Method for designing composite mold with wrinkle defect based on intelligent optimization algorithm

Abstract

The invention discloses an intelligent optimization algorithm-based design method for a composite material mold with a wrinkle defect, and relates to the technical field of aviation composite material structure design. The method is used for solving the technical problems that an existing composite material test piece with the wrinkle defect cannot ensure that the composite material test piece with the same wrinkle defect geometrical characteristics can be prepared in each batch, and one or more most representative wrinkle shapes cannot be selected, so that the test result is inaccurate. The mold design method comprises the following steps: obtaining a composite material with a wrinkle defect; counting the types of the wrinkle defects in the composite material and the number of each wrinkle defect; constructing a cubic spline function, and obtaining a fitness function; obtaining response values of the sample points; constructing an initial Kriging agent model, and obtaining an optimal value of the model to obtain a cubic spline function representing real defects of the composite material; determining the geometrical shape of a shape-preserving pressure head of the mold, and determining an upper panel, a lower panel and a pressure detection system of the mold;

Description

Technical Field

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

[0002] Various defects will inevitably occur in the manufacturing process of aerospace composite materials. Among them, fiber wrinkle defects are 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 bearing capacity of the material structure. In addition, wrinkle defects usually have no fixed morphology, and a composite material structure may contain multiple wrinkle defects. There is no fixed way to describe the geometric morphology of wrinkle defects. In order to study the influence of fiber wrinkle defects on the mechanical properties of composite materials, the prior art prepares composite material specimens with wrinkle defects by simulating the actual properties of the material, and then conducts mechanical property tests on the specimens. In the process of preparing composite material specimens with wrinkle defects, the prior art mostly adopts the stringer method and the steel rod method. Among them, the stringer method is to prepare a composite material with wrinkle defects by directly adding prepreg stringers between two layers of composite material prepreg. In this method, the prepreg stringers will be deformed due to resin flow during the curing process, and the geometric characteristics of the final wrinkle defects cannot be guaranteed; the steel rod method is to place a metal rod directly under the composite material prepreg to lift the prepreg, but this method still cannot accurately control the geometric characteristics of the wrinkle defects.

[0003] In summary, the existing preparation methods of composite material test pieces containing wrinkle defects cannot quantitatively prepare and characterize composite material test pieces containing wrinkle defects, which leads to the inability to ensure that composite material test pieces with the same geometric features of wrinkle defects can be prepared in each batch. For the study of the mechanical properties of composite materials containing wrinkle defects through experiments, this will directly lead to inaccurate test results, and it is impossible to know the true impact of wrinkle defects on the mechanical properties of composite materials. The morphology of wrinkle defects is diverse, and it is impossible to select one or several most representative wrinkle morphologies, which further leads to a mold that can only prepare wrinkle defects with a single morphology, and wrinkle defects with a single morphology cannot reasonably represent all wrinkle defects in the composite material structure. Therefore, the existing composite material test pieces containing wrinkle defects have the technical problem that it is impossible to ensure that composite material test pieces with the same geometric features of wrinkle defects can be prepared in each batch, and it is impossible to select one or several most representative wrinkle morphologies, resulting in inaccurate test results. Summary of the invention

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

[0005] A design method for a composite material mold containing wrinkle defects based on an intelligent optimization algorithm, comprising: 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 defect; 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; 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 based on the cubic spline function of the real defects of the composite material, and the upper and lower panels and pressure detection system of the mold are determined to complete the mold design. Compared with the prior art, in the design method of composite material mold containing wrinkle defects based on intelligent optimization algorithm of the present invention, according to the types of wrinkle defects in the composite material and the number of each wrinkle defect, a cubic spline function is constructed, and the fitness function is obtained. After obtaining the response value of the sample point, the cubic spline function representing the real defect of the composite material is obtained by constructing the initial Kriging proxy model and using the genetic algorithm to obtain the optimal value of the model. That is to say, the cubic spline function of the real defect of the composite material represents the performance of all wrinkle defects in the composite material. Further, in the mold, the geometric shape of the conformal pressure head is determined by the cubic spline function of the real defect of the composite material. The mold is used to prepare a specimen of composite material with wrinkle defects. The shape of the wrinkle defects in the specimen is the same as the shape of the conformal pressure head. The wrinkle defects in the specimen represent the performance of all wrinkle defects in the composite material to be studied. In actual research, it is only necessary to analyze the wrinkle defects in the specimen to obtain accurate test results. Through the above-mentioned technical scheme of the present invention, the technical problem that the existing composite material specimens containing wrinkle defects cannot ensure that composite material specimens with the same wrinkle defect geometric characteristics can be prepared in each batch, and one or several most representative wrinkle morphologies cannot be selected, resulting in inaccurate test results is solved.

[0006] Furthermore, in the method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm of the present invention, the step of 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; Determining the fitness of each sample function corresponding to the cubic spline function according to the error; Each sample function is a function corresponding to the cubic spline function at each set of hyperparameters.

[0007] Furthermore, in the method for designing a composite material mold containing wrinkle 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 wrinkle defect, it also includes: The errors are weighted averaged according to the probability of occurrence of each wrinkle defect.

[0008] Furthermore, in the method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm of the present invention, the experimental design method is a Latin hypercube method.

[0009] Furthermore, in the method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm of the present invention, the construction of an initial Kriging proxy model comprises: 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.

[0010] Furthermore, in the method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm of the present invention, 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.

[0011] Furthermore, in the method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm of the present invention, in the process of obtaining the optimal value of the model using a genetic algorithm, if the convergence condition is not met, the position of the initial sample point is redetermined 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.

[0012] Furthermore, in the method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm of the present invention, 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.

[0013] Furthermore, in the method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm of the present invention, both the upper panel and the lower panel are provided with the retaining 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.

[0014] Furthermore, in the method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm of the present invention, the types of wrinkle defects include narrow and long rectangular defects, triangular convex defects and circular convex defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a schematic flow chart of a method for designing a composite material mold containing wrinkle defects according to the present invention; Figure 2 is a schematic diagram of a narrow and long rectangular defect in the present invention; Figure 3 Schematic diagram of a triangular convex defect in the present invention; Figure 4 Schematic diagram of a circular convex defect in the present invention; Figure 5 Schematic diagram of the optimization convergence process of the geometric shape of the shape-preserving indenter in Example 3 of the present invention; Figure 6 Schematic diagram of dimensionless geometric shape of the shape-preserving indenter in Example 3 of the present invention; Figure 7 Schematic diagram of dimensionless three-dimensional shape of the shape-preserving indenter in Example 3 of the present invention; Figure 8 Schematic diagram of the structure of the upper panel of the mold in Example 3 of the present invention; Fig. 9 Schematic diagram of the structure of the lower panel of the mold in Example 3 of the present invention; Fig.10 It is a structural schematic diagram of a pressure detection system for a mold in Embodiment 3 of the present invention; Fig.11 This is a schematic diagram of a scenario of single curing of a type of composite material containing wrinkle defects in Example 3; Fig.12 This is a schematic diagram of a scenario of single-time curing of various types of composite materials containing wrinkle defects in Example 3; Fig.13 This is a schematic diagram of a wrinkle-containing test piece with an aspect ratio of 10% after being cured and cut in Example 3; Fig.14 Schematic diagram of the wrinkle defect morphology of the test piece in Example 3.

[0016] Reference numerals: 701, geometrical shape of the profile-retaining pressure head; 801, top plate; 802, middle plate; 803, upper profile-retaining pressure head; 901, bottom plate; 902, lower profile-retaining pressure head; 1001, U-shaped beam; 1002, pressure sensor. DETAILED DESCRIPTION

[0017] 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 is further described in detail below in conjunction with 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 intended to limit the present invention.

[0018] 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.

[0019] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0020] In order to study the influence of fiber wrinkle defects on the mechanical properties of composite materials, the prior art prepares composite material specimens with wrinkle defects by simulating the actual properties of the material, and then conducts mechanical property tests on the specimens. In the process of preparing composite material specimens with wrinkle defects, the prior art mostly adopts the stringer method and the steel rod method. Among them, the stringer method is to prepare a composite material with wrinkle defects by directly adding prepreg stringers between two layers of composite material prepreg. In this method, the prepreg stringers will deform due to resin flow during the curing process, and the geometric characteristics of the final wrinkle defects cannot be guaranteed; the steel rod method is to place a metal rod directly under the composite material prepreg to lift the prepreg, but this method still cannot accurately control the geometric characteristics of the wrinkle defects. In general, the existing preparation method of composite material specimens with wrinkle defects cannot quantitatively prepare and characterize composite material specimens with wrinkle defects, which leads to the inability to ensure that composite material specimens with the same geometric characteristics of wrinkle defects can be prepared in each batch. For the mechanical properties of composite materials with wrinkle defects studied by experiments, this will directly lead to inaccurate test results, and thus the true influence of wrinkle defects on the mechanical properties of composite materials cannot be known. However, the morphology of wrinkle defects is diverse, and it is impossible to select one or several most representative wrinkle morphologies, which further leads to a mold that can only produce wrinkle defects with a single morphology, and wrinkle defects with a single morphology cannot reasonably represent all wrinkle defects in the composite material structure. Therefore, the existing composite material specimens with wrinkle defects have the technical problem of not being able to ensure that composite material specimens with the same wrinkle defect geometric characteristics can be produced in each batch, and it is impossible to select one or several most representative wrinkle morphologies, resulting in inaccurate test results.

[0021] In order to solve the above technical problems, the present invention provides a method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm, comprising: 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 defect; 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; 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.

[0022] In the case of adopting the above technical solution, in the design method of composite material mold containing wrinkle defects based on intelligent optimization algorithm of the present invention, according to the types of wrinkle defects in the composite material and the number of each wrinkle defect, a cubic spline function is constructed, and the fitness function is obtained. After obtaining the response value of the sample point, the cubic spline function representing the real defect of the composite material is obtained by constructing an initial Kriging proxy model and using a genetic algorithm to obtain the optimal value of the model. That is to say, the cubic spline function of the real defect of the composite material represents the performance of all wrinkle defects in the composite material. Further, in the mold, the geometric shape of the conformal pressure head is determined by the cubic spline function of the real defect of the composite material. The mold is used to prepare a specimen of a composite material with wrinkle defects. The shape of the wrinkle defects in the specimen is the same as the shape of the conformal pressure head. The wrinkle defects in the specimen represent the performance of all wrinkle defects in the composite material to be studied. In actual research, it is only necessary to analyze the wrinkle defects in the specimen to obtain accurate test results. Through the above-mentioned technical scheme of the present invention, the technical problem that the existing composite material specimens containing wrinkle defects cannot ensure that composite material specimens with the same wrinkle defect geometric characteristics can be prepared in each batch, and one or several most representative wrinkle morphologies cannot be selected, resulting in inaccurate test results is solved.

[0023] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments.

[0024] Unless otherwise specified, the materials or raw materials used in the following examples are commercially available.

[0025] Example 1

[0026] This embodiment provides a method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm, comprising: S100, obtaining a composite material containing wrinkle defects; S200, counting the types of wrinkle defects in the composite material and the number of each type of wrinkle defects; S300, constructing a cubic spline function and obtaining a fitness function; S400, determining the position of the initial sample point by an experimental design method, and calling the fitness function to obtain the response value of the sample point; S500, constructing an initial Kriging proxy model, and using a genetic algorithm to obtain an optimal value of the model, and after convergence, obtaining a cubic spline function representing the real defects of the composite material; S600, 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, and determining the upper panel, lower panel and pressure detection system of the mold to complete the mold design.

[0027] Example 2

[0028] This embodiment provides a method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm, comprising: S100, obtaining a composite material containing wrinkle defects; S200, counting the types of wrinkle defects in the composite material and the number of each type of wrinkle defect; wherein, refer to Figures 2 to 4 , the types of wrinkle defects include narrow rectangular defects, triangular convex defects and circular convex defects; S300, constructing a cubic spline function, using the cubic spline function to describe the morphology of wrinkle defects, and determining a hyperparameter range of the cubic spline function; S400, obtaining an error between the cubic spline function and the morphology of each wrinkle defect, performing weighted averaging on the error according to the probability of occurrence of each wrinkle defect, and determining the fitness of each sample function corresponding to the cubic spline function; Wherein, each sample function is the function corresponding to the cubic spline function at each set of hyperparameters S500, determining the position of the initial sample point by using the Latin hypercube method, and calling the fitness function to obtain the response value of the sample point; S600, constructing an initial Kriging proxy model, and using a genetic algorithm to obtain an optimal value of the model, and after convergence, obtaining a cubic spline function representing the real defects of the composite material; This step further includes: S601, using a genetic algorithm to construct an initial Kriging proxy model according to the response values ​​of the sample points, wherein convergence of the genetic algorithm indicates that the initial Kriging proxy model is successfully constructed; S602, when the genetic algorithm has not converged, reconstructing the initial Kriging proxy model until the genetic algorithm converges; S603, in the process of obtaining the optimal value of the model by 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 rebuilt until the convergence condition is met to obtain the optimal value of the model; S700, 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, and determining the upper panel, lower panel and pressure detection system of the mold to complete the mold design; 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 pressure head; the upper panel and the lower panel are both provided with the conformal 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.

[0029] Example 3

[0030] This embodiment provides a method for designing a composite material mold with wrinkle defects based on an intelligent optimization algorithm. Figure 1 , including the following steps: S100, obtaining a composite material containing wrinkle defects; The obtained composite material containing wrinkle defects is the composite material to be studied; S200, counting the types of wrinkle defects in the composite material and the number of each type of wrinkle defects; In this step, the composite material structure is cut and sampled, and the types of wrinkle defects and the number of each type of wrinkle defect are observed and counted under a microscope; see Figures 2 to 4 ,Will Figure 2 The wrinkle defect is recorded as type I wrinkle defect. Figure 3 The wrinkle defect is recorded as type II wrinkle defect. Figure 4 The wrinkle defects are recorded as type III wrinkle defects. According to statistics, the composite material of this embodiment contains 20% type I wrinkle defects, 40% type II wrinkle defects, and 40% type III wrinkle defects. S300, constructing a cubic spline function, using the cubic spline function to describe the morphology of wrinkle defects, and determining a hyperparameter range of the cubic spline function; S400, obtaining an error between the cubic spline function and the morphology of each wrinkle defect, performing weighted averaging on the error according to the probability of occurrence of each wrinkle defect, and determining the fitness of each sample function corresponding to the cubic spline function; Wherein, each sample function is a function corresponding to the cubic spline function at each set of hyperparameters; the error is obtained by the following formula: ; in, represents the mean square error, For the i The response value of the sample points, For the i The predicted value of sample points, n is the number of sample points; S500, determining the position of the initial sample point by using the Latin hypercube method, and calling the fitness function to obtain the response value of the sample point; S600, constructing an initial Kriging proxy model, and using a genetic algorithm to obtain an optimal value of the model, and after convergence, obtaining a cubic spline function representing the real defects of the composite material; The step S600 further includes: S601, using a genetic algorithm to construct an initial Kriging proxy model according to the response values ​​of the sample points, wherein convergence of the genetic algorithm indicates that the initial Kriging proxy model is successfully constructed; S602, when the genetic algorithm has not converged, reconstructing the initial Kriging proxy model until the genetic algorithm converges; S603, in the process of obtaining the optimal value of the model by 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 rebuilt until the convergence condition is met to obtain the optimal value of the model; S700, 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, and determining the upper panel, lower panel and pressure detection system of the mold to complete the mold design; 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 pressure head; the upper panel and the lower panel are both provided with the conformal 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.

[0031] Further, in step S600 of the third embodiment, more specifically, in the above step S603, as Figure 5 As described above, the vertical coordinate fitness quickly converges to the optimal value in the first 20 iterations. After 98 iterations, the optimization process reaches the convergence condition and the design process is terminated. Through the design method of this embodiment, a geometric shape that can represent the internal defects of the current composite material structure is successfully obtained. Its dimensionless shape curve is as follows Figure 6 As shown in Figure 2, the dimensionless shape curve of the designed conformal pressure head is used for the conformal pressure head of the actual mold, and a mold that can reflect the statistical morphology of the actual wrinkles can be designed. The mold is used to prepare the specimens of the composite material with wrinkle defects. Please refer to Figure 7 The dimensionless three-dimensional shape of the conformal pressure head designed in this embodiment is as follows: Figure 7 As shown, 701 represents the conformal pressure head geometric shape 701 designed in this embodiment.

[0032] Furthermore, the mold body of this embodiment includes an upper panel, a lower panel, a pressure detection system, and a shape-keeping pressure head. For the upper panel, please refer to Figure 8For example, the upper panel is composed of a flat top plate 801, two intermediate plates 802 with adjustable spacing, and an upper retaining pressure head 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 function of the top plate is to provide positioning for the intermediate plate, the function of the intermediate plate is to determine the length of the wrinkle defect, and to fix the retaining pressure head. The top plate has 12 circular holes for passing the M12 standard bolts of the mold; in addition, there are 8 circular rectangular holes for passing the M12 standard bolts connecting the intermediate plates; each intermediate plate has 8 circular bolt holes for connecting and fixing with the top plate. Composite materials containing different types of wrinkle defects can be prepared by replacing the retaining pressure head. For the lower panel, please refer to Fig. 9 For example, the lower panel is composed of a bottom plate 901 and a lower pressure head 902. The lower panel can be connected to the upper panel by 8 M12 bolts. The shape of the lower pressure head matches the shape of the upper pressure head. Therefore, the lower pressure head usually appears or is replaced in pairs with the upper pressure head. For pressure detection systems, please refer to Fig.10 For example, the pressure detection system is composed of four U-shaped beams 1001 with holes 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 preload is applied to the mold by bolts, and the size of the preload is monitored in real time by the four pressure sensors, thereby realizing accurate control of the pressure during the molding process of the composite material specimen.

[0033] Further, for single-curing of one type of composite material with wrinkle defects, please refer to Fig.11 , for example, Fig.11 The figure shows an application scenario of single-time curing of composite materials containing one type of wrinkle defects. First, based on the type and statistical probability of wrinkle defects in the actual composite material structure, the geometric shape of the conformal pressure head is designed by the design method proposed in the present invention, and the upper and lower conformal pressure heads are cut out at one time using the wire cutting method. The prepreg is then placed in the middle of the mold, and the designed preload is applied after the mold is closed. The prepreg is then sent to a high-temperature oven or autoclave for curing to prepare a single type of composite material test piece containing wrinkles. In addition, by setting the angle between the composite fiber direction and the conformal pressure head, composite material test pieces with different wrinkle angles can be prepared. Furthermore, multiple types of composite material test pieces containing wrinkle defects can be cured at a single time. Please refer to Fig.12 , the same principle as the above-mentioned single-time curing of a single type of test piece, the mold is stacked and used, and each layer can be set with a different middle plate distance and type of retaining pressure head, so that multiple types of test pieces with or without wrinkles can be prepared in the same batch. This method effectively eliminates the difference in mechanical properties caused by the difference in curing molding pressure and temperature of different batches of test pieces.

[0034] Using the mold of the above-mentioned embodiment 3, the present invention prepares a glass fiber reinforced composite material test piece containing 10% aspect ratio wrinkle defects. The cured test piece rough material is cut by water jet to form a composite material test piece containing wrinkles. Fig.13 As shown, it can be seen that the surface of the test piece is smooth and flat, meeting the test requirements. Fig.14 In order to prepare the detailed morphology of the test piece containing wrinkle defects, the wrinkle defect morphology is accurately controllable, and the present invention realizes the parametric preparation of wrinkle defects.

[0035] For further information, see Figure 1 , based on the above embodiments, for example, combined with Figure 1 The technical solution of the present invention is further described: Figure 1 As can be seen from the left side, for the composite material to be studied, after the real wrinkles and statistical morphology are taken, 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. Figure 1 It can be seen from the right side that after the positions of the initial sample points are determined by experimental design (such as the Latin hypercube method), the fitness function is called to obtain the response values ​​of the sample points through the solver, and then the genetic algorithm is used to build the initial Kriging proxy model according to the response values ​​of the sample points. When the optimizer (genetic algorithm GA, etc.) determines whether it has converged, if it has converged, the optimal value of the model is further obtained. If it has not converged, the initial Kriging proxy model is rebuilt until the genetic algorithm converges. In the process of obtaining the optimal value of the model, a cubic spline function representing the real defects of the composite material is obtained after convergence. If the convergence condition is not met, the position of the initial sample point is re-determined according to the point adding criterion (new sample points are added), and the initial Kriging proxy model is rebuilt until the convergence condition is met, the optimal value of the model is obtained, and finally the cubic spline function representing the real defects of the composite material is obtained.

[0036] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0037] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on 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 defect; 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; 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.

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: The obtaining of the fitness function comprises: 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; Determining the fitness of each sample function corresponding to the cubic spline function according to the error; Each sample function is a function corresponding to the cubic spline function at each set of hyperparameters.

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: 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.

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: The experimental design method is the Latin hypercube method.

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: 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.

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 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.

7. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 6, 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.

8. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 7, characterized in that: 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.

9. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 8, 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.

10. The method for designing a composite material mold containing wrinkle defects based on an intelligent optimization algorithm according to claim 9, characterized in that: The types of wrinkle defects include narrow and long rectangular defects, triangular convex defects and circular convex defects.

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