Topology optimization method of unidirectional fiber reinforced composites based on variable stiffness components

Abstract

The present invention provides a unidirectional fiber reinforced composite material topology optimization method based on a variable stiffness component, the method includes setting the parameters of the composite material, the description function of the component and the optimization environment; calculating the unit stiffness matrix of the composite material of each component under the unidirectional fiber laying angle based on the parameters of the composite material and in combination with the angle variable in the description function of the component; allocating the unit stiffness matrix based on the unit description value, and assembling to obtain the overall stiffness matrix; setting the optimization target and constraint conditions of the unidirectional fiber reinforced composite material, and constructing a unidirectional fiber reinforced composite material topology optimization model based on the variable stiffness component based on the optimization target and constraint conditions; solving the sensitivity of the optimization target and constraint conditions, and judging whether the termination condition is met, and if so, outputting the optimization result. The present invention can greatly reduce the optimization variables, and while effectively and efficiently optimizing the efficiency of large structures, its optimized structure is also easy to actually manufacture.

Description

Technical Field

[0001] The invention relates to the technical field of topology optimization, and in particular to a topology optimization method for a unidirectional fiber reinforced composite material based on a variable stiffness component. Background Art

[0002] Unidirectional fiber reinforced composite materials are widely used due to their large design freedom, excellent mechanical properties, and strong fatigue resistance. Compared with traditional single-phase materials, unidirectional fiber reinforced composite materials can improve structural performance without changing the structural configuration and weight through variable stiffness optimization design. The variable stiffness optimization design of unidirectional fiber reinforced composite materials is based on analyzing the structural load-bearing conditions, distributing the corresponding parts of the structure at the optimal fiber angle, so as to give full play to the performance of the fiber reinforcement.

[0003] In the existing technology, traditional variable stiffness optimization often uses finite element units as the basic optimization units. Although this method can increase the designability of materials, it is extremely sensitive to the number of finite elements. As a result, when dealing with large structures, the variable stiffness optimization efficiency of unidirectional fiber reinforced composite materials is low due to the huge number of finite element units. In addition, in the optimized structure, a large number of adjacent unit optimizations are often presented with fiber designs at different angles. Such changes in the angles of small unit fibers are difficult to manufacture in reality, and have low engineering applicability and guidance. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide a topology optimization method for unidirectional fiber reinforced composite materials based on variable stiffness components to solve the deficiencies in the above-mentioned prior art.

[0005] The present invention provides a topology optimization method for a unidirectional fiber reinforced composite material based on a variable stiffness component, the method comprising:

[0006] Set the parameters of the composite material, the component description function and the optimization environment;

[0007] Calculating the unit stiffness matrix of the composite material of each component at the unidirectional fiber laying angle based on the parameters of the composite material and in combination with the angle variable in the description function of the component;

[0008] Calculating the unit description value of the unit under the description function of each component, and allocating the unit stiffness matrix based on the unit description value, and assembling to obtain the overall stiffness matrix;

[0009] Setting optimization objectives and constraints of the unidirectional fiber reinforced composite material, and constructing a topology optimization model of the unidirectional fiber reinforced composite material based on a variable stiffness component based on the optimization objectives and constraints;

[0010] Solve the optimization objective and the sensitivity of the constraint conditions, and determine whether the termination condition is met. If so, output the optimization result.

[0011] Compared with the prior art, the beneficial effects of the present invention are: by setting the stiffness matrix of the component according to the unidirectional fiber laying angle of the component, and by using the unidirectional fiber reinforced composite material topology optimization model based on the variable stiffness component, the laying direction of the limiting reinforcement body in the component conforms to the structural configuration, which not only can greatly reduce the optimization variables, but also effectively improve the optimization efficiency when facing large structures, and the optimized structure is also easy to actually manufacture.

[0012] Furthermore, the steps of setting the parameters of the composite material, the description function of the component and the optimization environment include:

[0013] Set the elastic modulus, shear modulus and Poisson's ratio parameters of unidirectional fiber reinforced composite materials measured under each axis system;

[0014] Describe the function expression of the component's geometry in the design domain, the function expression of its position, the function expression of its angle information, the load constraints during optimization, and the finite element information.

[0015] Furthermore, the step of calculating the unit stiffness matrix of the composite material of each component at the unidirectional fiber laying angle based on the parameters of the composite material and in combination with the angle variable in the description function of the component includes:

[0016] Extract different unidirectional fiber laying angle information of all components in the design domain, and calculate the equivalent stiffness matrix of unidirectional fiber reinforced composite materials under various angle information;

[0017] The calculation expression of the equivalent stiffness matrix of the unidirectional fiber reinforced composite material is:

[0018] ;

[0019] in:

[0020] ;

[0021] ;

[0022] ;

[0023] In the formula, for The equivalent stiffness matrix under the angle, is the area occupied by the unit, is the component angle, B is the strain displacement matrix, is the transpose of the strain displacement matrix, for The transformation matrix under the angle, for The inverse matrix of the transformation matrix under the angle, for The equivalent elastic matrix under the angle, D 0 is the elastic matrix in the main direction of the material, E 1 and E 2 represents the elastic modulus of the material in the longitudinal and transverse directions respectively, and denote the Poisson's ratio in the longitudinal and transverse directions respectively, G 12 is the shear modulus of the material.

[0024] Furthermore, the steps of calculating the unit description value of the unit under the description function of each component, allocating the unit stiffness matrix based on the unit description value, and assembling to obtain the overall stiffness matrix include:

[0025] Calculate the unit description value of the unit under the description function of each component, and determine whether there is a value greater than zero among all the unit description values;

[0026] If yes, then find the angle information of the description function of the component corresponding to the maximum unit description value, and assign the unit stiffness matrix to the corresponding unit based on the angle information, the equivalent stiffness matrix calculation formula and the allocation rule;

[0027] All the units that are assigned unit stiffness matrices are assembled into an overall stiffness matrix to obtain an overall stiffness matrix.

[0028] Furthermore, the expression of the unit description value of the computing unit under the description function of each component is:

[0029]

[0030] In the formula, Representation unit i In the component j The unit description value size under the description function is n represents the number of unit nodes, Representation Components j The description function of Representation unit i No. s Node coordinates;

[0031] The expression of the allocation rule is:

[0032] ;

[0033] ;

[0034] In the formula, express N The maximum unit description value corresponding to each component, Indicates from component 1 to component N The description value of each component unit, Indicates the number of components, Representation unit i The maximum description value corresponds to the component number, Representation Components p The corresponding angle information, Representation unit i The element stiffness matrix of D 0 is the elastic matrix in the main direction of the material, B is the strain displacement matrix, is the area occupied by the unit, is the transpose of the strain displacement matrix, Indicates that the material Component corresponding angle The equivalent elastic matrix under ;

[0035] The assembly rule expression for assembling the overall stiffness matrix of all the units assigned with the unit stiffness matrix is:

[0036]

[0037] in:

[0038] ;

[0039] In the formula, Represents the global stiffness matrix coordinate index i The value of M represents the total number of finite element elements in the design domain, n represents the number of unit nodes, for Heaviside function, represents the regularization parameter, represents a very small positive number, Representation unit j No. s The node coordinates, Representation unit j The corresponding component description function, Representation unit j The stiffness matrix is ​​at the coordinate index i If it does not exist, it is 0. Indicates the descriptive value of the input.

[0040] Furthermore, the expression of the topology optimization model of the unidirectional fiber reinforced composite material based on the variable stiffness component is:

[0041] ;

[0042] In the formula, Descriptor function variables representing all components, Indicates from component 1 to component The description function variables of each component of Indicates the number of components, represents the selected objective function, Indicates the setting I An optimization goal, represents the global stiffness matrix, represents the displacement of each node in the design domain, represents the external force vector, Indicates the actual constraints of the structure. represents the structural constraints, represents the feasible domain of component variables, represents the displacement field, Denotes the Dirichlet frontier A given displacement on .

[0043] Furthermore, the step of solving the optimization objective and the sensitivity of the constraint condition includes:

[0044] The calculation parameters of the corresponding optimization target are obtained to solve the target, and the sensitivity of the objective function under each component variable is calculated to update the component parameters for the next iteration.

[0045] Furthermore, after the step of determining whether the termination condition is met, the method further includes:

[0046] If not, then repeatedly calculate the unit stiffness matrix of the composite material of each component under the unidirectional fiber laying angle based on the parameters of the composite material and in combination with the angle variables in the description function of the component, calculate the unit description value of the unit under the description function of each component, and allocate the unit stiffness matrix based on the unit description value, and assemble to obtain the overall stiffness matrix, set the optimization target and constraints of the unidirectional fiber reinforced composite material, and construct a unidirectional fiber reinforced composite material topology optimization model based on variable stiffness components based on the optimization target and the constraints, solve the sensitivity of the optimization target and the constraints, until the termination condition is met, so as to output the optimization result. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a flow chart of a topology optimization method for a unidirectional fiber reinforced composite material based on a variable stiffness component in an embodiment of the present invention;

[0048] Figure 2 It is a schematic diagram of the design of a variable stiffness component in an embodiment of the present invention;

[0049] Figure 3 A schematic diagram of a structural design domain in an embodiment of the present invention;

[0050] Figure 4 is a schematic diagram of initial component distribution in an embodiment of the present invention;

[0051] Figure 5 Schematic diagram of the final optimized structure of the unidirectional fiber reinforced composite structure with variable stiffness components. Figure 5 (a) is a schematic diagram of the optimization results. Figure 5 (b) is a schematic diagram of the control optimization results;

[0052] Figure 6 Schematic diagram of the internal fiber orientation. Figure 6 (a) is a schematic diagram of the fiber orientation of the optimized result profile. Figure 6 (b) is a schematic diagram of the fiber orientation in the cross section of the control optimization result.

[0053] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0054] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0055] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0057] See also Figure 1, which shows a topology optimization method for a unidirectional fiber reinforced composite material based on a variable stiffness component in an embodiment of the present invention, and the method comprises steps S1 to S5:

[0058] S1, setting the parameters of the composite material, the component description function and the optimization environment;

[0059] Specifically, the step S1 includes steps S11 to S12:

[0060] S11, setting the elastic modulus, shear modulus and Poisson's ratio parameters of the unidirectional fiber reinforced composite material measured under each axis system;

[0061] S12, describing the function expression of the geometry of the component in the design domain, the function expression of the position, the function expression of the angle information, the load constraints during optimization, and the finite element information;

[0062] It can be understood that the parameters of the optimized unidirectional fiber reinforced composite material, the description function of the component and the optimization environment are set. In this embodiment, the design schematic diagram of the variable stiffness component is as shown in Figure 2 As shown, in this embodiment, the fibers in the cross section of the unidirectional fiber reinforced composite material are evenly distributed, and it is a transversely isotropic material. Without loss of generality, the parameters set are E 1=175Gpa, E 2=32Gpa, G 12 =12Gpa, =0.25, =0.31, the optimization environment takes the cantilever beam structure as an example, the length, width and height of the design domain are set to 15, 0.8 and 5 respectively, and the design domain is divided into finite element meshes, and the meshes in the length, width and height directions are divided into 150×8×50, the unit is set to an eight-node unit, and a 1N vertical downward load is set at the middle node of the lower right edge of the design domain, and all nodes on the left side of the design domain are fully constrained, as shown in the following example. Figure 3 As shown, in this embodiment, the description function of the component is in the form of a superelliptic equation, and the expression is:

[0063] ;

[0064] in:

[0065] ;

[0066] In the formula, A description function representing a component, represents the three-dimensional coordinates in the global coordinate system, Represents the three-dimensional coordinates in the component's local coordinate system. Respectively represent the three-dimensional coordinates of the component center in the global coordinate system, is the component angle.

[0067] By designing component variables, including component half-length l , half width t and half-height h ,angle And the component center coordinates , substituting into the component description function presents the initial component distribution in the design domain, such as Figure 4 As shown, the number of components is 12. In the initial component distribution, the center coordinates of every two components are the same and they are arranged cross-symmetrically. The half length, half width and half height of the components are set to 2.8, 0.35 and 0.43 respectively, and the component angle is = ±26.7°, the center of the component is Figure 4 The intersection position of the middle component.

[0068] S2, calculating the unit stiffness matrix of the composite material of each component under the unidirectional fiber laying angle based on the parameters of the composite material and in combination with the angle variable in the description function of the component;

[0069] Specifically, the step S2 includes step S21:

[0070] S21, extracting different unidirectional fiber laying angle information of all components in the design domain, and calculating the equivalent stiffness matrix of the unidirectional fiber reinforced composite material under each angle information;

[0071] It can be understood that to calculate the unit stiffness matrix of the unidirectional fiber reinforced composite material at each component angle, the material elastic and shear modulus parameters are first E 1. E 2. G 12 and Poisson's ratio , Substitute into the elasticity matrix D 0 Calculate the elastic matrix of the main direction of the unidirectional fiber reinforced composite material. The expression of the elastic matrix of the material in the main direction is:

[0072] ;

[0073] In the formula, D 0 is the elastic matrix in the main direction of the material, E 1 and E 2 represents the elastic modulus of the material in the longitudinal and transverse directions respectively, and denote the Poisson's ratio in the longitudinal and transverse directions respectively, G 12 is the shear modulus of the material;

[0074] Then bring different component angle variables into the transformation matrix The initial component angle can be calculated = ±26.7° Transformation Matrix and In this embodiment, the specific expression of the conversion matrix is:

[0075] ;

[0076] In the formula, is the transformation matrix, is the component angle.

[0077] The equivalent elastic matrix is ​​obtained by combining the main direction elastic matrix of the unidirectional fiber reinforced composite material with the angle. The calculation expression is:

[0078] ;

[0079] In the formula, for The equivalent elastic matrix under the angle, for The transformation matrix under the angle, for The inverse matrix of the transformation matrix under the angle, D 0 is the elastic matrix in the main direction of the material;

[0080] Then, the equivalent elastic matrix is ​​substituted into the unit stiffness matrix calculation formula to obtain the unit stiffness matrix of the unidirectional fiber reinforced composite material at the corresponding component angle. and In this embodiment, the calculation formula of the unit stiffness matrix is ​​expressed as:

[0081] ;

[0082] In the formula, for The equivalent stiffness matrix under the angle, B is the strain displacement matrix, is the transpose of the strain displacement matrix, The area occupied by the unit.

[0083] S3, calculating the unit description value of the unit under the description function of each component, and allocating the unit stiffness matrix based on the unit description value, and assembling to obtain the overall stiffness matrix;

[0084] Specifically, the step S3 includes steps S31 to S33:

[0085] S31, calculating the unit description value of the unit under the description function of each component, and determining whether there is a value greater than zero among all the unit description values;

[0086] S32, if yes, then searching for the angle information of the description function of the component corresponding to the maximum unit description value, and assigning the unit stiffness matrix to the corresponding unit based on the angle information, the equivalent stiffness matrix calculation formula and the allocation rule;

[0087] S33, assembling the overall stiffness matrix of all the units assigned with the unit stiffness matrix to obtain the overall stiffness matrix;

[0088] It can be understood that the element stiffness matrix is ​​assigned and the global stiffness matrix is ​​assembled according to the component variables W i = ,in, W i Representation Components i variables, Represented as components i The half-length, half-width and half-height of Representation Components i The center coordinates in the global coordinate system, Representation Components i From the perspective of , each unit in the design domain is substituted into each component description function to calculate the unit description value. The calculation expression of the unit description value is:

[0089]

[0090] In the formula, Representation unit i In the component j The unit description value size under the description function is n represents the number of unit nodes, Representation Components j The description function of Representation unit i No. s It is worth noting that in this embodiment, it is an eight-node unit, that is, n =8;

[0091] After calculating the unit description values ​​of all components, the unit stiffness matrix is ​​allocated. The allocation rule is expressed as:

[0092] ;

[0093] ;

[0094] In the formula, express NThe maximum unit description value corresponding to each component, Indicates from component 1 to component N The description value of each component unit, Indicates the number of components, Representation unit i The maximum description value corresponds to the component number, Representation Components p The corresponding angle information, Representation unit i The element stiffness matrix of D 0 is the elastic matrix in the main direction of the material, B is the strain displacement matrix, is the area occupied by the unit, is the transpose of the strain displacement matrix, Indicates that the material Component corresponding angle The equivalent elastic matrix under ;

[0095] After the unit stiffness matrix of each unit in the design domain is distributed, the overall stiffness matrix is ​​assembled. The expression of the overall stiffness matrix assembly rule is:

[0096]

[0097] in:

[0098] ;

[0099] In the formula, Represents the global stiffness matrix coordinate index i The value of M represents the total number of finite element elements in the design domain, n represents the number of unit nodes, for Heaviside function, represents the regularization parameter, represents a very small positive number, Representation unit j No. s The node coordinates, Representation unit j The corresponding component description function, Representation unit j The stiffness matrix is ​​at the coordinate index i If it does not exist, it is 0. Indicates the input description value. In this embodiment, M =150×8×50=60000, =0.25, =0.01.

[0100] S4, setting an optimization target and constraint conditions of the unidirectional fiber reinforced composite material, and constructing a topology optimization model of the unidirectional fiber reinforced composite material based on a variable stiffness component based on the optimization target and the constraint conditions;

[0101] It should be explained that, in this embodiment, the flexibility of the cantilever beam is set as the optimization target, the volume of the cantilever beam is set as the constraint, and the volume constraint is set as =0.4, and a topology optimization model of unidirectional fiber reinforced composite materials based on variable stiffness components is constructed. The specific expression is:

[0102] ;

[0103] In the formula, Descriptor function variables representing all components, Indicates from component 1 to component The description function variables of each component of Indicates the number of components, represents the selected objective function, Indicates the setting I An optimization goal, represents the global stiffness matrix, represents the displacement of each node in the design domain, represents the external force vector, Indicates the actual constraints of the structure. represents the structural constraints, represents the feasible domain of component variables, represents the displacement field, Denotes the Dirichlet frontier The given displacement on

[0104] S5, solving the sensitivity of the optimization objective and the constraint condition, and judging whether the termination condition is satisfied, and if so, outputting the optimization result;

[0105] Specifically, the step S5 includes step S51:

[0106] S51, obtaining the calculation parameters of the corresponding optimization target to solve the target, and calculating the sensitivity of the target function under each component variable, so as to update the component parameters in the next iteration;

[0107] It can be understood that the displacement U of each unit node is solved according to the overall stiffness matrix and the force conditions and substituted into the flexibility objective function to obtain the current structural flexibility value. At the same time, in order to optimize the flexibility of the structure for the next time, the sensitivity of the structural flexibility target and volume constraint to each component variable is calculated. The calculation expression is:

[0108] ;

[0109] ;

[0110] In the formula, represents partial derivative, Represents the design variable parameters of each component, represents the structural flexibility, represents the volume of the structure, M represents the total number of finite element elements in the design domain, n represents the number of unit nodes, for Heaviside function, Representation unit j The corresponding component description function, Representation unit j The displacement field, unit j The transpose of the displacement field, Representation unit j No. s The node coordinates, Representation unit j The corresponding element stiffness matrix.

[0111] It should be explained that the number of optimization iterations is set to 300 as the termination condition. In addition, if the termination condition is not met, the unit stiffness matrix of the composite material of each component under the unidirectional fiber laying angle is calculated repeatedly based on the parameters of the composite material and combined with the angle variable in the description function of the component, the unit description value of the unit under the description function of each component is calculated, and the unit stiffness matrix is ​​allocated based on the unit description value, and the overall stiffness matrix is ​​assembled, the optimization target and constraint conditions of the unidirectional fiber reinforced composite material are set, and a unidirectional fiber reinforced composite material topology optimization model based on a variable stiffness component is constructed based on the optimization target and the constraint conditions, and the sensitivity of the optimization target and the constraint conditions is solved until the termination condition is met to output the optimization result.

[0112] Specifically, in order to reflect the superiority of the variable stiffness component design, a control optimization group was set up. The material parameters, component description function, objectives, constraints, and optimization environment of the control optimization group were the same as those of the variable angle component design. The only difference was that the control optimized component was a fixed stiffness component. The final optimized structure of the unidirectional fiber reinforced composite structure of the variable stiffness component after 300 generations of optimization was as follows Figure 5 As shown, the internal fiber orientation is as follows Figure 6 Its structural flexibility is shown in Table 1:

[0113] Table 1

[0114]

[0115] From Table 1, it can be seen that the optimized flexibility values ​​of the unidirectional fiber reinforced composite material structures of variable / constant stiffness components show that the optimized flexibility of the variable stiffness component design is 71.045 less than that of the constant stiffness component design, which is 23.5% lower than the optimized flexibility of the constant stiffness component design, reflecting the superiority of the variable stiffness component design.

[0116] In summary, the topology optimization method of unidirectional fiber reinforced composite materials based on variable stiffness components in the above embodiments of the present invention sets the stiffness matrix of the component according to the unidirectional fiber laying angle of the component, and uses the topology optimization model of unidirectional fiber reinforced composite materials based on variable stiffness components to make the laying direction of the limiting reinforcement body in the component conform to the structural configuration. This not only greatly reduces the optimization variables, but also effectively improves the optimization efficiency when facing large structures, and its optimized structure is also easy to actually manufacture.

[0117] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0118] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A topology optimization method for unidirectional fiber reinforced composite materials based on variable stiffness components, characterized in that: The method comprises: Set the parameters of the composite material, the component description function and the optimization environment; Calculating the unit stiffness matrix of the composite material of each component at the unidirectional fiber laying angle based on the parameters of the composite material and in combination with the angle variable in the description function of the component; The step of calculating the unit stiffness matrix of the composite material of each component under the unidirectional fiber laying angle based on the parameters of the composite material and in combination with the angle variable in the description function of the component comprises: Extract different unidirectional fiber laying angle information of all components in the design domain, and calculate the equivalent stiffness matrix of unidirectional fiber reinforced composite materials under various angle information; The calculation expression of the equivalent stiffness matrix of the unidirectional fiber reinforced composite material is: ； in: ； ； ； In the formula, for The equivalent stiffness matrix under the angle, is the area occupied by the unit, is the component angle, B is the strain displacement matrix, is the transpose of the strain displacement matrix, for The transformation matrix under the angle, for The inverse matrix of the transformation matrix under the angle, for The equivalent elastic matrix under the angle, D 0 is the elastic matrix in the main direction of the material, E 1 and E 2 represents the elastic modulus of the material in the longitudinal and transverse directions respectively, and denote the Poisson's ratio in the longitudinal and transverse directions respectively, G 12 is the shear modulus of the material; Calculating the unit description value of the unit under the description function of each component, and allocating the unit stiffness matrix based on the unit description value, and assembling to obtain the overall stiffness matrix; Setting optimization objectives and constraints of the unidirectional fiber reinforced composite material, and constructing a topology optimization model of the unidirectional fiber reinforced composite material based on a variable stiffness component based on the optimization objectives and constraints; Solve the optimization objective and the sensitivity of the constraint conditions, and determine whether the termination condition is met. If so, output the optimization result.

2. The method for topology optimization of unidirectional fiber reinforced composite materials based on variable stiffness components according to claim 1, characterized in that: The steps of setting the parameters of the composite material, the description function of the component and the optimization environment include: Set the elastic modulus, shear modulus and Poisson's ratio parameters of unidirectional fiber reinforced composite materials measured under each axis system; Describe the function expression of the component's geometry in the design domain, the function expression of its position, the function expression of its angle information, the load constraints during optimization, and the finite element information.

3. The method for topology optimization of unidirectional fiber reinforced composite materials based on variable stiffness components according to claim 1, characterized in that: The steps of calculating the unit description value of the unit under the description function of each component, allocating the unit stiffness matrix based on the unit description value, and assembling to obtain the overall stiffness matrix include: Calculate the unit description value of the unit under the description function of each component, and determine whether there is a value greater than zero among all the unit description values; If yes, then find the angle information of the description function of the component corresponding to the maximum unit description value, and assign the unit stiffness matrix to the corresponding unit based on the angle information, the equivalent stiffness matrix calculation formula and the allocation rule; All the units that are assigned unit stiffness matrices are assembled into an overall stiffness matrix to obtain an overall stiffness matrix.

4. The method for topology optimization of unidirectional fiber reinforced composite materials based on variable stiffness components according to claim 3, characterized in that: The expression of the unit description value of the computing unit under the description function of each component is: In the formula, Representation unit i In the component j The unit description value size under the description function is n represents the number of unit nodes, Representation Components j The description function of Representation unit i No. s Node coordinates; The expression of the allocation rule is: ； ； In the formula, express N The maximum unit description value corresponding to each component, Indicates from component 1 to component N The description value of each component unit, Indicates the number of components, Representation unit i The maximum description value corresponds to the component number, Representation Components p The corresponding angle information, Representation unit i The element stiffness matrix of D 0 is the elastic matrix in the main direction of the material, B is the strain displacement matrix, is the area occupied by the unit, is the transpose of the strain displacement matrix, Indicates that the material Component corresponding angle The equivalent elastic matrix under ; The assembly rule expression for assembling the overall stiffness matrix of all the units assigned with the unit stiffness matrix is: in: ； In the formula, Represents the global stiffness matrix coordinate index i The value of M represents the total number of finite element elements in the design domain, n represents the number of unit nodes, for Heaviside function, represents the regularization parameter, represents a very small positive number, Representation unit j No. s The node coordinates, Representation unit j The corresponding component description function, Representation unit j The stiffness matrix is ​​at the coordinate index i If it does not exist, it is 0. Indicates the descriptive value of the input.

5. The method for topology optimization of unidirectional fiber reinforced composite materials based on variable stiffness components according to claim 1, characterized in that: The expression of the topology optimization model of the unidirectional fiber reinforced composite material based on the variable stiffness component is: ； In the formula, Descriptor function variables representing all components, Indicates from component 1 to component The descriptive function variables of each component, Indicates the number of components, represents the selected objective function, Indicates the setting I An optimization goal, represents the global stiffness matrix, represents the displacement of each node in the design domain, represents the external force vector, Indicates the actual constraints of the structure. represents the structural constraints, represents the feasible domain of component variables, represents the displacement field, Denotes the Dirichlet frontier A given displacement on .

6. The method for topology optimization of unidirectional fiber reinforced composite materials based on variable stiffness components according to claim 1, characterized in that: The step of solving the optimization objective and the sensitivity of the constraint condition comprises: The calculation parameters of the corresponding optimization target are obtained to solve the target, and the sensitivity of the objective function under each component variable is calculated to update the component parameters for the next iteration.

7. The method for topology optimization of unidirectional fiber reinforced composite materials based on variable stiffness components according to claim 1, characterized in that: After the step of determining whether the termination condition is met, the method further includes: If not, then repeatedly calculate the unit stiffness matrix of the composite material of each component under the unidirectional fiber laying angle based on the parameters of the composite material and in combination with the angle variables in the description function of the component, calculate the unit description value of the unit under the description function of each component, and allocate the unit stiffness matrix based on the unit description value, and assemble to obtain the overall stiffness matrix, set the optimization target and constraints of the unidirectional fiber reinforced composite material, and construct a unidirectional fiber reinforced composite material topology optimization model based on variable stiffness components based on the optimization target and the constraints, solve the sensitivity of the optimization target and the constraints, until the termination condition is met, so as to output the optimization result.

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