Composite board selection method, stress verification method and system

Abstract

The application provides a selection method, a stress verification method and a system for a composite board, and the technical scheme is as follows: a selection method for the thickness of a sublayer of a composite board, comprising the following steps: obtaining the elastic modulus and tensile strength of each sublayer veneer in the composite board; establishing a first mathematical model of the thickness ratio of the sublayer veneer and the equivalent elastic modulus of the composite board; establishing a second mathematical model of the tensile strength and the thickness ratio of the sublayer veneer based on the first mathematical model; and obtaining the thickness ratio of each sublayer veneer in the composite board through the second mathematical model; and a stress verification method for a composite board is also disclosed, which is used for verifying the thickness ratio of the sublayer veneer obtained by the selection method for the thickness of the sublayer of the multi-layer board; and the scheme can realize the optimization of the matching ratio of the thickness of each sublayer of the composite board, so that the composite board has excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of composite panel structures, and more particularly to a method for selecting values, a method for verifying the stress of composite panels, and a system thereof. Background Technology

[0002] Composite boards are a common type of board material, offering advantages such as affordability, high-quality materials, ease of processing, and recyclability. For a detailed description of the composite board structure, refer to the technical solution in patent application number 201920625553.4, which discloses a cutting board that reduces the impact of a knife blade. The board comprises a bottom board, a sandwich board, and a top board arranged sequentially from bottom to top. The bottom and top boards are parallel square boards. The sandwich board includes two or more parallel bamboo sheets, with the fiber direction of the bamboo sheets parallel to the bottom board. The bottom and top boards have the same thickness, the ratio of the height of the bamboo sheets to the thickness of the bottom board ranges from 2 to 4, and the ratio of the height of the bamboo sheets to the width of the bamboo sheets ranges from 1 to 5.

[0003] Although the above-mentioned solution discloses the ratio of the thickness of the sandwich bamboo board to the thickness of the bottom wood board, this ratio is based on the special structure formed by the sandwich, bottom, and top layers. It cannot be applied to composite boards with multi-layer flat stacking structures. Furthermore, it does not provide the selection range and matching ratio of the thickness of each sub-layer of the composite board, and therefore cannot obtain a composite board with excellent mechanical properties.

[0004] Therefore, the problem of this solution is how to optimize the matching ratio of the thickness of each sublayer of the composite board so that the composite board has excellent mechanical properties. Summary of the Invention

[0005] The purpose of this invention is to provide a method for selecting composite plate values, a method for verifying stress, and a system to optimize the matching ratio of the thickness of each sublayer of the composite plate, so that the composite plate has excellent mechanical properties.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for selecting the sublayer thickness of a composite board includes the following steps:

[0008] Obtain the elastic modulus and tensile strength of each sublayer veneer within the composite panel;

[0009] A first mathematical model is established to correlate the thickness ratio of the sublayer veneer with the equivalent elastic modulus of the composite board.

[0010] A second mathematical model is established based on the first mathematical model to determine the tensile strength and thickness ratio of the sublayer veneer.

[0011] The thickness percentage of each sublayer veneer within the composite board is obtained using a second mathematical model.

[0012] In the above-mentioned method for selecting the sublayer thickness of the composite plate, the steps for establishing the first mathematical model include:

[0013] Treating the composite plate as a composite beam, and using linear elasticity and small deformation theory, a composite beam calculation model of stress and deformation of pure bending beams of each sub-layer plate is established.

[0014] The combined beam calculation model of each sub-layer single plate is combined with the static calculation model of the beam cross section to form the elastic modulus transition calculation model;

[0015] The thickness ratio calculation model of each sublayer veneer is introduced into the elastic modulus transition calculation model to form the first mathematical model.

[0016] In the above method for selecting the sublayer thickness of the composite plate, the steps for establishing the second mathematical model include:

[0017] The composite beam calculation model of each sub-layer slab is converted into a composite calculation model of the static bending strength of the composite plate and the tensile strength of the sub-layer slab.

[0018] The composite operation models described above are combined with each other in an equal manner, and the thickness ratio operation model of each sub-layer board is introduced to form the second mathematical model.

[0019] In the above-mentioned method for selecting the sublayer thickness of the composite plate, the conversion step of transforming the composite beam calculation model into the static bending strength calculation model includes:

[0020] The composite beam calculation model is transformed using a variable continuous condition processing method, and the transformed composite beam calculation model is converted into the static bending strength calculation model using a strength condition method.

[0021] In the above-mentioned method for selecting the thickness of the sublayer of the composite board, when the thickness ratio of the sublayer single board in the composite board is 3 and the sum of the thickness ratios of the sublayer single board is greater than 1, one of the three sublayer single boards is selected as the adjustment board, and the thickness ratio of the adjustment board is reduced until the sum of the thickness ratios of the sublayer single boards is 1.

[0022] In the above-mentioned method for selecting the thickness of the sublayers of the composite board, the elastic modulus and tensile strength of the adjusting single layer are both lower than the elastic modulus and tensile strength of the other two sublayer single layers.

[0023] A composite board includes a plurality of sub-layer veneers, the sub-layer veneers being prepared based on the method for selecting the sub-layer thickness of the composite board as described above, and the plurality of the sub-layer veneers being sequentially bonded together with adhesive to form the composite board.

[0024] A method for verifying the stress of a composite plate, used to obtain the stress deformation of the composite plate prepared by the above-described value selection method, includes the following steps:

[0025] Based on the elastic modulus and tensile strength of each sub-layer veneer in the composite plate, a numerical simulation of the finite element mesh is performed using a three-point bending method.

[0026] In the above-mentioned stress verification method for composite plates, the maximum stress criterion is used as the damage initiation criterion for each sub-layer plate; the bilinear damage evolution law is used to express the damage variables; and the Poisson's ratio is taken as 0.23.

[0027] A stress verification system for a composite panel includes two support seats for supporting the bottom of a sub-layer panel, a press for pressing down on the center of the sub-layer panel and outputting a load value, and a computer device for performing the stress verification method described above; the two support seats are symmetrically arranged with the power output end of the press as the center of symmetry, and the computer device simulates and analyzes the stress deformation of the composite panel through the load value output by the press.

[0028] Compared with the prior art, the solution of the present invention has the following advantages:

[0029] This technical solution treats the bamboo multilayer structural board as a composite board symmetrically distributed along the thickness direction. Based on the bending theory of board beams (small deformation, linear elasticity), the mechanical properties of the bamboo multilayer structure are analyzed. In order to make full use of the material while taking into account the mechanical properties and lightweight requirements of the board, the thickness of each sublayer of the multilayer structural board is optimized based on the composite beam theory and the viewpoint of equal strength. An optimized calculation formula for the thickness of each sublayer is proposed to optimize the matching ratio of the thickness of each sublayer of the composite board, so that the composite board has excellent mechanical properties.

[0030] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0032] Figure 1 This is a flowchart illustrating the selection of sublayer thickness in a composite plate according to one embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of measurement points on a sublayer board in one embodiment of the present invention;

[0034] Figure 3 This is a bar chart showing the elastic modulus of each sublayer plate in one embodiment of the present invention.

[0035] Figure 4 This is a bar chart showing the static bending strength of each sublayer veneer in one embodiment of the present invention.

[0036] Figure 5 This is a schematic diagram of a three-layer plate loading in one embodiment of the present invention;

[0037] Figure 6 This is a graph showing the variation of the equivalent elastic modulus of the three-layer plate with the core plate thickness ratio x in one embodiment of the present invention.

[0038] Figure 7 This is a graph showing the equivalent elastic modulus versus surface thickness of a three-layer particleboard in one embodiment of the present invention.

[0039] Figure 8 This is a force-displacement curve of a three-layer plate in one embodiment of the present invention;

[0040] Figure 9 This is a graph showing the change in static bending strength of a three-layer plate with surface layer thickness in one embodiment of the present invention. Detailed Implementation

[0041] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0042] like Figure 1 As shown, the present invention provides a method for selecting the sublayer thickness of a composite plate, comprising the following steps:

[0043] Obtain the elastic modulus and tensile strength of each sublayer veneer within the composite panel;

[0044] A first mathematical model is established to correlate the thickness ratio of the sublayer veneer with the equivalent elastic modulus of the composite board.

[0045] A second mathematical model is established based on the first mathematical model to determine the tensile strength and thickness ratio of the sublayer veneer.

[0046] The thickness percentage of each sublayer veneer within the composite board is obtained using a second mathematical model.

[0047] Further improvements include the following steps in establishing the first mathematical model:

[0048] Treating the composite plate as a composite beam, and using linear elasticity and small deformation theory, a composite beam calculation model of stress and deformation of pure bending beams of each sub-layer plate is established.

[0049] The combined beam calculation model of each sub-layer single plate is combined with the static calculation model of the beam cross section to form the elastic modulus transition calculation model;

[0050] The thickness ratio calculation model of each sublayer veneer is introduced into the elastic modulus transition calculation model to form the first mathematical model.

[0051] Another improvement in this embodiment is that the steps for establishing the second mathematical model include:

[0052] The composite beam calculation model of each sub-layer slab is converted into a composite calculation model of the static bending strength of the composite plate and the tensile strength of the sub-layer slab.

[0053] The composite operation models described above are combined with each other in an equal manner, and the thickness ratio operation model of each sub-layer board is introduced to form the second mathematical model.

[0054] As a further improvement to this embodiment, the conversion step from the composite beam calculation model to the static bending strength calculation model includes:

[0055] The composite beam calculation is transformed using a variable continuous condition processing method, and the transformed composite beam calculation model is converted into the static bending strength calculation model using a strength condition method.

[0056] In some embodiments, when the number of thickness ratios of the sub-layer panels in the composite panel is 3 and the sum of the thickness ratios of the sub-layer panels is greater than 1, one of the three sub-layer panels is selected as the adjustment panel, and the thickness ratio of the adjustment panel is reduced until the sum of the thickness ratios of the sub-layer panels is 1.

[0057] Preferably, the elastic modulus and tensile strength of the adjusting veneer are both lower than those of the other two sub-layer veneers.

[0058] The specific implementation process is as follows: the bamboo multilayer structural board is regarded as a composite board symmetrically distributed along the thickness direction. Based on the bending theory of board beams (small deformation, linear elasticity), the mechanical properties of the bamboo multilayer structure are analyzed. In order to make full use of the material and at the same time take into account the mechanical properties and lightweight requirements of the board, the thickness of each sub-layer of the multilayer structural board is optimized based on the composite beam theory and the viewpoint of equal strength. The optimized calculation formula of each sub-layer thickness is proposed to achieve the optimized matching ratio of the thickness of each sub-layer of the composite board, so that the composite board has excellent mechanical properties.

[0059] For each specimen, mass and dimensions were measured, such as Figure 2 As shown. The intersection of the diagonals of the specimen is used as the thickness t measurement point. At the middle of the specimen, the length l and width b of the specimen are measured.

[0060] The density of each layer of the board can be calculated using the following formula:

[0061]

[0062] In the formula, ρ is the density of the specimen, m is the mass of the specimen, l is the length of the specimen, b is the width of the specimen, and t is the thickness of the specimen. In the test, 10 specimens of each type of laminate were taken to calculate the density, and the average value was taken as the density value of that laminate. The densities of the three types of laminates were measured experimentally as follows:

[0063] ρ 表层 =0.806 / m 3 , ρ 加强 =0.637 / m 3 , ρ 芯层 =0.54 / m 3

[0064] The tensile strength of a single-layer plate was tested using a UTM5004 tensile testing machine. To prevent slippage of the specimen during tension and to avoid excessive clamping force that could cause damage to the plate at the loading end, anti-slip metal sheets were attached to the left and right surfaces of the clamping end of the specimen. The test results are shown in Table 2-1.

[0065] Table 2-1 Tensile Test Results

[0066]

[0067]

[0068] Note: A represents the surface layer, B represents the reinforcing layer, and C represents the core layer.

[0069] As shown in Table 2-1, the surface layer has the highest tensile strength, followed by the reinforcing layers, while the core layer has the lowest tensile strength.

[0070] The data in Table 2-1 were processed, and the average value was taken to obtain the tensile material parameters of each sublayer, as shown in Table 2-2.

[0071] Table 2-2 Tensile property parameters of each sublayer

[0072]

[0073] The bending strength of each layer of the board was then determined by a three-point bending test. The results of the three-point bending test are shown in Table 2-3.

[0074] Table 2-3 Bending test data for each layer of the slab

[0075]

[0076]

[0077] Note: A represents the surface layer, B represents the reinforcing layer, and C represents the core layer.

[0078] The data in Table 2-3 were processed to obtain the bar charts of elastic modulus and static bending strength of each sublayer, as shown below. Figure 3 and Figure 4 As shown.

[0079] From Table 2-3 and Figure 3 and Figure 4 It is evident that among the three types of sub-layers, the surface layer has the highest flexural modulus of elasticity and static bending strength, followed by the reinforcing layer, while the core layer has the lowest.

[0080] The data in Table 2-3 were statistically analyzed, as shown in Table 2-4.

[0081] Table 2-4 Bending performance parameters of three types of sub-layer plates

[0082]

[0083] Comparing Tables 2-2 and 2-4, it can be seen that the flexural modulus of elasticity and the tensile modulus of elasticity of each sublayer are basically the same, but the tensile strength is lower than the bending strength. The tensile strength of brittle materials is usually lower than the bending strength, so this result is entirely consistent with the characteristics of brittle materials.

[0084] The three-layer structure consists of an upper and lower surface layer, and a middle core layer. Figure 5 As shown.

[0085] Let the total thickness of the three-layer bamboo particleboard be h, the thickness of the top and bottom layers be h1, and the thickness of the middle core layer be h2, then we have:

[0086] h = 2h1 + h2 (2-2)

[0087] Thickness optimization based on equivalent elastic modulus:

[0088] Treating the three-layer slab as a composite beam, let y be the distance from any point on the beam's cross-section to the neutral axis of the section, with downward as the positive direction, b be the beam's width, and ρ be the beam's radius of curvature after bending. Using the assumptions of linear elasticity and small deformation, the stress-deformation relationship of the purely bending beam is:

[0089]

[0090]

[0091] In the formula

[0092] Equations 2-3 and 2-5 are the calculation models for composite beams.

[0093] According to the static relationship on the beam cross-section, we have

[0094]

[0095] Substituting equations (2-3) and (2-4) into equation (2-5), we get:

[0096]

[0097] Equation 2-5 is the transition calculation model for elastic modulus.

[0098] Let the thickness ratio of the core layer be expressed as Ultimately, we can obtain:

[0099] E = E1 - (E1 - E2)x 3 (2-7)

[0100] Where E1 is the surface elastic modulus, E2 is the core elastic modulus, and x is the core thickness percentage. The equivalent elastic modulus of the three-layer plate changes nonlinearly with the core thickness percentage.

[0101] Equation 2-7 is the first mathematical model.

[0102] Thickness optimization based on static bending strength:

[0103] Based on the plane assumption of beam bending, the following geometric relationships exist:

[0104]

[0105] Where ε is the bending strain at any point on the cross section, y is the distance from that point to the neutral axis, and ρ is the radius of curvature of the neutral axis.

[0106] Based on the deformation continuity condition, we obtain from equations (2-3) to (2-5)

[0107]

[0108]

[0109] Based on the strength condition, we obtain

[0110]

[0111]

[0112] In the formula, [σ] represents the static bending strength of the entire plate. 表 ] and [σ 芯 [ ] represents the tensile strength of the surface layer and the core layer, respectively.

[0113] Equations 2-9 and 2-10 are the calculation models for composite beams, and Equations 2-11 and 2-12 are the calculation models for static bending strength.

[0114] From equations (2-11) and (2-12), we obtain...

[0115]

[0116]

[0117] Equations 2-13 and 2-14 are composite operation models.

[0118] According to the principle of equal strength, when both the core layer and the surface layer reach their respective strengths, that is...

[0119]

[0120] The formula for calculating the optimal core layer thickness ratio is as follows:

[0121]

[0122] Equation (2-16) shows that, from the perspective of equal strength, the thickness ratio of the core layer depends on the ratio of the static bending strength of the core layer to that of the surface layer and the ratio of their elastic moduli.

[0123] Conclusion: Based on the performance parameters in Table 2-2, if a three-layer structure of surface layer + core layer is adopted, the core layer thickness accounts for 0.73%; if a three-layer structure of surface layer + reinforcing layer is adopted, the core layer thickness accounts for 0.66%. Optimizing the thickness of the three-layer board according to this thickness ratio can ensure that the structural layers of the three-layer board meet the principle of equal strength and make full use of the material.

[0124] Equation 2-16 is the second mathematical model.

[0125] A composite board includes a plurality of sub-layer veneers, the sub-layer veneers being manufactured based on the method for selecting the sub-layer thickness of the composite board as described above, and the plurality of the sub-layer veneers being sequentially bonded together with adhesive to form the composite board.

[0126] A method for verifying the stress on a composite plate, used to obtain the stress deformation of the composite plate prepared by the method described above, includes the following steps:

[0127] Based on the elastic modulus and tensile strength of each sub-layer veneer in the composite plate, a numerical simulation of the finite element mesh is performed using a three-point bending method.

[0128] Further settings include using the maximum stress criterion as the damage initiation criterion for each sublayer plate; employing the bilinear damage evolution law to express damage variables; and taking a Poisson's ratio of 0.23 for all sublayer plates.

[0129] A stress verification system for a composite panel includes two support seats for supporting the bottom of a sub-layer panel, a press for pressing down on the center of the sub-layer panel and outputting a load value, and a computer device for performing the stress verification method described above; the two support seats are symmetrically arranged with the power output end of the press as the center of symmetry, and the computer device simulates and analyzes the stress deformation of the composite panel through the load value output by the press.

[0130] Using equations (2-7) and (2-16), and employing finite element numerical simulation, the thickness optimization of the three-layer plate is discussed. The material parameters in Table 2-2 are adopted, with Poisson's ratio set to 0.23. Considering the three-layer structure (surface layer + core layer), the relationship between the plate's equivalent elastic modulus E and x (core thickness percentage) is obtained as follows: Figure 6 As shown. By Figure 6 It can be seen that the value of E is between (E2, E1) and decreases non-linearly as x increases.

[0131] For a three-layer bamboo particleboard (surface layer + core layer) with a total thickness of 18mm, the relationship between its equivalent modulus of elasticity and the surface layer thickness is as follows: Figure 7 As shown.

[0132] The bending fracture problem of a three-layer plate was simulated using the extended finite element method in the Abaqus simulation software. The maximum principal stress criterion was used as the damage initiation criterion for each sub-plate.

[0133]

[0134] Among them, in the denominator The principal stress at which material damage begins is taken from the tensile strength in Table 2-1; <> represents Macolean brackets, indicating that the material will not be damaged under pure compressive deformation. When f is greater than 1, it indicates that the material will be damaged. If the material already has cracks before the analysis, then f greater than 1 indicates that the cracks will propagate.

[0135] Using the bilinear damage evolution law, the damage variable expression is as follows:

[0136]

[0137] In the formula, The crack separation displacement represents the point at which damage initiation begins, i.e. The corresponding displacement; This represents the maximum separation displacement of the material under load. This represents the final separation displacement at the end of the damage evolution process.

[0138] Take the failure displacement from Table 2-2.

[0139] Numerical simulation of three-point bending of bamboo particleboard was performed in Abaqus / Standard. C3R8 elements were used, and the mesh was refined in the longitudinal direction. Stress contour plots and crack propagation were also analyzed.

[0140] Consider a three-layer plate consisting of a surface layer and a core layer. The numerical simulation results are as follows: Figure 8 and Figure 9 As shown.

[0141] Depend on Figure 8 It can be seen that for a three-layer plate with a total thickness of 18mm, the ultimate load changes significantly with the thickness of the surface plate: the greater the thickness of the surface plate, the higher the load-bearing capacity of the plate and the enhanced fracture toughness.

[0142] To meet flatness requirements, the surface layer thickness generally needs to be greater than 3mm. Table 2-5 shows that when the surface layer thickness is 7mm, compared to a 3mm surface layer, the elastic modulus increases by 24.4%, the static bending strength increases by 23.3%, but the mass increases by 7.51%. Due to the high adhesive content in the surface layer, the adhesive content of the board will increase.

[0143] Table 2-5 Equivalent elastic modulus and static bending strength of three-layer boards (surface layer + core layer) with different surface layer thicknesses

[0144]

[0145] The mass increased by 7.51%. This is because the high surface adhesive content increases the adhesive content of the board.

[0146] As shown in Table 2-2, the tensile strength and failure displacement of the reinforcing layer are higher than those of the core layer. Therefore, it can be inferred that if the core layer is replaced with the reinforcing layer, the static bending strength of the three-layer board can be significantly improved.

[0147] Conclusion: For current bamboo-scented boards, the size of bamboo particles / shavings decreases from the middle to the surface layer, and the elastic modulus and static bending strength of the surface layer are higher than those of the core layer. To improve the equivalent elastic modulus and static bending strength of the three-layer board, the thickness ratio of the surface layer must be increased, but this will also increase the amount of glue used and the weight of the board, which is not conducive to environmental protection and lightweighting. For a three-layer board with an overall thickness of 18mm for the surface layer and core layer, a thickness distribution of 2.5-13-2.5 is already a relatively optimal layer structure that meets the requirements of equal strength and lightweighting.

[0148] The above description is only a partial embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for selecting the sublayer thickness of a composite plate, characterized in that, Includes the following steps: Obtain the elastic modulus and tensile strength of each sublayer veneer within the composite panel; A first mathematical model is established to correlate the thickness ratio of the sublayer veneer with the equivalent elastic modulus of the composite board. A second mathematical model is established based on the first mathematical model to determine the tensile strength and thickness ratio of the sublayer veneer. The thickness percentage of each sub-layer veneer within the composite board is obtained using a second mathematical model. The steps for establishing the first mathematical model include: Treating the composite plate as a composite beam, and using linear elasticity and small deformation theory, a composite beam calculation model of stress and deformation of pure bending beams of each sub-layer plate is established. The combined beam calculation model of each sub-layer single plate is combined with the static calculation model of the beam cross section to form the elastic modulus transition calculation model; The thickness ratio calculation model of each sub-layer single plate is introduced into the elastic modulus transition calculation model to form the first mathematical model; The steps for establishing the second mathematical model include: The composite beam calculation model of each sub-layer slab is converted into a composite calculation model of the static bending strength of the composite plate and the tensile strength of the sub-layer slab. The composite operation models described above are combined with each other in an equal manner, and the thickness ratio operation model of each sub-layer board is introduced to form the second mathematical model.

2. The method for selecting the sublayer thickness of the composite plate according to claim 1, characterized in that, The conversion steps from the composite beam calculation model to the static bending strength calculation model include: The composite beam calculation model is transformed using a variable continuous condition processing method, and the transformed composite beam calculation model is converted into the static bending strength calculation model using a strength condition method.

3. The method for selecting the sublayer thickness of the composite plate according to claim 1, characterized in that, When the thickness ratio of the sub-layer veneers in the composite board is 3 and the sum of the thickness ratios of the sub-layer veneers is greater than 1, one of the three sub-layer veneers is selected as the adjustment veneer, and the thickness ratio of the adjustment veneer is reduced until the sum of the thickness ratios of the sub-layer veneers is 1.

4. The method for selecting the sublayer thickness of the composite plate according to claim 3, characterized in that, The modulus of elasticity and tensile strength of the regulating veneer are both lower than those of the other two sub-layer veneers.

5. A composite board comprising a plurality of sub-layer veneers, characterized in that, The sublayer veneer is prepared based on the method for selecting the sublayer thickness of the composite board as described in any one of claims 1-4, and a plurality of the sublayer veneers are sequentially bonded together with adhesive to form a composite board.

6. A method for verifying the stress of a composite plate, used to obtain the stress deformation of the composite plate prepared by any of the selection methods described in 1-4, characterized in that, Includes the following steps: Based on the elastic modulus and tensile strength of each sub-layer veneer in the composite plate, a numerical simulation of the finite element mesh is performed using a three-point bending method.

7. The method for verifying the stress of a composite plate according to claim 6, characterized in that, The maximum stress criterion was used as the damage initiation criterion for each sublayer plate; the bilinear damage evolution law was used to express the damage variables; and the Poisson's ratio was taken as 0.

23.

8. A stress verification system for composite panels, characterized in that, It includes two support seats for supporting the bottom of the sublayer veneer, a press for pressing down the center of the sublayer veneer and outputting a load value, and a computer device for performing the stress verification method as described in claim 6; the two support seats are symmetrically arranged with the power output end of the press as the center of symmetry, and the computer device simulates and analyzes the stress deformation of the composite plate through the load value output by the press.

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