Wing body six-point butt joint symmetrical load distribution calculation method

Abstract

The invention belongs to the field of aviation structure design, particularly relates to a wing body six-point butt joint symmetrical load distribution calculation method, and mainly aims at carrying out main intersection point load distribution calculation in a three-beam six-point statically indeterminate butt joint mode commonly adopted by ultra-large type and large transport aircrafts. A mathematical physical model of main intersection load distribution under symmetrical loads is established by adopting a structural mechanics theory, and a main intersection load distribution analytical solution is obtained. According to the method, it is assumed that deformation between the main intersection points meets the linear coordination relation, and the connection rigidity of the wing body butt joint main intersection points is considered. According to the method, the load distribution principle of a three-beam six-point wing body butt joint form under symmetrical loads is disclosed theoretically, and key factors influencing load distribution can be given forward; meanwhile, the theoretical solving efficiency is high, and the optimization design requirements of various butt joint forms in the scheme stage can be met; in addition, the method can be popularized to a wing body butt joint form of any multiple main intersection points, and the applicability is wide.

Description

Technical Field

[0001] The present application belongs to the field of aviation structure design, and in particular relates to a method for calculating symmetrical load distribution of a wing-body six-point docking. Background Art

[0002] Transport aircraft often use a conventional high-wing layout, with the wing and fuselage connected at several concentrated load transfer points (also known as main intersections). For super-large and large transport aircraft, three-beam six-point docking is often used to reduce the load at the main intersection, such as Figure 6 However, the load distribution of the main intersection under this docking form is an over-determined problem in mechanics, and the factors affecting the load distribution of each main intersection are relatively complex.

[0003] At present, strength design requires the establishment of a large-scale simulation model to calculate the load distribution of each main intersection. The modeling efficiency is low and lacks theoretical support. It is difficult to obtain sensitive parameters that affect the load distribution. There is a lack of strong data support for the load control of the main intersection of the wing-body connection, and it is difficult to meet the needs of multi-scheme forward design. Summary of the invention

[0004] In order to solve the above problems, the present application provides a wing-body six-point docking symmetrical load distribution calculation method, comprising the following steps:

[0005] The first step is to calculate the total load P of the wing pressure center. Z , the heading distance L between the ith main intersection point and the wing pressure center i , the vertical load F of the ith main intersection i Establish a balanced equation; i = 1, 2, 3;

[0006] The second step is to calculate the connection stiffness K at the i-th main intersection. i , the displacement U at the i-th main intersection i , the vertical load F of the ith main intersection i Building physical equations;

[0007] The third step is to calculate the displacement U of the i-th main intersection point. i The pitch deflection angle θ of each main intersection point caused by the deformation relationship between the fuselage and the wing is linear, and the deformation coordination equation is established;

[0008] The fourth step is to combine the equilibrium equation, physical equation, and deformation coordination equation to obtain the matrix equation. Solve the matrix equation to obtain the vertical load F representing the jth principal intersection. j Relationship formula, j=1, 2, 3.

[0009] Preferably, the equilibrium equation is:

[0010]

[0011]

[0012] Preferably, the physical equation is:

[0013] K i U i =F i (i=1,2,3).

[0014] Preferably, the deformation coordination equation is:

[0015]

[0016] Where C is a constant.

[0017] Preferably, the matrix equation is:

[0018]

[0019] Preferably, the vertical load F representing the jth main intersection point is j The relationship formula is:

[0020]

[0021] K j is the connection stiffness of the jth principal intersection.

[0022] Preferably, the matrix equation is generalized to a matrix equation with n main intersection points as follows:

[0023]

[0024] L n is the heading distance between the nth main intersection and the wing pressure center, and the connection stiffness K at the nth main intersection n , the vertical load F at the nth main intersection n .

[0025] Preferably, the vertical load F at the nth main intersection is n The relationship formula is:

[0026]

[0027] Preferably, the calculation method of the connection stiffness of each main intersection is: according to the geometric dimensions and connection form of the main intersection connection joints, the fuselage joint stiffness, the wing joint stiffness and the pin stiffness are calculated respectively, and then the combined stiffness is calculated by the series method.

[0028] Preferably, the length of the fuselage joint is L f , the cross-sectional area is A f , the elastic modulus of the material is E f; The length of the wing joint is L w , the cross-sectional area is A w , the elastic modulus of the material is E w ; The pin diameter is D x , the effective length is L x , the shear modulus of the pin material is G x ;

[0029] The calculation formula of fuselage joint stiffness is:

[0030]

[0031] The calculation formula of wing joint stiffness is:

[0032]

[0033] The calculation formula of pin stiffness is:

[0034]

[0035] The effective length of the pin is L x In the case of single shear, the effective length is 1 / 4 of the total thickness of the connected plate, and in the case of double shear, the effective length is 1 / 2 of the single shear value;

[0036] According to the calculation method of series stiffness, the connection stiffness of the main intersection is

[0037]

[0038] Preferably, the total load P of the wing pressure center Z , the heading distance L between the ith main intersection point and the wing pressure center i , the displacement U at the i-th main intersection i , and according to the connection stiffness K at the i-th main intersection i It is obtained through the wing-body docking mechanical model under symmetrical working conditions.

[0039] Preferably, the wing-body docking mechanical model under the symmetrical working condition includes main intersection points distributed along the heading direction of a single-sided wing, a fuselage set to be rigid, and a spring set to a specific stiffness.

[0040] Preferably, the vertical load F based on the jth main intersection point is j , assuming that the connection stiffness of each main intersection point is the same, a curve diagram of the position of the midpoint intersection and the load coefficient is generated.

[0041] Preferably, the vertical load F based on the jth main intersection point is j The relationship formula is used, and the connection stiffness of the front and rear main intersections is assumed to be constant. The load distribution curve of the middle intersection connection stiffness for each main intersection is obtained.

[0042] The advantages of the present application include: the load distribution calculation method for the six-point wing-fuselage docking of transport aircraft provided in the present invention theoretically reveals the load distribution principle of the three-beam six-point wing-fuselage docking form under symmetrical load, and positively gives the key factors affecting the load distribution; at the same time, the theoretical solution efficiency is high, which can meet the optimization design requirements of various docking forms in the scheme stage; in addition, this method can be extended to the wing-fuselage docking form with any number of main intersection points, and has a wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a mechanical model diagram of the wing-fuselage connection area under symmetrical working conditions described in the present invention;

[0044] Figure 2 This is a schematic diagram of the typical structure of the main intersection of the wing and body;

[0045] Figure 3 This is a schematic diagram of the coordinated deformation of the wing;

[0046] Figure 4 is a trend diagram of the main intersection load changing with the relative position of the middle intersection point obtained by the calculation method of the present invention;

[0047] Figure 5 The figure is a trend diagram of the main intersection load and the connection stiffness of the middle intersection obtained by the calculation method of the present invention.

[0048] Figure 6 This is a structural diagram of the docking between the wing and the fuselage using three-beam six-point docking. DETAILED DESCRIPTION

[0049] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be further described in detail in detail and in detail in conjunction with the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments in the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0050] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installed", "connected", "connected" and similar terms used in the description of this application should be understood in a broad sense. For example, the 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, an indirect connection through an intermediate medium, or the internal connection of two components. Technical personnel in the field can understand their specific meanings in this application according to the specific circumstances.

[0051] The present invention will be further described in detail below with reference to the accompanying drawings. Figure 1-Figure 5 .

[0052] Specifically, the wing-body docking symmetric load distribution calculation method of the present invention comprises the following steps:

[0053] a) Establish a wing-body six-point docking mechanical model under symmetrical working conditions

[0054] Taking the typical severe load condition of the wing-body connection - the wing bending condition (symmetrical condition) as an example, the vertical load distribution of the three main intersection points on one side of the wing-body connection area is studied. This system is a typical hyperstatic structure, and its mechanical model is as follows Figure 1 Here, the wing is assumed to be a three-point beam fixed on the foundation (the fuselage is assumed to be rigid), and each main intersection is connected to the foundation through a spring with a specific stiffness.

[0055] The load on the wing in the upward bending condition can be simplified as the total load P acting on the wing pressure center Z , this load can generate shear force Q and symmetrical bending moment M at the wing-body connection. The shear force Q is balanced by vertical loads at the three main intersections, and the component M of the bending moment M x Self-balancing at the center wing, component M y The couples generated by the vertical loads at the three main intersections are balanced.

[0056] Let F i (i=1,2,3) is the vertical load of each main intersection point, K i is the connection stiffness at each main intersection, L i is the heading distance between each main intersection point and the wing pressure center, U i is the displacement at each main intersection point.

[0057] b) Calculate the main intersection connection stiffness

[0058] The connection stiffness of the main intersection can be preliminarily estimated based on the geometric dimensions and connection form of the main intersection connection joint (not considering the support stiffness of the fuselage and wing for the time being). Taking the typical hinged connection as an example, the main intersection of the wing-body connection is mainly composed of the fuselage joint, the wing joint and the pin shaft, such as Figure 2 shown.

[0059] Assume the length of the fuselage joint is L f , the cross-sectional area is A f , the elastic modulus of the material is E f ; The length of the wing joint is L w , the cross-sectional area is A w , the elastic modulus of the material is E w ; The pin diameter is D x , the effective length is L x, the shear modulus of the pin material is G x .

[0060] Fuselage joint stiffness

[0061]

[0062] Wing joint stiffness

[0063]

[0064] Pin stiffness

[0065]

[0066] The effective length of the pin is L x In the case of single shear, the effective length is 1 / 4 of the total thickness of the connected plates, and in the case of double shear, the effective length is 1 / 2 of the single shear value.

[0067] According to the calculation method of series stiffness, the connection stiffness of the main intersection is

[0068]

[0069] c) Constructing mathematical physics equations

[0070] According to mathematical physics relations, the mechanical model should satisfy the following equations:

[0071] 1) Balancing equations

[0072]

[0073]

[0074] 2) Physical equations

[0075] K i U i =F i (i=1,2,3) (7)

[0076] 3) Deformation coordination equation

[0077] Here, it is assumed that the wing is rigid, that is, the deformation relationship between the fuselage and the wing is linear. The deformation trend of the model is as follows: Figure 3 shown.

[0078] That is U i The pitch angle θ of each main intersection point caused by is the same, then the deformation coordination equation is

[0079]

[0080] The matrix equation can be obtained by combining equations (5), (6), (7), and (8):

[0081]

[0082] Similarly, it can be extended to the matrix equation with n principal intersection points:

[0083]

[0084] d) Derivation of analytical solution for wing-body docking load distribution

[0085] It is not difficult to see that equations (9) and (10) are multivariate linear equations with a unique solution. Solving equation (9) yields:

[0086]

[0087] Similarly, formula (10) can also be extended to the case where there are n main intersection points on one side, that is,

[0088]

[0089] The above method is used to analyze the factors affecting the load distribution in the wing-to-furment connection area.

[0090] a) Analysis of the influence of the position of the central intersection

[0091] Since the relative position of the front intersection point and the rear intersection point in the wing-body connection area is determined by the central wing width, there is basically no adjustable space, so the main research is the influence of the position of the central intersection point. The central intersection point is located between the front and rear intersection points, and its relative position can be expressed as (X1-X2) / (X1-X3), which is between 0.0-1.0, and X i The heading coordinate of the main intersection point.

[0092] Assume that the connection stiffness K of each main intersection is i Similarly, the wing pressure center is located 3m behind the heading position of the rear intersection point. According to formula (11), the relationship between the vertical load of the three main intersection points and the relative position of the mid-intersection point can be obtained as follows: Figure 4 As shown, the load factor ψ in the figure is F i / P Z .

[0093] It can be seen that as the relative position of the middle intersection point gradually increases, the loads of the three main intersection points all change nonlinearly. The front intersection point is under compression, and the load increases first and then decreases; the middle intersection point changes from compression to tension, and the load gradually increases; the rear intersection point is under tension, and the load increases first and then decreases. The closer the position of the middle intersection point is to 1.0, the more load the middle intersection point shares from the rear intersection point, and the loads of the three intersection points are relatively more evenly distributed.

[0094] b) Analysis of the influence of the connection stiffness at the intersection

[0095] Assuming that the connection stiffness of the front and rear intersections is constant (set to 1), the influence of the gradual change of the connection stiffness (K2) of the middle intersection on the load distribution of each main intersection is analyzed. The wing pressure center is located 3m behind the heading station of the rear intersection.

[0096] According to formula (11), the trend of the vertical load of the three main intersection points as the stiffness of the midpoint changes is as follows: Figure 5 As shown, the load factor ψ in the figure is F i / P Z When the stiffness of the middle intersection increases, the load on the front intersection gradually increases, but the change is not obvious; the load on the middle intersection itself increases significantly, and the load on the rear intersection decreases significantly. When the stiffness coefficient of the middle intersection is about 1.4, the loads on the middle and rear intersections are basically equal.

[0097] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for calculating symmetrical load distribution of a wing-body six-point docking, comprising the following steps: The first step is to calculate the total load P of the wing pressure center. Z , the heading distance L between the ith main intersection point and the wing pressure center i , the vertical load F of the ith main intersection i Establish a balanced equation; i = 1, 2, 3; The second step is to calculate the connection stiffness K at the i-th main intersection. i , the displacement U at the i-th main intersection i , the vertical load F of each i-th main intersection point i Building physical equations; The third step is to calculate the displacement U of the i-th main intersection point. i The pitch deflection angle θ of each main intersection point caused by the deformation relationship between the fuselage and the wing is linear, and the deformation coordination equation is established; The fourth step is to combine the equilibrium equation, physical equation, and deformation coordination equation to obtain the matrix equation. Solve the matrix equation to obtain the vertical load F representing the jth principal intersection. j Relationship formula, j=1, 2, 3.

2. The wing-body six-point docking symmetrical load distribution calculation method according to claim 1 is characterized in that: The equilibrium equation is:

3. The wing-body six-point docking symmetrical load distribution calculation method according to claim 2 is characterized in that: The physical equation is: K i U i =F i (i=1,2,3)。 4. The wing-body six-point docking symmetrical load distribution calculation method according to claim 3 is characterized in that: The deformation coordination equation is: Where C is a constant.

5. The wing-body six-point docking symmetrical load distribution calculation method according to claim 4 is characterized in that: The matrix equation is:

6. The wing-body six-point docking symmetrical load distribution calculation method according to claim 5, characterized in that: Characterize the vertical load F of the jth main intersection j The relationship formula is: K j is the connection stiffness of the jth principal intersection.

7. The wing-body six-point docking symmetrical load distribution calculation method according to claim 6, characterized in that: The matrix equation is extended to a matrix equation with n principal intersection points: L n is the heading distance between the nth main intersection and the wing pressure center, and the connection stiffness K at the nth main intersection n , the vertical load F at the nth main intersection n .

8. The wing-body six-point docking symmetrical load distribution calculation method according to claim 7, characterized in that: Vertical load F at the nth principal intersection n The relationship formula is:

9. The wing-body six-point docking symmetrical load distribution calculation method according to claim 7, characterized in that: The calculation method of the connection stiffness of each main intersection is as follows: according to the geometric dimensions and connection form of the main intersection connection joints, the fuselage joint stiffness, wing joint stiffness and pin stiffness are calculated respectively, and then the combined stiffness is calculated using the series method.

10. The wing-body six-point docking symmetrical load distribution calculation method according to claim 9, characterized in that: Assume the length of the fuselage joint is L f , the cross-sectional area is A f , the elastic modulus of the material is E f ; The length of the wing joint is L w , the cross-sectional area is A w , the elastic modulus of the material is E w ; The pin diameter is D x , the effective length is L x , the shear modulus of the pin material is G x ; The calculation formula of fuselage joint stiffness is: The calculation formula of wing joint stiffness is: The calculation formula of pin stiffness is: The effective length of the pin is L x In the case of single shear, the effective length is 1 / 4 of the total thickness of the connected plate, and in the case of double shear, the effective length is 1 / 2 of the single shear value; According to the calculation method of series stiffness, the connection stiffness of the main intersection is 11. The wing-body six-point docking symmetrical load distribution calculation method according to claim 9, characterized in that: Total load P of wing pressure center Z , the heading distance L between the ith main intersection point and the wing pressure center i , the displacement U at the i-th main intersection i , and according to the connection stiffness K at the i-th main intersection i It is obtained through the wing-body docking mechanical model under symmetrical working conditions.

12. The wing-body six-point docking symmetrical load distribution calculation method according to claim 9, characterized in that: The wing-body docking mechanical model under the symmetrical working condition includes a single-sided wing, a fuselage set to be rigid, and main intersection points distributed along the heading direction of a spring set to a specific stiffness.

13. The wing-body six-point docking symmetrical load distribution calculation method according to claim 9, characterized in that: Vertical load F based on the jth main intersection j , assuming that the connection stiffness of each main intersection point is the same, a curve diagram of the position of the midpoint intersection and the load coefficient is generated.

14. The wing-body six-point docking symmetrical load distribution calculation method according to claim 9, characterized in that: Vertical load F based on the jth main intersection j The relationship formula is used, and the connection stiffness of the front and rear main intersections is assumed to be constant. The load distribution curve of the middle intersection connection stiffness for each main intersection is obtained.

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