Rapid parameterization design method for wing

Abstract

The invention discloses a rapid parameterization design method for a wing. The method comprises the following steps: 1) automatically generating and designing a high-fairing wing profile curve; based on curve comprehensive fitting fairing of improved MVC, a spline curve fitting algorithm based on progressive iterative approximation is combined with an improved MVC curve fairing evaluation index, and a Pareto optimization calculation method based on NSGA-II is used as an optimization solver. And finally obtaining a curve comprehensive fitting fairing algorithm based on improved MVC as an automatic generation design method of the high-fairing airfoil profile curve. 2) constructing a skin curved surface; constructing a skin curved surface based on the B-spline curve; 3) performing rapid parameterization construction on the structure in the wing; the wing structure is based on a beam type structure, each design parameter of the wing is abstracted into an adjustable variable, and wing models in different forms are quickly generated by adjusting the variable parameters. By means of the wing rapid parametric modeling method, the design efficiency can be remarkably improved during wing design.

Description

Technical Field

[0001] The invention relates to the technical field of computer-aided geometric design, and in particular to a method for rapid parametric design of a wing. Background Art

[0002] There are three defects in the existing rapid parametric design methods of wings.

[0003] (1) NURBS (non-uniform rational B-spline) curves or CST (class shape transformation) methods are usually used to construct airfoil curves. These methods have a high degree of freedom in describing the airfoil, but the resulting airfoil curves have poor smoothness and cannot meet the high smoothness requirements.

[0004] (2) The level of automation and parameterization in the wing internal structure design is low, which reduces the design efficiency and raises the design threshold.

[0005] (3) All existing tools are secondary developed based on commercial software and lack independence and flexibility. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a method for rapid parametric design of a wing, which can significantly improve the design efficiency during wing design by utilizing the rapid parametric modeling method of the wing.

[0007] The present invention solves the technical problem by adopting the following technical solution:

[0008] A rapid parametric design method for a wing comprises the following steps:

[0009] 1) Automatically generate and design high smoothness airfoil curves;

[0010] Based on the improved MVC curve comprehensive fitting smoothing, a spline curve fitting algorithm based on progressive iterative approximation is used, combined with the improved MVC curve smoothing evaluation index, and the Pareto optimization calculation method based on NSGA-II is used as the optimization solver. Finally, the improved MVC curve comprehensive fitting smoothing algorithm is obtained as the automatic generation design method of high smooth airfoil curve.

[0011] 2) Skin surface construction;

[0012] Construct skin surface based on B-spline curve;

[0013] 3) Rapid parametric construction of wing internal structure;

[0014] The wing structure adopts a beam structure as its basis, and each design parameter of the wing is abstracted as an adjustable variable. By adjusting these variable parameters, wing models of different forms can be quickly generated.

[0015] Furthermore, the expression of the p-order B-spline curve equation is:

[0016]

[0017] Where i is the control point number, n is the number of control points minus 1, u is the node vector, and u p is the first node, u n+1 is the last node, C(u) is the curve expression, P i is the i-th control point, N i,p (u) is the i-th basis function.

[0018] Furthermore, the progressive iterative approximation PIA algorithm is as follows:

[0019] set up It is a cubic B-spline curve. If we move one of the control points P k (0≤k≤n) to a new position The new cubic B-spline curve becomes:

[0020]

[0021] Among them, k is the control point number, N i (t) is the i-th basis function, N k is the kth basis function;

[0022] Assume Δ k is the translation vector,

[0023]

[0024] Assume that given parameter t∈[u i ,u i+1 ], i = 0, 1, ... n-3, the corresponding point on the curve is P (t), and a point outside the curve is If we set the control point P k Move a certain distance Δ k , so that point P(t) and point Overlap, distance Δ k for:

[0025]

[0026] Among them, N k (t) is the basis function corresponding to the kth control point.

[0027] Furthermore, the MVC curve smoothing evaluation index is as follows:

[0028]

[0029] Where L is the curve, κ is the curvature, s is the arc length, κ(u) is the derivative of the curvature, and MVC is the fairness measure;

[0030] The local MVC is:

[0031]

[0032] Among them, u n is the node, and m is the last node number.

[0033] Furthermore, the curve comprehensive fitting smoothing algorithm is as follows:

[0034]

[0035] Among them, PLA error is the error, k is the segment number, p is the number of times, f k is the piecewise constraint function, f n-p+1 is the last piecewise constraint function, u is the node number, and ω is the coefficient.

[0036] Furthermore, the Pareto optimization calculation method based on NSGA-II is as follows:

[0037] Min / Max f(x)=(f1(x),f2(x),...f n (x),)n≥2

[0038] Subject to g i (x)≤0,i=1,2,...,m

[0039] h j (x)=0,j=1,2,...,p

[0040] where x=(x l ,x2,...,x n ) is an n-dimensional vector in the decision space, f is the mapping function, g i and h j are constraints. The other variables n, m, and p represent the number of objective functions, inequality constraints, and equality constraints, respectively.

[0041] Furthermore, based on the B-spline curve, the skin surface construction process is as follows:

[0042]

[0043] Let (9) be a rational or irrational cross-sectional curve; assume that all C k (u) is defined on the same node vector U and has a common degree p, and then in the v direction, the degree q is selected to determine the parameters Then, according to these parameters and the node vector, the control points of the cross-section curve are interpolated n+1 times to obtain the control points Q of the skin surface. i,j , i.e. Q i,j To interpolate at P i,0 ,…,P i,K The j-th control point of the q-degree curve.

[0044] Furthermore, the main load-bearing components of the wing structure include the skin, wing spars and wing ribs. The wing spars mainly bear bending moments, the wing ribs bear shear forces, and the closed chamber formed by the skin and wing spars bears torque.

[0045] Furthermore, the design parameters of the wing include aspect ratio, sweep angle, and wing thickness.

[0046] The invention discloses a method for rapid parametric design of a wing, which has the following beneficial effects:

[0047] 1. The airfoil curve has higher shape retention and improved curve smoothness;

[0048] 2. The wing skin surface constructed based on the smooth airfoil curve is naturally a high-smooth surface;

[0049] 3. The construction of the beam-structured wing is carried out in a parametric form. The complete wing can be constructed by simply providing various parameters of the airfoil, and the number of beams and plates can be given to meet different performance design requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a flow chart of the method of the present invention;

[0051] Figure 2 The present invention is a flow chart of the Pareto optimization calculation method based on NSGA-II;

[0052] Figure 3 A schematic diagram of the curved surface skinning process of the present invention;

[0053] Figure 4 The beam structure wing model of the present invention;

[0054] Figure 5 This is the NACA-0015 airfoil curve effect diagram of the present invention;

[0055] Figure 6 The wing skin curved surface with guide lines of the present invention;

[0056] Figure 7 It is a schematic diagram showing the airfoil curve of the present invention;

[0057] Figure 8 This is a rendering of the rapid parametric modeling of the wing of the present invention;

[0058] Fig. 9 This is a modeling effect diagram of the straight wing of the present invention. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] The present invention makes full use of the advantages of NURBS, combines the MVC smoothing criterion with the intelligent optimization algorithm to develop an efficient parametric modeling method for wing structures. In this method, various design parameters of the wing (such as airfoil, aspect ratio, sweep angle, wing thickness, etc.) are abstracted as adjustable variables. Designers can quickly generate wing models of different forms by adjusting these parameters, thereby achieving the purpose of rapid iteration and optimization. Using this parametric modeling method, designers can significantly improve design efficiency when designing wings.

[0061] refer to Figure 1 The invention discloses a method for rapid parametric design of a wing, comprising the following steps:

[0062] 1) Automatically generate and design high smoothness airfoil curves;

[0063] The curve comprehensive fitting and smoothing based on the improved MVC, the spline curve fitting algorithm based on progressive iterative approximation (PIA), combined with the improved MVC curve smoothing evaluation index, and the Pareto optimization calculation method based on NSGA-II were used as the optimization solver. Finally, the curve comprehensive fitting and smoothing algorithm based on the improved MVC was obtained as the automatic generation design method of high smoothness airfoil curve. Figure 5 (a) is the curvature comb effect diagram of the non-smooth airfoil curve. Figure 5 (b) is the curvature comb effect diagram of the smooth airfoil curve.

[0064] The expression of the p-order B-spline curve equation is:

[0065]

[0066] Where i is the control point number, n is the number of control points minus 1, u is the node vector, and u p is the first node, u n+1 is the last node, C(u) is the curve expression, P i is the i-th control point, N i,p (u) is the i-th basis function.

[0067] The progressive iterative approximation PIA algorithm is as follows:

[0068] set up It is a cubic B-spline curve. If we move one of the control points P k (0≤k≤n) to a new position The new cubic B-spline curve becomes:

[0069]

[0070] Among them, k is the control point number, N i (t) is the i-th basis function, N k is the kth basis function;

[0071] Assume Δ k is the translation vector,

[0072]

[0073] Assume that given parameter t∈[u i ,u i+1 ], i = 0, 1, ... n-3, the corresponding point on the curve is P (t), and a point outside the curve is If we set the control point P k Move a certain distance Δ k , so that point P(t) and point Overlap, distance Δ k for:

[0074]

[0075] Among them, N k (t) is the basis function.

[0076] The MVC curve smoothing evaluation indicators are as follows:

[0077]

[0078] Where L is the curve, κ is the curvature, s is the arc length, κ(u) is the derivative of the curvature, and MVC is the fairness measure;

[0079] The local MVC is:

[0080]

[0081] Among them, u n is the node, and m is the last node number.

[0082] The curve comprehensive fitting smoothing algorithm is as follows:

[0083]

[0084] Among them, PLA error is the error, k is the segment number, p is the number of times, f k is the piecewise constraint function, f n-p+1 is the last piecewise constraint function, u is the node number, and ω is the coefficient.

[0085] like Figure 2 As shown in the figure, the Pareto optimization calculation method based on NSGA-II is as follows:

[0086] Pareto optimization can be expressed as:

[0087] Min / Max f(x)=(f1(x),f2(x),...f n (x),)n≥2

[0088] Subject to g i (x)≤0,i=1,2,...,m

[0089] h j (x)=0,j=1,2,...,p

[0090] where x=(x l ,x2,...,x n ) is an n-dimensional vector in the decision space, f is the mapping function, g i and h j are constraints. The other variables n, m, and p represent the number of objective functions, inequality constraints, and equality constraints, respectively.

[0091] 2) Skin surface construction;

[0092] Based on the B-spline curve, the skin surface construction process is as follows:

[0093]

[0094] Let (9) be a rational or irrational cross-sectional curve; assume that all C k (u) is defined on the same node vector U and has a common degree p, and then in the v direction, the degree q is selected to determine the parameters Then, according to these parameters and the node vector, the control points of the cross-section curve are interpolated n+1 times to obtain the control points Q of the skin surface. i,j , i.e. Q i,j To interpolate at P i,0 ,…,P i,K The j-th control point of the q-degree curve.

[0095] Figure 3 The process of generating surfaces using the masked method is explained. Figure 3 (a) shows the initially given cross-sectional curves, which are C0(u), C1(u), C2(u), and C3(u) from front to back, and their node vectors are

[0096] C0(u):{0 0 0 0 0.5 0.7 1 1 1 1}

[0097] C1(u):{0 0 0 0 0.4 0.6 1 1 1 1}

[0098] C2(u):{0 0 0 0 0.2 0.8 1 1 1 1}

[0099] C3(u):{0 0 0 0 0.5 0.9 1 1 1 1}

[0100] After node difference refinement, the unified node vector is

[0101] {0 0 0 0 0.2 0.4 0.5 0.6 0.7 0.8 0.9 1 1 1 1}

[0102] This increases the number of control points in the u direction to 15. Figure 3 (b) shows the curve after compatibility processing. It can be seen from the figure that the number of new control points increases significantly, which is the price paid for increasing the flexibility of the curve. Figure 3 (c) Yes Figure 3 (d) The control mesh of the skin surface shown.

[0103] Based on the NACA four-digit airfoil, an algorithm for constructing NACA airfoil wing skin surfaces is developed. Different numbers of airfoil section lines and guide lines can be used to generate corresponding wing skin surfaces according to requirements, such as Figure 6 shown.

[0104] 3) Rapid parametric construction of wing internal structure;

[0105] The wing structure uses a beam structure as its foundation. The main load-bearing components of the wing structure include the skin, spar and rib. The spar mainly bears bending moment, the rib bears shear force, and the closed chamber composed of the skin and spar bears torque. The beam structure is simple, directly bears force, is light in weight, and is easy to use the internal volume of the wing.

[0106] In this method, various design parameters of the wing (such as aspect ratio, sweep angle, wing thickness, etc.) are abstracted as adjustable variables. Designers can quickly generate wing models of different forms by adjusting these parameters, thereby achieving the purpose of rapid iteration and optimization.

[0107] Figure 4An analytical wing structure model with a cross plate (yellow) added to the beam-type structure wing spar (red) and wing ribs (cyan).

[0108] The invention discloses a method for rapid parametric design of wings, which focuses on efficiently and accurately realizing the modeling of aircraft wings, and is committed to breaking through the limitations of traditional design patterns to meet the increasingly complex needs of modern aviation engineering. The design method of the invention makes the airfoil curve more shape-preserving and the curve smoothness improved; the wing skin surface constructed based on the smooth airfoil curve is naturally a high-smoothness surface; the construction of the beam-structured wing is carried out in a parametric form, and only various airfoil parameters need to be provided to construct a complete wing, and the number of beams and plates can be given to meet different performance design requirements.

[0109] Application Examples

[0110] like Figure 7-9 As shown, the software is written using MATLAB. The software design module provides users with an intuitive and powerful platform for creating interactive applications. Whether it is data analysis, visualization or algorithm demonstration, AppDesigner can help users quickly realize their ideas and improve work efficiency. By utilizing its rich components and flexible programming capabilities, users can build professional applications that meet specific needs. A modeling cycle takes 0.486929 seconds.

[0111] The UI mainly consists of three modules: parameter input module, airfoil curve modeling module, and wing rapid parameterized modeling module.

[0112] The adjustable parameters in the parameter adjustment module include: airfoil curve selection, number of calculation samples, number of fitting control points, number of wing beams, and wing type selection. Other parameters can be added as needed to meet more modeling requirements. You can choose wing types such as straight wing or swept wing, and click the modeling button to complete the wing modeling and display.

[0113] The airfoil curve modeling module mainly displays the control points of the airfoil curve and its spline curve.

[0114] The wing shape panoramic display module mainly displays the overall effect of the wing on the fuselage. Its display angle can be adjusted as needed.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for rapid parametric design of a wing, characterized in that: The steps include: 1) Automatically generate and design high smoothness airfoil curves; Based on the improved MVC curve comprehensive fitting smoothing, a spline curve fitting algorithm based on progressive iterative approximation is used, combined with the improved MVC curve smoothing evaluation index, and the Pareto optimization calculation method based on NSGA-II is used as the optimization solver. Finally, the improved MVC curve comprehensive fitting smoothing algorithm is obtained as the automatic generation design method of high smooth airfoil curve. 2) Skin surface construction; Construct skin surface based on B-spline curve; 3) Rapid parametric construction of wing internal structure; The wing structure adopts a beam structure as its basis, and each design parameter of the wing is abstracted as an adjustable variable. By adjusting these variable parameters, wing models of different forms can be quickly generated.

2. A wing rapid parameterized design method according to claim 1, characterized in that: The expression of the p-order B-spline curve equation is: Where i is the control point number, n is the number of control points minus 1, u is the node vector, and u p is the first node, u n+1 is the last node, C(u) is the curve expression, P i is the i-th control point, N i,p (u) is the i-th basis function.

3. A wing rapid parameterized design method according to claim 2, characterized in that: The progressive iterative approximation PIA algorithm is as follows: set up It is a cubic B-spline curve. If we move one of the control points P k (0≤k≤n) to a new position The new cubic B-spline curve becomes: Among them, k is the control point number, N i (t) is the i-th basis function, N k is the kth basis function; Assume Δ k is the translation vector, Assume that given parameter t∈[u i ,u i+1 ], i = 0, 1, ... n-3, the corresponding point on the curve is P (t), and a point outside the curve is If we set the control point P k Move a certain distance Δ k , so that point P(t) and point Overlap, distance Δ k for: Among them, N k (t) is the basis function corresponding to the kth control point.

4. A wing rapid parameterized design method according to claim 3, characterized in that: The MVC curve smoothing evaluation indicators are as follows: Where L is the curve, κ is the curvature, s is the arc length, κ(u) is the derivative of the curvature, and MVC is the fairness measure; The local MVC is: Among them, u n is an internal node, and m is the last internal node number.

5. A wing rapid parameterized design method according to claim 4, characterized in that: The curve comprehensive fitting smoothing algorithm is as follows: Among them, PLA error is the error, k is the segment number, p is the number of times, f k is the piecewise constraint function, f n-p+1 is the last piecewise constraint function, u is the node number, and ω is the coefficient.

6. A wing rapid parameterized design method according to claim 5, characterized in that: The Pareto optimization calculation method based on NSGA-II is as follows: Min / Max f(x)=(f1(x),f2(x),...f n (x),)n≥2 Subjectto g i (x)≤0,i=1,2,...,m h j (x)=0,j=1,2,...,p where x=(x l ,x2,...,x n ) is an n-dimensional vector in the decision space, f is the mapping function, g i and h j are constraints. The other variables n, m, and p represent the number of objective functions, inequality constraints, and equality constraints, respectively.

7. A wing rapid parametric design method according to claim 6, characterized in that: Based on the B-spline curve, the skin surface construction process is as follows: Let (9) be a rational or irrational cross-sectional curve; assume that all C k (u) is defined on the same node vector U and has a common degree p, and then in the v direction, the degree q is selected to determine the parameters Then, according to these parameters and the node vector, the control points of the cross-section curve are interpolated n+1 times to obtain the control points Q of the skin surface. i,j , i.e. Q i,j To interpolate at P i,0 ,…,P i,K The j-th control point of the q-degree curve.

8. A wing rapid parameterized design method according to claim 7, characterized in that: The main load-bearing components of the wing structure include the skin, wing spars and wing ribs. The wing spars mainly bear bending moments, the wing ribs bear shear forces, and the closed chamber formed by the skin and wing spars bears torque.

9. A method for rapid parametric design of a wing according to claim 8, characterized in that: The design parameters of the wing include aspect ratio, sweep angle, and wing thickness.

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