Hybrid layup performance equivalent design method for composite laminates

Abstract

The application discloses a kind of composite laminated plate hybrid layup performance equivalent design methods, belong to the field of composite layup design.Method includes: according to alternative, the material and layup angle used by original laminated plate, determine hybrid laminated plate Tsai modulus and stiffness component input parameter;According to the hybrid laminated plate Tsai modulus obtained, determine hybrid ratio;By hybrid layup Double-Double theory, determine the equivalent conversion after hybrid layup alternative angle when stiffness component is consistent or uniaxial stiffness is consistent;According to the homogeneity requirement of laminated plate, determine the stacking mode and minimum overlap times of hybrid Double-Double unit in Double-Double hybrid layup composite material of laminated plate.The hybrid layup of the composite laminated plate provided by the application has higher homogeneity in the overall structure of laminated plate, and is easier to carry out layup design and optimization.The hybrid layup can exhibit pseudo-ductility effect under certain conditions, improve the safety factor, and the method provides a more effective means for composite layup design.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of composite material layer design, and particularly relates to a hybrid layer performance equivalent design method of a composite material laminated plate. BACKGROUND

[0002] The laminated plate is a structural material composed of a plurality of fiber reinforced composite material single-layer plates, and is widely used in large equipment such as automobiles, airplanes and spacecraft. The traditional laminated plate layer design is composed of four fiber direction layers, and the layer direction is four angles of 0°, ±45° and 90°. The four fixed angle layer method needs to be limited by a series of semi-empirical layer rules, such as requiring symmetrical and balanced layering and the proportion of each angle layering being higher than 10%. Therefore, the fixed fiber angle direction limits the performance design and optimization of the composite material.

[0003] Under this background, researchers proposed a new Double-Double layer method, which is in the form of [±Φ / ±ψ] r Wherein Φ and Ψ can be any angle, and r represents the number of repetitions of the sub-layer group. The Double-Double layer can be equivalent to replace the traditional layer laminated plate, and has a series of advantages such as homogenization, lightweight, strong designability and many choices of layer types, and has great application potential in the field of composite materials. However, the research on the Double-Double layer mainly focuses on the single material carbon fiber laminated plate, and the research on the performance equivalent design of the hybrid layer of the Double-Double layer has not been reported.

[0004] Therefore, the application provides a hybrid layer performance equivalent design method of a composite material laminated plate, which realizes the layer design of the Double-Double hybrid composite material of multiple materials and the equivalent replacement of the traditional layer under the premise of ensuring the overall stiffness of the hybrid laminated plate and the consistency of each stiffness component. SUMMARY

[0005] The purpose of the application is to realize the advantages of the Double-Double layer in the hybrid composite material, realize the layer design of the Double-Double hybrid composite material of multiple materials and the equivalent replacement of the traditional layer under the premise of ensuring the overall stiffness of the hybrid laminated plate and the consistency of each stiffness component, and provide a hybrid layer performance equivalent design method of a composite material laminated plate.

[0006] The specific technical scheme adopted by the application is as follows:

[0007] The application provides a hybrid layer performance equivalent design method of a composite material laminated plate, which is as follows:

[0008] S1: Determine the Tsai modulus and stiffness component input parameters of the hybrid laminate according to the alternative, the material used in the original laminate and the ply angle; the single-layer composite material of the hybrid laminate is carbon fiber composite material or glass fiber composite material;

[0009] S2: Determine the hybrid ratio according to the Tsai modulus of the hybrid laminate obtained in S1, and estimate the single-layer stiffness of the laminate by using the Tsai modulus single parameter;

[0010] S3: Determine the equivalent conversion after the hybrid ply angle is consistent or the uniaxial stiffness is consistent by the hybrid ply Double-Double theory;

[0011] S4: Determine the stacking mode and minimum overlap number of the hybrid Double-Double unit in the Double-Double hybrid ply composite material according to the homogeneity requirement of the laminate; estimate the material parameters by the Tsai modulus, calculate the stiffness matrix after different unit repetition numbers, and obtain the minimum repetition number that satisfies [+Φ_g / -Ψ_c / +ψ_c / -Φ_g] r the ply homogeneity requirement.

[0012] As preferred, S1 is specifically as follows:

[0013] Determine the Tsai modulus and stiffness component input parameters of the hybrid laminate according to the alternative, the material used in the original laminate and the ply angle based on formulas (1) and (2); the hybrid laminate includes carbon fiber laminate and glass fiber laminate;

[0014]

[0015] Tr(Q)=kE1 (2)

[0016] Wherein, Tr(Q) is the Tsai modulus of the single layer in the hybrid laminate; is the normalized stiffness component after normalization by the Tsai modulus; Q ii (Q 11 ,Q 22 ,Q 33 ) is the corresponding element of the in-plane stiffness matrix Q of the single layer of the hybrid laminate; k is a parameter related to the type of fiber in the corresponding single-layer laminate material, k c = 1.12 for carbon fiber laminate, and k g = 1.25 for glass fiber laminate; E1 is the tensile modulus at 0°.

[0017] Further, the alternative is ply substitution or material substitution.

[0018] As preferred, S2 is specifically as follows:

[0019] The hybrid ratio is determined by formula (3) according to the Tsai modulus of the hybrid laminate plate S1;

[0020]

[0021] Wherein, p c , p g are the thickness ratios of the carbon fiber laminate and the glass fiber laminate in the hybrid laminate; Tr(Q c ), Tr(Q g ) are the Tsai moduli of the carbon fiber laminate and the glass fiber laminate; are the Tsai modulus ratios contributed by the carbon fiber laminate and the glass fiber laminate respectively;

[0022] Based on formula (4), the single parameter of Tsai modulus is used to estimate the single-layer stiffness of the laminate;

[0023]

[0024] For the off-axis stiffness, the stiffness component can be represented by the off-axis angle θ and the uniaxial stiffness Q, and the corresponding relationship is as follows:

[0025]

[0026] Wherein, U i (i=1, 2, 3, 4) is a material-related intermediate parameter, and the calculation formula is as follows:

[0027] U1=0.375Q 11 +0.375Q 22 +0.25Q 21 +0.5Q 33 (6)

[0028] U2=0.5Q 11 -0.5Q 22 (7)

[0029] U3=0.125Q 11 +0.125Q 22 -0.25Q 21 -0.5Q 33 (8)

[0030] U4=0.125Q 11 +0.125Q 22 +0.75Q 21 -0.5Q 33 (9)。

[0031] As preferred, the calculation formula of the equivalent conversion in S3 is as follows:

[0032]

[0033] Where Ψ and Φ represent the layup angles of carbon fiber laminate and glass fiber laminate, respectively; The intermediate calculation parameters are calculated using the following formula:

[0034]

[0035] Among them, a c b c and c c These represent the proportions of the thickness of the carbon fiber laminate at angles of 0°, ±45°, and 90° to the total thickness of the carbon fiber laminate, respectively; a g b g and c g The figures represent the proportions of the thickness of the fiberglass laminate at angles of 0°, ±45°, and 90° to the total thickness of the original laminate.

[0036] If no completely equivalent replacement angle exists at the corresponding scale, then the angle replacement should be performed with priority given to ensuring that the stiffness components in the uniaxial direction are consistent. The calculation formula is as follows:

[0037]

[0038] The equivalent transformation yields a Double-Double hybrid ply of [+Φ_g / -Ψ_c / +Ψ_c / -Φ_g]. r , where r represents the number of times the sub-layout is repeated.

[0039] Preferably, the homogeneity requirement of the laminate is as follows:

[0040] ||B * ||<0.02&||A * -D * ||<0.02 (13)

[0041] Among them, A * B * D * These are the tensile stiffness, coupling stiffness, and bending stiffness of the laminate after normalization using the traces of their respective matrices.

[0042] The normalized stiffness matrix for different element repetition numbers is calculated as follows:

[0043]

[0044]

[0045]

[0046] Where H is the total thickness of the laminate. is the single layer off-axis stiffness of the i-th layer, z i is the distance from the lower surface of the i-th layer to the symmetric midplane;

[0047] The material parameters are estimated by Tsai modulus, the stiffness matrix after different number of unit repetitions is calculated, and the [ + Φ_g / - Ψ_c / + Ψ_c / - Φ_g] r The minimum number of repetitions required by the layer homogeneity requirement; the [ + Φ_g / - Ψ_c / + Ψ_c / - Φ_g] r The layer homogeneity requirement is:

[0048]

[0049]

[0050] As preferred, the Double-Double hybrid layer composite material is obtained by equivalent conversion of a traditional layer composite material through a tensile stiffness matrix, and the layer angle of the Double-Double hybrid layer composite material equivalent to the tensile stiffness of the traditional layer composite material is obtained; the traditional layer composite material includes 0°, ±45°, 90° four angle layer composite materials.

[0051] Compared with the prior art, the present application has the following beneficial effects:

[0052] The present application provides a hybrid layer performance equivalent design method of a composite material laminate, which realizes hybrid Double-Double layer design of multiple materials and equivalent replacement of traditional layers under the premise of ensuring the overall stiffness of the laminate and the consistency of each stiffness component. The Double-Double hybrid layer simplifies the layer sequence, and the designer can use the method of the present application to select the initial design material and layer. The hybrid Double-Double laminate can avoid the warping failure of the component during use, and reduce the burden of the designer in the tedious layer design work. The calculation program can be prepared according to the present layer optimization method, and the most suitable hybrid Double-Double laminate layer under the given working condition can be directly generated, so that the preliminary design can be completed conveniently and quickly. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 is the layer design process flowchart of the present application;

[0054] Figure 2 is the hybrid Double-Double layer replacement schematic diagram of the present application;

[0055] Figure 3 is the allowable angle replacement range in the embodiment;

[0056] Figure 4 is the convergence speed of the different configuration homogeneity condition in the embodiment. DETAILED DESCRIPTION

[0057] To make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work belong to the protection scope of the present application.

[0058] As shown in Figure 1 , the present application provides a hybrid layup performance equivalent design method for a composite laminate, and the method specifically includes the following steps:

[0059] S1: determining the Tsai modulus and stiffness component input parameters of the hybrid laminate according to the replacement scheme, the materials used in the original laminate and the layup angle; the single-layer composite material of the hybrid laminate is carbon fiber composite material or glass fiber composite material.

[0060] As a preferred embodiment of the present application, the step specifically includes the following steps:

[0061] determining the Tsai modulus and stiffness component input parameters of the hybrid laminate based on formulas (1) and (2) according to the replacement scheme, the materials used in the original laminate and the layup angle; the hybrid laminate includes a carbon fiber laminate and a glass fiber laminate;

[0062]

[0063] Tr(Q)=kE1 (2)

[0064] wherein Tr(Q) is the Tsai modulus of the single layer in the hybrid laminate; is the normalized stiffness component after normalization by the Tsai modulus; Q ii (Q 11 ,Q 22 ,Q 33 ) is the corresponding element of the in-plane stiffness matrix Q of the single layer of the hybrid laminate; k is a parameter related to the type of fiber in the material of the corresponding single-layer laminate, k c = 1.12 for a carbon fiber laminate, and k g = 1.25 for a glass fiber laminate; E1 is the tensile modulus at 0°.

[0065] Specifically, the replacement scheme is a layup replacement (i.e., changing the layup angle of the original laminate) or a material replacement (i.e., changing the layup material of the original laminate).

[0066] The laminated plate adopts a double-angle non-orthogonal Double-Double lay-up, and the lay-up mode is [+Φ_g / -Ψ_c / +Ψ_c / -Φ_g] r The single-layer composite material is carbon fiber composite material or glass fiber composite material.

[0067] S2: Determine the hybrid ratio according to the Tsai modulus of the hybrid laminated plate obtained in S1, and estimate the single-layer stiffness of the laminated plate by using the single parameter of the Tsai modulus.

[0068] As a preferred embodiment of the present application, the step is specifically as follows:

[0069] According to the Tsai modulus of the hybrid laminated plate obtained in S1, the hybrid ratio is determined by using formula (3);

[0070]

[0071] Wherein, p c , p g are the thickness ratios of the carbon fiber laminated plate and the glass fiber laminated plate in the hybrid laminated plate; Tr(Q c ), Tr(Q g ) are the Tsai moduli of the carbon fiber laminated plate and the glass fiber laminated plate; are the Tsai modulus ratios contributed by the carbon fiber laminated plate and the glass fiber laminated plate, respectively;

[0072] Based on formula (4), the single-layer stiffness of the laminated plate is estimated by using the single parameter of the Tsai modulus;

[0073]

[0074] For the off-axis stiffness, the stiffness component can be represented by the off-axis angle θ and the uniaxial stiffness Q, and the corresponding relationship is as follows:

[0075]

[0076] Wherein, U i (i=1, 2, 3, 4) is a material-related intermediate parameter, and the calculation formula is as follows:

[0077] U1=0.375Q 11 +0.375Q 22 +0.25Q 21 +0.5Q 33 (6)

[0078] U2=0.5Q 11 -0.5Q 22 (7)

[0079] U3=0.125Q 11+0.125Q 22 -0.25Q 21 -0.5Q 33 (8)

[0080] U4=0.125Q 11 +0.125Q 22 +0.75Q 21 -0.5Q 33 (9)。

[0081] S3: through the hybrid layer Double-Double theory, determine the stiffness component consistent or uniaxial stiffness consistent equivalent conversion after hybrid layer replacement angle.

[0082] As a preferred embodiment of the application, the calculation formula of equivalent conversion is:

[0083]

[0084] Wherein, Ψ, Φ respectively represent the carbon fiber laminate and glass fiber laminate layer angle; It is an intermediate calculation parameter, and the calculation formula is as follows:

[0085]

[0086] Wherein, a c , b c and c c The thickness of the carbon fiber layer in the original layer is respectively accounted for the proportion of the total thickness of the carbon fiber layer; a g , b g And c g The thickness of the glass fiber layer in the original layer is respectively accounted for the proportion of the total thickness of the glass fiber layer;

[0087] If there is no completely equivalent replacement angle under the corresponding proportion, the uniaxial direction stiffness component consistent angle replacement is preferred, and the calculation formula is:

[0088]

[0089] The Double-Double hybrid layer obtained by equivalent conversion is [+Φ_g / -ψ_c / +ψ_c / -Φ_g] r Wherein, r represents the repetition number of the sub-layer.

[0090] The Double-Double hybrid layup composite material is obtained by equivalent conversion of a traditional layup composite material through a tensile stiffness matrix, and the layup angle of the Double-Double hybrid layup composite material equivalent to the tensile stiffness of the traditional layup composite material is obtained; the traditional layup composite material includes 0°, ±45°, 90° four-angle layup composite materials.

[0091] S4: according to the homogeneity requirement of the laminate, the stacking mode and the minimum overlap number of the hybrid Double-Double unit in the Double-Double hybrid layup composite material are determined; the material parameters are estimated through the Tsai modulus, the stiffness matrix after different unit repetition numbers is calculated, and the [+Φ_g / -Ψ_c / +Ψ_c / -Φ_g] is obtained. r The minimum repetition number of the layup homogeneity requirement.

[0092] That is, the repetition number of the layup unit of the laminate is determined by the homogeneity requirement; the stiffness matrix of the laminate and the element components are determined based on the Tsai modulus and the hybrid ratio. The hybrid laminate layup homogeneity is determined by the hybrid ratio and the normalized stiffness matrix, so as to determine the minimum Double-Double unit repetition number meeting the homogeneity requirement.

[0093] As a preferred embodiment of the present application, the laminate homogeneity requirement is

[0094] ‖B * ‖<0.02&‖A * -D * ‖<0.02 (13)

[0095] Wherein, A * ,B * ,D * are the tensile stiffness, coupling stiffness and bending stiffness of the laminate normalized by the trace of the matrix respectively;

[0096] The normalized stiffness matrix under different unit repetition numbers is calculated as:

[0097]

[0098]

[0099]

[0100] Wherein, H is the total thickness of the laminate, is the single-layer off-axis stiffness of the i-th layer, z i is the distance from the lower surface of the i-th layer to the symmetric intermediate surface;

[0101] The [+Φ_g / -Ψ_c / +Ψ_c / -Φ_g]r The ply homogeneity requirement is:

[0102]

[0103]

[0104] The method and effects of the present application will be further illustrated by the following examples.

[0105] Example

[0106] The present example provides a hybrid ply performance equivalent design method for a composite laminate, the steps of which are as follows:

[0107] S1: Determine the Tsai modulus and stiffness component input parameters according to the replacement scheme (ply replacement / material replacement), the materials used in the original laminate, and the ply angle; the calculation formula involved is:

[0108] Tr(Q) = Q 11 + Q 22 + 2Q 33

[0109] wherein Tr(Q) is the Tsai modulus of a single layer in a hybrid laminate; is the normalized stiffness component after normalization with the Tsai modulus; Q ii (Q 11 , Q 22 , Q 33 ) are the corresponding elements of the in-plane stiffness matrix Q of a single layer in a hybrid laminate; k is a parameter related to the type of fiber in the corresponding single layer laminate material, k c = 1.12 for a carbon fiber laminate, and k g = 1.25 for a glass fiber laminate; E1 is the 0° tensile modulus.

[0110] The present example is to realize the equivalent replacement of quasi-isotropic hybrid laminates. The carbon fiber layer stiffness E1 = 120 GPa, the glass fiber layer stiffness E1 = 50 GPa, and the original ply is [(0 / ±45 / 90)g / (0 / ±45 / 90)c] S , the hybrid layer thickness ratio is p g : p c = 2:1. The Tsai modulus of the carbon fiber layer and the glass fiber layer is Tr(Q c ) = k c E1 = 1.12 x 120 = 134.4 GPa, and Tr(Q g ) = k g E1 = 1.25 x 50 = 62.5 GPa. The stiffness component is

[0111] S2: Determine the hybrid ratio according to the Tsai modulus of the hybrid laminate, involving the calculation formula:

[0112]

[0113] Wherein, p c , p g are the thickness ratios of carbon fiber laminates and glass fiber laminates in the hybrid laminates; Tr(Q c ), Tr(Q g ) are the Tsai modulus of carbon fiber laminates and glass fiber laminates; are the Tsai modulus ratios contributed by carbon fiber laminates and glass fiber laminates respectively.

[0114] This embodiment is the stiffness replacement of hybrid laminates. The Tsai modulus of the laminates and the hybrid ratio remain consistent: Tr(Q) = p c Tr(Q c )+p g Tr(Q g ) = 0.33 * 120 + 0.66 * 50 = 72.6 GPa, and the Tsai modulus ratios are

[0115] The single parameter of Tsai modulus is used to estimate the single-layer stiffness of the laminates, involving the calculation formula:

[0116]

[0117] For off-axis stiffness, the stiffness component can be represented by the off-axis angle θ and the uniaxial stiffness Q, and the corresponding relationship is:

[0118]

[0119] Where U i (i = 1, 2, 3, 4) is a material-related parameter, and the calculation formula is:

[0120] U1 = 0.375Q 11 + 0.375Q 22 + 0.25Q 21 + 0.5Q 33

[0121] U2 = 0.5Q 11 - 0.5Q 22

[0122] U3 = 0.125Q 11 + 0.125Q 22 - 0.25Q 21 - 0.5Q 33

[0123] U4 = 0.125Q 11 + 0.125Q 22 + 0.75Q 21 - 0.5Q 33

[0124] S3: Determine the equivalent conversion of the hybrid lay-up to replace the angle of consistent stiffness components or uniaxial stiffness consistency by the hybrid lay-up theory of Double-Double, as shown in Figure 2 , the replaced lay-up unit is [+Φ_g / -Ψ_c / +Ψ_c / -Φ_g] r . The calculation formula of equivalent conversion is:

[0125]

[0126] Wherein, Ψ, Φ represent the angle of carbon fiber layer and glass fiber layer respectively. To calculate the parameters, the calculation formula is as follows:

[0127]

[0128] Wherein, a c , b c and c c are the thickness of carbon fiber layer at 0°, ±45°, 90° angle respectively, which accounts for the proportion of the total thickness of carbon fiber layer in the original layer; a g , b g and c g are the thickness of glass fiber layer at 0°, ±45°, 90° angle respectively, which accounts for the proportion of the total thickness of glass fiber layer in the original layer;

[0129] For the quasi-isotropic hybrid layer of the embodiment, a c = 0.33 × 0.25, b c = 0.33 × 0.5, b c = 0.33 × 0.25, a g = 0.66 × 0.25, b g = 0.66 × 0.5, b g = 0.66 × 0.25, so that The corresponding hybrid lay-up angle is obtained: Φ_g = 68°, Ψ_c = 23° or Φ_g = 22°, Ψ_c = 67°. The equivalent conversion of Double-Double lay-up composite material is [+Φ_g / -Ψ_c / +Ψ_c / -Φ_g] r , wherein r represents the repetition number of sub-lay-up. The allowable parameter range of equivalent replacement is as follows: Figure 3As shown, if there is no completely equivalent alternative angle under the corresponding proportion, the uniaxial direction stiffness component is guaranteed to be consistent, and the calculation formula is:

[0130]

[0131] For this embodiment: 0.371 = 0.371 + 0.420 × (0.5 × (0.545cos2Ψ + 0.53cos2Φ)) + 0.103 × (0.5 × (0.545cos4Ψ + 0.53cos4Φ)). Any angle value that satisfies the equation can guarantee the consistency of the uniaxial direction stiffness component.

[0132] S4: Determine the stacking mode and minimum overlap number of the hybrid Double-Double unit according to the homogeneity requirement of the laminate. The homogeneity requirement of the laminate is

[0133] ‖B * ‖<0.02&‖A * -D * ‖<0.02

[0134] Wherein, A * ,B * ,D * are the tensile stiffness, coupling stiffness and bending stiffness of the laminate after standardization by the trace of the matrix, respectively.

[0135] The normalized stiffness matrix under different unit repetition numbers is calculated as:

[0136]

[0137]

[0138]

[0139] Wherein, H is the total thickness of the laminate, is the single-layer off-axis stiffness of the i-th layer, z i is the distance from the lower surface of the i-th layer to the symmetric mid-plane;

[0140] The [+Φ_g / -Ψ_c / +Ψ_c / -Φ_g] r The laminate homogeneity requirement is:

[0141]

[0142]

[0143] In this embodiment, the homogeneity condition of the hybrid Double-Double laminate is:

[0144]

[0145] and

[0146]

[0147] The relationship between the homogeneity and the repetition number of different hybrid Double-Double layer sequences is shown in Table 1. Figure 4 The layer sequence and the minimum repetition number satisfying the homogeneity requirement are: [+68°_g / -23°_c / +23°_c / -68°_g]4.

[0148] Compared with the prior art, the embodiment of the application has the following advantages:

[0149] 1. On the premise of ensuring the overall stiffness of the laminated plate and the consistency of each stiffness component, the application realizes the design of multiple material hybrid Double-Double layer and the equivalent replacement of the traditional layer. The hybrid Double-Double layer simplifies the layer sequence, and the designer can use the method of the application to select the material and layer of the initial design. The hybrid Double-Double laminated plate can avoid the warping failure of the component during use, and reduce the burden of the designer in the tedious layer design work. The calculation program can be prepared according to the layer optimization method, and the most suitable hybrid Double-Double laminated plate under the given working condition can be directly generated, so that the preliminary design is completed conveniently and quickly.

[0150] 2. The hybrid layer of the composite laminated plate provided by the application has higher homogeneity in the overall structure of the laminated plate, and is easier to design and optimize the layer. The hybrid layer can exhibit pseudo-ductility effect under certain conditions, improve the safety factor, and provide a more effective means for the composite material layer design.

[0151] The above-described embodiments are only a preferred scheme of the application, and are not intended to limit the application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the application. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the application.

Claims

1. A method for the performance equivalent design of hybrid plies of a composite laminate characterized in that, The specific process is as follows: S1: according to the replacement scheme, the material used for the original laminate and the layer angle, determine the Tsai modulus and the stiffness component input parameter of the hybrid laminate; the single layer composite material of the hybrid laminate is carbon fiber composite material or glass fiber composite material; S2: according to the Tsai modulus of the hybrid laminate obtained in S1, determine the hybrid ratio, and estimate the single layer stiffness of the laminate by using the single parameter of Tsai modulus; S3: by the hybrid layer Double-Double theory, determine the equivalent conversion of the hybrid layer after the replacement angle is consistent or the uniaxial stiffness is consistent; S4: According to the requirements of laminate homogeneity, determine the stacking sequence and the minimum repeating number of the hybrid Double-Double unit in the Double-Double hybrid laminates; estimate the material parameters by Tsai's modulus, calculate the stiffness matrix after different repeating numbers of the unit, and obtain the minimum repeating number of the unit that meets the requirements of laminate homogeneity laminates homogeneity The calculation formula of the equivalent conversion in S3 is: （10）； wherein, respectively represent the ply angles of the carbon fiber laminate and the glass fiber laminate; is an intermediate calculation parameter, and the calculation formula is as follows: （11）； wherein, , and are the thickness of the carbon fiber laminate at 0°, ±45°, 90° angle respectively in the original laminate layup as a proportion of the total thickness of the carbon fiber laminate; , and are the thickness of the glass fiber laminate at 0°, ±45°, 90° angle respectively in the original laminate layup as a proportion of the total thickness of the glass fiber laminate; If there is no completely equivalent replacement angle under the corresponding ratio, the uniaxial direction stiffness component is consistent to replace the angle, and the calculation formula is: （12）； The equivalent conversion of the Double-Double hybrid lay-up is wherein represents the number of repetitions of the sub-lay-up.

2. The method for designing a hybrid ply of a composite laminate according to claim 1, wherein The specific process of S1 is as follows: According to the replacement scheme, the material used for the original laminate and the layer angle, determine the Tsai modulus and the stiffness component input parameter of the hybrid laminate based on formula (1) and (2); the hybrid laminate includes carbon fiber laminate and glass fiber laminate; （1）； （2）； wherein, Tsai modulus of the single layer in the hybrid laminate; normalized stiffness component after normalization with the Tsai modulus; corresponding element of the in-plane stiffness matrix of the single layer in the hybrid laminate a parameter related to the fiber type in the corresponding single layer laminate material, for carbon fiber laminates , for glass fiber laminates 0° tensile modulus.​​​​ 3. The method for designing a hybrid ply of a composite laminate according to claim 2, wherein The replacement scheme is layer replacement or material replacement.

4. The method of claim 1, wherein, The specific process of S2 is as follows: According to the Tsai modulus of the hybrid laminate obtained in S1, determine the hybrid ratio by using formula (3); （3）； wherein, , is the thickness ratio of carbon fiber laminates and glass fiber laminates in the hybrid laminates; , is the Tsai modulus of carbon fiber laminates and glass fiber laminates; is the Tsai modulus ratio contributed by carbon fiber laminates and glass fiber laminates, respectively; Based on formula (4), estimate the single layer stiffness of the laminate by using the single parameter of Tsai modulus; （4）； For off-axis stiffness, the stiffness components can be expressed in terms of off-axis angle and uniaxial stiffness The correspondence is as follows: （5）； wherein is an intermediate parameter related to the material, the calculation formula of which is as follows: （6）； （7）； （8）； （9）。 5. The method of claim 1, wherein the method is characterized by: The homogeneity requirement of the laminate is （13）； wherein, respectively the tensile stiffness, the coupling stiffness, the bending stiffness of the laminate normalized with the trace of the respective matrix. The normalized stiffness matrix under different unit repetition times is calculated as follows: （14）； （15）； （16）； wherein, is the total thickness of the laminate, is the thickness of the first is the single-layer off-axis stiffness of the first is the distance from the lower surface of the first is the distance from the lower surface of the first The Layup homogeneity requirements are that: （17）； （18）。 6. The method of claim 1, wherein, The Double-Double hybrid layer composite material is obtained by stretching the stiffness matrix equivalent conversion of the traditional layer composite material, and the layer angle of the Double-Double hybrid layer composite material equivalent to the stretching stiffness of the traditional layer composite material is obtained; the traditional layer composite material includes 0°, ±45°, 90° four angle layer composite materials.

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