of the landing gear landing impact test close to the actual load of the landing gear, the present invention provides a method for compiling the landing gear landing impact test load spectrum, which can quickly and accurately compile the landing gear landing impact test load spectrum.

[0023] The present invention provides the following specific embodiments that can be combined with each other. The same or similar concepts or processes may not be described in detail in some embodiments. The present invention provides a method for compiling a landing gear landing impact test load spectrum. The test load spectrum compilation process diagram is as follows: Figure 1 As shown, the following steps are included: Step 1: Select the measured overload data of multiple landing impact mission segments from the landing gear overload data; Step 2: Statistically process the measured overload data from multiple landing and impact missions to obtain vertical overload spectra, directional overload spectra, and lateral overload spectra. The directional overload spectrum includes the rotational overload spectrum, rebound overload spectrum, and oscillation overload spectrum. Step 3: Convert the directional overload spectrum obtained by the measured overload data into a directional standard block spectrum; wherein the directional overload spectrum refers to the directional overload values ​​and corresponding overload times under the measured take-off and landing times, and the standard block spectrum refers to the directional overload values ​​and corresponding overload times obtained by conversion under the set take-off and landing times; Step 4: Perform trend fitting on the converted isotropic standard block spectrum to make it conform to the Weibull distribution, then round the overload values ​​in the isotropic overload spectrum after trend fitting, and obtain the overload times corresponding to the rounded overload values ​​by interpolation to obtain the rounded isotropic overload spectrum; Step 5: perform high-load interception on the rounded overload spectrum, and perform equal damage conversion on the overload spectrum after high load interception to obtain the equal damage overload value of each direction for the specified number of take-offs and landings. ; Step 6: Set the isotropic damage overload value Multiply it by the landing gear parking load Pg to obtain the test load value in each direction ; Step 7: Test load values ​​in all directions The loading sequence is combined to obtain the load spectrum of the landing gear landing impact test.

[0024] The above steps of the method for compiling a landing gear landing impact test load spectrum provided by an embodiment of the present invention are described in detail below.

[0025] Step 1: The landing impact mission segment starts when the aircraft landing gear compression begins to increase, and ends when the aircraft landing gear yaw load becomes significantly larger again. The time history curve of the measured overload of the landing gear is screened to select the measured overload data of the landing impact mission segment corresponding to each measured takeoff and landing, thus obtaining the measured overload data of the landing impact mission segment, such as Figure 2 The measured overload spectrum is shown.

[0026] Step 2: Perform statistical processing on the measured vertical and lateral overload data of multiple landing and impact mission segments using the rain flow method to obtain vertical and lateral overload spectra. For directional overloads, the maximum positive overload occurring once in each takeoff and landing is counted to obtain the take-off and rotational overload spectrum, and the minimum negative overload occurring once in each takeoff and landing is counted to obtain the rebound overload spectrum. Statistical processing is performed on other directional overload data of the landing and impact mission segment using the rain flow method to obtain the oscillation overload spectrum.

[0027] In step 2, the vertical overload spectrum, heading overload spectrum and lateral overload spectrum are obtained based on the measured overload data of landing impact. The heading overload spectrum is divided into the rotation overload spectrum, rebound overload spectrum and oscillation overload spectrum. The vertical overload spectrum is as follows: Figure 3 As shown in Table 1.

[0028] Step 3: Based on the directional overload spectrum obtained from the measured overload data, the overload times under the measured take-off and landing times in the directional overload spectrum are calculated. Convert it into the standard overload number corresponding to the set take-off and landing number in the standard block spectrum. The overload value remains unchanged during the conversion process, and the standard block spectrum in each direction is obtained, such as Figure 3 As shown in Table 2.

[0029] In one embodiment of the present invention, the standard block spectrum is set to include the directional overload values ​​under 1000 take-off and landing times and the corresponding standard overload times; in step 3, the standard overload times are converted as follows: ; Among them, M is the measured number of take-offs and landings, which is set to 226 times. is the number of overloads corresponding to different overload values ​​in the measured isotropic overload spectrum, Set the overload times corresponding to the rise and fall times for the converted standard block spectrum.

[0030] Step 4: Perform trend fitting on the transformed isotropic standard block spectrum, as Figure 4 As shown, the isotropic overload spectrum that conforms to the Weibull distribution is obtained, as shown in Figure 3 As shown in Table 3. Each overload value in the isotropic overload spectrum that conforms to the Weibull distribution is rounded to an integer of 0.1 order difference, and the number of take-offs and landings is linearly interpolated to obtain the overload number corresponding to the rounded overload value, and the rounded isotropic overload spectrum is obtained, as shown in Figure 3As shown in Table 4.

[0031] Step 5: In order to avoid the high-load hysteresis effect on crack propagation caused by high load, the overload value corresponding to the overload number of take-off and landing times occurring once is set as the cutoff value using the isotropic standard block spectrum. The overload data above the cutoff value is truncated to reduce the impact of large loads on the aircraft. The isotropic overload spectrum after high-load truncation is obtained, as shown in the figure below: Figure 3 As shown in Table 5. Furthermore, the equal damage conversion is performed on the overload spectrum after high load interception, and the overload spectrum corresponding to the overload number of multi-level overload values ​​in each direction is converted into the overload value of each direction corresponding to the specified overload number. ,like Figure 3 As shown in Table 6.

[0032] Step 6: Set the equal damage overload value in each direction Multiply it by the landing gear parking load Pg=195KN to obtain the test load value in each direction :

[0033] in, F 垂 is the vertical test load value, g 垂 is the vertical equal damage overload value; F 起 is the test load value for starting rotation, g 起 This is the overload value for damage such as starting and rotating; F 回 is the test load value of rebound, g 回 This is the overload value for damage such as rebound; F 侧 is the lateral test load value, g 侧 is the lateral damage overload value; F 震 is the test load value of the oscillation, g 震 This is the overload value for damage such as shock.

[0034] Step 7: Test load values ​​in all directions The loading sequence is combined to obtain the landing gear landing impact test load spectrum, such as Figure 5 shown.

[0035] In a possible implementation of the present invention, the test load values ​​in each direction in step 7 are The loading sequence is combined as follows: the vertical load, heading load and lateral load are loaded to the maximum value at the same time, the maximum heading load is the rotation load, the loading direction of the lateral load alternates left and right with each takeoff and landing, and only appears once in each takeoff and landing; the vertical load remains at the maximum value, the heading load and the lateral load return to 0 at the same time, and the lateral load remains at 0; the heading load is loaded from 0 to the rebound load and then returns to 0, and then the heading load is loaded from 0 to the maximum value of the oscillation load and returns to the minimum value of the oscillation load. The oscillation load is loaded for two complete takesoffs and landings in each takeoff and landing, and finally returns to 0 at the same time as the vertical load.

[0036] Due to the random nature of landing gear impact loads, the peak times of vertical, yaw, and side loads are random and vary from one landing to the next, making it difficult to discern statistical patterns. To ensure landing gear safety, the test was conducted under the most severe conditions, with vertical, yaw, and side loads simultaneously applied to their maximum values.

[0037] The present invention provides a method for compiling a load spectrum for a landing impact test of a landing gear. The method comprises the following steps: statistically processing the measured overload data of landing impact mission segments corresponding to multiple measured take-offs and landings to obtain a vertical overload spectrum, a heading overload spectrum and a lateral overload spectrum, wherein the heading overload spectrum includes a rotation overload spectrum, a rebound overload spectrum and an oscillation overload spectrum; converting the directional overload spectrum obtained by the measured overload data into an directional standard block spectrum; performing trend fitting on the converted directional standard block spectrum, rounding the overload values ​​in the directional overload spectrum after trend fitting, and obtaining the overload number corresponding to the rounded overload value by interpolation to obtain the rounded directional overload spectrum; performing high-load interception and equal-damage conversion on the rounded directional overload spectrum to obtain the directional equal-damage overload value for a specified number of take-offs and landings. , combined with the landing gear parking load Pg, the test load values ​​in each direction are obtained ; Finally, the test load values ​​in each direction The loading sequence is combined to obtain the load spectrum of the landing gear landing impact test.

[0038] The technical solution provided by the present invention has the following beneficial effects: on the one hand, by proposing the concept of an oscillating overload spectrum, the load borne by the landing gear during a landing impact can be fully described, thereby reducing errors introduced by simplification in the overload spectrum processing process; on the other hand, in the loading of the test load spectrum, the peak and valley arrival times of the vertical load, the heading load, and the lateral load are comprehensively considered, resulting in more rigorous test assessments and ensuring the safety of the landing gear; on the other hand, the landing gear landing impact test load spectrum compiled using the method provided by the present invention is closer to the actual load on the landing gear, and accurately evaluates the impact of the load on the landing gear life during a landing impact; on the other hand, the method provided by the present invention is simple and can accurately and quickly calculate the landing gear landing impact test load spectrum.

[0039] In one embodiment of the present invention, according to the requirements of steps 1 to 5 in claim 1, the vertical, rotation, rebound, lateral and oscillation damage overloads are obtained as follows: =0.992, =0.559, =0.139, =0.245, =0.099. When the main landing gear parking load Pg=195KN, the corresponding load values ​​in each direction for:

[0040] The vertical load, heading load and side load were simultaneously loaded to their respective maximum values ​​of 193.440KN, 109.005KN and 47.775KN. The side load was loaded to the right during odd-numbered lifts and to the left during even-numbered lifts, alternating between left and right, and occurring only once in each lift. The vertical load remained constant at 193.440KN, while the heading load and side load returned to 0 simultaneously. The side load remained constant at 0, and the heading load was loaded from 0 to 47.775KN and then returned to 0. The heading load was then loaded from 0 to 19.305KN and then returned to -19.305KN, and then loaded to 19.305KN again and then returned to -19.305KN. The oscillating load was loaded for two complete lifts in each lift and finally returned to 0 simultaneously with the vertical load.

[0041] Although the embodiments disclosed herein are as described above, the contents are merely provided to facilitate understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art may make any modifications and variations in the form and details of the embodiments without departing from the spirit and scope of the present invention. However, the scope of patent protection of the present invention shall remain subject to the scope defined by the appended claims.

Claims

1. A method for compiling a load spectrum for a landing gear landing impact test, characterized in that: include: Step 1: Select the measured overload data of multiple landing impact mission segments from the landing gear overload data; Step 2: Statistically process the measured overload data from multiple landing and impact missions to obtain vertical overload spectra, directional overload spectra, and lateral overload spectra. The directional overload spectrum includes the rotational overload spectrum, rebound overload spectrum, and oscillation overload spectrum. Step 3: Convert the directional overload spectrum obtained by the measured overload data into a directional standard block spectrum; wherein the directional overload spectrum refers to the directional overload values ​​and corresponding overload times under the measured take-off and landing times, and the standard block spectrum refers to the directional overload values ​​and corresponding overload times obtained by conversion under the set take-off and landing times; Step 4: Perform trend fitting on the converted isotropic standard block spectrum to make it conform to the Weibull distribution, then round the overload values ​​in the isotropic overload spectrum after trend fitting, and obtain the overload times corresponding to the rounded overload values ​​by interpolation to obtain the rounded isotropic overload spectrum; Step 5: perform high-load interception on the rounded overload spectrum, and perform equal damage conversion on the overload spectrum after high load interception to obtain the equal damage overload value of each direction for the specified number of take-offs and landings. ; Step 6: Set the isotropic damage overload value Multiply it by the landing gear parking load Pg to obtain the test load value in each direction ; Step 7: Test load values ​​in all directions The loading sequence is combined to obtain the load spectrum of the landing gear landing impact test.

2. The method for compiling a landing gear landing impact test load spectrum according to claim 1, characterized in that: The measured overload data of the landing gear includes data of the takeoff taxiing mission segment, the air flight mission segment, the landing impact mission segment, and the landing taxiing mission segment; the measured overload data of multiple landing impact mission segments selected in step 1 include: The landing impact mission segment starts when the aircraft landing gear compression begins to increase, and ends when the aircraft landing gear directional load becomes significantly larger again. The measured overload data of the landing impact mission segment corresponding to multiple measured takeoffs and landings are determined.

3. The method for compiling a landing gear landing impact test load spectrum according to claim 1, characterized in that: The step 2 includes: Step 21: Statistically process the measured vertical overload data and lateral overload data of the multiple landing and impact mission segments using the rainflow method to obtain vertical overload spectra and lateral overload spectra. Step 22: For directional overload, the maximum positive overload that occurs once during each takeoff and landing is counted to obtain the takeoff and rotation overload spectrum. The minimum negative overload that occurs once during each takeoff and landing is counted to obtain the rebound overload spectrum. The other directional overload data during the landing and impact mission segment are statistically processed using the rain flow method to obtain the oscillation overload spectrum.

4. The method for compiling a landing gear landing impact test load spectrum according to claim 1, characterized in that: The step 3 comprises: Based on the directional overload spectrum obtained from the measured overload data, the overload times under the measured take-off and landing times in the directional overload spectrum are calculated. Converted into the standard overload number corresponding to the set take-off and landing times in the standard block spectrum , the overload value remains unchanged during the transformation process, and the isotropic standard block spectrum is obtained.

5. The method for compiling a landing gear landing impact test load spectrum according to claim 4, characterized in that: The standard block spectrum is set to include the overload values ​​in each direction under 1000 take-off and landing times and the corresponding standard overload times; in step 3, the method of converting the standard overload times is: ； Where M is the measured number of take-offs and landings, is the number of overloads corresponding to different overload values ​​in the measured isotropic overload spectrum, is the standard overload number corresponding to different overload values ​​in the converted standard block spectrum.

6. The method for compiling a landing gear landing impact test load spectrum according to claim 1, characterized in that: The step 4 comprises: The converted isotropic standard block spectrum is trend fitted to obtain an isotropic overload spectrum that conforms to the Weibull distribution. The overload values ​​in the isotropic overload spectrum that conforms to the Weibull distribution are rounded according to the order difference of 0.1, and the overload times are linearly interpolated to obtain the overload times corresponding to the rounded overload values, that is, the rounded isotropic overload spectrum is obtained.

7. The method for compiling a landing gear landing impact test load spectrum according to claim 1, characterized in that: The step 5 comprises: Step 51, using the overload value at which the rise and fall times occur once in the standard block spectrum of each direction as the cutoff value, and truncating the overload data above the cutoff value to obtain the overload spectrum of each direction after high load truncation; Step 52: perform equal damage conversion on the overload spectrum after high load interception, and convert the overload spectrum corresponding to the overload times of the multi-level overload values ​​in each direction into the overload value of level 1 in each direction corresponding to the specified overload times. .

8. The method for compiling a landing gear landing impact test load spectrum according to claim 7, characterized in that: The test load values ​​in each direction obtained in step 6 are include: in, F 垂 is the vertical test load value, g 垂 is the vertical equal damage overload value; F 起 is the test load value for starting rotation, g 起 This is the overload value for damage such as starting and rotating; F 回 is the test load value of rebound, g 回 This is the overload value for damage such as rebound; F 侧 is the lateral test load value, g 侧 is the lateral damage overload value; F 震 is the test load value of the oscillation, g 震 This is the overload value for damage such as shock.

9. The method for compiling a landing gear landing impact test load spectrum according to any one of claims 1 to 8, characterized in that: In step 7, the loading order of the test load values ​​in each direction is combined as follows: The vertical load, heading load, and lateral load are loaded to their maximum values ​​simultaneously. The maximum heading load is the rotation load. The loading direction of the lateral load alternates left and right with each takeoff and landing, and only occurs once in each takeoff and landing. The vertical load remains at its maximum value, and the heading load and lateral load return to 0 simultaneously. The lateral load remains at 0, and the heading load is loaded from 0 to the rebound load and then back to 0. Then, the heading load is loaded from 0 to the maximum oscillation load and back to the minimum oscillation load. The oscillation load is loaded for two complete takeoffs and landings in each takeoff and landing, and finally the heading load and vertical load return to 0 simultaneously.

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