A resin-based composite hollow fan blade material-structure integrated design method

Abstract

This invention relates to an integrated material-structure design method for hollow fan blades made of resin-based composite materials. The method proposes a parametric modeling approach for hollow fan blades; it achieves automatic updating of ply parameters and structural dimension parameters through a finite element model meshing strategy, enabling efficient mechanical performance analysis of the hollow fan blade structure; it obtains key variables and main effect diagrams by conducting parametric sensitivity analysis of the composite material's strength and modulus; it determines the selection range for strength and modulus based on the main effect diagrams, and selects several materials from a material database according to this range; based on a multi-island genetic algorithm and the Cai-Wu failure criterion, it optimizes the overall volume of the hollow fan blade using its modal performance, strength performance, and stiffness performance as optimization constraints to achieve weight reduction.

Description

Technical Field

[0001] This invention belongs to the field of aerospace engine technology, specifically relating to an integrated material-structure design method for hollow fan blades made of resin-based composite materials. Background Technology

[0002] Fan blades are one of the most important structural components of civil high-bypass turbofan engines. To meet the growing requirements for low fuel consumption and high thrust-to-weight ratio, advanced civil turbofan engines are developing towards larger bypass ratios and more stable structural mechanical properties. Resin-based composite material fan blades are used in civil high-bypass turbofan engines due to their light weight and good vibration reduction performance, and lightweight design of them is of great significance.

[0003] The optimization design of resin-based composite fan blades mainly consists of three aspects: material type selection, blade layup structure optimization, and blade hollow structure size optimization. Traditional optimization design methods fail to consider the hollow structure of composite fan blades, and the selection of optimization variables is relatively limited, mainly focusing on the layup angle. The optimization objectives are primarily strength or resonance margin, with little consideration for blade mass optimization. This makes it impossible to maximize material utilization and is detrimental to improving the overall thrust-to-weight ratio of the engine. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a material-structure integrated design method for hollow fan blades made of resin-based composite materials. It employs an efficient automatic modeling method for hollow blades and the Cai-Wu failure criterion, and optimizes the mass of the hollow fan blades based on a multi-island genetic algorithm, using the modal performance, strength performance, and stiffness performance of the hollow fan blades as optimization constraints. This method can consider the influence of composite material parameters, layup angles, and hollow foam structure dimensions on blade performance, further reducing the mass of the fan blades.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A material-structure integrated design method for hollow fan blades made of resin-based composite materials, comprising the following steps:

[0007] Step 1: Using 3D modeling software, import the blade configuration curve data points, generate curves using splines, construct surfaces through curve groups, and finally use stitching to model solid fan blades. Then, introduce reference planes and offsets to achieve parametric modeling of the geometric model of hollow fan blades.

[0008] Step 2: Run the simulation software, import the hollow fan blade and PMI (polymethacrylimide) foam sandwich solid model established in Step 1, perform geometric model processing, automatic mesh generation, ply attribute assignment, load and boundary condition application, and start structural mechanical performance analysis calculation to obtain the Cai-Wu strength factor distribution, blade elongation, and modal frequencies of each order, and generate command scripts; the ply attribute assignment includes ply angle selection;

[0009] Step 3: Integrate the automatic update module of the parametric geometric model using multidisciplinary design software: Extract the key parameters of the hollow fan blades from the key parameter control file as design variables, complete the integration of the command script in Step 2, the command script reads the key parameters in the design variables, completes the update of its own program, and uses the command script to complete the automatic partitioning of the hollow fan blades in the finite element analysis software, realizing the transfer of parameters in the 3D modeling software model, command script and finite element model;

[0010] Step 4: Based on the parameter transfer method established in Step 3, perform parameter sensitivity analysis on the material strength and modulus of the composite material to obtain key variables and main effect diagrams; combine the main effect diagrams to obtain the selection range of strength and modulus, and select several materials from the material database according to the selection range;

[0011] Step 5: Based on the variable variation range obtained in Steps 1 to 4, an optimization model is established using the geometric parameters of the hollow fan blades in Step 1 (offset, height of the reference plane defined in the hollow cavity), the ply angle in the finite element model in Step 2, and the key material parameters of the composite material determined in Step 3 (modulus, Poisson's ratio) as design variables, the Cai-Wu strength factor, blade elongation and modal frequency as optimization constraints, and the blade mass function as the optimization objective. A multi-island genetic algorithm is then used to optimize the ply angle and hollow structure dimensions of the hollow fan blades.

[0012] Further, in step 1, the parametric modeling of the geometric model specifically includes: defining five reference planes from the blade tip to the bottom of the cavity as M0-M4, and the height intervals between the five sections as H1-H4; offsetting the blade profile within each section by offsets of G1-G5, thereby forming five closed curves L0-L4, and stitching these five closed curves together to complete the modeling.

[0013] Furthermore, the processing and range constraint criteria for the parametric modeling of the geometric model are as follows: The sizes of H2-H4 are constrained by parameter E, and the size of H1 is constrained by parameter H; wherein the value range of H should be 7% to 17% of the blade height. If the value of H is less than 7% of the blade height, the plane near the blade tip will not be able to generate a contour curve. If the value of H is greater than 17% of the blade height, the M1 surface will coincide with the M2 surface. If the value of E is less than 9% of the blade height, the contour curve will not be able to be stitched into a solid. If the value of E is greater than 25% of the blade height, it will exceed the range of the blade height.

[0014] The area enclosed by the curves of each section of the hollow inner cavity remains basically consistent to form a regular foam filling the inner cavity; the offset G4 of the L4 curve is set as parameter G, and the offsets of L0-L3 decrease sequentially, namely 0.9G, 0.85G, 0.82G, and 0.76G, respectively, and the value range of G is limited to 11% to 19% of the cross-sectional blade width.

[0015] Furthermore, in step 2, the automatic mesh division specifically includes: first, separating the hollow and solid regions of the blade, with the dividing plane being the M4 plane; then, separating the smooth region in the middle of the blade from the irregularly shaped regions on both sides of the blade edge, and determining that the points required for the dividing plane are all structural midpoints, which are obtained in the 3D modeling software and input into the command script.

[0016] Further, in step 2, the constraint criteria for selecting the ply angle specifically include: (1) Ply balance and symmetry principle: the ply sequence is symmetrical about the center plane, the ply angle is balanced, and the number of ply at -45 degrees is the same as that at +45 degrees; (2) Ply orientation principle according to the load condition: 0-degree ply has a stronger ability to withstand uniaxial tensile loads; 90-degree ply has a stronger ability to withstand shear loads; ±45-degree ply has a stronger ability to withstand torsional loads; select the ply method according to the actual load condition; (3) Ply sequence principle: adopt a staggered plying method to reduce interlayer stress and improve strength performance, and 0-degree ply is not laid on the upper and lower surfaces of the component.

[0017] Furthermore, the key variable in step 4 includes: transverse tensile strength Y. T The longitudinal elastic modulus E1 and the transverse elastic modulus E2 are used to obtain the selection range of the key variables through the main effect diagram: transverse tensile strength Y. T >40MPa, longitudinal elastic modulus E1>160GPa, transverse elastic modulus E2<9000Mpa.

[0018] Furthermore, in step 5, the limits of the optimization constraints are determined using the following method: if the Cai-Wu strength factor is greater than or equal to 1, it indicates that the composite material structure has been damaged and does not meet the strength requirements; if it is less than 1, it indicates that the composite material structure has not failed and meets the strength requirements; the safety factor of the composite material is not less than 1.5, that is, the Cai-Wu strength factor is less than 0.66; the ratio of the maximum deformation to the blade height is less than 1%; and the resonance margin of the blade is at least 10%.

[0019] The advantages of this invention compared to the prior art are:

[0020] In terms of geometric modeling, compared to traditional geometric modeling of composite fan blades, this paper adds consideration to the hollow foam cavity structure of the composite fan blades. Combining existing foam sandwich technology, a geometric parameterization strategy for hollow blade structures is proposed, which can standardize the 3D modeling of the hollow cavity and reasonably simplify existing parameters to improve optimization design efficiency. In terms of simulation modeling, compared to traditional automatic mesh generation, a finite element modeling partitioning strategy is proposed to meet the computational needs of composite ply structures. This strategy can achieve automatic mesh generation for hollow fan blades with different structures while ensuring mesh quality and ply direction, enabling automatic updating of the finite element model and improving optimization efficiency. Regarding optimization criteria, compared to the traditional fan blade optimization with its single optimization variable and lack of focus on blade mass, a new integrated material-structure design method is proposed. This method uses the modal performance, strength performance, and stiffness performance of the hollow fan blade as optimization constraints to optimize its mass. It can consider the influence of composite parameters, ply angles, and hollow foam structure dimensions on blade performance, further reducing fan blade mass. Attached Figure Description

[0021] Figure 1 This is a flowchart of an integrated material-structure design method for hollow fan blades made of resin-based composite materials according to the present invention;

[0022] Figure 2 The basic plane and positional parameters of the hollow foam cavity;

[0023] Figure 3 This is a schematic diagram showing the offset configuration of the hollow foam inner cavity cross-section;

[0024] Figure 4 The results of partitioning hollow fan blades;

[0025] Figure 5 This is the mesh generation result for the hollow fan blades. Detailed Implementation

[0026] The technical solution of the material-structure integrated design method for hollow fan blades based on resin-based composite materials of the present invention will be further described below with reference to the accompanying drawings.

[0027] As Figure 1 shown, a material - structure integrated design method for a resin - based composite hollow fan blade of the present invention mainly includes: geometric parameterization modeling of the composite hollow blade, selection of materials and material ranges, finite - element analysis of the modal performance, strength performance and stiffness performance of the composite hollow blade, and optimization of the blade ply structure and hollow structure dimensions. The specific implementation steps are as follows:

[0028] Step 1: Use the three - dimensional modeling software UG to realize the geometric model parameterization modeling of the fan blade and the hollow foam inner cavity. Five reference datum planes are defined from the blade tip to the bottom of the hollow inner cavity, which are respectively defined as M0 - M4, and the height intervals between the five cross - sections are respectively H1 - H4, as Figure 2 . Use the offset function in UG to offset the blade profile within each cross - section. The offset results are as Figure 3 , and the offset amounts are respectively G1 - G5, so as to form closed curves L0 - L4, and suture these five curves to complete the modeling of the hollow foam inner cavity.

[0029] Adopt a parameterization strategy to standardize the three - dimensional modeling of the hollow inner cavity: the sizes of H2 - H4 are constrained by the parameter E, and the size of H1 is constrained by the parameter H; the value range of H should be 7% - 17% of the blade body height. When the value of H is less than 7% of the blade body height, the curved surface near the blade tip of the plane cannot generate a contour curve. When the value of H is greater than 17% of the blade body height, the M1 curved surface coincides with the M2 curved surface; when the value of E is less than 9% of the blade body height, the contour curve cannot be sutured into a solid, and when the value of E is greater than 25% of the blade body height, it will exceed the blade body height range. To sum up, the value range of H is determined to be 40 < H < 90, and the value range of E is 50 < E < 140. The units of E and H are determined according to the actual length and width of the blade.

[0030] For the convenience of PMI foam sandwich filling and bonding, the areas enclosed by the cross - section curves of the hollow inner cavity should be kept basically the same to form a regular foam - filled inner cavity. At the same time, since the cross - sectional area of each cross - section of the fan blade airfoil shows an increasing relationship, the cross - section closer to the blade tip has a larger airfoil cross - sectional area. Therefore, the offset amount G5 of the L4 curve is set as the parameter G, and the offset amounts of L0 - L3 decrease in a fixed - ratio relationship with G. Here, the offset amount of the N3 cross - section is set as 0.9G, the offset amount of the N2 cross - section is 0.85G, the offset amount of the N1 cross - section is 0.82G, and the offset amount of the N0 cross - section is 0.76G. To ensure that the skin thickness is not too small and the contour curve of the blade tip cross - section can maintain a large area, the value range of G is restricted to 11% - 19% of the cross - section blade width, that is, 3.7 < G < 6.5.

[0031] By adopting a parametric strategy, the nine independent parameters (H1~H4, G1~G5) of the hollow cavity are simplified into three independent parameters (H, E, G), which greatly improves the efficiency of parametric modeling and optimization design. Furthermore, by standardizing the forming of the hollow cavity through the interrelationship between parameters, it meets the processing requirements.

[0032] Step 2: Run the ABAQUS simulation software, import the hollow fan blade and PMI foam sandwich solid model established in Step 1, and then perform geometric model processing, mesh generation, layup attribute assignment, load and boundary condition application, etc., to perform structural mechanical performance analysis calculations. To facilitate automatic calculation of parameter transfer in subsequent steps, automatic mesh generation is required. This requires reasonable partitioning of the complex blade structure. The specific partitioning strategy is as follows: the blade partitioning is controlled by the ABAQUS Python command script. First, the hollow and solid regions of the blade are separated, with the M4 plane as the partitioning plane. Then, the smooth central region of the blade is separated from the irregularly shaped regions on both sides of the blade edge. The points required to determine the partitioning plane are all structural midpoints, which can be obtained in UG software and input into the Python command script. Using this partitioning strategy, hollow fan blades of different structural dimensions can achieve automatic hexahedral mesh generation in ABAQUS, greatly improving the efficiency of finite element modeling. The partitioning results are as follows. Figure 4 As shown, the mesh generation result under this partitioning strategy is as follows: Figure 5 As shown.

[0033] In assigning ply properties, too many ply directions can cause many inconveniences to the production, processing and storage of prepregs. In engineering, there are usually only 4 ply directions, namely 0 degrees, ±45 degrees and 90 degrees. In the aerospace field, the ply sequence design of composite materials should meet the following principles: (1) Ply balance and symmetry principle: the ply sequence is symmetrical about the mid-plane, the ply angle is balanced, and the number of ply at -45 degrees should be the same as that at +45 degrees. (2) Ply orientation principle according to load conditions: 0-degree ply has a stronger ability to withstand uniaxial tensile loads; 90-degree ply has a stronger ability to withstand shear loads; ±45-degree ply has a stronger ability to withstand torsional loads; select the ply method according to the actual load conditions. (3) Ply sequence principle: the staggered ply method can reduce interlaminar stress and improve strength performance. 0-degree ply has poor impact resistance, so 0-degree ply should not be laid on the upper and lower surfaces of the component. Given that the hollow part of the blade has a skin thickness of 3mm and the solid part has an average thickness of approximately 10mm, while the single-layer prepreg thickness of the EH918-HF40C resin-based composite material is 0.187mm, the number of layers for the blade skin is set to 16. Following layup design principles, a symmetrical layup method is adopted, with initial layup angles of [-45, 0, 0, 45, 0, 0, 90, 0]. sThe solid portion of the blade is set to 48 layers, with the layup angle set to [-45, 0, 0, 45, 0, 0, 90, 0]. 3s This means the skin layer is laid up three times. This layup method ensures that the layup on both the upper and lower surfaces of the blade is consistent, resulting in continuous layup between the solid part and the skin, reducing processing defects. For areas at the blade root exceeding 48 layers of prepreg thickness, continue with the layup pattern [-45,0,0,45,0,0,90,0]. s The layup method involves repeated laying from the surface to the center to ensure the continuity of prepreg laying during processing. For the parameterization required for optimization, based on the layup design principle and considering symmetry, only the layup angle on one side of the symmetrical plane is set as a parameter group [x1,x2,…,x8] every 8 layers. The parameter group satisfies the constraint x1≠0. For the 24 layers of the solid part, the layup is repeated 3 times.

[0034] Step 3: Integrate the automatic update module of the parametric geometric model using the Simcode module in the multidisciplinary design software ISIGHT: Extract the offset G and reference surface height H of the hollow structure from the key parameter control file as design variables, and use the Data Exchanger module to integrate the Python command script in Step 2. The Python command script reads the key parameters in the design variables and updates its own program. The Python command script is also used to automatically partition the hollow fan blades in the finite element analysis software ABAQUS, realizing the transfer of parameters between the UG model, the Python command script, and the finite element model.

[0035] Step 4: Based on the parameter transfer method established in Step 3, perform sensitivity analysis on the material parameters of the composite material and obtain the key variables and their main effect plots. Select the key variable, transverse tensile strength Y, through the Pareto plot of the sensitivity analysis. T The longitudinal elastic modulus E1 and the transverse elastic modulus E2 are used to determine the selection range of key variables through the main effects diagram: transverse tensile strength Y. T >40MPa, longitudinal elastic modulus E1>160GPa, transverse elastic modulus E2<9000MPa. Several materials meeting the key variable selection criteria were chosen from the material database; here, M40J / 5182 was selected.

[0036] Step 5: Based on the geometric variables and their ranges obtained in Step 1, the ply angle variables and their ranges obtained in Step 2, and the material variables and their ranges obtained in Step 4, an optimization model is established with material parameters, ply angles, and blade hollow structure dimensions as design variables, Cai-Wu strength factor, blade elongation, and modal frequency as optimization constraints, and blade mass function as the optimization objective.

[0037] In selecting optimization constraints, a safety factor of 2.7 was chosen, and the Cai-Wu factor was constrained to not exceed 0.364. By drawing the Campbell diagram of the blade, the critical speed of the blade was determined using the graphical method, and the resonance margin of the hollow fan blade was determined. According to the requirements of the "Design Guidelines for Turbojet and Turbofan Engine Structures", the resonance margin of the blade should be at least 10%. In actual design, a 20% resonance margin is usually used as the design standard. In this example, the first and sixth natural frequencies are close to the speed line and need to be constrained. The maximum deformation of the blade cannot exceed 1% of the blade height ratio.

[0038] In summary, it can be transformed into an optimization problem:

[0039]

[0040] Where x1 to x8 are the ply angles; x9 to x 11 denoted as dimensional parameters of the hollow structure; W(x) is the mass function of the hollow fan blade, expressed using the total volume of the blade; g(x) is the sixth-order natural frequency function; f(x) is the first-order natural frequency function; TW(x) is the strength performance function of the hollow fan blade, expressed using the Cai-Wu strength factor; U(x) is the stiffness performance function of the hollow fan blade, expressed using the maximum deformation value.

[0041] In terms of strength performance, the Cai-Wu strength factor is a dimensionless quantity. A Cai-Wu strength factor greater than or equal to 1 indicates that the composite material structure has suffered damage and does not meet the strength requirements; if it is less than 1, it indicates that the composite material structure has not failed and meets the strength requirements. In practical engineering applications, a margin needs to be reserved, and a safety factor is introduced to determine whether the structure meets the design requirements. The safety factor for composite materials is generally required to be no less than 1.5, that is, the Cai-Wu strength factor is less than 0.66. Considering special requirements such as environmental corrosion, the required value of the safety factor will be larger, generally above 2.

[0042] In terms of stiffness performance, the clearance between the blade tip and the casing needs to be strictly controlled. If the clearance is too large, it will reduce aerodynamic efficiency, and if the clearance is too small, it will cause rubbing failure. Generally, the ratio of the maximum deformation to the blade height is required to be less than 1%.

[0043] In terms of modal performance, it is necessary to ensure that the operating speed is close to the natural frequency of the blade to avoid resonance. According to the requirements of the "Design Guidelines for Turbojet and Turbofan Engine Structures", the resonance margin of the blade should be at least 10%, and in actual design, a 20% resonance margin is usually used as the design standard. The frequency order that needs to be constrained can be obtained from the Campbell diagram of the blade, and constraints can be applied according to the 20% resonance margin.

[0044] Using M40J / 5182 as the blade material and WH75, commonly used in domestic composite hollow fan blade manufacturing processes, as the foam core material, a multi-island genetic algorithm was employed to optimize the ply angle and hollow structure dimensions of the hollow fan blade. The population size, island size, total generations, and crossover probability in the multi-island genetic algorithm were set to 20, 5, and 20 respectively. The optimization process consisted of 2000 iterations and took 33 hours and 56 minutes. By referring to the ply design criteria in step 2, the optimal solution satisfying the process constraints was obtained by selecting the best solution.

[0045] The above embodiments are provided merely for the purpose of describing the present invention and are not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principles of the invention should be covered within the scope of the invention.

Claims

1. A material-structure integrated design method for hollow fan blades made of resin-based composite materials, characterized in that, Includes the following steps: Step 1: Using 3D modeling software, import the blade configuration curve data points, generate curves using splines, construct surfaces through curve groups, and finally use stitching to model solid fan blades. Then, introduce reference planes and offsets to achieve parametric modeling of the geometric model of hollow fan blades. Step 2: Run the simulation software, import the hollow fan blade and polymethacrylamide foam sandwich solid model established in Step 1, perform geometric model processing, automatic mesh generation, ply attribute assignment, load and boundary condition application, and start structural mechanical performance analysis calculation to obtain the Cai-Wu strength factor distribution, blade elongation, and modal frequencies of each order, and generate command scripts; the ply attribute assignment includes ply angle selection; Step 3: Integrate the automatic update module of the parametric geometric model using multidisciplinary design software: Extract the key parameters of the hollow fan blades from the key parameter control file as design variables, complete the integration of the command script in Step 2, the command script reads the key parameters in the design variables, completes the update of its own program, and uses the command script to complete the automatic partitioning of the hollow fan blades in the finite element analysis software, realizing the transfer of parameters in the 3D modeling software model, command script and finite element model; Step 4: Based on the parameter transfer method established in Step 3, perform parameter sensitivity analysis on the material strength and modulus of the composite material to obtain key variables and main effect diagrams; combine the main effect diagrams to obtain the selection range of strength and modulus, and select several materials from the material database according to the selection range; Step 5: Based on the range of variation of design variables and key variables obtained in Steps 1 to 4, an optimization model is established using the geometric parameters of the hollow fan blade in Step 1, the ply angle in the finite element model in Step 2, and the key parameters of the composite material determined in Step 3 as design variables, the Cai-Wu strength factor, blade elongation, and modal frequency as optimization constraints, and the blade mass function as the optimization objective. A multi-island genetic algorithm is then used to optimize the ply angle and size of the hollow fan blade.

2. The method of material-structure integrated design of resin based composite hollow fan blade according to claim 1, characterized in that: In step 1, the parametric modeling of the geometric model specifically includes: defining five reference planes from the blade tip to the bottom of the cavity as M0-M4, and the height intervals between the five sections as H1-H4; offsetting the blade profile within each section by offsets of G1-G5, thereby forming five closed curves L0-L4, and stitching the five closed curves together to complete the modeling.

3. The method of material-structure integrated design of resin based composite hollow fan blade according to claim 2, characterized in that: The processing and range constraint criteria for the parametric modeling of the geometric model are as follows: the size of H2-H4 is constrained by parameter E, and the size of H1 is constrained by parameter H; where the value of H is in the range of 7% to 17% of the blade height, so that the M1 surface coincides with the M2 surface; the value of E is 9% to 25% of the blade height; The areas enclosed by the cross-sectional curves of the hollow inner cavity remain basically consistent to form a regular foam filling the inner cavity; the offset G5 of curve L4 is set as parameter G, and the offsets of L0-L3 decrease sequentially, each being 0.

9. G 0.85 G 0.82 G 0.76 G ,limit G The value range is 11% to 19% of the cross-sectional blade width.

4. The integrated material-structure design method for hollow fan blades made of resin-based composite materials according to claim 3, characterized in that: In step 2, the automatic mesh division specifically includes: first, separating the hollow and solid regions of the blade, with the dividing plane being the M4 plane; then, separating the smooth region in the middle of the blade from the irregularly shaped regions on both sides of the blade edge, and determining that the points required for the dividing plane are all structural midpoints, which are obtained in the 3D modeling software and input into the command script.

5. The integrated material-structure design method for hollow fan blades made of resin-based composite materials according to claim 4, characterized in that: In step 2, the specific constraints for selecting the ply angle include: (1) the principle of ply balance and symmetry: the ply sequence is symmetrical about the center plane, the ply angle is balanced, and the number of ply at -45 degrees is the same as that at +45 degrees; (2) the principle of ply orientation according to the load: 0-degree ply has a stronger ability to withstand uniaxial tensile loads; 90-degree ply has a stronger ability to withstand shear loads; ±45-degree ply has a stronger ability to withstand torsional loads; the ply method is selected according to the actual load; (3) the principle of ply sequence: the staggered ply method is used to reduce interlayer stress, and 0-degree ply is not laid on the upper and lower surfaces of the component.

6. The integrated material-structure design method for hollow fan blades made of resin-based composite materials according to claim 5, characterized in that: The key variable in step 4 includes: transverse tensile strength. Y T Longitudinal elastic modulus E 1 and transverse elastic modulus E 2 The selection range of the key variable, transverse tensile strength, is obtained through the main effect plot. Y T > 40MPa, longitudinal elastic modulus E 1 > 160GPa, transverse elastic modulus E 2 < 9000Mpa.

7. The method of material-structure integrated design of resin based composite hollow fan blade according to claim 6, characterized in that: In step 5, the limits of the optimization constraints are determined by the following methods: the Cai-Wu strength factor is less than 0.66; the ratio of the maximum deformation to the blade height is less than 1%; and the resonance margin of the blade is at least 10%.

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