A flutter constraint-based optimization design method for wing-jointed structures

Abstract

The present invention belongs to the field of aircraft structure design, and discloses a connecting wing structure optimization design method based on flutter constraints. The connecting wing structure optimization design method based on flutter constraints of the present invention includes determining the connecting wing structure design variables; determining the connecting wing structure performance evaluation index and establishing optimization criteria; establishing a preliminary design scheme for the connecting wing structure and performing finite element analysis; performing connecting wing structure optimization; and carrying out three-dimensional structural design of the connecting wing structure. The connecting wing structure optimization design method based on flutter constraints of the present invention comprehensively considers the connecting wing structure layout parameters, size parameters, target quality parameters, composite material layup parameters, and flutter critical speed parameters, and has high design efficiency and success rate, and has theoretical research and application value.

Description

Technical Field

[0001] The invention belongs to the field of aircraft structure design, and in particular relates to a connecting wing structure optimization design method based on flutter constraints. Background Art

[0002] A connected wing layout aircraft refers to an aircraft layout configuration in which the swept front wing and the swept rear wing are connected to form a diamond frame structure. From the front view and the top view, the connected wing frames are diamond-shaped projections, and the fuselage is the connecting diagonal of the diamond frame. The connected wing layout has the characteristics of light structural weight, small induced drag, and high maximum lift coefficient when trimmed. It is a very competitive layout form for aircraft with long flight time or long range design requirements.

[0003] Due to the interdependence between its unique aerodynamic shape and structural topology, the aircraft with a connected wing layout will show a significant aeroelastic coupling effect during flight. Its critical flutter speed is closely related to the front and rear sweep angles, connection positions, composite layer shearing methods, modal vibration shapes, mass distribution, etc. of the front and rear wings. The substantial increase in design variables has put forward higher requirements for the structural design of the connected wing. The conventional design method is to design the structure such as size, structural form and composite layer according to the given layout, and then check the critical flutter speed. If it is found that the structure that meets the requirements cannot be designed during the size and composite design stage, the wing structure layout needs to be revised. This design method leads to problems such as long design cycle and high cost.

[0004] In order to reduce the design time of the connecting wing structure, it is urgent to develop a connecting wing structure optimization design method based on flutter constraints. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for optimizing the design of a connecting wing structure based on flutter constraints, so as to overcome the defects of the prior art.

[0006] The flutter-constrained connecting wing structure optimization design method of the present invention comprises the following steps:

[0007] S10. Determine the design variables of the connecting wing structure;

[0008] According to the design objectives of the connecting wing structure, the design variables of the connecting wing structure are determined; the design variables of the connecting wing structure include the connecting wing structure layout parameters, structure size parameters and composite material layer parameters;

[0009] S20. Determine the performance evaluation index of the connecting wing structure and establish the optimization criteria;

[0010] The evaluation indexes of the connecting wing structure performance include the first four modal parameters, flutter velocity, maximum stress and strain;

[0011] Establish optimization criteria for connecting wing structure;

[0012] S30. Establish a preliminary design scheme for the connecting wing structure and conduct finite element analysis;

[0013] According to the value range of each connecting wing structure design variable, a preliminary design scheme of the connecting wing structure with similar structural dynamic characteristics is established, and a finite element analysis is performed on the preliminary design scheme of the connecting wing structure to obtain various performance index data of the preliminary design scheme of the connecting wing structure;

[0014] S40. Optimize the connecting wing structure;

[0015] The static-modal-flutter joint optimization process of the connecting wing structure is established by using the optimization workflow software and finite element analysis software. The optimization criteria and flutter critical speed parameters are used as constraints, and the multi-parameter and multi-objective optimization algorithm is used to optimize the connecting wing structure. The optimization objectives are to ensure that the maximum stress and strain, modal frequency and vibration shape, and model flutter speed of the connecting wing structure meet the design objectives of the connecting wing structure at the same time.

[0016] S50. Carry out three-dimensional structural design of the connecting wing structure.

[0017] Furthermore, the optimization criterion is based on the premise of similar stiffness, that is, the flexibility coefficient matrix of the connecting wing structure is and the target flexibility matrix Similar; before stiffness optimization, the material density in the connecting wing structure is assigned to 0, and the model mass directly uses the target mass parameter. After the stiffness optimization is completed, the mass optimization is performed according to each partition; when performing stiffness optimization, the function of the design variable or the function of the structural response is used as the mathematical target of optimization;

[0018] The optimization criteria are as follows:

[0019] ①Flexibility coefficient matrix of the model and the target flexibility matrix The ratio of the diagonal items of is the same, and the mathematical expression is:

[0020] ;

[0021] in, is the diagonal error parameter of the flexibility coefficient matrix; is the diagonal flexibility coefficient, is the diagonal target flexibility coefficient, is the displacement direction and force direction on the diagonal line;

[0022] ② Solve the error average of all items in the flexibility coefficient matrix. The mathematical expression is:

[0023] ;

[0024] in, is the error parameter of all items in the flexibility coefficient matrix; is the flexibility coefficient, is the target flexibility coefficient, is the direction of displacement and the direction of applied force;

[0025] ③Frequency similarity criterion, the mathematical expression is:

[0026] ;

[0027] in, is the frequency error parameter, is the model frequency, is the target frequency, is the frequency order;

[0028] ④ Mode similarity criterion is achieved by setting the modal confidence coefficient, and the mathematical expression is:

[0029] ;

[0030] in, is the vibration mode error parameter, is the model vibration shape vector, is the target vibration mode vector, Represents matrix transpose.

[0031] Furthermore, the multi-parameter and multi-objective optimization algorithm is a multi-island genetic algorithm.

[0032] The flutter-constrained connecting wing structure optimization design method of the present invention comprehensively considers the connecting wing structure layout parameters, size parameters, target mass parameters, composite material layup parameters, and flutter critical speed parameters, and constructs a collaborative optimization framework for aeroelasticity, structural strength, and dynamic characteristics in the connecting wing structure design by integrating parametric modeling technology and multi-objective optimization strategies. It breaks through the limitations of traditional single-discipline optimization, realizes the systematic matching of structural layout, composite material layup scheme, and flutter characteristics, significantly improves the design efficiency and scheme reliability, can avoid potential aeroelastic instability risks in the early stages of design, greatly shortens the iteration cycle of complex airfoil structures, and reduces reliance on empirical trial and error. It provides a highly versatile solution for the design of aircraft connecting wing structures, expands the optimization dimension of composite material applications while ensuring flutter safety, and plays an important role in promoting the lightweight and high-performance development of aviation equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a flow chart of the method for optimizing the design of the connecting wing structure based on flutter constraints. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0035] Example: Figure 1 As shown, the flutter constraint-based connecting wing structure optimization design method of this embodiment includes the following steps:

[0036] S10. Determine the design variables of the connecting wing structure;

[0037] According to the design objectives of the connecting wing structure, the design variables of the connecting wing structure are determined; the design variables of the connecting wing structure include the connecting wing structure layout parameters, structure size parameters and composite material layer parameters;

[0038] S20. Determine the performance evaluation index of the connecting wing structure and establish the optimization criteria;

[0039] The evaluation indexes of the connecting wing structure performance include the first four modal parameters, flutter velocity, maximum stress and strain;

[0040] Establish optimization criteria for connecting wing structure;

[0041] S30. Establish a preliminary design scheme for the connecting wing structure and conduct finite element analysis;

[0042] According to the value range of each connecting wing structure design variable, a preliminary design scheme of the connecting wing structure with similar structural dynamic characteristics is established, and a finite element analysis is performed on the preliminary design scheme of the connecting wing structure to obtain various performance index data of the preliminary design scheme of the connecting wing structure;

[0043] S40. Optimize the connecting wing structure;

[0044] The static-modal-flutter joint optimization process of the connecting wing structure is established by using the optimization workflow software and finite element analysis software. The optimization criteria and flutter critical speed parameters are used as constraints, and the multi-parameter and multi-objective optimization algorithm is used to optimize the connecting wing structure. The optimization objectives are to ensure that the maximum stress and strain, modal frequency and vibration shape, and model flutter speed of the connecting wing structure meet the design objectives of the connecting wing structure at the same time.

[0045] S50. Carry out three-dimensional structural design of the connecting wing structure.

[0046] Furthermore, the optimization criterion is based on the premise of similar stiffness, that is, the flexibility coefficient matrix of the connecting wing structure is and the target flexibility matrix Similar; before stiffness optimization, the material density in the connecting wing structure is assigned to 0, and the model mass directly uses the target mass parameter. After the stiffness optimization is completed, the mass optimization is performed according to each partition; when performing stiffness optimization, the function of the design variable or the function of the structural response is used as the mathematical target of optimization;

[0047] The optimization criteria are as follows:

[0048] ①Flexibility coefficient matrix of the model and the target flexibility matrix The ratio of the diagonal items of is the same, and the mathematical expression is:

[0049] ;

[0050] in, is the diagonal error parameter of the flexibility coefficient matrix; is the diagonal flexibility coefficient, is the diagonal target flexibility coefficient, is the displacement direction and force direction on the diagonal line;

[0051] ② Solve the error average of all items in the flexibility coefficient matrix. The mathematical expression is:

[0052] ;

[0053] in, is the error parameter of all items in the flexibility coefficient matrix; is the flexibility coefficient, is the target flexibility coefficient, is the direction of displacement and the direction of applied force;

[0054] ③Frequency similarity criterion, the mathematical expression is:

[0055] ;

[0056] in, is the frequency error parameter, is the model frequency, is the target frequency, is the frequency order;

[0057] ④ Mode similarity criterion is achieved by setting the modal confidence coefficient, and the mathematical expression is:

[0058] ;

[0059] in, is the vibration mode error parameter, is the model vibration shape vector, is the target vibration mode vector, Represents matrix transpose.

[0060] Furthermore, the multi-parameter and multi-objective optimization algorithm is a multi-island genetic algorithm.

[0061] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. For those familiar with the art, without departing from the principles of the present invention, all features disclosed in the present invention, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for optimizing the design of a connecting wing structure based on flutter constraints, characterized in that: The following steps are involved: S10. Determine the design variables of the connecting wing structure; According to the design objectives of the connecting wing structure, the design variables of the connecting wing structure are determined; The design variables of the connecting wing structure include the connecting wing structure layout parameters, structure size parameters and composite material layer parameters; S20. Determine the performance evaluation index of the connecting wing structure and establish the optimization criteria; The evaluation indexes of the connecting wing structure performance include the first four modal parameters, flutter velocity, maximum stress and strain; Establish optimization criteria for connecting wing structure; The premise of the optimization criterion is the similarity of stiffness, that is, the flexibility coefficient matrix of the connecting wing structure is and the target flexibility matrix Similar; before stiffness optimization, the material density in the connecting wing structure is assigned to 0, and the model mass directly uses the target mass parameter. After the stiffness optimization is completed, the mass optimization is performed according to each partition; when performing stiffness optimization, the function of the design variable or the function of the structural response is used as the mathematical target of optimization; The optimization criteria are as follows: ①Flexibility coefficient matrix of the model and the target flexibility matrix The ratio of the diagonal items of is the same, and the mathematical expression is: ； in, is the diagonal error parameter of the flexibility coefficient matrix; is the diagonal flexibility coefficient, is the diagonal target flexibility coefficient, is the displacement direction and force direction on the diagonal line; ② Solve the error average of all items in the flexibility coefficient matrix. The mathematical expression is: ； in, is the error parameter of all items in the flexibility coefficient matrix; is the flexibility coefficient, is the target flexibility coefficient, is the direction of displacement and the direction of applied force; ③Frequency similarity criterion, the mathematical expression is: ； in, is the frequency error parameter, is the model frequency, is the target frequency, is the frequency order; ④ Mode similarity criterion is achieved by setting the modal confidence coefficient, and the mathematical expression is: ； in, is the vibration mode error parameter, is the model vibration shape vector, is the target vibration mode vector, Represents matrix transpose; S30. Establish a preliminary design scheme for the connecting wing structure and conduct finite element analysis; According to the value range of each connecting wing structure design variable, a preliminary design scheme of the connecting wing structure with similar structural dynamic characteristics is established, and a finite element analysis is performed on the preliminary design scheme of the connecting wing structure to obtain various performance index data of the preliminary design scheme of the connecting wing structure; S40. Optimize the connecting wing structure; The static-modal-flutter joint optimization process of the connecting wing structure is established by using the optimization workflow software and finite element analysis software. The optimization criteria and flutter critical speed parameters are used as constraints, and the multi-parameter and multi-objective optimization algorithm is used to optimize the connecting wing structure. The optimization objectives are to ensure that the maximum stress and strain, modal frequency and vibration shape, and model flutter speed of the connecting wing structure meet the design objectives of the connecting wing structure at the same time. S50. Carry out three-dimensional structural design of the connecting wing structure.

2. The method for optimizing the design of a connecting wing structure based on flutter constraints according to claim 1, characterized in that: The multi-parameter multi-objective optimization algorithm is a multi-island genetic algorithm.

Images