A method for simplifying a flight test load spectrum

Abstract

The application belongs to the technical field of aircraft repeated pressure test, and particularly relates to a repeated pressure test load spectrum simplification method, which comprises the following steps: step one, determining a repeated pressure load spectrum and a maximum pressure load; step two, performing rain flow counting on the pressure load spectrum of different mission profiles in the repeated pressure load spectrum, and determining load levels according to the rain flow results; step three, calculating the relative damage of each mission profile based on the load levels; step four, calculating the relative damage of all mission profiles; step five, simplifying the number of load levels of the repeated pressure load spectrum to obtain the number of load levels of a simplified load spectrum; and step six, determining the load values and their proportions of different load levels of the simplified load spectrum according to the principle of equal relative damage.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft repeated pressurization tests, and in particular relates to a method for simplifying a load spectrum of an aircraft repeated pressurization test. Background Art

[0002] Fuselage pressurization is one of the important sources of load, especially for civil aircraft and transport aircraft, the pressurization load is the main load of the fuselage.

[0003] The aircraft repeated pressurization test is a test to verify the aircraft's ability to withstand pressurization loads. The fuselage pressurization load is related to the aircraft's design mission profile type, flight altitude, mission segment, etc. The complete aircraft repeated pressurization test load spectrum is very complex, which is not conducive to the test. Therefore, it is of great significance to simplify the aircraft repeated pressurization test load spectrum. In view of this, this application is proposed. Summary of the Invention

[0004] The purpose of this application is to provide a method for simplifying the load spectrum of an aircraft repeated pressurization test to overcome or alleviate at least one of the existing technical deficiencies.

[0005] The technical solution of this application is:

[0006] A method for simplifying a load spectrum for an aircraft repeated pressurization test, comprising:

[0007] Step 1: Determine the repeated pressurization load spectrum and the maximum pressurization load;

[0008] Step 2: Count the rain flow of the pressurization load spectrum of different mission profiles in the repeated pressurization load spectrum, and determine the load level according to the rain flow results;

[0009] Step 3: Based on the load level, calculate the relative damage of each mission profile;

[0010] Step 4: Calculate the relative damage of all mission sections;

[0011] Step 5, simplifying the load series of the repeated pressurization load spectrum to obtain the load series of the simplified load spectrum;

[0012] Step 6: According to the principle of equal relative damage, determine the load values ​​and their proportions of different load levels in the simplified load spectrum.

[0013] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the aircraft repressurization test load spectrum, in step 1, it is determined that the repressurization load spectrum is composed of pressurization load spectra under different mission profiles.

[0014] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the load spectrum of the aircraft repeated pressurization test, in step one, the maximum pressurization load is the maximum pressurization load under all mission profiles.

[0015] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the aircraft repeated pressurization test load spectrum, in step two, rainflow counting is performed on the pressurization load spectrum of different mission profiles in the repeated pressurization load spectrum, and the pressurization load spectrum is compiled to include different numbers of load levels.

[0016] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the load spectrum of the aircraft repeated pressurization test, in step 2, the load level determined according to the rain flow result can be expressed as (P i,j , ρ i,j ),in,

[0017] P i,j is the peak load of the jth load pair under the i-th mission profile;

[0018] ρ i,j is the valley load of the jth load pair under the i-th mission profile.

[0019] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the load spectrum of the aircraft repeated pressurization test, step three is specifically as follows:

[0020]

[0021] in,

[0022] ζ i is the relative damage of the i-th mission profile;

[0023] n is the total number of payloads in the mission profile;

[0024] Q i,j is the relative damage of the jth load in the i-th mission profile, and is the load level (P i,j , ρ i,j ) function;

[0025] α is the characteristic parameter for relative damage calculation.

[0026] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the load spectrum of the aircraft repeated pressurization test, in step three, the relative damage calculation characteristic parameter α is selected to be 4.

[0027] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the load spectrum of the aircraft repeated pressurization test, in step 3, Q i,j =[P i,j ×(P i,j -ρ i,j )] 1 / 2 .

[0028] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the load spectrum of the aircraft repeated pressurization test, step four is specifically as follows:

[0029]

[0030] in,

[0031] ζ is the relative damage of all mission profiles;

[0032] N is the total number of mission profiles;

[0033] ψ i is the profile ratio of the i-th mission profile.

[0034] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the aircraft repressurization test load spectrum, in step five, the load levels of the repressurization load spectrum are simplified, and the load levels of the simplified load spectrum are obtained to be levels 1-3.

[0035] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the load spectrum of the aircraft repeated pressurization test, in step six, it is determined that the simplified load spectrum includes the maximum pressurization load.

[0036] According to at least one embodiment of the present application, in the above-mentioned method for simplifying the load spectrum of the aircraft repeated pressurization test, in step six, the minimum load in the simplified load spectrum is determined to be 5-10 KPa.

[0037] This application has at least the following beneficial technical effects:

[0038] A method for simplifying the load spectrum of an aircraft repressurization test is provided. By simplifying the load levels of the repressurization load spectrum, the load levels of the simplified load spectrum are obtained. Then, based on the principle of relative damage equality, the load values ​​and their proportions of different load levels of the simplified load spectrum are determined, thereby simplifying the repressurization load spectrum and facilitating the repressurization test. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of a method for simplifying a load spectrum for an aircraft repeated pressurization test provided in an embodiment of the present application;

[0040] Figure 2 Schematic diagram of the pressurization load spectrum of typical tasks 1 and 2 of the repeated pressurization load spectrum provided in the embodiment of the present application;

[0041] Figure 3 It is a schematic diagram of the pressurization load spectrum of the repeated pressurization load spectrum training task 2 provided in an embodiment of the present application.

[0042] In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be understood as limiting this application. DETAILED DESCRIPTION

[0043] To make the technical solution and its advantages of this application more clear, the technical solution of this application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only some of the embodiments of this application and are only used to explain this application, not to limit this application. It should be noted that for ease of description, only the parts relevant to this application are shown in the accompanying drawings, and other relevant parts can refer to the general design.

[0044] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application should have the usual meanings understood by those skilled in the art in the field to which this application belongs. The words indicating orientation used in the description of this application are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application means that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0045] A simplified method for aircraft repeated pressurization test load spectrum, such as Figure 1 shown.

[0046] Step 1: Determine the repeated charging load spectrum and the maximum charging load.

[0047] The repeated pressurization load spectrum is a description of the pressurization loads in different mission profiles during aircraft design and use, and is composed of pressurization load spectra under different mission profiles.

[0048] The maximum pressure load of the repeated pressure load spectrum is the maximum pressure load under all mission profiles, and is expressed as P max express.

[0049] Step 2: Count the rain flow of the pressurization load spectrum of different mission profiles in the repeated pressurization load spectrum, and determine the load level based on the rain flow results.

[0050] Rainflow counting is a load spectrum processing method that can remove load levels in the load spectrum that do not cause damage. Rainflow counting is performed on the pressurization load spectra of different mission profiles in the repeated pressurization load spectrum, and the pressurization load spectrum can be compiled into a system containing different numbers of load levels.

[0051] The load level determined based on the rain flow results can be expressed as (P i,j , ρ i,j ),in,

[0052] P i,j is the peak load of the jth load pair under the i-th mission profile;

[0053] ρ i,jis the valley load of the jth load pair under the i-th mission profile.

[0054] Step 3: Based on the load level, calculate the relative damage of each mission profile.

[0055]

[0056] in,

[0057] ζ i is the relative damage of the i-th mission profile;

[0058] n is the total number of payloads in the mission profile;

[0059] Q i,j is the relative damage of the jth load in the i-th mission profile, and is the load level (P i,j , ρ i,j ) function;

[0060] α is the characteristic parameter for relative damage calculation, which is related to the SN curve. For aircraft fuselage structures, 4 can generally be selected.

[0061] Q i,j =[P i,j ×(P i,j -ρ i,j )] 1 / 2 .

[0062] Step 4: Calculate the relative damage of all mission sections.

[0063]

[0064] in,

[0065] ζ is the relative damage of all mission profiles;

[0066] N is the total number of mission profiles;

[0067] ψ i is the profile ratio of the i-th mission profile.

[0068] Step 5: Simplify the load series of the repeated pressurization load spectrum to obtain the load series of the simplified load spectrum.

[0069] The load levels of the simplified load spectrum can generally be selected from 1 to 3, which is determined based on the repeated pressurization test results.

[0070] Step 6: According to the principle of equal relative damage, determine the load values ​​and their proportions of different load levels in the simplified load spectrum.

[0071] The relative damage calculation of the simplified load spectrum can be performed by the relative damage of each mission profile and the relative damage of all mission profiles mentioned above, which will not be repeated here.

[0072] The simplified load spectrum generally needs to include the maximum pressure load P max , the minimum load is generally selected as 5-10KPa.

[0073] In a specific implementation, it is proposed to simplify the load spectrum of the aircraft repeated pressurization test. The simplified load spectrum includes two levels, each accounting for 50%. The simplified method of the aircraft repeated pressurization test load spectrum disclosed in the above embodiment is implemented as follows:

[0074] S1. Obtain the repeated inflation load spectrum and the maximum inflation load.

[0075] The aircraft mission profile and its maximum pressurization load are as follows

[0076] Serial number Mission Profile Maximum filling load / KPa Section Scale 1 Typical Task 1 50 25％ 2 Typical Task 2 55 10％ 3 Typical Task 3 30 25％ 4 Training Mission 1 0 20％ 5 Training Mission 2 50 20％

[0077] Maximum pressure load P max =55KPa.

[0078] Among them, the pressure load spectrum of typical mission 1 and 2 sections is as follows: Figure 2 As shown, the pressure load spectrum of the training task 2 section is as follows: Figure 3 shown.

[0079] S2. Count the rain flow of the pressurization load spectrum of different mission profiles in the repeated pressurization load spectrum, and determine the load level based on the rain flow results, as shown in the following table:

[0080]

[0081]

[0082] S3. Based on the load level, calculate the relative damage of each mission profile, as shown in the following table:

[0083] Mission Profile Typical Task 1 Typical Task 2 Typical Task 3 Training Mission 1 Training Mission 2 Relative damage 6250000 12213125 810000 1 6250000

[0084] S4. Calculate the relative damage of all mission profiles ζ = 4236312.5.

[0085] S5. Simplify the load order of the repeated pressurization load spectrum, and obtain a simplified load order of 2.

[0086] S6. Based on the principle of equal relative damage, determine the load values ​​and their proportions for different load levels of the simplified load spectrum, as shown in the following table:

[0087] Load level Maximum load / KPa Minimum load / KPa Proportion 1 55 5 50％ 2 38.7 5 50％

[0088] The method for simplifying the aircraft repressurization test load spectrum disclosed in the above embodiment simplifies the load levels of the repressurization load spectrum to obtain the load levels of the simplified load spectrum, and then determines the load values ​​and their proportions of different load levels of the simplified load spectrum based on the principle of relative damage equality, thereby achieving the simplification of the repressurization load spectrum and facilitating the repressurization test.

[0089] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or replacements to the relevant technical features, and the technical solutions after these changes or replacements will fall within the scope of protection of the present application.

Claims

1. A method for simplifying the load spectrum of an aircraft repeated pressurization test, characterized in that: include: Step 1: Determine the repeated pressurization load spectrum and the maximum pressurization load; Step 2: Count the rain flow of the pressurization load spectrum of different mission profiles in the repeated pressurization load spectrum, and determine the load level according to the rain flow results; Step 3: Based on the load level, calculate the relative damage of each mission profile; Step 4: Calculate the relative damage of all mission sections; Step 5, simplifying the load series of the repeated pressurization load spectrum to obtain the load series of the simplified load spectrum; Step 6: According to the principle of equal relative damage, determine the load values ​​and their proportions of different load levels in the simplified load spectrum.

2. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 1, characterized in that: In step 1, it is determined that the repeated pressurization load spectrum is composed of pressurization load spectra under different mission profiles.

3. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 2, characterized in that: In step 1, the maximum pressure load is the maximum pressure load under all mission profiles.

4. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 3, characterized in that: In step 2, rain flow counting is performed on the pressurization load spectra of different mission profiles in the repeated pressurization load spectra, and the pressurization load spectra are compiled into a system containing different numbers of load levels.

5. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 4, characterized in that: In step 2, the load level determined based on the rain flow results can be expressed as (P i,j , ρ i,j ),in, P i,j is the peak load of the jth load pair under the i-th mission profile; ρ i,j is the valley load of the jth load pair under the i-th mission profile.

6. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 5, characterized in that: Step three is as follows: in, ζ i is the relative damage of the i-th mission profile; n is the total number of payloads in the mission profile; Q i,j is the relative damage of the jth load in the i-th mission profile, and is the load level (P i,j , ρ i,j ) function; α is the characteristic parameter for relative damage calculation.

7. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 6, characterized in that: In step 3, the relative damage calculation characteristic parameter α is selected as 4.

8. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 7, characterized in that: In step 3, Q i,j =[P i,j ×(P i,j -ρ i,j )] 1 / 2 .

9. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 8, characterized in that: Step 4 is as follows: in, ζ is the relative damage of all mission profiles; N is the total number of mission profiles; ψ i is the profile ratio of the i-th mission profile.

10. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 9, characterized in that: In step 5, the load levels of the repeated pressurization load spectrum are simplified, and the load levels of the simplified load spectrum are obtained to be 1-3.

11. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 10, characterized in that: In step six, the simplified load spectrum is determined to include the maximum inflation load.

12. The method for simplifying the load spectrum of an aircraft repeated pressurization test according to claim 11, characterized in that: In step 6, determine the minimum load in the simplified load spectrum and select 5-10KPa.

Images