阅读说明：本技术 一种结构疲劳试验大变形加载点设计方法 (Design method for large-deformation loading point of structural fatigue test ) 是由 严冲 杜星 夏龙 何月洲 王亚星 任鹏 于 2021-08-23 设计创作，主要内容包括：本申请属于结构强度试验领域,特别涉及一种结构疲劳试验大变形加载点设计方法。本申请的结构疲劳试验大变形加载点设计方法,通过挠曲线确定第一点位,再根据加载设备长度以及第一点位确定满足试验要求的第二点位,能够快速的确定第一点位以及第二点位,通过设置在加载平台上的加载设备连接两个点位,实现对飞机机翼的加载,从而完成结构疲劳试验。本申请的结构疲劳试验大变形加载点设计方法,可对飞机疲劳试验大变形引起的加载点载荷误差进行精准分析,加载点设计可兼顾载荷精度及试验效率。(The application belongs to the field of structural strength tests, and particularly relates to a structural fatigue test large-deformation loading point design method. According to the design method for the large-deformation loading point for the structural fatigue test, the first point position is determined through the bending line, the second point position meeting the test requirement is determined according to the length of the loading equipment and the first point position, the first point position and the second point position can be rapidly determined, the loading equipment arranged on the loading platform is connected with the two point positions, the loading of the aircraft wing is achieved, and therefore the structural fatigue test is completed. The method for designing the large deformation loading point for the structural fatigue test can accurately analyze the loading point load error caused by the large deformation of the aircraft fatigue test, and the loading point design can give consideration to both the load precision and the test efficiency.)

1. A structural fatigue test large deformation loading point design method is characterized by comprising the following steps:

step one, obtaining a deflection line under the maximum deformation working condition of an airplane wing;

secondly, obtaining coordinates of a loading point on the airplane wing closest to the wing tip, positioning the loading point on the deflection line to obtain a first point position, and obtaining a normal of the deflection line at the first point position;

step three, acquiring the length of loading equipment, and determining a second point location according to the length of the loading equipment and the first point location;

step four, connecting the first point location and the second point location to obtain a point location connecting line, obtaining a first angle between the point location connecting line and a normal of the flexible line at the first point location, and calculating a first load error according to the first angle;

step five, calculating a first bending moment error of the first load error on the wing control section, judging whether the first bending moment error meets the test requirement or not,

if so, taking the second point position as a large deformation loading point of the structural fatigue test;

if not, entering the step six;

step six,

S601, selecting a second angle between 0 degree and the first angle, and re-determining a second point location according to the second angle;

s602, calculating a second load error according to the second angle; and

s603, calculating a second bending moment error of the second load error on the wing control section, judging whether the second bending moment error meets the test requirement,

if so, taking the second point position as a large deformation loading point of the structural fatigue test;

and if not, returning to the step S601, and reselecting the second angle until determining the large deformation loading point of the structural fatigue test.

2. The method for designing a large deformation loading point for a structural fatigue test according to claim 1, wherein in the first step, the obtaining of the deflection line under the maximum deformation condition of the aircraft wing comprises:

s101, obtaining load data and deformation data of a static test, and fitting a first flexible line under the maximum deformation working condition of the airplane wing, wherein variables in a first flexible line equation comprise: total wing load or wing load distribution;

s102, fatigue test load data and deformation data are obtained, and fatigue test loads under the maximum deformation working condition of the airplane wing are substituted into a curve equation of the first flexible line to obtain a second flexible line.

3. The structural fatigue test large deformation loading point design method according to claim 2, wherein in step three, the obtaining the length of the loading device and determining the second point position according to the length of the loading device and the first point position includes:

s301, selecting loading equipment according to the maximum load and the maximum deformation of a loading point on the wing of the airplane, which is closest to the wingtip part, and acquiring the length of the loading equipment;

s302, selecting a second point location on a loading platform, wherein the distance from the second point location to the first point location is the length of a loading device.

4. The method of claim 3, wherein the calculating a first load error based on the first angle comprises:

F₁＝1-cosα₁

wherein, F₁Is a first loadError, α₁Is at a first angle.

5. The method for designing a structural fatigue test large deformation loading point according to claim 4, wherein in the fifth step, the calculating the first bending moment error of the first load error at the wing control section comprises:

wherein M is₁Error of first bending moment, α₁Is a first angle, L is the distance from the second point location to the airfoil control profile, L₀The theoretical distance of the load from the airfoil control profile.

6. The method for designing a large deformation loading point for a structural fatigue test according to claim 5, wherein in step S602, the calculating a second load error according to the second angle includes:

F₂＝1-cosα₂

wherein, F₂Is the second load error, α₂Is at a second angle.

7. The structural fatigue test large deformation loading point design method of claim 6, wherein in S603, the calculating the second bending moment error of the second load error at the airfoil control profile comprises:

wherein M is₂Error in the second bending moment, α₂Is a second angle, L is the distance from the second point location to the airfoil control profile, L₀The theoretical distance of the load from the airfoil control profile.

8. The method for designing a large deformation loading point for a structural fatigue test according to claim 7, wherein in S601, a plurality of second angles between 0 ° and the first angle are selected, and the corresponding second point position is determined again according to each second angle.

9. The method for designing a large deformation loading point for a structural fatigue test according to claim 8, wherein in step S603, the smallest second bending moment error is selected from a plurality of second bending moment errors satisfying the test requirements, and the second point location corresponding to the smallest second bending moment error is used as the large deformation loading point for the structural fatigue test.

10. The method for designing a large deformation load point for a structural fatigue test according to claim 9, wherein if the large deformation load point for the structural fatigue test cannot be determined in the sixth step, the load point design is performed according to follow-up loading.

Technical Field

The application belongs to the field of structural strength tests, and particularly relates to a structural fatigue test large-deformation loading point design method.

Background

In the fatigue test of the airplane structure, under partial test load, the wing tip of the wing can generate large deformation, at the moment, the angle between the force line of the loading point and the plane of the wing chord changes, if the angle cannot be kept vertical, the test load has errors, and when the angle deviation is large, the load error is correspondingly large. In the design of a fatigue test, if the load error cannot be effectively evaluated, and a proper loading method is adopted, the problems of large error of a test result, low efficiency, low safety and the like can be caused.

Accordingly, a technical solution is desired to overcome or at least alleviate at least one of the above-mentioned drawbacks of the prior art.

Disclosure of Invention

The application aims to provide a structural fatigue test large-deformation loading point design method to solve at least one problem in the prior art.

The technical scheme of the application is as follows:

a design method for a large deformation loading point of a structural fatigue test comprises the following steps:

step one, obtaining a deflection line under the maximum deformation working condition of an airplane wing;

secondly, obtaining coordinates of a loading point on the airplane wing closest to the wing tip, positioning the loading point on the deflection line to obtain a first point position, and obtaining a normal of the deflection line at the first point position;

step three, acquiring the length of loading equipment, and determining a second point location according to the length of the loading equipment and the first point location;

step four, connecting the first point location and the second point location to obtain a point location connecting line, obtaining a first angle between the point location connecting line and a normal of the flexible line at the first point location, and calculating a first load error according to the first angle;

step five, calculating a first bending moment error of the first load error on the wing control section, judging whether the first bending moment error meets the test requirement or not,

if so, taking the second point position as a large deformation loading point of the structural fatigue test;

if not, entering the step six;

step six,

S601, selecting a second angle between 0 degree and the first angle, and re-determining a second point location according to the second angle;

s602, calculating a second load error according to the second angle; and

s603, calculating a second bending moment error of the second load error on the wing control section, judging whether the second bending moment error meets the test requirement,

if so, taking the second point position as a large deformation loading point of the structural fatigue test;

and if not, returning to the step S601, and reselecting the second angle until determining the large deformation loading point of the structural fatigue test.

In at least one embodiment of the present application, in step one, the obtaining a deflection line under a maximum deformation condition of an aircraft wing includes:

s101, obtaining load data and deformation data of a static test, and fitting a first flexible line under the maximum deformation working condition of the airplane wing, wherein variables in a first flexible line equation comprise: total wing load or wing load distribution;

s102, fatigue test load data and deformation data are obtained, and fatigue test loads under the maximum deformation working condition of the airplane wing are substituted into a curve equation of the first flexible line to obtain a second flexible line.

In at least one embodiment of the present application, in step three, the obtaining the length of the loading device, and determining the second point location according to the length of the loading device and the first point location includes:

s301, selecting loading equipment according to the maximum load and the maximum deformation of a loading point on the wing of the airplane, which is closest to the wingtip part, and acquiring the length of the loading equipment;

s302, selecting a second point location on a loading platform, wherein the distance from the second point location to the first point location is the length of a loading device.

In at least one embodiment of the present application, the calculating the first load error according to the first angle in step four includes:

F₁＝1-cosα₁

wherein, F₁Is the first load error, α₁Is at a first angle.

In at least one embodiment of the present application, in step five, the calculating the first bending moment error of the first load error at the wing control profile includes:

wherein M is₁Error of first bending moment, α₁Is a first angle, L is the distance from the second point location to the airfoil control profile, L₀The theoretical distance of the load from the airfoil control profile.

In at least one embodiment of the present application, in S602, the calculating a second load error according to the second angle includes:

F₂＝1-cosα₂

wherein, F₂Is the second load error, α₂Is at a second angle.

In at least one embodiment of the present application, the calculating the second bending moment error of the second load error at the wing control profile in S603 includes:

wherein M is₂Error in the second bending moment, α₂Is a second angle, L is the distance from the second point location to the airfoil control profile, L₀The theoretical distance of the load from the airfoil control profile.

In at least one embodiment of the present application, in S601, a plurality of second angles between 0 ° and the first angle are selected, and a corresponding second point location is determined again according to each of the second angles.

In at least one embodiment of the present application, in S603, the smallest second bending moment error is selected from the plurality of second bending moment errors satisfying the test requirements, and the second point location corresponding to the smallest second bending moment error is used as the structural fatigue test large deformation loading point.

In at least one embodiment of the present application, if the structure fatigue test large deformation load point cannot be determined in the sixth step, the load point design is performed according to the follow-up load.

The invention has at least the following beneficial technical effects:

the method for designing the large-deformation loading point for the structural fatigue test can evaluate the load error caused by deformation with high precision, and can provide a reasonable and efficient loading point design result according to the test task requirement.

Drawings

Fig. 1 is a flow chart of a method for designing a large deformation load point in a structural fatigue test according to an embodiment of the present application.

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are a subset of the embodiments in the present application and not all embodiments in the present application. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application and should not be construed as limiting the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

In the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present application and for simplifying the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore should not be construed as limiting the scope of the present application.

The present application is described in further detail below with reference to fig. 1.

The application provides a structural fatigue test large-deformation loading point design method, which comprises the following steps:

s100, obtaining a deflection line under the maximum deformation working condition of the airplane wing;

s200, obtaining coordinates of a loading point on the airplane wing closest to a wing tip, positioning the loading point on the deflection line to obtain a first point position, and obtaining a normal of the deflection line at the first point position;

s300, acquiring the length of the loading equipment, and determining a second point location according to the length of the loading equipment and the first point location;

s400, connecting the first point location and the second point location to obtain a point location connecting line, obtaining a first angle between the point location connecting line and a normal of the flexible line at the first point location, and calculating a first load error according to the first angle;

s500, calculating a first bending moment error of the first load error on the wing control section, judging whether the first bending moment error meets the test requirement or not,

if so, taking the second point position as a large deformation loading point of the structural fatigue test;

if not, entering S600;

S600、

s601, selecting a second angle between 0 degree and the first angle, and re-determining a second point location according to the second angle;

s602, calculating a second load error according to the second angle; and

s603, calculating a second bending moment error of the second load error on the wing control section, judging whether the second bending moment error meets the test requirement or not,

if so, taking the second point position as a large deformation loading point of the structural fatigue test;

and if not, returning to the step S601, and reselecting the second angle until determining the large deformation loading point of the structural fatigue test.

In a preferred embodiment of the present application, the obtaining the deflection line under the maximum deformation condition of the aircraft wing in S100 includes:

s101, obtaining load data and deformation data of a static test, and fitting a first flexible line under the maximum deformation working condition of the airplane wing, wherein variables in a first flexible line equation comprise: total wing load F or wing load distribution q;

s102, fatigue test load data and deformation data are obtained, and fatigue test loads under the maximum deformation working condition of the airplane wing are substituted into a curve equation of the first flexible line to obtain a second flexible line.

According to the structural fatigue test large deformation loading point design method, firstly, a static test is carried out before a fatigue test, a first flexible line is fitted according to load data and deformation data obtained by the previous static test, and then a fatigue test load under the maximum deformation working condition of the airplane wing is substituted into a curve equation of the first flexible line according to a fatigue test load processing result, so that a second flexible line is obtained.

According to the structural fatigue test large-deformation loading point design method, the loading point closest to the wing tip is selected according to the fatigue test load processing result, the point is positioned on the second bending line, and the normal of the point is obtained.

In a preferred embodiment of the present application, in S300, obtaining the length of the loading device, and determining the second point location according to the length of the loading device and the first point location includes:

s301, selecting loading equipment according to the maximum load and the maximum deformation of a loading point on the wing of the airplane, which is closest to the wingtip part, and acquiring the length of the loading equipment;

s302, selecting a second point location on the loading platform, wherein the distance from the second point location to the first point location is the length of a loading device.

In this embodiment, the maximum load of the loading point on the aircraft wing closest to the wing tip portion may be obtained according to the fatigue test load processing result, and the maximum deformation of the loading point on the aircraft wing closest to the wing tip portion may be obtained from the first point position of the second deflection line, or calculated according to the curve equation of the second deflection line. And selecting loading equipment with proper stroke loading and metering to obtain the length of the loading equipment, and determining the initial point position according to the length of the loading equipment.

The application provides a structural fatigue test large deformation loading point design method, and in S400, calculating a first load error according to a first angle includes:

F₁＝1-cosα₁

wherein, F₁Is the first load error, α₁Is at a first angle.

In S500, calculating a first bending moment error of the first load error at the airfoil control profile includes:

wherein M is₁Error of first bending moment, α₁Is a first angle, L is the distance from the second point location to the airfoil control profile, L₀The theoretical value can be obtained according to the load processing result of the fatigue test, wherein the theoretical distance is from the load to the control section of the wing.

And when the first bending moment error does not exceed the error threshold, judging that the first bending moment error meets the test requirement, and taking the second point position as a large deformation loading point of the structural fatigue test.

When the first bending moment error does not meet the test requirements, the load point needs to be redesigned. And selecting a second angle between 0 degrees and the first angle, and re-determining the second point position according to the second angle.

In S602, calculating the second load error according to the second angle includes:

F₂＝1-cosα₂

wherein, F₂Is the second load error, α₂Is at a second angle.

In S603, calculating a second bending moment error of the second load error at the airfoil control profile includes:

wherein M is₂Error in the second bending moment, α₂Is a second angle, L is the distance from the second point location to the airfoil control profile, L₀The theoretical distance of the load from the airfoil control profile.

And when the second bending moment error does not exceed the error threshold, judging that the second bending moment error meets the test requirement, and determining a corresponding second point position as a large deformation loading point of the structural fatigue test.

Advantageously, in this embodiment, a plurality of second angles between 0 ° and the first angle may be directly selected in S601, and the corresponding second point locations may be determined again according to the respective second angles. Wherein, the selection of the plurality of second angles can adopt a dichotomy. In S603, the smallest second bending moment error is selected from the plurality of second bending moment errors meeting the test requirements, and the second point location corresponding to the smallest second bending moment error is used as the large deformation loading point of the structural fatigue test.

According to the structural fatigue test large-deformation loading point design method, if in S600, the second angle selected between 0 degrees and the first angle does not meet the test requirements and the structural fatigue test large-deformation loading point cannot be determined, the loading point design is carried out according to the follow-up loading with relatively low test efficiency.

According to the design method for the large-deformation loading point for the structural fatigue test, the first point position and the second point position can be rapidly determined, the two point positions are connected through the loading equipment arranged on the loading platform, loading on the airplane wing is achieved, and therefore the structural fatigue test is completed.

The method for designing the large deformation loading point for the structural fatigue test can accurately analyze the loading point load error caused by the large deformation of the aircraft fatigue test, and the loading point design can give consideration to both the load precision and the test efficiency.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.