A Modeling Method and System for Stiffened Shells Based on Free Deformation

Abstract

This invention relates to a method and system for modeling stiffened shells based on free deformation. The method includes: acquiring the coordinate position information of finite element nodes in a finite element model of a simple stiffened shell; determining the control volume and setting control points; establishing a mapping relationship between the coordinate position information of the finite element nodes and the coordinate position information of the control points based on basis functions; building a solid model according to the geometric features of the target surface; meshing the solid model to determine the target surface finite element model; moving the coordinate position information of the control points using a free deformation method based on the coordinate position information of the finite element nodes in the target surface finite element model; and generating the target surface stiffened shell finite element model based on the mapping relationship and the moved coordinate position information of the control points. This invention enables layout optimization for modeling complex stiffened shells, thereby shortening the design cycle and reducing design costs.

Description

Technical Field

[0001] This invention relates to the field of engineering structure optimization design, and in particular to a method and system for modeling stiffened shells with curved surfaces based on free deformation. Background Technology

[0002] Due to their high specific stiffness, specific strength, and high reliability, curved stiffened shell structures are widely used in the aerospace field, such as in the sealed cabin structures of space stations, cargo spacecraft, and manned spacecraft. However, due to thrust limitations, the mass of stiffened shell structures is subject to strict requirements, thus necessitating parametric modeling and optimization design to achieve structural lightweighting.

[0003] Existing parametric modeling methods for stiffened shells describe the model using analytical equations or mathematical forms and are programmed using CAD platform languages ​​to achieve parametric modeling of simple curved surfaces, such as stiffened plates or stiffened cylinders.

[0004] However, for complex models, existing technologies using analytical equations struggle to achieve parametric modeling of stiffened surfaces. Furthermore, describing the configuration and layout of complex stiffened surfaces is difficult, hindering layout optimization of such structures and leading to increased design cycles and costs.

[0005] Therefore, there is an urgent need for a new method or system for modeling stiffened shells on curved surfaces to optimize the layout of complex stiffened shells, thereby shortening the design cycle and reducing design costs. Summary of the Invention

[0006] The purpose of this invention is to provide a modeling method and system for stiffened shells based on free-form deformation (FFD), which can optimize the layout of modeling complex stiffened shells, thereby shortening the design cycle and reducing design costs.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A method for modeling stiffened shells on curved surfaces based on free deformation includes:

[0009] Establish a finite element model of a simple curved stiffened shell and obtain the coordinate position information of the corresponding finite element nodes; the simple curved surfaces include: plane, cylindrical surface and torus;

[0010] The control volume is determined based on the geometric characteristics of a simple curved stiffened shell;

[0011] A corresponding number of control points are set along the length, width, and height of the control body, and the coordinate position information of the control points is obtained.

[0012] Based on basis functions, a mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points is established for a finite element model of a simple curved stiffened shell.

[0013] A solid model is established based on the geometric characteristics of the target surface in the stiffened shell; and the solid model is meshed to determine the finite element model of the target surface; the number of finite element nodes in the finite element model of the target surface is the same as the number of control points of the control body;

[0014] Based on the coordinate position information of the finite element nodes of the target surface finite element model, determine the coordinate change of each control point in the control volume, and based on the coordinate change of each control point, use the free deformation method to determine the coordinate position information of the deformed control point.

[0015] Based on the mapping relationship and the coordinate position information of the control points after deformation, the coordinate position information of the finite element nodes after the free deformation of the finite element model of the simple curved surface stiffened shell is determined, and then the target curved surface stiffened shell finite element model is generated.

[0016] Optionally, the step of establishing a finite element model of a simple curved stiffened shell and obtaining the coordinate position information of the corresponding finite element nodes specifically includes:

[0017] A finite element model of a simple curved stiffened shell was established based on the CAE platform.

[0018] Optionally, the basis functions are Bernstein basis functions, B-spline basis functions, or NURBS basis functions.

[0019] Optionally, the step of establishing the mapping relationship between the coordinate position information of the finite element nodes and the coordinate position information of the control points of the finite element model of a simple curved stiffened shell based on basis functions specifically includes:

[0020] Using formula Determine the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell;

[0021] Among them, X p For the finite element nodes of a simple curved surface stiffened shell finite element model, x p y p , z pThis provides the coordinate position information of the finite element nodes in the finite element model of a simple curved stiffened shell, where p = 1, 2, 3, ..., N, N is the number of finite element nodes in the finite element model of the simple curved stiffened shell, S is the length of the control body, T is the width of the control body, U is the height of the control body, l is the number of control points set along the length direction of the control body, m is the number of control points set along the width direction of the control body, n is the number of control points set along the height direction of the control body, and i, j, k represent the sequence numbers of the control points along the length, width, and height of the control body, respectively, i = 1, 2, 3, ..., l, j = 1, 2, 3, ..., m, k = 1, 2, 3, ..., n, R i Let R be the basis functions along the length direction. i =C l i (x p / S) i (1-(x p / S)) l-i R j Let R be the basis function along the width direction. j =C m j (y p / T) j (1-(y p / T)) m-j R k Let R be the basis function along the height direction. k =C n k (z p / U) k (1-(z p / U)) n-k M i,j,k This refers to the coordinate position information of the control points.

[0022] A surface stiffened shell modeling system based on the free deformation method includes:

[0023] The finite element model creation module for simple curved stiffened shells is used to create finite element models of simple curved stiffened shells and obtain the coordinate position information of the corresponding finite element nodes; including planes, cylindrical surfaces, and toroidal surfaces;

[0024] The control volume determination module is used to determine the control volume based on the geometric characteristics of a simple curved stiffened shell;

[0025] The control point determination module is used to set a corresponding number of control points along the length, width, and height of the control body, and to obtain the coordinate position information of the control points.

[0026] The mapping relationship establishment module is used to establish the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell based on the basis function.

[0027] The target surface finite element model determination module is used to establish a solid model based on the geometric characteristics of the target surface in the target surface stiffened shell; and to perform mesh generation on the solid model to determine the target surface finite element model; the number of finite element nodes in the target surface finite element model is the same as the number of control points of the control body;

[0028] The control point movement module is used to determine the coordinate change of each control point in the control body based on the coordinate position information of the finite element nodes of the target surface finite element model, and to determine the coordinate position information of the deformed control point using the free deformation method based on the coordinate change of each control point.

[0029] The target surface stiffened shell finite element model generation module is used to determine the finite element node coordinate position information after free deformation of the finite element model of the simple surface stiffened shell according to the mapping relationship and the coordinate position information of the control points after deformation, and then generate the target surface stiffened shell finite element model.

[0030] Optionally, the finite element model building module for the simple curved stiffened shell specifically includes:

[0031] This is a finite element modeling unit for simple curved stiffened shells, used to build finite element models of simple curved stiffened shells based on a CAE platform.

[0032] Optionally, the basis functions are Bernstein basis functions, B-spline basis functions, or NURBS basis functions.

[0033] Optionally, the mapping relationship establishment module specifically includes:

[0034] The mapping relationship establishment unit is used to establish mapping relationships using formulas. Determine the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell;

[0035] Among them, X p For the finite element nodes of a simple curved surface stiffened shell finite element model, x p y p , z pThis provides the coordinate position information of the finite element nodes in the finite element model of a simple curved stiffened shell, where p = 1, 2, 3, ..., N, N is the number of finite element nodes in the finite element model of the simple curved stiffened shell, S is the length of the control body, T is the width of the control body, U is the height of the control body, l is the number of control points set along the length direction of the control body, m is the number of control points set along the width direction of the control body, n is the number of control points set along the height direction of the control body, and i, j, k represent the sequence numbers of the control points along the length, width, and height of the control body, respectively, i = 1, 2, 3, ..., l, j = 1, 2, 3, ..., m, k = 1, 2, 3, ..., n, R i Let R be the basis functions along the length direction. i =C l i (x p / S) i (1-(x p / S)) l-i R j Let R be the basis function along the width direction. j =C m j (y p / T) j (1-(y p / T)) m-j R k Let R be the basis function along the height direction. k =C n k (z p / U) k (1-(z p / U)) n-k M i,j,k This refers to the coordinate position information of the control points.

[0036] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0037] This invention provides a method and system for modeling stiffened shells based on free deformation. It establishes a mapping relationship between the coordinate positions of finite element nodes and control points in a finite element model of a simple stiffened shell. Then, based on the geometric characteristics of the target surface, the change in control points is determined. The free deformation method is used to change the coordinates of the nodes of the simple stiffened shell, thereby generating the finite element model of the target stiffened shell. This invention can transform a simple stiffened shell model into a complex stiffened shell model, unlike traditional model modification methods. It also solves the problem of difficulty in using analytical equations to describe the complex model for parametric modeling of stiffened surfaces, while possessing high efficiency and robustness. The method proposed in this invention is simple to operate and facilitates subsequent optimization design of complex stiffened surface structures. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A schematic diagram of the process for modeling a stiffened shell surface based on a free deformation method provided by the present invention;

[0040] Figure 2 A schematic diagram of a finite element model of a simple curved surface stiffened shell;

[0041] Figure 3 This is a schematic diagram of the control points;

[0042] Figure 4 A schematic diagram of the finite element model of the target surface;

[0043] Figure 5 This is a schematic diagram of the deformed model after the control points determined by the free deformation method are used.

[0044] Figure 6 This is a schematic diagram of a surface stiffened shell modeling system based on the free deformation method provided by the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] The purpose of this invention is to provide a modeling method and system for stiffened shells based on free deformation, which can optimize the layout of modeling complex stiffened shells, thereby shortening the design cycle and reducing design costs.

[0047] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Figure 1 This is a schematic diagram of a surface stiffening shell modeling method based on free deformation provided by the present invention, as shown below. Figure 1 As shown, the present invention provides a method for modeling stiffened shells based on free deformation, comprising:

[0049] S101, establish a finite element model of a simple curved surface stiffened shell and obtain the coordinate position information of the corresponding finite element nodes; simple curved surfaces include, but are not limited to: planes, cylindrical surfaces, toroidal surfaces, etc. Simple curved surfaces are surfaces with similar topological features to the target surface and are easy to stiffen and model.

[0050] S101 specifically includes:

[0051] A finite element model of a simple curved stiffened shell was established based on the CAE platform.

[0052] S102, determine the control volume based on the geometric characteristics of a simple curved, stiffened shell. The control volume should encompass the geometric dimensions of the model to be deformed.

[0053] S103, set a corresponding number of control points along the length S, width T, and height U of the control body, and obtain the coordinate position information of the control points.

[0054] As a specific embodiment, l control points are set in the length S direction, m control points are set in the width T direction, and n control points are set in the height U direction. Then the coordinates of any control point can be expressed as ((i-1) / (l-1)*S, (j-1) / (m-1)*T, (k-1) / (n-1)*U), where i, j, and k represent the control point numbers along the length, width, and height, respectively, i = 1, 2, 3, ..., l, j = 1, 2, 3, ..., m, and k = 1, 2, 3, ..., n.

[0055] S104. Based on basis functions, establish the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell; the basis functions are Bernstein basis functions, B-spline basis functions, and NURBS basis functions.

[0056] S104 specifically includes:

[0057] Using formula Determine the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell.

[0058] Among them, X p For the finite element nodes of a simple curved surface stiffened shell finite element model, x p y p , z pThis provides the coordinate position information of the finite element nodes in the finite element model of a simple curved stiffened shell, where p = 1, 2, 3, ..., N, N is the number of finite element nodes in the finite element model of the simple curved stiffened shell, S is the length of the control body, T is the width of the control body, U is the height of the control body, l is the number of control points set along the length direction of the control body, m is the number of control points set along the width direction of the control body, n is the number of control points set along the height direction of the control body, and i, j, k represent the sequence numbers of the control points along the length, width, and height of the control body, respectively, i = 1, 2, 3, ..., l, j = 1, 2, 3, ..., m, k = 1, 2, 3, ..., n, R i Let R be the basis functions along the length direction. i =C l i (x p / S) i (1-(x p / S)) l-i R j Let R be the basis function along the width direction. j =C m j (y p / T) j (1-(y p / T)) m-j R k Let R be the basis function along the height direction. k =C n k (z p / U) k (1-(z p / U)) n-k M i,j,k This refers to the coordinate position information of the control points.

[0059] S105, establish a solid model based on the geometric features of the target surface in the target surface stiffened shell; and mesh the solid model to determine the target surface finite element model; the number of finite element nodes in the target surface finite element model is the same as the number of control points of the control body.

[0060] As a specific implementation, l-1, m-1, and n-1 local mesh seeds are set along the length, width, and height directions of the solid model, respectively, for mesh generation.

[0061] S106. Based on the coordinate position information of the finite element nodes of the target surface finite element model, determine the coordinate change of each control point in the control volume, and based on the coordinate change of each control point, use the free deformation method to determine the coordinate position information of the deformed control point.

[0062] Among them, the coordinate position information of the finite element nodes of the target surface finite element model is the final position to which the control point moves.

[0063] S107. Based on the mapping relationship and the coordinate position information of the control points after deformation, determine the coordinate position information of the finite element nodes after the free deformation of the finite element model of the simple curved surface stiffened shell, and then generate the target curved surface stiffened shell finite element model.

[0064] This invention uses saddle-surface reinforcement modeling as an example. The specific modeling process is as follows:

[0065] S1. In the CAE platform ABAQUS, create a finite element model of a planar stiffened shell. Its three-dimensional dimensions are 1000mm in length, 500mm in width, and 15mm in stiffener height. There are 10 stiffeners in both the horizontal and vertical directions. Mesh the model and create a finite element model with 11466 elements and 11300 nodes. Figure 2 As shown.

[0066] S2. A cuboid is chosen as the control volume for the finite element model of the planar stiffened shell. The length, width, and height of the control volume are 1000mm, 500mm, and 20mm, respectively. 6, 5, and 3 control points are set along the length, width, and height directions, respectively. That is, control points are spaced 200mm apart along the length, 125mm apart along the width, and 10mm apart along the height, for a total of 6*5*3 = 90 control points. The coordinates of any control point can be represented as M. i,j,k = ((i-1) / (6-1)*1000, (j-1) / (5-1)*500, (k-1) / (3-1)*20), where i, j, and k represent the ordinal numbers along the length, width, and height, respectively, i = 1, 2, 3, ..., 6, j = 1, 2, 3, ..., 5, k = 1, 2, 3, ..., 6. Figure 3 As shown.

[0067] S3, based on the finite element model, the coordinates X of all nodes can be obtained. p (x p y p , z p ), where p = 1, 2, 3, ..., N, where N is the number of finite element nodes, which is 11300 here. The coordinates of the control points M for the free deformation method are established by equation (1). i,j,k and the X coordinates of the node positions in the finite element model p Mapping relationship:

[0068]

[0069] Where R is the basis function, and in this embodiment, Bernstein basis functions are used to establish the mapping relationship. The basis function along the length direction is R. i =C l i (x p / S) i (1-(x p / S)) l-i The basis functions along the width direction are R. j =C m j (y p / T) j (1-(y p / T)) m-j The basis functions along the height direction are R. k =C n k (z p / U) k (1-(z p / U)) n-k ,

[0070] S4. Change the coordinates of the free deformation control points. Based on the saddle surface model information, establish a solid model of the saddle surface, and set 5, 4, and 2 local mesh seeds along the length, width, and height directions of the saddle surface model respectively to perform mesh generation. A schematic diagram of the finite element mesh model of the saddle surface is shown below. Figure 4 As shown, the number of finite element nodes is 90, consistent with the number of control points in the planar model. By changing the position coordinates of the control points in the free deformation method in the second step, and moving the position coordinates of the control points of each planar model to the corresponding finite element nodes of the complex curved surface finite element model, the difference in the change of the position coordinates of the control points before and after is ΔM. i,j,k Based on the mapping relationship established in S3, the change in the coordinates of the finite element node positions as the control points change is ΔX. p Equation (2) can be used to solve for the coordinates of the deformed finite element nodes, generating a complex surface stiffened model, which can then be used as the finite element model for subsequent optimization design, such as... Figure 5 As shown.

[0071]

[0072] This invention uses a saddle surface as an example. In finite element software, a parametric modeling script is established based on the platform language to automatically generate the finite element model. Then, a cuboid is selected as the control volume for the planar stiffened shell, and control points are set along the X, Y, and Z directions. Based on Bernstein basis functions, a mapping relationship is established between the coordinates of the free deformation control points and the coordinates of the nodes in the planar stiffened shell finite element model. Finally, by changing the coordinates of the free deformation control points, and based on the mapping relationship, the automatic generation of a complex curved surface stiffened model is achieved. The method proposed in this invention is simple to operate and facilitates subsequent structural optimization design.

[0073] Figure 6 A schematic diagram of a surface stiffened shell modeling system based on the free deformation method provided by the present invention is shown below. Figure 6 As shown, the present invention provides a surface stiffening shell modeling system based on the free deformation method, comprising:

[0074] The finite element model creation module 601 for simple curved stiffened shells is used to create finite element models of simple curved stiffened shells and obtain the coordinate position information of the corresponding finite element nodes; the simple curved surfaces include: planes, cylindrical surfaces and tori.

[0075] The control volume determination module 602 is used to determine the control volume based on the geometric characteristics of a simple curved surface stiffened shell.

[0076] The control point determination module 603 is used to set a corresponding number of control points along the length, width and height of the control body, and to obtain the coordinate position information of the control points.

[0077] The mapping relationship establishment module 604 is used to establish a mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points of a finite element model of a simple curved stiffened shell based on basis functions; the basis functions are Bernstein basis functions, B-spline basis functions, and NURBS basis functions.

[0078] The target surface finite element model determination module 605 is used to establish a solid model based on the geometric features of the target surface in the target surface stiffened shell; and to perform mesh generation on the solid model to determine the target surface finite element model; the number of finite element nodes in the target surface finite element model is the same as the number of control points of the control body;

[0079] The control point movement module 606 determines the coordinate change of each control point in the control body based on the coordinate position information of the finite element nodes of the target surface finite element model, and determines the coordinate position information of the deformed control point by using the free deformation method based on the coordinate change of each control point.

[0080] The target surface stiffened shell finite element model generation module 607 determines the finite element node coordinate position information after free deformation of the finite element model of the simple surface stiffened shell based on the mapping relationship and the coordinate position information of the control points after deformation, and then generates the target surface stiffened shell finite element model.

[0081] The finite element model establishment module 601 for the simple curved stiffened shell specifically includes:

[0082] This is a finite element modeling unit for simple curved stiffened shells, used to build finite element models of simple curved stiffened shells based on a CAE platform.

[0083] The mapping relationship establishment module 604 specifically includes:

[0084] The mapping relationship establishment unit is used to establish mapping relationships using formulas. Determine the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell;

[0085] Among them, X p For the finite element nodes of a simple curved surface stiffened shell finite element model, x p y p , z p This provides the coordinate position information of the finite element nodes in the finite element model of a simple curved stiffened shell, where p = 1, 2, 3, ..., N, N is the number of finite element nodes in the finite element model of the simple curved stiffened shell, S is the length of the control body, T is the width of the control body, U is the height of the control body, l is the number of control points set along the length direction of the control body, m is the number of control points set along the width direction of the control body, n is the number of control points set along the height direction of the control body, and i, j, k represent the sequence numbers of the control points along the length, width, and height of the control body, respectively, i = 1, 2, 3, ..., l, j = 1, 2, 3, ..., m, k = 1, 2, 3, ..., n, R i Let R be the basis functions along the length direction. i =C l i (x p / S) i (1-(x p / S)) l-i R j Let R be the basis function along the width direction. j =C m j (y p / T) j (1-(y p / T)) m-j R k Let R be the basis function along the height direction. k =Cn k (z p / U) k (1-(z p / U)) n-k M i,j,k This refers to the coordinate position information of the control points.

[0086] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0087] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for modeling stiffened shells based on free deformation, characterized in that, include: Establish a finite element model of a simple curved stiffened shell and obtain the coordinate position information of the corresponding finite element nodes; Simple curved surfaces include: planes, cylindrical surfaces, and tori. The control volume is determined based on the geometric characteristics of a simple curved stiffened shell; A corresponding number of control points are set along the length, width, and height of the control body, and the coordinate position information of the control points is obtained. Based on basis functions, a mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points is established for a finite element model of a simple curved stiffened shell. A solid model is established based on the geometric characteristics of the target surface in the stiffened shell; and the solid model is meshed to determine the finite element model of the target surface; the number of finite element nodes in the finite element model of the target surface is the same as the number of control points of the control body; Based on the coordinate position information of the finite element nodes of the target surface finite element model, determine the coordinate change of each control point in the control volume, and based on the coordinate change of each control point, use the free deformation method to determine the coordinate position information of the deformed control point. Based on the mapping relationship and the coordinate position information of the control points after deformation, the coordinate position information of the finite element nodes after the free deformation of the finite element model of the simple curved surface stiffened shell is determined, and then the target curved surface stiffened shell finite element model is generated. The mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell, based on basis functions, specifically includes: Using formula Determine the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell; Among them, X p For the finite element nodes of a simple curved surface stiffened shell finite element model, x p y p , z p This provides the coordinate position information of the finite element nodes in the finite element model of a simple curved stiffened shell, where p = 1, 2, 3, ..., N, N is the number of finite element nodes in the finite element model of the simple curved stiffened shell, S is the length of the control body, T is the width of the control body, U is the height of the control body, l is the number of control points set along the length direction of the control body, m is the number of control points set along the width direction of the control body, n is the number of control points set along the height direction of the control body, and i, j, k represent the sequence numbers of the control points along the length, width, and height of the control body, respectively, i = 1, 2, 3, ..., l, j = 1, 2, 3, ..., m, k = 1, 2, 3, ..., n, R i Let R be the basis functions along the length direction. i =C l i (x p / S) i (1-(x p / S)) l-i R j Let R be the basis function along the width direction. j =C m j (y p / T) j (1-(y p / T)) m-j R k Let R be the basis function along the height direction. k =C n k (z p / U) k (1-(z p / U)) n-k M i,j,k This refers to the coordinate position information of the control points.

2. The method for modeling stiffened shells based on free deformation according to claim 1, characterized in that, The establishment of a finite element model of a simple curved stiffened shell and the acquisition of the coordinate position information of the corresponding finite element nodes specifically include: A finite element model of a simple curved stiffened shell was established based on the CAE platform.

3. The method for modeling stiffened shells based on free deformation according to claim 1, characterized in that, The basis functions are Bernstein basis functions, B-spline basis functions, and NURBS basis functions.

4. A surface stiffened shell modeling system based on the free deformation method, characterized in that, include: The finite element model building module for simple curved stiffened shells is used to build finite element models of simple curved stiffened shells and obtain the coordinate position information of the corresponding finite element nodes. Simple curved surfaces include: planes, cylindrical surfaces, and tori. The control volume determination module is used to determine the control volume based on the geometric characteristics of a simple curved stiffened shell; The control point determination module is used to set a corresponding number of control points along the length, width, and height of the control body, and to obtain the coordinate position information of the control points. The mapping relationship establishment module is used to establish the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell based on the basis function. The target surface finite element model determination module is used to establish a solid model based on the geometric characteristics of the target surface in the target surface stiffened shell; and to perform mesh generation on the solid model to determine the target surface finite element model; the number of finite element nodes in the target surface finite element model is the same as the number of control points of the control body; The control point movement module is used to determine the coordinate change of each control point in the control body based on the coordinate position information of the finite element nodes of the target surface finite element model, and to determine the coordinate position information of the deformed control point using the free deformation method based on the coordinate change of each control point. The target surface stiffened shell finite element model generation module is used to determine the finite element node coordinate position information after free deformation of the finite element model of the simple surface stiffened shell according to the mapping relationship and the coordinate position information of the control points after deformation, and then generate the target surface stiffened shell finite element model. The mapping relationship establishment module specifically includes: The mapping relationship establishment unit is used to establish mapping relationships using formulas. Determine the mapping relationship between the coordinate position information of finite element nodes and the coordinate position information of control points in the finite element model of a simple curved stiffened shell; Among them, X p For the finite element nodes of a simple curved surface stiffened shell finite element model, x p y p , z p This provides the coordinate position information of the finite element nodes in the finite element model of a simple curved stiffened shell, where p = 1, 2, 3, ..., N, N is the number of finite element nodes in the finite element model of the simple curved stiffened shell, S is the length of the control body, T is the width of the control body, U is the height of the control body, l is the number of control points set along the length direction of the control body, m is the number of control points set along the width direction of the control body, n is the number of control points set along the height direction of the control body, and i, j, k represent the sequence numbers of the control points along the length, width, and height of the control body, respectively, i = 1, 2, 3, ..., l, j = 1, 2, 3, ..., m, k = 1, 2, 3, ..., n, R i Let R be the basis functions along the length direction. i =C l i (x p / S) i (1-(x p / S)) l-i R j Let R be the basis function along the width direction. j =C m j (y p / T) j (1-(y p / T)) m-j R k Let R be the basis function along the height direction. k =C n k (z p / U) k (1-(z p / U)) n-k M i,j,k This refers to the coordinate position information of the control points.

5. A surface stiffened shell modeling system based on the free deformation method according to claim 4, characterized in that, The finite element model building module for the simple curved stiffened shell specifically includes: This is a finite element modeling unit for simple curved stiffened shells, used to build finite element models of simple curved stiffened shells based on a CAE platform.

6. The surface stiffened shell modeling system based on the free deformation method according to claim 4, characterized in that, The basis functions are Bernstein basis functions, B-spline basis functions, and NURBS basis functions.

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