Layering design method for composite material fan blade

Abstract

The invention discloses a composite material fan blade layering design method in the technical field of aero-engine fan blade design, and the method comprises the following steps: S1, constructing a blade model, and carrying out optimization based on a model structure; s2, prepreg is selected, the curing thickness of a single layer of prepreg is obtained through a laminated plate curing process, a laying layer profile diagram is extracted according to the blade optimization model, and laying layers are grouped according to the height; s3, paving layers are uniformly arranged according to a height marshalling method under the paving layer design criterion condition, paving layer angles are given, whether the requirements are met or not is judged, and a preliminary blanking drawing is generated; and S4, carrying out cutting design on the prepreg according to the blanking drawing. According to the method, through parametric modeling and actual measurement data calibration, tenon extension design and layering angle distribution and sorting design are optimized, fiber continuity is ensured, process accumulative errors are eliminated, then, 90-degree layering is locally introduced to enhance out-of-plane rigidity, stress concentration is dispersed in combination with step transition treatment, and therefore the method has the advantages of being simple in structure and convenient to operate. And the peak value of the interlayer shear stress of a tenon-blade body transition area is reduced, and the impact resistance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine fan blade design, and particularly relates to a composite material fan blade layup design method. BACKGROUND

[0002] The aero-engine fan blade is one of the core components of the aviation propulsion system, and its design directly affects the efficiency, thrust and reliability of the engine. Based on the characteristics of high specific strength, light weight and excellent fatigue resistance of composite materials (such as carbon fiber reinforced resin matrix composite materials), the traditional metal materials such as titanium alloy are gradually replaced in modern aero-engine fan blades, which is the core way to promote commercial aircraft with high bypass ratio, high thrust-to-weight ratio, low fuel consumption and low noise.

[0003] However, the aero-engine fan blade needs to face severe working environment and complex load conditions during service, which will cause obvious bending and twisting and other damages, resulting in performance degradation, which will directly affect the safety and reliability of the engine.

[0004] At present, the layup design process is one of the most effective methods to improve and enhance the ability of the aero-engine fan blade to resist the service environment. The layup design of the aero-engine composite fan blade is a complex and highly systematic process, mainly to deeply integrate materials, mechanics and technology, and needs to consider aerodynamic performance, structural strength, fatigue life and process feasibility. The core lies in balancing lightweight and impact resistance through layup optimization, and relying on advanced manufacturing technology to maintain consistency. The core elements of the layup design mainly include layup angle selection, layup sequence optimization and cutting design.

[0005] In the experiment of Jiangsu Institute of Technology, although the finite element, machine learning and multi-objective optimization algorithm are combined to optimize the layup design method, the manufacturing cost and time cost are saved to a certain extent, but the accuracy of the finite element modeling is low due to the complicated process, which affects the accurate forming of the composite material fan blade. In the experiment of Chengzaitailei New Material Technology Co., Ltd. (Shandong), the uniformity of stress transmission on the composite material layup is improved through digital data processing technology, but the design intention is difficult to implement in the product, with process test as the main method, strength check and structure design optimization as the auxiliary method. Therefore, a composite material fan blade layup design method is proposed. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a composite material fan blade layup design method, which establishes a fan blade layup design process, changes different layup sequences and layup angles, so that the stress distribution inside the blade is reasonable, thereby realizing the forward design of the composite material fan blade, and facilitating the subsequent implementation of the design intention in the product.

[0007] The purpose of the present application is achieved in that a composite fan blade layup design method comprises the following steps: S1, constructing a blade model and optimizing based on the model structure; S2, preparing a prepreg, obtaining a single-layer prepreg curing thickness through a laminated plate curing process, refining a layup contour map according to the blade optimization model, and grouping the layup according to the height; S3, the layup grouping method will be uniformly arranged under the condition of the layup design criterion, the layup angle is given, and it is judged whether the requirement is met, and a preliminary cutting map is generated; S4, cutting design is performed on the prepreg according to the cutting map; The blade model includes a blade body model, a tenon model, a blade middle surface, a blade leaf basin and a blade back surface.

[0008] Optionally, in step S1, the optimization based on the model structure is specifically: The outer edge based on the tenon model structure is extended, wherein the tenon model extends downward along the two sides and beyond the tenon bottom.

[0009] Optionally, the optimized tenon model is regionally divided, and the tenon model original range is defined as a tenon main body and a cutting main body after the extension of the tenon model; Wherein, the outer side of the tenon main body is provided with a machining allowance area.

[0010] Optionally, in step S2, the layup height grouping is specifically: Based on the blade three-dimensional model contour, the height of each layer of prepreg layup is digitally calibrated in the height direction of the blade model, and a height value is given, the height value is the normalized height value of the center line of the layup in the global coordinate system of the blade; Each layer of prepreg is divided into low, medium and high prepreg layups, and according to the structure of the blade, the high layup is distributed and arranged according to the proportion distribution, and the corresponding medium layup and low layup are inserted between adjacent high layups; According to the load direction of the blade model, the prepreg layup angle is preliminarily distributed; Based on the main bearing characteristics of the blade model, 0° prepreg layup is arranged, wherein ±45° prepreg layup is arranged in the transition area.

[0011] Optionally, in step S3, the layup design criterion is specifically: 1) Symmetry principle: the layup sequence is symmetric to the middle surface, and is laid in a symmetric distribution form; 2) Balance criterion: for each non-0° or 90° layup, there must be a negative angle layup corresponding to it, which satisfies together with the symmetry; 3) Dispersion criterion: plies of the same direction should be evenly dispersed in the whole laminate structure, avoiding plies of the same direction stacking together; 4) Proportion criterion: plies of the three main load directions should all account for at least 20% of the total number of plies; 5) Orientation criterion: ply direction is preferentially selected as the main load direction; The three main load directions specifically include: 0° prepreg plies, ±45° prepreg plies.

[0012] Optionally, in step S3, if the ply height grouping meets the condition of uniform laying under the ply design criterion, the laying angle of the blade ply is determined, the plies are symmetrically arranged in the ply surface, the blanking drawing is prepared, and step S4 is executed; If not, the plies are locally optimized until the design criterion requirement is met, and then the ply angle and order are determined, and finally the blanking drawing is prepared, and step S4 is executed.

[0013] Optionally, the local optimization specifically includes: problem area optimization, ply angle adjustment, and ply order optimization; The problem area positioning: through finite element simulation and process database verification, high strain or high stress concentration areas of the blade model are identified, and ply grouping positions that do not meet the design criterion are marked; The problem areas include tenon connection areas, stiffness mutation areas (blade body-tenon transition areas), ply angle transition areas, and blade tip-blade root transition areas.

[0014] Optionally, the ply angle adjustment: the overall distribution of the ply height grouping is preferentially maintained, the fiber direction of the marked problem area plies is adjusted, and it is ensured that the adjusted angle meets the proportion criterion of the plies; The ply order optimization: 1-2 layers of intermediate plies are added in the stiffness mutation area, and a stepped transition treatment is adopted.

[0015] Optionally, the stepped transition treatment specifically includes: Mark the area where the height difference between adjacent plies is >3mm through modeling software; Determine the stepped shape: preferentially adopt equal-height decreasing laying, and adopt nonlinear decreasing treatment for high load areas; Each ply extends and covers the next step, is laid in a staggered manner, and forms an overlapping area.

[0016] Optionally, in the machining process of the tenon model, after the prepreg laying and curing, in the rough machining stage, first, the cutting main body of the tenon model is cut off, then the excess area of the tenon model is milled, then the tenon model is finished, and finally the surface is treated.

[0017] Compared with the prior art, the present application optimizes the tenon extension design and the ply height grouping through parameterized modeling and measured data calibration, ensures fiber continuity and eliminates process cumulative error, secondly, locally introduces 90° ply reinforcement surface outer stiffness, disperses stress concentration combined with step transition processing, reduces the interlaminar shear stress peak value of the tenon-blade transition area, improves the impact resistance, and significantly reduces the delamination and curing deformation risk.

[0018] Secondly, based on digital calibration and ply rule automatic verification, quickly positioning the high stress area and optimizing the ply angle and sequence, reducing the trial and error cost, the whole process data is connected from parameterized design to machining, solving the pain point of "design intention landing difficult" in traditional method, reducing the weight of the blade while improving the fatigue life, suitable for high precision and high reliability demand scenes such as aero-engine. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on the provided drawings.

[0020] Figure 1 It is a composite material fan blade ply design method process schematic diagram provided by the present application.

[0021] Figure 2 It is a composite material fan blade ply design method framework schematic diagram provided by the present application.

[0022] Figure 3 It is a tenon optimization extension and cutting schematic diagram provided by the present application.

[0023] Figure 4 It is a blade ply pasting schematic diagram provided by the present application.

[0024] Figure 5 It is a ply distribution schematic diagram provided by the present application.

[0025] Figure 6 It is a prepreg cutting schematic diagram provided by the present application.

[0026] In the figure: 1, tenon main body; 2, cutting main body; 3, film pasting surface; 4, machining allowance. DETAILED DESCRIPTION

[0027] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0028] As shown in a composite fan blade layup design method, comprising the following steps: Figures 1 to 6 S1, constructing a blade model, and optimizing based on the model structure; S2, preparing a prepreg, obtaining a single-layer prepreg curing thickness through a laminated plate curing process, refining a layup contour map according to the blade optimization model, and grouping the layup according to height; S3, the layup grouping method will be uniformly arranged under the condition of layup design criteria, the layup angle is given, and whether the requirements are met is judged, and a preliminary cutting map is generated; S4, cutting design of the prepreg according to the cutting map. The blade model includes a blade body model, a tenon model, a blade middle surface, a blade leaf basin and a blade back surface.

[0029] It should be noted that part of the operation in the method process of the present application adopts a parameterized modeling tool, including: CAD software, CAE integrated tool and special composite material tool and other software tools, which are all prior art;

[0030] In step S1, the modeling software automatically generates an optimized tenon extension model, the parameterized modeling tool dynamically associates the tenon extension with the blade thickness, reduces manual intervention, ensures geometric consistency, reserves machining allowance, avoids assembly conflicts, the extension structure directly matches the subsequent machining requirements, and after curing, the target thickness is accurately cut, and the structural integrity of the blade-tennon transition area is improved; In step S2, the measured data is calibrated (the measured value of the prepreg curing thickness), and the accurate layup contour map is obtained based on the measured prepreg curing thickness, which can eliminate the cumulative error between theoretical design and actual process, ensure the accuracy of the layup angle and position, and at the same time, the calibrated layup distribution makes the main bearing fiber (0° direction) accurately cover the high stress area, improves the interlayer stress distribution, and reduces the failure risk. Further, the automatically generated model and the measured data are jointly input into simulation analysis, the problem area (such as the tenon connection area and the stiffness mutation area) is quickly located and optimized, the trial and error cost is reduced, the data from parameterized design to process feedback is connected, the pain point of "design intention difficult to land" in the traditional method is solved, and the product performance and design target are highly consistent.

[0031]

[0032] ​Specifically, in step S1, the optimization based on the model structure is specifically as follows: extending the outer edge based on the tenon model structure, wherein the tenon model extends downward along the two sides and beyond the bottom of the tenon; dividing the optimized tenon model into regions, defining the original range of the tenon model as the tenon main body and the region after the extension of the tenon model as the cutting main body; wherein the outer side of the tenon main body is provided with a machining allowance region.

[0033] Specifically, during the machining process of the tenon model, after pre-impregnated material laying and curing, in the rough machining stage, the cutting main body of the tenon model is first cut off, then the excess region of the tenon model is milled, then the tenon model is finished, and finally the surface is treated.

[0034] As shown in Figure 3 , the tenon extends downward and beyond the bottom, ensuring the continuity of the fiber layup in the tenon-blade transition area, increasing the area of the tenon model structure during pre-impregnated material laying, and reducing the difficulty of machining by cutting to the target size after overall curing, avoiding the risk of delamination, the extension structure allows the fibers of the pre-impregnated material layup of the tenon structure to transition naturally, avoiding the layer separation problem caused by sudden truncation in traditional design, and ensuring the overall strength of the tenon structure after complete curing and milling.

[0035] Specifically, in step S2, the layup height grouping is specifically as follows: based on the profile of the blade three-dimensional model, digitally marking the height of each layer of pre-impregnated material layup along the height direction of the blade model and assigning a height value, the height value being the normalized height value of the center line of the layup in the global coordinate system of the blade; dividing each layer of pre-impregnated material into low, medium and high pre-impregnated material layups, and according to the blade structure form, dispersing the high layups according to the proportion distribution, and inserting corresponding medium and low layups between adjacent high layups; initially assigning the angle of the pre-impregnated material layup according to the load direction of the blade; based on the main load characteristics of the fan blade, arranging 0° pre-impregnated material layup, wherein the transition region is arranged with ±45° pre-impregnated material layup; Further, when arranging, according to the main load characteristics of the blade model, a large proportion of 0° pre-impregnated material layup is arranged first, ±45° pre-impregnated material layup is arranged in the transition region, and in the region with a high number of layups, 0° pre-impregnated material layup is used first.

[0036] wherein the high layup accounts for about 25%, the medium layup accounts for about 40%, and the rest is low layup; Further, based on the blade model, the geometric profile data thereof is extracted, the center line position of each layer of prepreg is calculated along the height direction (Z axis) of the blade model, and the total height of the blade is normalized to 0~1; The height value of each layer of layup = (the center line Z coordinate of the layer of prepreg layup - the root Z coordinate) / (the tip Z coordinate - the root Z coordinate); Further, the height statistics of the low, medium and high three types of prepreg layups are as follows: according to the material properties and process requirements, the height threshold values of the three types of layups are defined, the low layup ≤0.1mm, the medium layup 0.1~0.8mm, and the high layup ≥0.8mm; Then, each layer of prepreg is classified into low, medium and high categories according to its height, and its normalized height value is recorded; Among them, the key area is divided as follows: according to the load bearing characteristics of the fan blade, the 0° layup accounts for about 60%, and the ±45° layup accounts for about 40%; Fiber continuity along the height direction: preferentially using 0° layup to cover the entire blade, effectively utilizing the high modulus and strength of the fiber; Layup transition zone: using ±45° layup to balance torsional and shear load, and to improve impact damage tolerance; Local area: 90° layup can be added to improve chordwise stiffness; High layup in the main load bearing area preferentially uses 0° layup to maximize axial stiffness; In the transition zone, ±45° high layup is allowed, but the angle difference with the adjacent layer should be ≤45° to avoid stress concentration; Further, 0° prepreg layup is used for efficient transmission of main load, and ±45° prepreg layup is used for suppression of shear deformation, forming a multidirectional reinforced structure; Specifically, in step S3, the layup design criteria are as follows: 1) Symmetry principle: the layup sequence is symmetric about the middle surface, and symmetric distribution is used for laying; 2) Balance criterion: for each non-0° or 90° layup, there must be a negative angle layup corresponding to it, which satisfies together with the symmetry; 3) Dispersion criterion: the same direction layup should be evenly distributed in the entire laminate structure to avoid stacking of the same direction layup together; 4) Proportion criterion: the prepreg layup of the three main load directions should account for at least 20% of the total number of layers; 5) Orientation criterion: the layup direction preferentially selects the main load direction; The three main load directions specifically include: 0° prepreg layup, ±45° prepreg layup.

[0037] Further, the symmetry principle is used to avoid curing deformation and improve dimensional stability; The balance criterion is used to suppress the shear coupling effect and ensure isotropy; The dispersion criterion is used to prevent local stiffness mutation and reduce interlaminar stress; The proportion criterion is used to balance the multi-directional bearing requirement and enhance the ability to resist complex load; The orientation criterion is used to maximize the proportion of 0° prepreg layers to improve axial stiffness.

[0038] Further, based on the above criteria, on the basis of meeting symmetry and balance, through dispersion layout and proportion control, an optimized structure with high stiffness, low weight and fatigue resistance is realized, which is especially suitable for scenarios such as aviation blades that need to bear multi-directional dynamic load.

[0039] Specifically, in step S3, if the ply height grouping meets the uniform laying under the condition of the ply design criterion, the laying angle of the blade ply is determined, the blade ply is symmetrically arranged, the blanking drawing is prepared, and step S4 is executed; If not, the ply is locally optimized until the design criterion requirement is met, and then the ply angle and order are determined. Finally, the blanking drawing is prepared, and step S4 is executed.

[0040] Specifically, the local optimization specifically includes problem area optimization, ply angle adjustment, and ply order optimization. Problem area positioning: through finite element simulation and process database verification, high strain or high stress concentration areas of the blade model are identified, and ply grouping positions that do not meet the design criterion are marked; The problem areas include the tenon connection area, the stiffness mutation area (blade body-tenon transition area), the ply angle transition area, and the blade tip-blade root transition area.

[0041] Further, first, based on the three-dimensional model of the blade model, actual working load (such as centrifugal force, aerodynamic load, etc.) is applied, statics / dynamics simulation is performed, high strain areas, high stress concentration areas, and interlaminar shear stress abnormal areas are extracted, and then historical process data (such as curing deformation, delamination failure cases) are compared to mark areas prone to defects (such as resin-rich areas, ply wrinkle areas); Among them, the conditions of each problem area are as follows: The tenon connection area: high shear stress concentration, prone to interface debonding; The stiffness mutation area (blade body-tenon transition area): stress gradient increases sharply due to cross-section change; The ply angle transition area (such as 0°→±45°): fiber direction mutation causes interlaminar peeling; The blade tip-blade root transition area: bending load and centrifugal force coupling, fatigue crack sensitive.

[0042] Specifically, the ply angle adjustment: the overall distribution of the ply height grouping is preferentially maintained, the fiber direction of the ply is adjusted for the marked problem area, and the adjusted angle satisfies the ply proportion criterion.

[0043] For example, as shown in FIG. 1, where the green contour is the 0° prepreg fiber direction, the red contour is the 45° prepreg fiber direction, and the blue contour is the -45° prepreg fiber direction. Figure 5 Further, to improve the chord-wise stiffness of the engine fan blade, the fiber direction of the internal ply is modified by selecting a suitable internal ply, and the individual ply is modified for 90° fiber laying; The initial design of the ply angle distribution (0° / 45° / 0° / -45° / 0°) is modified to (0° / 45° / 90° / 45° / 0°) or (0° / -45° / 90° / -45° / 0°) to achieve local optimization of the prepreg ply.

[0044] Further, the engine fan blade may encounter external impact (such as bird strike, hail) during operation. Although the conventional ply design is excellent in meeting the in-plane stiffness and strength requirements, the interlayer performance is mainly dominated by the matrix, and when facing high-speed out-of-plane impact, the interlayer shear and transverse tensile stress concentration easily causes delamination damage, and further leads to structural failure.

[0045] By means of an innovative asymmetric / quasi-symmetric ply architecture, a small amount of 90° ply is strategically introduced in the characteristic area (such as the leading edge impact area, the blade stiffness transition area), which can "fine-tune" and improve the chord-wise stiffness of the area, and ensure its shape stability.

[0046] Specifically, the ply sequence optimization: 1-2 layers of intermediate plies are added in the stiffness mutation area, and a step transition is used, which is specifically: Mark the area where the height difference between adjacent plies is > 3mm by modeling software; Determine the step shape: preferentially use equal height decreasing laying, and use nonlinear decreasing treatment for high load areas; Each ply extends and covers the next step, and is laid in a staggered manner to form an overlapping area.

[0047] Further, in the stiffness mutation area (such as the blade-nose transition area), the height difference between adjacent plies > 3mm will cause stress concentration and resin enrichment defects. The use of equal height decreasing laying (for conventional areas) or nonlinear decreasing (for high load areas) gradually reduces the ply drop, which can smooth the stiffness change, avoid stress singular points caused by cross-section mutation, disperse the load transmission path in the stiffness mutation area, make the stiffness gradient more continuous, improve the fatigue life of the high load area (such as the nose), and through finite element analysis verification, it can significantly reduce the interlayer shear stress peak value in the transition area, and improve the uniformity of resin flow. ​

[0048] Secondly, staggered laying (each layer extends to cover the next step) forms overlapping areas, which can enhance interlaminar bonding strength, and chamfering can reduce the risk of edge peeling. Overlapping areas can avoid stress concentration at the end of the layer, and chamfering can reduce edge cracks during curing, thereby reducing curing deformation and eliminating the need for additional mold costs.

[0049] In summary, the present application optimizes the design of tenon extension and the height of the layer by parameterized modeling and measured data calibration, ensures fiber continuity and eliminates process cumulative error. Secondly, locally introduce 90° layer to enhance chordwise stiffness, combined with step transition to disperse stress concentration, reduce the interlaminar shear stress peak in the transition area of the tenon-blade, improve impact resistance, and significantly reduce the risk of delamination and curing deformation.

[0050] Secondly, based on digital calibration and automatic verification of layering criteria, quickly locate high stress areas and optimize layering angle and sequence, reduce trial and error costs, and solve the pain point of "design intent landing difficult" in traditional methods. Reduce the weight of the blade while improving fatigue life, suitable for high-precision and high-reliability demand scenarios such as aircraft engines.

[0051] The above description of the embodiments is only used to help understand the method of the present application and its core idea. It should be noted that for ordinary skilled persons in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways. These improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for designing composite material fan blade layup, characterized in that: Includes the following steps: S1. Construct a blade model and optimize it based on the model structure; S2, Prepreg preparation, obtain the curing thickness of a single layer of prepreg through the laminate curing process, refine the layup outline based on the blade optimization model and group the layups by height; S3, the layup will be evenly arranged according to the layup design criteria by the height grouping method, the layup angle will be assigned and it will be judged whether the requirements are met, and a preliminary cutting diagram will be generated. S4, Design the cutting of the prepreg according to the cutting diagram; The blade model includes a blade body model, a tenon model, a blade mid-surface, a blade base, and a blade back.

2. The composite material fan blade layup design method according to claim 1, characterized in that: In step S1, the optimization based on the model structure specifically involves: The outer edge of the tenon model structure is extended, wherein the tenon model extends downward along both sides and beyond the bottom of the tenon.

3. The composite material fan blade layup design method according to claim 2, characterized in that: The optimized tenon model is divided into regions, defining the original range of the tenon model as the tenon body and the extended area of ​​the tenon model as the cutting body. The outer side of the tenon body is provided with a machining allowance area.

4. The composite material fan blade layup design method according to claim 1, characterized in that: In step S2, the ply height grouping is specifically as follows: Based on the 3D model outline of the blade, the height of each prepreg layer is digitally calibrated along the height direction of the blade model and assigned a height value. The height value is the normalized height value of the center line of the layer in the global coordinate system of the blade. Each layer of prepreg is divided into three types of prepreg layers: low, medium and high. According to the blade structure, the high ply is distributed according to the proportion, and the corresponding medium and low ply are inserted between adjacent high ply layers. The prepreg layup angles are initially assigned based on the load direction of the blade model; Based on the main load-bearing characteristics of the blade model, a 0° prepreg layer is arranged, while a ±45° prepreg layer is arranged in the transition area.

5. The composite material fan blade layup design method according to claim 1, characterized in that: In step S3, the specific ply design criteria are as follows: 1) Symmetry principle: The layup sequence is symmetrical about the center plane and is laid in a symmetrical distribution. 2) Balance criterion: For every ply that is not 0° or 90°, there must be a corresponding negative angle ply, which, together with symmetry, must be satisfied; 3) Dispersion criterion: Plies in the same direction should be evenly distributed throughout the laminated structure to avoid stacking plies in the same direction together; 4) Proportioning Criterion: Prepreg layers in all three principal load directions should account for at least 20% of the total number of layers; 5) Orientation criterion: The layup direction should preferably be selected from the direction of the principal load; The three main load directions specifically include: 0° prepreg layup and ±45° prepreg layup.

6. The composite material fan blade layup design method according to claim 1, characterized in that: In step S3, if the ply height grouping satisfies the condition of uniform laying under the ply design criteria, then determine the layup angle of the blade ply, arrange them symmetrically on the ply mid-surface, prepare the cutting diagram, and then proceed to step S4. If the requirements are not met, perform local optimization of the layup until the design criteria are met, then determine the layup angle and sequence, and finally prepare the cutting diagram before proceeding to step S4.

7. The composite material fan blade layup design method according to claim 6, characterized in that: The local optimization specifically includes: optimization of the problem area, adjustment of the ply angle, and optimization of the ply sequence; The problem area is located by identifying high strain or high stress concentration areas in the blade model through collaborative verification using finite element simulation and process database, and marking the ply formation locations that do not meet the design criteria. The problem areas include the tenon connection area, the stiffness abrupt change area (blade-tenon transition area), the layup angle transition area, and the blade tip-root transition area.

8. The composite material fan blade layup design method according to claim 7, characterized in that: The ply angle adjustment prioritizes maintaining the overall distribution of ply height groups, adjusts the fiber direction for ply in marked problem areas, and ensures that the adjusted angle meets the ply ratio criteria. The ply sequence optimization involves adding 1-2 intermediate ply layers in the stiffness abrupt change region and using a stepped transition treatment.

9. The composite material fan blade layup design method according to claim 7, characterized in that: The stepped transition process is specifically as follows: Mark areas with a height difference greater than 3mm between adjacent layers using modeling software; Determine the shape of the steps: prioritize paving with equal height decreases, and use non-linear decreases for high-load areas; Each layer extends and covers the next layer, staggered to form overlapping areas.

10. The composite material fan blade layup design method according to claim 3, characterized in that: During the processing of the tenon model, after the prepreg is laid and cured, in the rough processing stage, firstly, the main body of the tenon model is cut off, then the remaining area of ​​the tenon model is milled, then the tenon model is finely processed, and finally the surface is treated.

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