A fast design method of symmetrically balanced composite angle box
By using a rapid design method for symmetrical and balanced composite corner boxes, the proportion of 0° ply can be easily calculated and 45° and 90° ply can be reasonably allocated. This solves the problem of design complexity of composite corner boxes for variable thickness aluminum alloy structures and achieves efficient design with equal stiffness and equal strength.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHU STATE-OWNED FACTORY OF MACHINING
- Filing Date
- 2026-03-12
- Publication Date
- 2026-06-19
AI Technical Summary
Existing technologies make it difficult to quickly and effectively design composite corner boxes with varying thickness and constant stiffness and strength, resulting in complex and inefficient designs for composite material patching and repair of aluminum alloy structures.
Through simple theoretical calculations, the proportion of 0° ply in each region of a variable-thickness symmetrical balanced composite corner box can be quickly obtained, and 45° and 90° ply can be reasonably allocated to complete the variable-thickness symmetrical balanced ply design.
Under the design principles of equal stiffness and equal strength, composite corner boxes with varying thickness can be designed quickly. The method is simple and the design efficiency is high.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of composite material patching and repair of aircraft aluminum alloy structures, specifically a rapid design method for symmetrical and balanced composite material corner boxes. Background Technology
[0002] Aluminum alloy structures are one of the main materials used in aircraft both domestically and internationally. Under the influence of service loads, corrosive environments, and accidental impacts, aluminum alloy structures are prone to damage such as fatigue cracks and stress corrosion cracks. Composite material patching is an important method for repairing damage to lightweight aluminum alloy structures. Aluminum alloy structures are typically sheet metal or L-shaped structural components of varying thicknesses. Correspondingly, composite material patches also need to be designed with varying thicknesses to ensure that patching repairs of aluminum alloys of different thicknesses meet the principles of equal strength and stiffness. Variable-thickness composite material layups are achieved through layer drop; however, due to the numerous variations in the layup angles and quantities, the design of variable-thickness composite corner boxes is very complex and inefficient.
[0003] Currently, there are many designs for composite laminates and composite box segments in China, but few design methods for composite materials used in the repair and patching of aluminum alloy structures. For example, Chinese patent CN202411906260.5 discloses a parameter optimization design method for composite main box segments using a genetic algorithm, but this method is complex, cumbersome, and requires a certain level of professional expertise. Chinese patent CN202111434644.8 discloses a variable-thickness layup method for continuous fiber-reinforced composite parts designed based on structural load-bearing requirements; however, this method requires complex modal analysis and stress analysis, making the process quite complicated. Therefore, there is an urgent need to propose an effective and simple design method for variable-thickness composite corner boxes to address the repair and patching needs of complex damaged aluminum alloy structures.
[0004] To address these issues, those skilled in the art have provided a rapid design method for symmetrical and balanced composite material corner boxes. Summary of the Invention
[0005] The purpose of this invention is to provide a rapid design method for symmetrical and balanced composite material corner boxes. In the repair of aluminum alloy structures using composite material patching, when repairing aluminum alloy structures with varying thickness, it is possible to quickly and effectively design composite material corner boxes with varying thickness and equal stiffness and strength, thereby solving the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A rapid design method for symmetrical and balanced composite material corner boxes includes the following steps: Step 1: Based on the fundamental principles of composite material patching and repair of metals with equal strength and stiffness, calculate the minimum equivalent elastic modulus E when a composite material patch of thickness h1 is used to patch an aluminum alloy structure of thickness d1. x1min Maximum equivalent elastic modulus E x1max And the minimum equivalent elastic modulus E when a composite material patch with thickness h2 is applied to an aluminum alloy structure with thickness d2. x2min Maximum equivalent elastic modulus E x2max ; Step 2: Based on the longitudinal elastic modulus E1, transverse elastic modulus E2, and in-plane shear modulus G of the unidirectional strip of the composite prepreg. 12 Poisson's ratio v 12 Calculate the uniaxial stiffness matrix; Step 3: Based on the uniaxial stiffness matrix, calculate the basic material invariants U1, U2, U3, U4, and U5; Step 4: Set the proportions of 0°, +45°, -45°, and 90° layups in a composite material patch with thickness h as α, β, β, and γ, respectively. Substitute the basic invariants of the material into the preset formula to calculate the stiffness matrix of the composite material patch and obtain the relationship between the layup angle proportions and the stiffness matrix. Step 5: The longitudinal tensile stiffness A in the stiffness matrix... 11 Lateral tensile stiffness A 22 Poisson coupling stiffness A 12 Substituting into the formula, we obtain the equivalent elastic modulus E of the composite material patch. x The relationship between the ply angle and the proportion of the ply angle; Step 6: Calculate E respectively x1max The corresponding maximum 0° ply ratio α 1max E x1min The corresponding minimum 0° ply ratio α 1min ; Step 7: Calculate E respectively x2max The corresponding maximum 0° ply ratio α 2max E x2min The corresponding minimum 0° ply ratio α 2min ; Step 8: Combine the composite material thickness h1, the prepreg thickness t, and α 1max α 1min Rounding down, we get the total number of plies n1 and the number of 0° plies n. 10 The maximum value n 10max Minimum value n 10min ; Step 9: Combine the composite material thickness h2, the prepreg thickness t, and α 2max α 2min Rounding down, we get the total number of plies n2 and the number of 0° plies n.20 The maximum value n 20max Minimum value n 20min ; Step 10: Select n 20 Based on the numerical value and the principle that the number of plies for 45° and 90° are approximately equal, the number of plies n for +45°, -45°, and 90° is determined. 2+45 n 2-45 n 290 ; Step 11, keep n 1+45 =n 2+45 n 1-45 =n 2-45 n 190 =n 290 Based on the total number of layups n1, the number of 0° layups n of the composite patch with thickness h1 is obtained. 10 ; Step 12: Arrange the plies according to the principle of uniformly distributing +45°, -45° and 90° plies in the 0° ply to complete the design of a symmetrical and balanced composite corner box with variable thickness.
[0007] As a further aspect of the present invention, the theoretical calculation process in steps 1 to 9 is completed by compiling an Excel spreadsheet or calculation program code.
[0008] As a further aspect of the present invention: the ply angle ratio in step 4 satisfies the mathematical relationship: α + 2β + γ = 1.
[0009] As a further aspect of the present invention: in step 2, the unidirectional stiffness matrix includes the longitudinal stiffness coefficient Q. 11 Poisson coupling stiffness coefficient Q 12 Poisson coupling stiffness coefficient Q 21 lateral stiffness coefficient Q 22 In-plane shear stiffness coefficient Q 66 And each coefficient is determined by E1, E2, v 12 G 12 It is calculated using a pre-set formula.
[0010] As a further aspect of the present invention: in step 6, α is calculated 1max When β=0 and γ=1-α, 1max Substitute the equivalent elastic modulus into the formula relating ply angle ratio; calculate α. 1min When γ=0 and β=1-α, 1min And substitute it into the relation.
[0011] As a further aspect of the present invention: in step 7, α is calculated 2max When β=0 and γ=1-α,2max Substitute the equivalent elastic modulus into the formula relating ply angle ratio; calculate α. 2min When γ=0 and β=1-α, 2min And substitute it into the relation.
[0012] As a further aspect of the present invention: the 45° ply in step 10 is the sum of +45° and -45° plies, and n 2+45 With n 2-45 The values are equal.
[0013] Compared with the prior art, the beneficial effects of the present invention are: This invention rapidly obtains the proportion of 0° layup in each region of a variable-thickness symmetrical balanced composite corner box through simple theoretical calculations. Then, by rationally allocating 45° and 90° layups, the design of the variable-thickness symmetrical balanced layup composite corner box is completed. This allows for the effective design of variable-thickness composite corner boxes for aluminum alloy structures while meeting the design principles of equal stiffness and equal strength. The method is simple and highly efficient. Attached Figure Description
[0014] Figure 1 A flowchart of a rapid design method for symmetrical and balanced composite material corner boxes; Figure 2 This is a schematic diagram of the aluminum alloy structure for repairing a composite corner box with varying thickness according to this application; Figure 3 This is a schematic diagram of the variable layup of the composite material corner box of this application.
[0015] In the diagram: 1. Aluminum alloy structure; 2. Composite material patch; 3. Prepreg unidirectional tape. Detailed Implementation
[0016] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.
[0017] As mentioned in the background section of this application, research has found that in the existing methods of repairing aluminum alloy structures with composite materials, it is difficult to quickly and effectively design composite corner boxes with equal stiffness and strength for aluminum alloy structures with varying thickness, which has certain drawbacks.
[0018] To address the aforementioned shortcomings, this application discloses a rapid design method for symmetrical and balanced composite material corner boxes. Through simple theoretical calculations, the proportion of 0° layups in each region of a variable-thickness symmetrical and balanced composite material corner box is quickly obtained. Then, by rationally allocating 45° and 90° layups, the design of the variable-thickness symmetrical and balanced layup composite material corner box is completed. This allows for the effective design of variable-thickness composite material corner boxes for aluminum alloy structures while meeting the design principles of equal stiffness and equal strength. The method is simple and highly efficient.
[0019] The following will describe in detail, with reference to the accompanying drawings, how the solution of this application solves the above-mentioned technical problems.
[0020] Please see Figure 1 In this embodiment of the invention, a rapid design method for symmetrical and balanced composite material corner boxes includes the following steps: Step 1: Based on the basic principle of composite material patching and repairing metal with equal strength and equal stiffness as stated in formula (1.1a), and using formulas (1.1b)-(1.1c), calculate the minimum equivalent elastic modulus E of the composite material patch 2 with thickness h1 when patching an aluminum alloy structure 1 with thickness d1. x1min and maximum equivalent elastic modulus E x1max Using formulas (1.1d)-(1.1e), the minimum equivalent elastic modulus E of the composite material patch 2 with thickness h2 when patching an aluminum alloy structure 1 with thickness d2 is calculated. x2min and maximum equivalent elastic modulus E x2max In the formula, E x E represents the equivalent elastic modulus of composite patch 2, h is the thickness of composite patch 2, and E is the equivalent elastic modulus of composite patch 2. Al Let d be the elastic modulus of aluminum alloy structure 1, d be the thickness of aluminum alloy structure 1, h1 and h2 be the thicknesses of the two composite material patches 2 respectively, and d1 and d2 be the thicknesses of the two aluminum alloy structures 1 respectively. x1min and E x1max The minimum and maximum equivalent elastic modulus E of the composite patch 2 with thickness h1 are respectively. x2min and E x2max The minimum and maximum equivalent elastic moduli of the composite patch 2 with a thickness h2 are respectively determined.
[0021] (1.1a) (1.1b) (1.1c) (1.1d) (1.1e) Step 2: Based on the three parameters E1, E2, and ν of the unidirectional belt of the composite prepreg 12 G 12 Substitute into formulas (1.2a)-(1.2f) to calculate the stiffness matrix of the unidirectional prepreg belt 3. In the formula, E1 is the longitudinal elastic modulus, E2 is the transverse elastic modulus, and G... 12 v is the in-plane shear modulus. 12 The main Poisson ratio, Q 11 Q is the longitudinal stiffness coefficient. 12 Q is the Poisson coupling stiffness coefficient. 21 Q is the Poisson coupling stiffness coefficient. 22 Q is the lateral stiffness coefficient. 66 This is the in-plane shear stiffness coefficient; (1.2a) (1.2b) (1.2c) (1.2d) (1.2e) (1.2f) Step 3: Based on the 3-stiffness matrix of the prepreg unidirectional belt Substitute the values into formulas (1.3a)-(1.3e) to calculate the basic material invariants U1, U2, U3, U4, and U5 of the prepreg unidirectional strip 3; where U1 is the first stiffness invariant, U2 is the second stiffness invariant, U3 is the third stiffness invariant, U4 is the fourth stiffness invariant, and U5 is the fifth stiffness invariant. (1.3a) (1.3b) (1.3c) (1.3d) (1.3e) Step 4: In the composite material patch 2 with thickness h, the proportions of 0°, +45°, -45°, and 90° are α, β, β, and γ, respectively. Substitute the basic invariants U1, U2, U3, U4, and U5 into formulas (1.4a)-(1.4e) to calculate the stiffness matrix of the composite material patch 2. The relationship between the ply angle proportion and the matrix is obtained; where α, β, β, and γ are the proportions of 0°, +45°, -45°, and 90° plies in the composite patch, respectively, and α + 2β + γ = 1; A 11 For longitudinal tensile stiffness, A 22 For lateral tensile stiffness, A 12 For Poisson coupling stiffness, A 66 This represents the in-plane shear stiffness.
[0022] (1.4a) (1.4b) (1.4c) (1.4d) (1.4e) Step 5, place A 11 A 22 A 12 Substituting into formula (1.5), we obtain the equivalent elastic modulus E of composite patch 2. x The relationship between the ply angle and the proportion of the ply angle; (1.5) Step 6: Set β=0 and γ=1-α 1max and E x =E x1max Substituting into formula (1.5), the formula now only has α. 1max E is an unknown quantity and can be calculated. x1max The maximum value α of the corresponding 0° ply ratio 1max ; with γ=0 and β=1-α 1min and E x =E x1min Substitute into formula (1.5) to calculate E. x1min The corresponding minimum 0° ply ratio α 1min ; Step 7: Set β=0 and γ=1-α 2max and E x =E x2max Substitute into formula (1.5) to calculate E. x2max The maximum value α of the corresponding 0° ply ratio 2max ; with γ=0 and β=1-α 2min and E x =E x2min Substitute into formula (1.5) to calculate E. x2min The corresponding maximum 0° ply ratio α 2min ; Step 8: Combine the composite patch 2 (thickness h1), the prepreg unidirectional tape 3 (thickness t), and α. 1max and α 1min Substituting into formula (1.6a)-(1.6c) and rounding, we obtain the total number of plies n1 and the number of 0° plies n. 10 The maximum value n 10max and minimum value n 10min ; (1.6a) (1.6b) (1.6c) Step 9: Combine the composite patch 2 (thickness h2), the prepreg unidirectional tape 3 (thickness t), and α. 2max and α 2min Substituting into formula (1.7a)-(1.7c) and rounding, we obtain the total number of plies n2 and the number of 0° plies n. 20 The maximum value n 20max and minimum value n 20min ; (1.7a) (1.7b) (1.7c) Step 10: Select the number of 0° layups n 20 Based on the principle that the number of plies for 45° (inclusive) and 90° is similar, the number of plies n for +45°, -45° and 90° can be determined. 2+45 n 2-45 n 290 ; Step 11: When transitioning from a thick composite material to a thin composite material through lay-up layers, the elastic modulus E is mainly reduced by decreasing the number of 0° lay-ups. x , by n 1+45 =n 2+45 n 1-45 =n 2-45 n 190 =n 290 Given the total number of plies n1, the number of 0° plies n of the composite patch 2 with thickness h1 can be obtained. 10 .
[0023] Step 12: Following the principle of distributing the +45°, -45° and 90° layups as evenly as possible in the 0° layup, the layups are arranged to complete the design of the variable thickness symmetrical balanced composite corner box.
[0024] In this embodiment, the theoretical calculation process can be completed by creating a simple Excel spreadsheet or a calculation program code.
[0025] To further illustrate the present invention, the following describes in detail a rapid design method for symmetrical and balanced composite material corner boxes provided by the present invention, in conjunction with embodiments.
[0026] Example 1: Taking the repair of an aluminum alloy structure 1 with a thickness reduced from 7mm to 3mm using an L-shaped composite laminate made of CCF300 / QY8911 prepreg with a thickness reduced from 5mm to 3mm as an example, such as Figure 2 , Figure 3 As shown, a method for designing a symmetrical and balanced ply composite corner box is described, including the following steps: Step 1: Based on the basic principle of composite material patching and repairing metal with equal strength and equal stiffness as per formula (1.1a), calculate the equivalent elastic modulus E corresponding to patching and repairing aluminum alloy structure 1 with thicknesses of d1=7mm and d2=3mm with L-shaped composite laminates of thicknesses h1=5mm and h2=3mm. x1min =100GPa, E x1max =120GPa, E x2min =72GPa and E x2max =84GPa, where E Al =72GPa (i.e., the equivalent elastic modulus E corresponding to the repair of an aluminum alloy structure 1 with a thickness of d1=7mm and an L-shaped composite laminate with a thickness of h1=5mm). x1min =100GPa, E x1max =120GPa; Calculate the equivalent elastic modulus E corresponding to the repair of aluminum alloy structure 1 with thickness d2 =3mm and thickness of L-shaped composite laminate with thickness h2 = 3mm. x2min =72GPa and E x2max =84GPa); Based on the fundamental principle of composite material patching and repair of metal with equal strength and stiffness as stated in formula (1.1a), formulas (1.1b)-(1.1c) are used to calculate the minimum equivalent elastic modulus E of the composite material patch 2 with thickness h1=5mm when patching an aluminum alloy structure 1 with thickness d1=7mm. x1min =100GPa and maximum equivalent elastic modulus E x1max =120GPa; Using formula (1.1d)-(1.1e), calculate the minimum equivalent elastic modulus E of the composite material patch 2 with a thickness of h2=3mm when it is applied to the aluminum alloy structure 1 with a thickness of d2=3mm. x2min =84GPa and maximum equivalent elastic modulus Ex2max =84GPa, where E Al =72GPa is the elastic modulus of the aluminum alloy structure; (1.1a) (1.1b) (1.1c) (1.1d) (1.1e) Step 2, based on the CCF300 / QY8911 prepreg unidirectional belt parameters E1=135GPa, E2=9.12GPa, ν 12 =0.3, G 12 Substituting 5.67 GPa into formula (1.2a)-(1.2f), the stiffness matrix along the unidirectional band 3 of the prepreg is calculated. Q 11 =135.83GPa, Q 12 =2.75GPa, Q 22 =9.18GPa, Q 66 =5.67 GPa; (1.2a) (1.2b) (1.2c) (1.2d) (1.2e) (1.2f) Step 3: Based on the CCF300 / QY8911 prepreg unidirectional belt stiffness matrix Substitute these values into formulas (1.3a)-(1.3e) to calculate the basic material invariants U1=57.90GPa, U2=63.33GPa, U3=14.60GPa, U4=17.35GPa, U5=20.27GPa; (1.3a) (1.3b) (1.3c) (1.3d) (1.3e) Step 4: In the composite material patch 2 with thickness h, the proportions of 0°, +45°, -45°, and 90° are α, β, β, and γ, respectively. Substitute the basic invariants U1, U2, U3, U4, and U5 into formulas (1.4a)-(1.4e) to calculate the matrix of composite material patch 2. This yields the relationship between the ply angle ratio and the matrix; (1.4a) (1.4b) (1.4c) (1.4d) (1.4e) Step 5, place A 11 A 22 A 12 Substituting into formula (1.5), we obtain the equivalent elastic modulus E of composite patch 2. x The relationship between the ply angle and the proportion of the ply angle; (1.5) Step 6: Set β=0 and γ=1-α 1max and E x =E x1max Substituting into formula (1.5), E can be calculated. x1max The maximum value α of the corresponding 0° ply ratio 1max =0.88; γ=0 and β=1-α 1min and E x =E x1min Substitute into formula (1.5) to calculate E. x1min The corresponding minimum 0° ply ratio α 1min =0.68; Step 7: Set β=0 and γ=1-α 2max and E x =E x2max Substitute into formula (1.5) to calculate E. x2max The maximum value α of the corresponding 0° ply ratio 2max =0.59; γ=0 and β=1-α 2min and E x =E x2min Substitute into formula (1.5) to calculate E. x2min The corresponding maximum 0° ply ratio α 2min =0.45; Step 8: Combine the composite material patch 2 (thickness h1), the prepreg unidirectional tape 3 (thickness t=0.125mm), and α... 1max and α1min Substituting into formula (1.6a)-(1.6c) and rounding, we get the total number of plies n1=40, and the number of 0° plies n 10 The maximum value n 10max =34 and minimum value n 10min =24, which means the number of layers n 10 The range is 24-34 layers, and half of the symmetrical plywood has 14-17 layers; (1.6a) (1.6b) (1.6c) Step 9: Combine the composite material patch 2 (thickness h2), the prepreg unidirectional tape 3 (thickness t=0.125mm), and α... 2max and α 2min Substituting into formula (1.7a)-(1.7c) and rounding, we get the total number of plies n2=24, and the number of 0° plies n 20 The maximum value n 20max =14 and minimum value n 20min =12, that is, the number of 0° plies n 20 The range is 12-14 layers, and half of the symmetrically ply laminates have 6-7 layers; (1.7a) (1.7b) (1.7c) Step 10: Select the number of 0° layups n 20 When the ply count is 14, the ply counts n for +45° (inclusive of +45° and -45°) and 90° can be determined by considering the principle that the number of plies for +45°, -45° and 90° are similar. 2+45 =2, n 2-45 =2, n 290 =6; Step 11: When transitioning from a thick composite material to a thin composite material through lay-up layers, the elastic modulus E is mainly reduced by decreasing the number of 0° lay-up layers. x , by n 1+45 =n 2+45 =2, n 1-45 =n 2-45 =2, n 190 =n 290 The composite material with thickness h1 can be obtained by using n=6 and n1=40, and the number of 0° layups n 10 =30.
[0027] Step 12: Following the principle of distributing +45°, -45°, and 90° layups as evenly as possible within the 0° layup, the composite material layups are arranged to obtain a symmetrical, balanced composite corner box with varying thickness. Specifically, the 5mm layup is: [0 / 0 / 90 / 0 / 0 / 0 / 45 / 0 / 0 / 0 / 90 / 0 / 0 / 0 / -45 / 0 / 0 / 0 / 90 / 0]s, and the 3mm layup is: [0 / 0 / 90 / 0 / 45 / 0 / 90 / 0 / -45 / 0 / 90 / 0]s. This completes the design of the symmetrical, balanced composite corner box with varying thickness.
[0028] This invention rapidly obtains the proportion of 0° layup in each region of a variable-thickness symmetrical balanced composite corner box through simple theoretical calculations. Then, by rationally allocating 45° and 90° layups, the design of the variable-thickness symmetrical balanced layup composite corner box is completed. This allows for the effective design of variable-thickness composite corner boxes for aluminum alloy structures while meeting the design principles of equal stiffness and equal strength. The method is simple and highly efficient.
[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A rapid design method for symmetrical and balanced composite material corner boxes, characterized in that, Includes the following steps: Step 1: Based on the fundamental principles of composite material patching and repair of metals with equal strength and stiffness, calculate the minimum equivalent elastic modulus E when a composite material patch of thickness h1 is used to patch an aluminum alloy structure of thickness d1. x1min Maximum equivalent elastic modulus E x1max And the minimum equivalent elastic modulus E when a composite material patch with thickness h2 is applied to an aluminum alloy structure with thickness d2. x2min Maximum equivalent elastic modulus E x2max ; Step 2: Based on the longitudinal elastic modulus E1, transverse elastic modulus E2, and in-plane shear modulus G of the unidirectional strip of the composite prepreg. 12 Poisson's ratio v 12 Calculate the uniaxial stiffness matrix; Step 3: Based on the uniaxial stiffness matrix, calculate the basic invariants U1, U2, U3, U4, and U5 of the composite material; Step 4: Set the proportions of 0°, +45°, -45°, and 90° layups in a composite material patch with thickness h as α, β, β, and γ, respectively. Substitute the basic invariants of the composite material into the preset formula to calculate the stiffness matrix of the composite material patch and obtain the relationship between the layup angle proportions and the stiffness matrix. Step 5: The longitudinal tensile stiffness A in the stiffness matrix... 11 Lateral tensile stiffness A 22 Poisson coupling stiffness A 12 Substituting into the formula, we obtain the equivalent elastic modulus E of the composite material patch. x The relationship between the ply angle and the proportion of the ply angle; Step 6: Arrange the plies according to the principle of uniformly distributing +45°, -45° and 90° plies in the 0° ply to complete the design of a symmetrical and balanced composite corner box with variable thickness.
2. The rapid design method for a symmetrical and balanced composite material corner box according to claim 1, characterized in that, The following steps are included between step 5 and step 6: Calculate E respectively x1max The corresponding maximum 0° ply ratio α 1max E x1min The corresponding minimum 0° ply ratio α 1min ; Calculate E respectively x2max The corresponding maximum 0° ply ratio α 2max E x2min The corresponding minimum 0° ply ratio α 2min ; Combining the composite material thickness h1, the prepreg thickness t, and α 1max α 1min Rounding down, we get the total number of plies n1 and the number of 0° plies n. 10 The maximum value n 10max Minimum value n 10min ; Combining the composite material thickness h2, the prepreg thickness t, and α 2max α 2min Rounding down, we get the total number of plies n2 and the number of 0° plies n. 20 The maximum value n 20max Minimum value n 20min ; Select n 20 Based on the numerical value and the principle that the number of plies for +45° and -45° are equal, the number of plies n for +45°, -45°, and 90° is determined. 2+45 n 2-45 n 290 ; Keep n 1+45 =n 2+45 n 1-45 =n 2-45 n 190 =n 290 Based on the total number of layups n1, the number of 0° layups n of the composite patch with thickness h1 is obtained. 10 .
3. The rapid design method for a symmetrical and balanced composite material corner box according to claim 2, characterized in that, In step 4, the ply angle ratio satisfies the mathematical relationship: α + 2β + γ = 1.
4. The rapid design method for a symmetrical and balanced composite material corner box according to claim 3, characterized in that, In step 2, the unidirectional belt stiffness matrix includes the longitudinal stiffness coefficient Q. 11 Poisson coupling stiffness coefficient Q 12 Poisson coupling stiffness coefficient Q 21 lateral stiffness coefficient Q 22 In-plane shear stiffness coefficient Q 66 And each coefficient is determined by E1, E2, v 12 G 12 It is calculated using a pre-set formula.
5. The rapid design method for a symmetrical and balanced composite material corner box according to claim 4, characterized in that, Calculate the α 1max When β=0 and γ=1-α, 1max Substitute the equivalent elastic modulus into the formula relating ply angle ratio; calculate α. 1min When γ=0 and β=1-α, 1min And substitute it into the relation.
6. The rapid design method for a symmetrical and balanced composite material corner box according to claim 5, characterized in that, Calculate the α 2max When β=0 and γ=1-α, 2max Substitute the equivalent elastic modulus into the formula relating ply angle ratio; calculate α. 2min When γ=0 and β=1-α, 2min And substitute it into the relation.
7. The rapid design method for a symmetrical and balanced composite material corner box according to claim 6, characterized in that, The 45° ply is the sum of the +45° and -45° plies, and n 2+45 With n 2-45 The values are equal.