A Design Method of Composite Material Molds with Wrinkle Defects Based on Intelligent Optimization Algorithm

Abstract

The present invention discloses a design method for a composite material mold with wrinkle defects based on an intelligent optimization algorithm, which relates to the technical field of aviation composite material structure design and is used to solve the technical problems that existing composite material specimens with wrinkle defects cannot ensure that composite material test pieces with the same geometric characteristics of wrinkle defects can be prepared in each batch, and one or several most representative wrinkle morphologies cannot be selected, resulting in inaccurate test results. The mold design method includes: obtaining a composite material with wrinkle defects; counting the types of wrinkle defects in the composite material and the quantity of each type of wrinkle defect; constructing a cubic spline function and obtaining a fitness function; obtaining the response values of sample points; constructing an initial Kriging surrogate model and obtaining the optimal value of the model to obtain a cubic spline function representing the true defects of the composite material; determining the geometric shape of the conformal punch of the mold, and determining the upper panel, lower panel and pressure detection system of the mold.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace composite material structure design, and more specifically, to a design method for a composite material mold with wrinkling defects based on an intelligent optimization algorithm. Background Art

[0002] Various defects will inevitably occur during the manufacturing process of aerospace composite materials. Among them, the fiber wrinkling defect is one of the most significant defects affecting the longitudinal (fiber direction) performance of composite materials, which will significantly change the failure mode of the composite material structure and reduce the load-bearing capacity of the material structure. In addition, the wrinkling defect usually has no fixed morphology, and a composite material structural part will contain multiple wrinkling defects, and there is no fixed way to describe its geometric morphology for the wrinkling defect. In order to study the influence of fiber wrinkling defects on the mechanical properties of composite materials, the prior art prepares composite material specimens with wrinkling defects by simulating the actual performance of the material, and then conducts mechanical property tests on the specimens. In the process of preparing composite material test pieces with wrinkling defects, the prior art mostly adopts the stringer method and the steel bar method. Among them, the stringer method is to directly add pre-impregnated stringers between two layers of composite material prepregs to prepare composite materials with wrinkling defects. In this kind of method, the pre-impregnated stringers will deform due to resin flow during the curing process, and the geometric characteristics of the final wrinkling defects cannot be guaranteed; the steel bar method is to directly place a metal bar under the composite material prepreg and lift the prepreg, but this method still cannot accurately control the geometric characteristics of the wrinkling defects.

[0003] Generally speaking, the existing methods for preparing composite material test pieces with wrinkling defects cannot quantitatively prepare and characterize composite material test pieces with wrinkling defects, which in turn leads to the inability to ensure that composite material test pieces with the same geometric characteristics of wrinkling defects can be prepared in each batch. For studying the mechanical properties of composite materials with wrinkling defects through experiments, this will directly lead to inaccurate test results, and thus the true influence of wrinkling defects on the mechanical properties of composite materials cannot be known. Moreover, the morphologies of wrinkling defects are diverse, and one or several most representative wrinkling morphologies cannot be selected, which further leads to the fact that a mold can only prepare wrinkling defects with a single morphology, and the wrinkling defects with a single morphology cannot reasonably represent all the wrinkling defects in the composite material structure. Therefore, the existing composite material specimens with wrinkling defects have the technical problems that composite material test pieces with the same geometric characteristics of wrinkling defects cannot be prepared in each batch, and one or several most representative wrinkling morphologies cannot be selected, resulting in inaccurate test results. Summary of the Invention

[0004] The purpose of the present invention is to provide a design method for a composite material mold with wrinkling defects based on an intelligent optimization algorithm, which is used to solve the technical problems that existing composite material specimens with wrinkling defects cannot ensure that composite material test pieces with the same geometric characteristics of wrinkling defects can be prepared in each batch, and one or several most representative wrinkling morphologies cannot be selected, resulting in inaccurate test results. In view of this, the present invention is realized through the following technical solutions.

[0005] A design method for a composite material mold with wrinkling defects based on an intelligent optimization algorithm, comprising:

[0006] Obtain a composite material with wrinkling defects;

[0007] Count the types of wrinkling defects in the composite material and the number of each type of wrinkling defect;

[0008] Construct a cubic spline function and obtain a fitness function;

[0009] Determine the positions of the initial sample points through an experimental design method, and call the fitness function to obtain the response values of the sample points;

[0010] Construct an initial Kriging surrogate model, and use a genetic algorithm to obtain the optimal value of the model. After convergence, obtain a cubic spline function representing the true defects of the composite material;

[0011] Determine the geometric shape of the conformal punch of the mold according to the cubic spline function of the true defects of the composite material, and determine the upper panel, lower panel and pressure detection system of the mold to complete the mold design

[0012] Compared with the prior art, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, according to the types of wrinkling defects in the composite material and the number of each type of wrinkling defect, a cubic spline function is constructed, and a fitness function is obtained. After obtaining the response values of the sample points, by constructing an initial Kriging surrogate model and using a genetic algorithm to obtain the optimal value of the model, a cubic spline function representing the true defects of the composite material is obtained. That is to say, the cubic spline function of the true defects of the composite material represents the performance of all the wrinkling defects in the composite material. Further, in this mold, the geometric shape of the conformal punch is determined by the cubic spline function of the true defects of the composite material. This mold is used to prepare specimens of composite materials with wrinkling defects. The shape of the wrinkling defects in the specimens is the same as the shape of the conformal punch. The wrinkling defects in the specimens represent the performance of all the wrinkling defects in the composite material to be studied. In actual research, only by analyzing the wrinkling defects in this specimen can accurate test results be obtained. Through the above technical solution of the present invention, the technical problem that existing composite material specimens with wrinkling defects cannot ensure that composite material test pieces with the same geometric characteristics of wrinkling defects can be prepared in each batch, and one or several most representative wrinkling morphologies cannot be selected, resulting in inaccurate test results is solved.

[0013] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, the obtaining of the fitness function includes:

[0014] Using the cubic spline function to describe the morphology of the wrinkling defects and determining the range of hyperparameters of the cubic spline function;

[0015] Obtaining the error between the cubic spline function and the morphology of each type of wrinkling defect;

[0016] Determining the fitness of each sample function corresponding to the cubic spline function according to the error;

[0017] Wherein, each sample function is the function corresponding to the cubic spline function at each set of hyperparameters.

[0018] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, after obtaining the error between the cubic spline function and the morphology of each type of wrinkling defect, it further includes:

[0019] Performing weighted averaging on the error according to the probability of occurrence of each type of wrinkling defect.

[0020] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, the experimental design method is the Latin hypercube method.

[0021] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, the construction of the initial Kriging surrogate model includes:

[0022] Using a genetic algorithm, an initial Kriging surrogate model is constructed according to the response values of the sample points, and after the genetic algorithm converges, it represents the successful construction of the initial Kriging surrogate model.

[0023] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, during the process of constructing the initial Kriging surrogate model according to the response values of the sample points, when the genetic algorithm does not converge, the initial Kriging surrogate model is reconstructed until the genetic algorithm converges.

[0024] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, during the process of using the genetic algorithm to obtain the optimal value of the model, if the convergence condition is not met, the position of the initial sample points is re - determined according to the point - adding criterion, and the initial Kriging surrogate model is reconstructed until the convergence condition is met, and then the optimal value of the model is obtained.

[0025] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, during the process of determining the geometric shape of the conformal punch of the mold according to the cubic spline function of the real defects of the composite material, the geometric figure of the cubic spline function of the real defects of the composite material in the coordinate system is the same as the geometric shape of the conformal punch.

[0026] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, the upper panel and the lower panel are both provided with the conformal punch, and the pressure detection system is used to connect the upper panel and the lower panel and provide or release pressure between the upper panel and the lower panel.

[0027] Further, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, the types of the wrinkling defects include long and narrow rectangular defects, triangular protrusion defects, and circular protrusion defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 is a schematic flow chart of the method for designing a composite material mold with wrinkling defects of the present invention;

[0030] Figure 2 Schematic diagram of the long and narrow rectangular defect in the present invention;

[0031] Figure 3 Schematic diagram of the triangular protrusion defect in the present invention;

[0032] Figure 4 Schematic diagram of the circular protrusion defect in the present invention;

[0033] Figure 5 Schematic diagram of the convergence process of the geometric shape optimization of the conformal indenter in Embodiment 3 of the present invention;

[0034] Figure 6 Schematic diagram of the dimensionless geometric shape of the conformal indenter in Embodiment 3 of the present invention;

[0035] Figure 7 Schematic diagram of the dimensionless three-dimensional shape of the conformal indenter in Embodiment 3 of the present invention;

[0036] Figure 8 Schematic diagram of the structure of the upper panel of the mold in Embodiment 3 of the present invention;

[0037] Figure 9 Schematic diagram of the structure of the lower panel of the mold in Embodiment 3 of the present invention;

[0038] Figure 10 Schematic diagram of the structure of the pressure detection system of the mold in Embodiment 3 of the present invention;

[0039] Figure 11 Schematic diagram of the scenario of curing a single type of composite material with wrinkled defects in Embodiment 3;

[0040] Figure 12 Schematic diagram of the scenario of curing multiple types of composite materials with wrinkled defects in a single time in Embodiment 3;

[0041] Figure 13 Schematic diagram of the test piece with a height-width ratio of 10% containing wrinkles after curing and cutting in Embodiment 3;

[0042] Figure 14 Schematic diagram of the wrinkled defect morphology of the test piece in Embodiment 3.

[0043] Reference numerals:

[0044] 701, geometric shape of the conformal indenter; 801, top plate; 802, middle plate; 803, upper conformal indenter; 901, bottom plate; 902, lower conformal indenter; 1001, U-shaped beam; 1002, pressure sensor. Detailed implementation manners

[0045] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0047] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined. "Several" means one or more, unless otherwise specifically defined.

[0048] In order to study the influence of fiber wrinkling defects on the mechanical properties of composites, the existing technology prepares composite specimens with wrinkling defects by simulating the actual properties of the materials, and then conducts mechanical property tests on the specimens. In the process of preparing composite specimens with wrinkling defects, the existing technology mostly adopts the spar method and the steel bar method. Among them, the spar method prepares composites with wrinkling defects by directly adding pre-impregnated spar between two layers of composite pre-preg. In this method, the pre-impregnated spar will deform due to resin flow during the curing process, and it is impossible to ensure the geometric characteristics of the final wrinkling defects. The steel bar method directly places a metal bar under the composite pre-preg to lift the pre-preg, but this method still cannot accurately control the geometric characteristics of the wrinkling defects. Generally speaking, the existing preparation methods of composite specimens with wrinkling defects cannot quantitatively prepare and characterize composite specimens with wrinkling defects, which leads to the inability to ensure that composite specimens with the same geometric characteristics of wrinkling defects can be prepared in each batch. For the study of the mechanical properties of composites with wrinkling defects through experiments, this will directly lead to inaccurate test results, and thus it is impossible to know the true influence of wrinkling defects on the mechanical properties of composites. Moreover, the morphologies of wrinkling defects are diverse, and it is impossible to select one or several most representative wrinkling morphologies. This further leads to the fact that a mold can only prepare wrinkling defects with a single morphology, and the wrinkling defects with a single morphology cannot reasonably represent all the wrinkling defects in the composite structure. Therefore, the existing composite specimens with wrinkling defects have the technical problems that it is impossible to ensure that composite specimens with the same geometric characteristics of wrinkling defects can be prepared in each batch, and it is impossible to select one or several most representative wrinkling morphologies, resulting in inaccurate test results.

[0049] To solve the above technical problems, the present invention provides a method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm, including:

[0050] Obtain composite materials with wrinkling defects;

[0051] Count the types of wrinkling defects in the composite materials and the number of each type of wrinkling defect;

[0052] Construct a cubic spline function and obtain a fitness function;

[0053] Determine the positions of the initial sample points through an experimental design method, and call the fitness function to obtain the response values of the sample points;

[0054] Construct an initial Kriging surrogate model, and use a genetic algorithm to obtain the optimal value of the model. After convergence, a cubic spline function representing the true defects of the composite material is obtained;

[0055] Determine the geometry of the conformal indenter of the mold according to the cubic spline function of the real defects of the composite material, and determine the upper panel, lower panel and pressure detection system of the mold to complete the mold design.

[0056] In the case of adopting the above technical solution, in the method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm of the present invention, according to the types of wrinkling defects in the composite material and the number of each type of wrinkling defect, a cubic spline function is constructed, and a fitness function is obtained. After obtaining the response values of the sample points, by constructing an initial Kriging surrogate model and using a genetic algorithm to obtain the optimal value of the model, a cubic spline function representing the real defects of the composite material is obtained. That is to say, the cubic spline function of the real defects of the composite material represents the performance of all the wrinkling defects in the composite material. Further, in this mold, the geometry of the conformal indenter is determined by the cubic spline function of the real defects of the composite material. This mold is used to prepare specimens of composite materials with wrinkling defects. The shape of the wrinkling defects in the specimens is the same as the shape of the conformal indenter. The wrinkling defects in the specimens represent the performance of all the wrinkling defects in the composite material to be studied. In actual research, only by analyzing the wrinkling defects in this specimen can accurate test results be obtained. Through the above technical solution of the present invention, the technical problem that existing composite material specimens with wrinkling defects cannot ensure that composite material test pieces with the same geometric characteristics of wrinkling defects can be prepared in each batch, and one or several most representative wrinkling morphologies cannot be selected, resulting in inaccurate test results is solved.

[0057] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments.

[0058] The materials or raw materials used in the following embodiments are all commercially available unless otherwise specified.

[0059] Embodiment 1

[0060] This embodiment provides a method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm, including:

[0061] S100, obtain a composite material with wrinkling defects;

[0062] S200, count the types of wrinkling defects in the composite material and the number of each type of wrinkling defect;

[0063] S300, construct a cubic spline function and obtain a fitness function;

[0064] S400, determine the positions of the initial sample points by an experimental design method, and call the fitness function to obtain the response values of the sample points;

[0065] S500. Construct an initial Kriging surrogate model, and use the genetic algorithm to obtain the optimal value of the model. After convergence, obtain a cubic spline function representing the true defects of the composite material;

[0066] S600. Determine the geometric shape of the conformal punch of the mold according to the cubic spline function of the true defects of the composite material, and determine the upper panel, lower panel and pressure detection system of the mold to complete the mold design.

[0067] Example 2

[0068] This example provides a method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm, including:

[0069] S100. Obtain a composite material with wrinkling defects;

[0070] S200. Count the types of wrinkling defects in the composite material and the number of each type of wrinkling defect; among them, please refer to Figures 2 to 4 , the types of the wrinkling defects include long and narrow rectangular defects, triangular protrusion defects and circular protrusion defects;

[0071] S300. Construct a cubic spline function, use the cubic spline function to describe the morphology of the wrinkling defects, and determine the range of hyperparameters of the cubic spline function;

[0072] S400. Obtain the error between the cubic spline function and the morphology of each type of wrinkling defect, perform weighted averaging on the error according to the probability of occurrence of each type of wrinkling defect, and determine the fitness of each sample function corresponding to the cubic spline function;

[0073] Among them, each sample function is the function corresponding to the cubic spline function at each set of hyperparameters

[0074] S500. Determine the positions of the initial sample points by the Latin hypercube method, and call the fitness function to obtain the response values of the sample points;

[0075] S600. Construct an initial Kriging surrogate model, and use the genetic algorithm to obtain the optimal value of the model. After convergence, obtain a cubic spline function representing the true defects of the composite material;

[0076] This step further includes:

[0077] S601. Use the genetic algorithm to construct an initial Kriging surrogate model according to the response values of the sample points. After the genetic algorithm converges, it represents that the initial Kriging surrogate model is successfully constructed;

[0078] S602. When the genetic algorithm does not converge, reconstruct the initial Kriging surrogate model until the genetic algorithm converges;

[0079] S603. In the process of using the genetic algorithm to obtain the optimal value of the model, if the convergence condition is not met, re-determine the position of the initial sample points according to the point-adding criterion and reconstruct the initial Kriging surrogate model until the convergence condition is met, and then obtain the optimal value of the model;

[0080] S700. Determine the geometric shape of the conformal punch of the mold according to the cubic spline function of the real defect of the composite material, and determine the upper panel, lower panel and pressure detection system of the mold to complete the mold design;

[0081] Wherein, the geometric graph of the cubic spline function of the real defect of the composite material in the coordinate system is the same as the geometric shape of the conformal punch; the conformal punch is provided on both the upper panel and the lower panel, and the pressure detection system is used to connect the upper panel and the lower panel and provide or release pressure between the upper panel and the lower panel.

[0082] Embodiment 3

[0083] This embodiment provides a method for designing a composite material mold with wrinkling defects based on an intelligent optimization algorithm. Please refer to Figure 1 , which includes the following steps:

[0084] S100. Obtain a composite material with wrinkling defects;

[0085] The obtained composite material with wrinkling defects is the composite material to be studied;

[0086] S200. Count the types of wrinkling defects in the composite material and the quantity of each type of wrinkling defect;

[0087] In this step, the composite material structure is cut and sampled, and the types of wrinkling defects and the quantity of each type of wrinkling defect are observed and counted through a microscope; refer to Figures 2 to 4 , and the Figure 2 wrinkling defects are recorded as type I wrinkling defects, Figure 3 wrinkling defects are recorded as type II wrinkling defects, Figure 4 wrinkling defects are recorded as type III wrinkling defects. After statistics, this composite material in this embodiment contains 20% type I wrinkling defects, 40% type II wrinkling defects, and 40% type III wrinkling defects;

[0088] S300. Construct a cubic spline function, use the cubic spline function to describe the morphology of the wrinkling defects, and determine the range of hyperparameters of the cubic spline function;

[0089] S400. Obtain the error between the cubic spline function and the morphology of each wrinkle defect, perform weighted averaging on the error according to the probability of occurrence of each wrinkle defect, and determine the fitness of each sample function corresponding to the cubic spline function;

[0090] Among them, each of the sample functions is the function corresponding to the cubic spline function at each set of hyperparameters; the error is obtained by the following formula:

[0091] ;

[0092] Among them, represents the mean square error, is the response value of the i th sample point, is the predicted value of the i th sample point, and n is the number of sample points;

[0093] S500. Determine the positions of the initial sample points by the Latin hypercube method, and call the fitness function to obtain the response values of the sample points;

[0094] S600. Construct an initial Kriging surrogate model, and use the genetic algorithm to obtain the optimal value of the model. After convergence, obtain the cubic spline function representing the true defects of the composite material;

[0095] This step S600 further includes:

[0096] S601. Use the genetic algorithm to construct an initial Kriging surrogate model according to the response values of the sample points. After the genetic algorithm converges, it represents the successful construction of the initial Kriging surrogate model;

[0097] S602. When the genetic algorithm does not converge, reconstruct the initial Kriging surrogate model until the genetic algorithm converges;

[0098] S603. During the process of using the genetic algorithm to obtain the optimal value of the model, if the convergence condition is not met, re-determine the positions of the initial sample points according to the point addition criterion, and reconstruct the initial Kriging surrogate model until the convergence condition is met, and then obtain the optimal value of the model;

[0099] S700. Determine the geometric shape of the conformal punch of the mold according to the cubic spline function of the true defects of the composite material, and determine the upper panel, lower panel and pressure detection system of the mold to complete the mold design;

[0100] Among them, the geometric figure of the cubic spline function of the real defect of the composite material in the coordinate system is the same as the geometric shape of the conformal indenter; the upper panel and the lower panel are both provided with the conformal indenter, and the pressure detection system is used to connect the upper panel and the lower panel and provide or release pressure between the upper panel and the lower panel.

[0101] Furthermore, in step S600 of Embodiment 3, more specifically, in the above step S603, as Figure 5 described, the vertical coordinate fitness quickly converges to near the optimal value in the first 20 iterations, and after 98 iterations, the optimization process reaches the convergence condition and the design process terminates. Through the design method of this embodiment, the geometric shape that can represent the internal defects of the current composite material structure is successfully obtained, and its dimensionless shape curve is as Figure 6 shown. Using the dimensionless shape curve of the designed conformal indenter for the conformal indenter of the actual mold, a mold that can reflect the statistical morphology of the real wrinkles can be designed. This mold is used to prepare specimens of composite materials with wrinkle defects. Please refer to Figure 7 , the dimensionless three-dimensional shape of the conformal indenter designed in this embodiment is as Figure 7 shown, where 701 represents the geometric shape 701 of the conformal indenter designed in this embodiment.

[0102] Furthermore, the mold body of this embodiment includes an upper panel, a lower panel, a pressure detection system, and a conformal indenter. For the upper panel, please refer to Figure 8 , for example, the upper panel is composed of a flat top plate 801, two intermediate plates 802 with adjustable spacing, and an upper conformal indenter 803. For example, the two intermediate plates are connected and fixed to the top plate by bolts, and the spacing and offset position of the two intermediate plates can be freely determined before fixation. The role of the top plate is to provide positioning for the intermediate plates. The role of the intermediate plates is to determine the length of the wrinkle defect and fix the conformal indenter. The top plate is provided with 12 round holes for passing through the M12 standard bolts of the mold; in addition, 8 round rectangular holes are also provided for passing through the M12 standard bolts connecting the intermediate plates; each intermediate plate is provided with 8 circular bolt holes for connecting and fixing to the top plate. By replacing the conformal indenter, composite materials with different types of wrinkle defects can be prepared. For the lower panel, please refer to Figure 9 , for example, the lower panel is composed of a bottom plate 901 and a lower conformal indenter 902. The lower panel can be connected to the upper panel by 8 M12 bolts. The shape of the lower conformal indenter matches the shape of the upper conformal indenter. Therefore, the lower conformal indenter usually appears or is replaced in pairs with the upper conformal indenter. For the pressure detection system, please refer to Figure 10, for example, the pressure detection system consists of four open-hole U-shaped beams 1001 and four pressure sensors 1002. The U-shaped beams 1001 are connected to the upper and lower panels of the mold by bolts, and the pressure sensors 1002 are located between the U-shaped beams 1001. After the mold is closed, a pre-tightening force is applied to the mold through bolts, and the magnitude of this pre-tightening force is monitored in real time by the four pressure sensors, thereby realizing precise control of the pressure during the forming process of the composite material specimen.

[0103] Furthermore, for the experiment of curing a single type of composite material specimen with wrinkling defects at one time, please refer to Figure 11 , for example, Figure 11 The application scenario of curing a single type of composite material with wrinkling defects at one time is shown. First, according to the type and statistical probability of the wrinkling defects in the actual composite material structure, the geometric shape of the conformal punch is designed by the design method proposed in the present invention, and the upper and lower conformal punches are cut out at one time using wire cutting. Then, the prepreg is placed in the middle of the mold, and after the mold is closed, the designed pre-tightening force is applied, and it is sent to a high-temperature oven or autoclave for curing, and a single type of composite material specimen with wrinkles can be prepared. In addition, by setting the angle between the fiber direction of the composite material and the conformal punch, composite material specimens with different wrinkling angles can be prepared. Furthermore, it is also possible to cure multiple types of composite material specimens with wrinkling defects at one time. Please refer to Figure 12 , which is the same as the principle of curing a single type of specimen at one time above. The molds are stacked and used, and different intermediate plate distances and conformal punch types can be set for each layer, so that multiple types of specimens with or without wrinkling defects can be prepared in the same batch. This method effectively eliminates the mechanical property differences caused by the differences in curing pressure and temperature of specimens in different batches.

[0104] Using the mold of the above-mentioned Embodiment 3, the present invention prepared a glass fiber-reinforced composite material specimen with a 10% aspect ratio of wrinkling defects. The cured specimen blank was made into a formal specimen of the composite material with wrinkles by water cutting, as Figure 13 shown, it can be seen that the surface of the specimen is smooth and flat, meeting the test requirements. Figure 14 The detailed morphology of the prepared specimen with wrinkling defects is shown. The morphology of the wrinkling defects is precisely controllable, and the present invention realizes the parametric preparation of the wrinkling defects.

[0105] Furthermore, please refer to Figure 1 , based on the above embodiment, for example, in combination with Figure 1 to further illustrate the technical solution of the present invention: As can be seen from the left side of Figure 1 , for the composite material to be studied, after statistically analyzing its real wrinkles, a spline function is constructed. Through cubic spline interpolation and the error between the spline function and the statistical morphology of the real wrinkles, the fitness of each sample function corresponding to the spline function is determined. FromFigure 1 As can be seen from the right side in the middle, after initially determining the positions of the sample points through experimental design (such as the Latin hypercube method), the response values of the sample points are obtained by calling the fitness function through a solver. Then, using a genetic algorithm, an initial Kriging surrogate model is constructed based on the response values of the sample points. When determining whether to converge according to an optimizer (such as the genetic algorithm GA), if it converges, the optimal value of the model is further obtained. If it does not converge, the initial Kriging surrogate model is reconstructed until the genetic algorithm converges; during the process of obtaining the optimal value of the model, after convergence, a cubic spline function representing the true defect of the composite material is obtained. If the convergence condition is not met, the positions of the initial sample points are re-determined according to the point addition criterion (new sample points are added), and the initial Kriging surrogate model is reconstructed until the convergence condition is satisfied, and then the optimal value of the model is obtained. Finally, a cubic spline function representing the true defect of the composite material is obtained.

[0106] In the description of the above embodiments, the specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner.

[0107] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm, characterized in that: include: Obtaining a composite material containing wrinkle defects; Counting the types of wrinkle defects in the composite material and the number of each type of wrinkle defects; wherein the types of wrinkle defects include narrow and long rectangular defects, triangular convex defects and circular convex defects; Construct a cubic spline function and obtain the fitness function; Determine the position of the initial sample point by an experimental design method, and call the fitness function to obtain the response value of the sample point; the experimental design method is a Latin hypercube method; An initial Kriging proxy model is constructed, and a genetic algorithm is used to obtain an optimal value of the model, and after convergence, a cubic spline function representing the real defects of the composite material is obtained; The geometric shape of the mold's conformal pressure head is determined according to the cubic spline function of the real defect of the composite material, and the upper panel, lower panel and pressure detection system of the mold are determined to complete the mold design; in the process of determining the geometric shape of the mold's conformal pressure head according to the cubic spline function of the real defect of the composite material, the geometric figure of the cubic spline function of the real defect of the composite material in the coordinate system is the same as the geometric shape of the conformal pressure head; Wherein, obtaining the fitness function includes: Using the cubic spline function to describe the morphology of wrinkle defects, and determining the hyperparameter range of the cubic spline function; Obtaining the error between the cubic spline function and the morphology of each wrinkle defect; The fitness of each sample function corresponding to the cubic spline function is determined according to the error; each sample function is a function corresponding to the cubic spline function at each set of hyperparameters.

2. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 1, characterized in that: After obtaining the error between the cubic spline function and the morphology of each wrinkle defect, the method further includes: The errors are weighted averaged according to the probability of occurrence of each wrinkle defect.

3. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 2, characterized in that: The initial Kriging proxy model is constructed, including: An initial Kriging proxy model is constructed according to the response values ​​of the sample points by using a genetic algorithm, and convergence of the genetic algorithm indicates that the initial Kriging proxy model is successfully constructed.

4. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 3, characterized in that: In the process of constructing the initial Kriging proxy model according to the response values ​​of the sample points, when the genetic algorithm has not converged, the initial Kriging proxy model is reconstructed until the genetic algorithm converges.

5. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 4, characterized in that: In the process of obtaining the optimal value of the model using the genetic algorithm, if the convergence condition is not met, the position of the initial sample point is re-determined according to the point adding criterion, and the initial Kriging proxy model is reconstructed until the convergence condition is met to obtain the optimal value of the model.

6. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 5, characterized in that: In the mold, the upper panel and the lower panel are both provided with the shape-maintaining pressure head, and the pressure detection system is used to connect the upper panel and the lower panel and provide or release pressure between the upper panel and the lower panel.

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