Aircraft wing spar fatigue test load spectrum design method

Abstract

The application belongs to the technical field of aircraft wing beam fatigue test load spectrum design, and particularly relates to a kind of aircraft wing beam fatigue test load spectrum design method, comprising: drawing stress spectrum of aircraft wing beam upper edge strip and lower edge strip under various working conditions;The stress spectrum of the aircraft wing beam upper edge strip and the lower edge strip under various working conditions is converted into the load spectrum at the test loading point;The load spectrum at the test loading point is analyzed under various working conditions, and the maximum value of the absolute value is taken;The load spectrum at the test loading point is converted into a multi-stage constant amplitude spectrum.

Description

Technical Field

[0001] This application belongs to the field of aircraft wing spars fatigue test load spectrum design technology, specifically relating to a method for designing aircraft wing spars fatigue test load spectra. Background Technology

[0002] Current fatigue tests on aircraft wing spars mostly use a first-order constant amplitude spectrum, which cannot effectively reflect the characteristics of the load spectrum. Furthermore, in the air, the wing spars are subjected to upward compression and downward tension, with the critical part located on the lower edge. In the ground, they are subjected to upward tension and downward compression, with the critical part located on the upper edge. The critical part of the wing spars changes with the change of operating conditions. Existing test load spectrum designs only consider the lower edge of the wing as the critical part, which cannot truly reproduce the actual situation and makes it difficult to obtain reliable test results.

[0003] This application is made in view of the aforementioned technical deficiencies.

[0004] It should be noted that the above background information is only used to assist in understanding the inventive concept and technical solution of this invention, and it does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] The purpose of this application is to provide a method for designing the load spectrum of aircraft wing spars for fatigue testing, so as to overcome or mitigate at least one of the known technical defects.

[0006] The technical solution of this application is:

[0007] A method for designing the load spectrum for aircraft wing spars fatigue tests includes:

[0008] Plot the stress spectra of the upper and lower edge strips of an aircraft wing spars under various working conditions;

[0009] The stress spectra of the upper and lower edge strips of the aircraft wing spars under various working conditions are converted into load spectra at the test loading points;

[0010] The load spectrum at the test loading point was subjected to containment analysis under various working conditions, and the value with the largest absolute value was taken.

[0011] The load spectrum at the test loading point is converted into a multi-level constant amplitude spectrum.

[0012] According to at least one embodiment of this application, in the above-described method for designing the load spectrum of aircraft wing spars for fatigue testing, the step of converting the stress spectra of the upper and lower edge strips of the aircraft wing spars under various working conditions into the load spectrum at the test loading point specifically involves:

[0013] ;

[0014] ;

[0015] ;

[0016] ;

[0017] in,

[0018] The load spectrum at the test loading point;

[0019] To test the stress at the test site;

[0020] The moment of inertia of the cross section at the test site;

[0021] The lever arm is the distance from the test evaluation point to the test loading point;

[0022] The centroid of the cross-section of the test site;

[0023] The length of the i-th region of the cross-section of the test site;

[0024] The width of the i-th region of the cross-section of the test site;

[0025] Let i be the area of ​​the i-th region of the cross-section of the test site;

[0026] The centroid of the i-th region of the cross-section of the test site;

[0027] n represents the number of regions divided into sections at the test site.

[0028] According to at least one embodiment of this application, in the above-described method for designing the load spectrum of an aircraft wing spars fatigue test, the load spectrum at the test loading point is converted into a multi-level equal amplitude spectrum, and the Odin transform is used to perform equal damage conversion on the load spectrum of the test assessment part.

[0029] According to at least one embodiment of this application, in the above-described method for designing the load spectrum for aircraft wing spars fatigue tests, the step of converting the load spectrum at the test loading point into a multi-level constant amplitude spectrum specifically includes:

[0030] Rainflow was applied to the load on the test site, and Odin transformation was performed on each load level of the rainflow results to calculate the damage.

[0031] Calculate the relative damage of each level of equal amplitude spectrum in one cycle;

[0032] Calculate the number of cycles for each level of equal amplitude spectrum.

[0033] According to at least one embodiment of this application, in the above-described aircraft wing sparsity fatigue test load spectrum design method, the calculation of the relative damage of one cycle of each level of equal amplitude spectrum specifically includes:

[0034] ;

[0035] in,

[0036] The relative damage for each level of equal amplitude spectrum in one cycle;

[0037] The maximum load corresponding to each level of equal amplitude spectrum;

[0038] This represents the minimum load corresponding to each level of equal amplitude spectrum.

[0039] According to at least one embodiment of this application, in the above-described aircraft wing sparsity fatigue test load spectrum design method, the calculation of the number of cycles for each level of constant amplitude spectrum specifically involves:

[0040] ;

[0041] in,

[0042] This represents the number of cycles for each level of equal amplitude spectrum;

[0043] The damage of a single flight of the i-th random spectrum corresponding to each level of equal amplitude spectrum;

[0044] Let be the number of flights of the i-th random spectrum corresponding to each level of equal amplitude spectrum.

[0045] According to at least one embodiment of this application, in the above-described method for designing the load spectrum of an aircraft wing spars fatigue test, the load spectrum at the test loading point is converted into a multi-level equal amplitude spectrum, specifically into a four-level equal amplitude spectrum.

[0046] This application has at least the following beneficial technical effects:

[0047] This paper presents a method for designing the load spectrum of aircraft wing spars for fatigue testing. It comprehensively considers the stress spectra of the upper and lower edge strips of the aircraft wing spars under various working conditions, converts them into load spectra at the test loading points, and performs inclusive analysis on the load spectra at the test loading points under various working conditions. The value with the largest absolute value is taken, and the load spectrum at the test loading points is converted into a multi-level equal amplitude spectrum, which can realistically reproduce the actual situation and obtain reliable fatigue test results. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the aircraft wing spars fatigue test load spectrum design method provided in the embodiments of this application;

[0049] Figure 2 This is a schematic diagram of the stress spectrum of the upper edge strip of an aircraft wing spars under various working conditions, provided in an embodiment of this application.

[0050] Figure 3 This is a schematic diagram of the stress spectrum of the lower edge strip of an aircraft wing spars under various working conditions, provided in an embodiment of this application.

[0051] Figure 4 This is a schematic diagram of the load spectrum at the test loading point provided in the embodiments of this application, and the envelopment analysis is performed under various working conditions;

[0052] Figure 5 This is a schematic diagram of the load spectrum obtained by applying the aircraft wing spars fatigue test load spectrum design method provided in the embodiments of this application. Detailed Implementation

[0053] To make the technical solution and advantages of this application clearer, the technical solution of this application will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some 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 related to this application are shown in the accompanying drawings. Other related parts can be referred to the general design. In the absence of conflict, the embodiments and technical features in the embodiments of this application can be combined with each other to obtain new embodiments.

[0054] Furthermore, unless otherwise defined, the technical or scientific terms used in this application description shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "upper," "lower," "left," "right," "center," "vertical," "horizontal," "inner," and "outer," etc., used in this application description to indicate relative direction or positional relationship are used only to indicate relative orientation or positional relationship, and do not imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly, and therefore should not be construed as a limitation on this application. The terms "first," "second," "third," and similar terms used in this application description are used only for descriptive purposes to distinguish different components, and should not be construed as indicating or implying relative importance. The terms "a," "one," or "the," etc., used in this application description should not be construed as an absolute limitation on quantity, but should be construed as indicating the existence of at least one. The terms "including," "comprising," etc., used in this application description mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects.

[0055] Furthermore, it should be noted that, unless otherwise explicitly specified and limited, terms such as “installation,” “connection,” and “linkage” used in the description of this application should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can be a connection within two components. Those skilled in the art can understand its specific meaning in this application according to the specific circumstances.

[0056] The following is in conjunction with the appendix Figures 1 to 5 The method for designing the fatigue test load spectrum of aircraft wing spars provided in this application is further described in detail.

[0057] Plot the stress spectra of the upper and lower wing spars of an aircraft under various operating conditions, such as... Figure 2 , 3 As shown.

[0058] The stress spectra of the upper and lower wing spars under various working conditions were converted into load spectra at the test loading points:

[0059] Since the aircraft wing spars fatigue test uses a cantilever beam design, the moment of inertia of the tested section is first calculated. In a specific embodiment, the calculation is as follows:

[0060] ;

[0061] ;

[0062] ;

[0063] ;

[0064] ;

[0065] ;

[0066] ;

[0067] This is then converted into the load spectrum at the test loading point. ,in, To test the stress at the test site, The moment of inertia of the cross section at the test site, The lever arm is the distance from the test site to the test loading point. The centroid of the cross section of the test site.

[0068] For the load spectrum at the test loading point, containment analysis was performed under various working conditions, and the value with the largest absolute value was taken, such as... Figure 4 As shown.

[0069] The load spectrum of the test site is converted to equal damage using the Odin transform, and the process is as follows:

[0070] ;

[0071] ;

[0072] in,

[0073] Damage caused by a single flight of the random spectrum;

[0074] This represents the damage caused by one cycle of the constant amplitude spectrum.

[0075] Rainflow was applied to the load spectrum of the test area, and Odin transformation was performed on each load level of the rainflow results to calculate the damage. The Odin transformation formula is shown below:

[0076] .

[0077] Calculate the relative damage of a single flight of the random spectrum:

[0078] ;

[0079] In one specific embodiment, the damage during the calculation process for each typical flight and the total damage over one lifetime are shown in the table below:

[0080]

[0081] The constant amplitude spectrum is composed of four-level spectrum combinations:

[0082] Using a maximum load of 93055N and a minimum load of -74516N for conversion, with R=-0.8, the relative damage for one cycle of the first-level constant amplitude spectrum is calculated as follows:

[0083]

[0084] The number of cycles for the first-order constant amplitude spectrum after conversion should be:

[0085] ;

[0086] Using a maximum load of 105775N and a minimum load of -74516N for conversion, with R=-0.7, the relative damage for one cycle of the second-order constant amplitude spectrum is calculated as follows:

[0087]

[0088] The number of cycles for the second-order constant amplitude spectrum after conversion should be:

[0089] ;

[0090] Using a maximum load of 128188N and a minimum load of -74516N for conversion, with R=-0.58, the relative damage for one cycle of the third-order constant amplitude spectrum is calculated as follows:

[0091]

[0092] The number of cycles for the converted third-order constant amplitude spectrum should be:

[0093] ;

[0094] Using a maximum load of 138171 N and a minimum load of -74516 N for conversion, with R = -0.54, the relative damage for one cycle of the fourth-order constant amplitude spectrum is calculated as follows:

[0095]

[0096] The number of cycles for the fourth-order constant amplitude spectrum after conversion should be:

[0097] ;

[0098] The converted load spectrum is as follows Figure 5 As shown, different numbers of cycles result in different levels of damage.

[0099] The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0100] The technical solution of this 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 this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A method for designing load spectra for aircraft wing spars fatigue tests, characterized in that, include: Plot the stress spectra of the upper and lower edge strips of an aircraft wing spars under various working conditions; The stress spectra of the upper and lower edge strips of the aircraft wing spars under various working conditions are converted into load spectra at the test loading points; The load spectrum at the test loading point was subjected to containment analysis under various working conditions, and the value with the largest absolute value was taken. The load spectrum at the test loading point is converted into a multi-level equal amplitude spectrum after taking the value with the largest absolute value. The process of converting the stress spectra of the upper and lower wing spars under various working conditions into load spectra at the test loading points is specifically as follows: ； ； ； ； in, The load spectrum at the test loading point; To test the stress at the test site; The moment of inertia of the cross section at the test site; The lever arm is the distance from the test evaluation point to the test loading point; The centroid of the cross-section of the test site; The length of the i-th region of the cross-section of the test site; The width of the i-th region of the cross-section of the test site; Let i be the area of ​​the i-th region of the cross-section of the test site; The centroid of the i-th region of the cross-section of the test site; n represents the number of regions divided into sections at the test site.

2. The method for designing the load spectrum for aircraft wing spars fatigue tests according to claim 1, characterized in that, The load spectrum at the test loading point is converted into a multi-level equal amplitude spectrum, and the Odin transform is used to perform equal damage conversion on the load spectrum of the test assessment part.

3. The method for designing the load spectrum for aircraft wing spars fatigue tests according to claim 2, characterized in that, The load spectrum at the test loading point is converted into a multi-level constant amplitude spectrum, specifically: Rainflow was applied to the load on the test site, and Odin transformation was performed on each load level of the rainflow results to calculate the damage. Calculate the relative damage of each level of equal amplitude spectrum in one cycle; Calculate the number of cycles for each level of equal amplitude spectrum.

4. The method for designing the load spectrum for aircraft wing spars fatigue tests according to claim 3, characterized in that, The calculation of the relative damage of each level of equal amplitude spectrum for one cycle is specifically as follows: ； in, The relative damage for each level of equal amplitude spectrum in one cycle; The maximum load corresponding to each level of equal amplitude spectrum; This represents the minimum load corresponding to each level of equal amplitude spectrum.

5. The method for designing the load spectrum for aircraft wing spars fatigue tests according to claim 4, characterized in that, The calculation of the number of iterations for each level of equal amplitude spectrum is specifically as follows: ； in, This represents the number of cycles for each level of the equal-amplitude spectrum; The damage of a single flight of the i-th random spectrum corresponding to each level of equal amplitude spectrum; Let be the number of flights of the i-th random spectrum corresponding to each level of equal amplitude spectrum.

6. The method for designing the load spectrum for aircraft wing spars fatigue tests according to claim 1, characterized in that, The load spectrum at the test loading point is specifically converted into a fourth-order constant amplitude spectrum.

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