Structure and design method of large-size hollow composite material component

Abstract

The invention belongs to the technical field of wind energy utilization, and particularly relates to a structure and design method of a large-size hollow composite material component, the structure comprises a skin and reinforcing ribs, and the reinforcing ribs form a mutually staggered structure on the inner surface of a product. The design method comprises the following steps that firstly, initial parameters of the reinforcing ribs in the structure are set to determine the positions, shapes, sizes and materials of the reinforcing ribs, indexes needing to optimize the structure are determined, and the indexes comprise the static strength strain index, the displacement index, the buckling stability safety coefficient index and the fatigue damage value index; aiming at each index of the structure, sequentially adjusting each parameter of the reinforcing rib in the structure until the corresponding index meets the requirement; and when the indexes are optimized according to the sequence, the optimized indexes are considered. Partial or overall structure replacement of a product with a cavity inside can be completed, the weight is reduced, restriction on function design of the product can be reduced through the complete cavity, and the function design thought is expanded.

Description

Technical Field

[0001] The invention belongs to the technical field of wind energy utilization, and in particular relates to a structure and a design method of a large-size hollow composite material component. Background Art

[0002] Under the grand vision of achieving carbon neutrality, renewable energy has taken the stage as the protagonist for the first time, and among the many new energy sources, wind energy plays a key role with its unique advantages. At present, wind energy utilization devices with great market application prospects include wind turbine blades, ship sails, etc.

[0003] Composite materials are widely used in existing products such as wind turbine blades and sails due to their many advantages, including high specific strength and specific stiffness, good mechanical property design, good fatigue resistance, good environmental adaptability and high safety.

[0004] In the current design of composite materials products, sandwich structures are widely used as a mature composite structure. This structure can be designed into various structures such as plates, shells, columns, etc. to meet engineering needs. It has many advantages such as high specific strength, high specific stiffness, good thermal conductivity and excellent designability.

[0005] In the manufacture of large-sized composite wind turbine blades, beam cap structures are widely used. The main beam, uniform thickness sandwich structure shell and intracavity web support structure almost dominate the design of all composite products, resulting in a high degree of homogeneity in all blade structures currently on the market. When the power generation of the blades becomes higher and higher and the size becomes larger, the weight of the blades increases faster, making it more prone to overweight problems. At the same time, the internal web support structure also limits the utilization of the internal space and the design of some functions.

[0006] Compared with wind turbine blades, sails can be said to be an ancient yet emerging product. Under the current background of new energy utilization, various types of marine sail devices have appeared on the market, which can be mainly divided into rotary barrel sails and wing-shaped sails. In terms of wind energy utilization, wing-shaped sails have obvious advantages, but they are more difficult to manufacture, and have higher requirements on the reliability of the sail structure and the manufacturing process.

[0007] As far as wing-shaped sails are concerned, there are currently several main structures:

[0008] First, the steel sail surface and steel profile frame have a simple structure and good workmanship, but it is difficult to optimize the local structural design according to the usage scenario. At the same time, the excessive use of metal materials leads to a high cost for improving the anti-corrosion performance.

[0009] Second, the carbon fiber sail surface and steel sail frame. This structure is difficult to give full play to the structural design advantages of composite materials. The process cost is high. There are a large number of metal and composite material connection interfaces in the product. The reliability and maintainability are poor and the cost is high.

[0010] Third, the glass fiber sandwich structure sail body has high reliability and mature technology. However, for large-sized products with wide airfoils such as sails, the weight is difficult to control, the rigidity of the molded product is poor, and it is easy to be damaged during transportation and assembly. It will also affect the reliability of the product's maintenance and use in extreme weather conditions. Summary of the invention

[0011] In order to solve the technical problems of overweight and poor reliability of the above-mentioned composite material structure, the present invention provides a structure and design method of a large-sized hollow composite material component.

[0012] The purpose of the present invention is to achieve the following technical solution. According to the structure of a large-sized hollow composite material component proposed by the present invention, it includes a skin and reinforcing ribs located inside the skin and protruding inward, the reinforcing ribs follow the airfoil of the component, the reinforcing ribs form a mutually staggered structure on the inner surface of the product, and a complete cavity without division is formed inside the product.

[0013] Furthermore, the reinforcing ribs are made of pure glass fiber, pure carbon fiber, a core material coated with glass fiber or carbon fiber, or a combination of the above materials.

[0014] Furthermore, the cross-sectional shape of the reinforcement rib adopts a regular geometric figure or an irregular geometric figure or a mixed cross-sectional design. When a mixed cross-sectional design is adopted, a single mixed cross-sectional reinforcement rib is adopted at the intersection of reinforcement ribs with different cross-sectional shapes in the same reinforcement rib, so that the cross-sectional shape of the reinforcement rib at the intersection gradually changes.

[0015] Furthermore, when the reinforcement ribs are laid in fiber layers, the fiber laying thickness at the intersection position of the reinforcement ribs is equal to the thickness at the non-intersection position, and at the intersection position, the fibers in two directions are disconnected in sequence in the laying direction, that is, when the nth layer of transverse fibers are disconnected, the nth layer of longitudinal fibers are continuous, the n+1th layer of transverse fibers are continuous, and the n+1th layer of longitudinal fibers are disconnected; or, the fiber layup is cut as a whole into reinforcement ribs in the shape of a cross structure, and the cutting positions of each layer of fibers are staggered by an appropriate distance.

[0016] Furthermore, when the reinforcing ribs adopt a core material structure, the sandwich structure is processed into cross-shaped reinforcing ribs and after the reinforcing ribs are laid, glass fiber or carbon fiber or glass-carbon mixed material is wrapped around the outside of the reinforcing ribs.

[0017] Furthermore, the large curvature region of the component airfoil is filled with core material.

[0018] A structural design method for a large-size hollow composite material component comprises the following steps: when simulating, analyzing and designing the structure, firstly setting the initial parameters of the reinforcing ribs in the structure to determine the position, shape, size and material of the reinforcing ribs, and determining the indicators that need to be optimized for the structure, the indicators including the static strength strain index, the displacement index, the buckling stability safety factor index and the fatigue damage value index; for each indicator of the structure, adjusting the various parameters of the reinforcing ribs in the structure in turn until the corresponding indicator meets the requirements; when optimizing the indicators in sequence, taking into account the indicators that have been optimized before.

[0019] Furthermore, the above indicators are optimized in the order of static strength strain indicator, displacement indicator, buckling stability safety factor indicator, and fatigue damage value indicator. When adjusting the parameters, the spacing, thickness, material, and cross-sectional shape of the reinforcement are adjusted in turn.

[0020] Furthermore, when optimizing the fatigue damage value index of the stiffener and adjusting the cross-sectional shape, the angle between the stiffener and the shell skin is increased.

[0021] Furthermore, when adjusting the cross-sectional shape of the reinforcement, first ensure equal stiffness replacement of the cross section, and secondly ensure consistency of the cross-sectional size of a single reinforcement. If multiple cross-sectional mixing of a single reinforcement is required, the conversion connector between the two cross-sectional shapes should be located outside the weak position of the original structure.

[0022] Compared with the prior art, the present invention is beneficial in that:

[0023] The present invention aims to solve the problems of large-sized closed airfoil hollow composite products currently on the market, such as insufficient rigidity, heavy weight, and the use of a beam cap structure that causes the existence of an internal web support structure that affects their design functionality. The present invention provides a new hollow composite component structure with a closed airfoil cross-section, which can replace part or all of the structure of composite products with internal cavities. The complete cavity can also reduce constraints on the functional design of the product and expand the functional design ideas.

[0024] The structure of the closed airfoil-shaped large-size hollow composite material component involved in the present invention can be adapted to wind turbine blades with large chord lengths and large-size airfoil-shaped sails.

[0025] Compared with the spar cap structure of traditional composite materials, which requires the design of webs to improve the structural rigidity, the structure of the present invention can form a complete cavity that is conformable and undivided inside. When the main beam structure is removed, the requirements of structural strength, rigidity, weight limit and internal space functional design are better taken into account. In particular, the internal complete cavity that is undivided and conformable can achieve greater structural rigidity and strength in the design of wide-wing sails, thereby achieving the nesting and barrier-free lifting of the sail body while better maintaining its own shape, so that the wing sail can be dropped under extreme wind conditions, extending the service life of the sail body. It has obvious advantages over existing products in terms of cost, reliability, realization of special functions and convenience of maintenance.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a A schematic diagram of a structural member of a large-sized hollow composite material member of the present invention is used as a whole;

[0028] Figure 1b for Figure 1a A cross-sectional view of

[0029] Figure 1c A schematic diagram of a component of a structural embodiment of a large-sized hollow composite material component of the present invention is partially used;

[0030] Figure 1d for Figure 1c A cross-sectional view of

[0031] Figure 2a A schematic diagram of reinforcing ribs made of different materials in a structural embodiment of a large-sized hollow composite material component of the present invention;

[0032] Figure 2b , 2c Both Figure 2a Cross-sectional view of the middle reinforcement rib;.

[0033] Figure 3a A schematic diagram of reinforcing ribs of different cross-section forms in a structural embodiment of a large-sized hollow composite material component of the present invention;

[0034] Figure 3b A schematic diagram of a structure embodiment of a large-sized hollow composite material component of the present invention in which a single reinforcing rib with different cross-sections is mixed;

[0035] Figure 4aA schematic diagram of reinforcing ribs that are distributed at unequal intervals and cross each other perpendicularly in a structural embodiment of a large-sized hollow composite material component of the present invention;

[0036] Figure 4b A schematic diagram of reinforcing ribs that are equally spaced and non-vertically crossed in a structural embodiment of a large-sized hollow composite material component of the present invention;

[0037] Figure 4c It is a schematic diagram of the structure of the cross position of the reinforcing ribs in a structural embodiment of a large-sized hollow composite material component of the present invention;

[0038] Figure 5a A schematic diagram showing the effect of using a large-sized hollow composite material component of the present invention for an airfoil sail;

[0039] Figure 5b for Figure 5a Front view of the diagram;

[0040] Figure 5c for Figure 5a A cross-sectional view of

[0041] Figure 5d for Figure 5c The enlarged schematic diagram of point A in the middle;

[0042] Figure 5e for Figure 5c The enlarged schematic diagram of point B in the middle;

[0043] Figure 6a A schematic diagram of the effect of using a large-sized hollow composite material component of the present invention for a wind turbine blade;

[0044] Figure 6b for Figure 6a A cross-sectional view of

[0045] Figure 6c for Figure 6b The enlarged schematic diagram of the center C;

[0046] Figure 6d for Figure 6b Enlarged schematic diagram of point D in the middle.

[0047] [Reference Signs]

[0048] 101- overall reinforcement rib structure; 102- local reinforcement rib structure; 103- reinforcement rib; 104- sandwich structure;

[0049] 201-pure glass fiber reinforcement; 202-pure carbon fiber reinforcement; 203-carbon glass hybrid reinforcement; 204-core material coated with glass fiber reinforcement; 205-core material coated with carbon fiber reinforcement; 206-core material coated with carbon glass hybrid reinforcement;

[0050] 301-triangular cross-section reinforcement rib; 302-semicircular cross-section reinforcement rib; 303-rectangular cross-section reinforcement rib; 304-semi-elliptical cross-section reinforcement rib; 305-trapezoidal cross-section reinforcement rib; 306-irregular cross-section reinforcement rib; 307-single cross-section mixed reinforcement rib;

[0051] 401- non-uniformly spaced reinforcement structure; 402- non-vertical cross reinforcement structure; 403- reinforcement cross structure;

[0052] 501-sail body; 502-sail base; 503-sail trapezoidal cross-section reinforcement ribs; 504-sail irregular cross-section reinforcement ribs;

[0053] 601- wind turbine blade; 602- trapezoidal cross-section reinforcement ribs inside the blade; 603- irregular cross-section reinforcement ribs inside the blade. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] An embodiment of the structure of a large-sized hollow composite material component of the present invention is as follows: Figures 1a to 4c The structure can be applied to a variety of composite products with closed airfoil sections, such as wind turbine blades with large chord lengths, rigid rotary barrel sails for ships, composite sails with symmetrical airfoil wide bodies, etc.

[0056] The structure includes a composite skin made of glass fiber, carbon fiber or other materials and reinforcing ribs located inside the skin and protruding a certain height toward the inside of the product. The reinforcing ribs are constructed separately or in combination of glass fiber, carbon fiber, core material, etc., and follow the airfoil of the product component. The reinforcing ribs form a criss-cross structure on the inner surface of the product, and a complete undivided cavity can be formed inside the product. Compared with existing similar products (the existing mainstream large-scale composite products use a beam cap structure, a sandwich structure shell composed of a core material of uniform thickness, and a supporting web is added on the inner side of the beam to improve the overall stiffness, and the web destroys the integrity of the shell cavity), this structure can achieve more effective consideration of design requirements such as structural strength, stiffness, weight limit and cavity functionality under the premise that the structure has a complete and undivided conformal cavity.

[0057] like Figure 1a to Figure 1b As shown, the product adopts an integral reinforcement rib structure 101, and crisscross reinforcement ribs 103 are distributed on the inner side of the entire skin. Figure 1c to Figure 1dAs shown, the product adopts a local reinforcement rib structure 102, some areas of the inner side of the skin are provided with reinforcement ribs 103, and other areas are provided with a sandwich structure 104. In some unimportant areas, reinforcement ribs can be used instead of sandwich structures to reduce the overall weight.

[0058] The structural form of the inward protruding reinforcement rib under the skin is used. The reinforcement rib material can be pure glass fiber, pure carbon fiber, core material coated with glass fiber or carbon fiber (PET, PVC, Balsa), or a combination of the above materials. Reinforcements of different materials can be used at different positions in the design, and different materials can be used at different positions on the same reinforcement rib according to design requirements. Figure 2a to Figure 2c As shown, according to the need, the reinforcement 103 can simultaneously use pure glass fiber reinforcement 201, pure carbon fiber reinforcement 202, carbon glass hybrid reinforcement 203, core material coated glass fiber reinforcement 204, core material coated carbon fiber reinforcement 205, core material coated carbon glass hybrid reinforcement 206 and arranged on the inner side of the skin. Different materials can achieve different strengths and stiffness of the structure. According to the cost requirements, low-cost materials can be selected in non-weak areas, and only high-cost and better-effect materials can be used in key weak areas.

[0059] The cross-sectional shape of the reinforcement rib can be a regular geometric shape (the cross-sectional shape of the reinforcement rib can be a triangle, rectangle, trapezoid, semicircle, semi-ellipse, etc.) or a customized irregular geometric shape. The cross-sectional shape is selected according to the design requirements, such as Figure 3a The different products shown use triangular cross-sectional reinforcing ribs 301, semicircular cross-sectional reinforcing ribs 302, rectangular cross-sectional reinforcing ribs 303, semi-elliptical cross-sectional reinforcing ribs 304, trapezoidal cross-sectional reinforcing ribs 305, and irregular cross-sectional reinforcing ribs 306 of different cross-sectional shapes. It is also possible to achieve a mixed cross-sectional design on a single reinforcing rib through a customized conversion connector to achieve a customized design for the product, so as to ensure the continuity and uniformity of force transmission on the structure and avoid stress concentration, such as Figure 3b The single cross-section mixed reinforcing rib 307 shown is used at the intersection of the trapezoidal cross-section reinforcing rib 305 and the triangular cross-section reinforcing rib 301, so that the cross-sectional shape of the reinforcing rib at the intersection gradually changes. Reinforcing ribs with different cross-sections can achieve different strengths and stiffnesses of the structure. When the requirements for strength and stiffness are low, reinforcing ribs with cross-sectional shapes that are easy to prepare and light in weight can be selected.

[0060] The distribution of the stiffeners can be set according to the characteristics of the airfoil and the operating conditions, including adjusting the spacing and the direction of the stiffeners. It can also be iteratively adjusted based on the simulation verification results.

[0061] The core material part of all the reinforcing ribs made of core materials can be prefabricated with V-shaped grooves to achieve airfoil-conforming during laying, especially cutting V-shaped grooves on the reinforcing ribs at positions with larger airfoil curvature to make them fit the airfoil profile.

[0062] The spacing between the reinforcing ribs in the skin and the angles between the intersecting reinforcing ribs can be adjusted according to design requirements, such as Figure 4a The structure 401 is a non-uniformly spaced reinforcing rib structure, in which the spacings between adjacent reinforcing ribs 103 are not equal, and the intersecting reinforcing ribs 103 are perpendicular to each other; Figure 4b The non-vertical crossed reinforcing rib structure 402 is shown, in which the spacings between adjacent reinforcing ribs 103 are equal, and the mutually crossed reinforcing ribs 103 are not perpendicular to each other.

[0063] When the reinforcement ribs are laid in fiber layers (glass fiber or carbon fiber or glass-carbon hybrid), the fiber laying thickness at the cross position of the reinforcement ribs 103 needs to be equal to the thickness at the non-cross position, such as Figure 4c The reinforcement cross structure 403 shown in the figure, therefore, at the cross position, the fibers in the longitudinal and transverse directions are disconnected in sequence in the laying direction, that is, when the nth layer of transverse fibers are disconnected, the nth layer of longitudinal fibers are continuous, the n+1th layer of transverse fibers are continuous, and the n+1th layer of longitudinal fibers are disconnected, and so on. At the structurally sensitive position, the fiber ply can be cut as a whole, that is, the fiber ply at this position itself is cut into reinforcements in the shape of a cross structure, and it is ensured that the cutting positions of each layer of fibers are staggered by an appropriate distance during laying.

[0064] When the reinforcement ribs are made of core material structure, they are machined into designed reinforcement ribs. At this time, the reinforcement ribs at the intersection can process the entire sandwich structure into cross-shaped reinforcement ribs. The core material at the intersection of the reinforcement ribs (especially the intersection of reinforcement ribs with different cross-sectional shapes) needs to be designed separately, and the position is smoothed and maintained through machining to make the mechanical transmission path smooth and avoid stress concentration. After the reinforcement ribs made of the core material are laid, they are wrapped with glass fiber or carbon fiber or glass-carbon mixed material.

[0065] For structurally sensitive or special locations such as large curvature areas, free ends, and connection interfaces of components, the reinforcement ribs should be customized using irregular cross-sections. For example, core materials can be used to fill the large curvature areas of the component airfoil to improve the anti-buckling performance and local structural stiffness.

[0066] Without affecting the design function, when the product is wider or the chordal center area is heavily loaded, and the weight limit is extremely strict, the product may also have a problem of insufficient stiffness. At this time, the structure can show strong compatibility with traditional composite structures, and partitions or honing frames can be added at certain positions inside the structure to further ensure the stiffness of the product and the stability of its posture under load.

[0067] Compared with traditional composite structures, this type of structure has more adjustable parameters, better designability, higher flexibility in specific design matching methods, and is more convenient for design optimization iteration, thus achieving iterative design of structural parameters for multi-objective optimization.

[0068] like Figure 5a to Figure 5e As shown, the wing-shaped sail made by the structure of the present invention includes a sail body 501 and a sail base 502. The sail body 501 is formed by wrapping two arc-shaped sheets, and the interior thereof is a complete cavity. The inner wall of the structure is distributed with sail trapezoidal cross-section reinforcement ribs 503, and the sail irregular cross-section reinforcement ribs 504 are used at the docking position of the two arc-shaped sheets to fill the gap at the docking position (i.e., the large curvature position). Since the interior of the wing-shaped sail is a complete cavity, the rotating shaft on the sail base 502 can be directly penetrated and rotated in the cavity set in the sail body 501, without considering the internal structure, and the wing-shaped sail can be conveniently designed according to needs, and a greater structural rigidity and strength can be achieved, so that the sail body can be nested and lifted without obstacles while maintaining its own shape, so that the wing sail can be dropped under extreme wind conditions, extending the service life of the sail body, and has obvious advantages over existing products in terms of cost, reliability, special function realization and maintenance convenience.

[0069] like Figures 6a to 6d As shown, a wind turbine blade 601 is made by utilizing the structure of the present invention. The wind turbine blade 601 is formed by butting two blade shells together, and a blade inner trapezoidal cross-section reinforcing rib 602 is distributed on the inner wall thereof. An irregular cross-section reinforcing rib 603 is arranged in the position where the two blade shells are butted together and the curvature changes greatly. The wind turbine blade 601 has no structures such as a web and a main beam inside, thereby reducing the weight. During manufacturing, the blade shells are poured, solidified, demolded, and then butt-jointed, and manufacturing is completed, thereby improving production efficiency.

[0070] In an embodiment of a structural design method for a large-size hollow composite material component of the present invention, a fluid-solid coupling structural design method is used to simulate and analyze the designed structure itself and the structure in the corresponding environment, and the structural strength and stiffness of all envelope working conditions are comprehensively calculated. The parameters such as the material, cross-section, and distribution position of the reinforcement ribs of the structural simulation model are iteratively adjusted to meet the multi-objective results such as the static strength strain index, displacement index (reflecting stiffness), buckling stability safety factor index, and fatigue damage value index. The design method specifically includes the following steps:

[0071] The designed stiffeners are set in the corresponding structure. The default parameters of the first iteration of the stiffeners are set as follows: the stiffeners in the horizontal and vertical directions are evenly distributed, with a spacing of a, the cross-sectional shape of the stiffeners is uniformly set to a trapezoid, the thickness of the stiffeners is set, and the material of the stiffeners is uniformly set to a multi-axial glass fiber layer coated on the outside of the core material.

[0072] The strain level of each layer of material under each working condition of each stiffener is calculated. After eliminating the stress concentration caused by the model, the proportion and distribution of dangerous positions are evaluated based on the static strength strain index. When the proportion of dangerous positions is less than 1 / 3 and the distribution is relatively concentrated, local optimization is selected, otherwise the overall structure is adjusted. When adjusting the stiffeners, the order of parameter adjustment is stiffener spacing, stiffener cross-sectional thickness, and finally stiffener material adjustment, step by step.

[0073] After the optimization of static strength and strain index is completed, the displacement index optimization is started. The same adjustment method as the static strength and strain index optimization is adopted to adjust the stiffener structural parameters, that is, the stiffener spacing, stiffener cross-sectional thickness, and stiffener material are adjusted in turn, while the static strength and strain index needs to be taken into account.

[0074] After the displacement index is optimized, the buckling stability safety factor index optimization is started. The stiffener structural parameters are adjusted using the same adjustment method as the static strength strain index optimization, that is, the stiffener spacing, stiffener cross-sectional thickness, and stiffener material are adjusted in turn, while taking into account the static strength strain index and displacement index.

[0075] After the optimization of the buckling stability safety factor index is completed, the fatigue damage value index is optimized. The stiffener structural parameters are adjusted using the same adjustment method as the static strength strain index optimization, that is, the stiffener spacing, stiffener cross-sectional thickness, and stiffener material are adjusted in turn. At the same time, the static strength strain index, displacement index, and buckling stability safety factor index need to be taken into account.

[0076] When optimizing indicators, optimize in the order from static indicators to dynamic indicators, start from the basic indicators, reduce the number of optimization adjustments, and improve optimization efficiency. When adjusting parameters, consider material costs and design costs, first adjust easy-to-adjust parameters, such as the spacing and thickness of the reinforcement, and then adjust the material and shape of the reinforcement.

[0077] The specific adjustment method of the rib parameters needs to be adjusted in combination with the dimensions x and y of the product in the horizontal and vertical directions. The amplitude of each adjustment of the rib spacing size shall not exceed 1 / 30 of the overall size in that direction (determined according to the overall size of the design), and the rib thickness size shall not exceed 5% of the spacing each time (determined according to the overall size of the design). When the thickness increase makes the stiffness of the rib exceed the equal stiffness value required by the structural design and still does not meet the standard, the rib material shall be converted to a higher strength material (pure glass fiber or core material coated with carbon fiber, carbon fiber, etc.) in combination with the weight level. Based on experience and specific results, each parameter is adjusted three times on average (the number of adjustments is determined according to design requirements). If the corresponding index of the rib does not show significant improvement (according to the design requirements, the corresponding index growth rate after adjusting the parameter does not reach the set value), then turn to the adjustment of the next parameter, and adjust the rib parameters repeatedly until the corresponding index requirements are met.

[0078] When the fatigue damage value index of certain positions of the stiffener is difficult to reduce to a safe range through the above adjustment methods, the cross-sectional shape of the stiffener at the local position should be changed. Through the cross-sectional shape design, the angle between the stiffener and the shell skin is increased, that is, the transition between the stiffener and the shell skin is smoother. When other indicators are difficult to achieve, the shape can also be adjusted.

[0079] When replacing the cross-sectional shape of a reinforcement, first ensure that the cross-sectional stiffness is equal. For example, when replacing a rectangle with a trapezoid, the initial stiffness of the trapezoid is equal to the stiffness of the adjusted rectangle before the replacement. Secondly, try to ensure the consistency of the cross-sectional dimensions of a single reinforcement. If multiple cross-sectional mixing of a single reinforcement is required, the conversion connector between the two cross-sectional shapes should be located outside the weak position of the original structure. For example, a single reinforcement includes a rectangular reinforcement and a trapezoidal reinforcement. The trapezoidal reinforcement is located at a weak position of the structure. The conversion connector between the rectangular reinforcement and the trapezoidal reinforcement is not set at the weak position of the structure where the trapezoidal reinforcement is located. That is, a trapezoidal reinforcement is set at a weak position, and a rectangular reinforcement is set at a non-weak position. When setting the conversion connector, the conversion connector replaces a section of the rectangular reinforcement close to the trapezoidal reinforcement.

[0080] The initial cross-section of the reinforcement ribs at certain locations in the structure with small spaces or large curvatures is a special-shaped cross-section. The cross-section design iteration at this location can be adjusted according to the specific situation, referring to the adjustment method of the regular cross-section. For example, since the reinforcement rib is at a location with small space or large curvature, the spacing with the reinforcement ribs at other locations and its own shape have been determined, and the thickness and material of the reinforcement rib here can be adjusted until the requirements of the corresponding indicators are met.

[0081] During the design iteration process, attention should be paid to the weight change of the product. When approaching the weight limit, the mass added in the weak position in each iteration should be compensated by deleting some reinforcement ribs in the non-weak position. For example, the size of the reinforcement ribs in the non-weak position can be reduced. During the iteration process, if the index meets the standard, the iteration can be stopped.

[0082] Each iteration needs to ensure that the other indicators do not deteriorate significantly under the premise that the current indicators are optimized. The adjustments are repeated repeatedly to finally complete the multi-indicator structural design iteration process, achieve or exceed the strength and stiffness of the product with a beam cap structure, and reduce the weight at the same time to ensure that the interior has a complete, undivided conformal cavity.

[0083] By adjusting the parameters of the stiffeners to optimize the structure, when the stiffeners are in the product without the beam cap structure, the strength and stiffness of the product are equal to or exceed those of the product with the beam cap structure, which can reduce the weight of the product. By setting stiffeners, in the annularly closed airfoil cavity, annularly closed stiffeners and longitudinal stiffeners crossing the annularly closed stiffeners are set, the final effect can replace the beam cap structure, and the complete internal cavity can be used for functional design.

[0084] The steps of a structural design method for a large-size hollow composite material component of the present invention are summarized as follows:

[0085] When conducting simulation analysis and design on the structure, the initial parameters of the reinforcement ribs in the structure are first set to determine the position (spacing between each reinforcement rib), shape, size (thickness), material, and indicators that need to be optimized for the structure (including static strength strain index, displacement index (reflecting stiffness), buckling stability safety factor index, fatigue damage value index); for each indicator of the structure, the various parameters of the reinforcement ribs in the structure are adjusted in sequence until the corresponding indicator meets the requirements; when optimizing the indicators in sequence, the indicators that have been optimized before are taken into account.

[0086] The following uses a wing-shaped sail as an example and combines the accompanying drawings to more clearly and completely illustrate the manufacturing process of a product suitable for this structure.

[0087] The simplified process of product manufacturing is as follows:

[0088] Step 1: Complete the production of prefabricated parts.

[0089] Step 2: Lay the reinforcement layer in each area under the component skin and stiffeners.

[0090] Step 3: Complete the positioning and laying of the reinforcement ribs (503 / 504) according to the designed reinforcement rib structure.

[0091] Step 4: When laying the reinforcement layer on the reinforcement, pay attention to the treatment of the intersection position. When laying the reinforcement layer on the reinforcement at the intersection position, ensure the continuity of the reinforcement layer on the reinforcement.

[0092] Step 5: Lay out the auxiliary materials needed for pouring, create vacuum, and pour and solidify in one piece.

[0093] Step 6: After curing, complete half-piece demoulding, bond the steel frame, and close the mold.

[0094] Step 7: Demolding the product and completing the post-processing and assembly of the product.

[0095] The wind turbine blades and the airfoil sails are also made by connecting two shells. The manufacturing processes of the two are similar and will not be described in detail here.

[0096] Compared with the prior art, the beneficial effects of the present invention are summarized as follows:

[0097] 1) At present, the mainstream large-scale composite products on the market all adopt beam cap structure. The beam is used as the main load-bearing structure, and a web needs to be set on the inside to increase the structural rigidity. The shell adopts a sandwich structure. This approach often appears to be insufficiently rigid for products with strict weight control. At the same time, the web and other supporting structures occupy the internal space, which limits the functional design of the internal space and makes it impossible to nest other components or accommodate larger products. However, this structure can provide higher structural rigidity while having a complete and undivided conformal cavity inside the component, so that the weight of the product can be effectively controlled, and a component nesting structure can be realized. It can also realize the relative movement between the components in the cavity and the component itself, and complete certain unique product functions. Compared with the traditional structure, the rigidity-to-weight ratio is greatly improved, and the static state can better maintain its own shape, which is convenient for assembly, transportation, installation and maintenance.

[0098] 2) The present invention has more adjustable parameters in terms of cross-sectional shape, layout position, material selection, etc., which greatly increases the design convenience, can provide a more matching structure for specific products, and is more convenient for design optimization and iteration.

[0099] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A structure of a large-sized hollow composite material component, characterized in that: It includes a skin and reinforcing ribs located inside the skin and protruding inward, the reinforcing ribs follow the airfoil of the component, the reinforcing ribs form a mutually staggered structure on the inner surface of the product, and an undivided complete cavity is formed inside the product.

2. The structure of a large-sized hollow composite material component according to claim 1, characterized in that: The reinforcing ribs are made of pure glass fiber, pure carbon fiber, a core material coated with glass fiber or carbon fiber, or a combination of the above materials.

3. The structure of a large-sized hollow composite material component according to claim 1, characterized in that: The cross-sectional shape of the reinforcement rib adopts a regular geometric figure or an irregular geometric figure or a mixed cross-sectional design. When the mixed cross-sectional design is adopted, a single mixed cross-sectional reinforcement rib is adopted at the intersection of reinforcement ribs with different cross-sectional shapes in the same reinforcement rib, so that the cross-sectional shape of the reinforcement rib at the intersection gradually changes.

4. The structure of a large-sized hollow composite material component according to claim 1, characterized in that: When the reinforcement ribs are laid in fiber layers, the fiber laying thickness at the intersection position of the reinforcement ribs is equal to the thickness at the non-intersection position, and at the intersection position, the fibers in two directions are disconnected in sequence in the laying direction, that is, when the nth layer of transverse fibers are disconnected, the nth layer of longitudinal fibers are continuous, the n+1th layer of transverse fibers are continuous, and the n+1th layer of longitudinal fibers are disconnected; or, the fiber layup is cut as a whole into reinforcement ribs in the shape of a cross structure, and the cutting positions of each layer of fibers are staggered by an appropriate distance.

5. The structure of a large-sized hollow composite material component according to claim 1, characterized in that: When the reinforcing ribs adopt the core material structure, the sandwich structure is processed into cross-shaped reinforcing ribs and after the reinforcing ribs are laid, glass fiber or carbon fiber or glass-carbon mixed material is wrapped around the outside of the reinforcing ribs.

6. The structure of a large-sized hollow composite material component according to claim 1, characterized in that: The large curvature region of the component airfoil is filled with core material.

7. A structural design method for a large-sized hollow composite material component, characterized in that: The following steps are involved: When conducting simulation analysis and design on the structure, the initial parameters of the reinforcement ribs in the structure are first set to determine the position, shape, size, and material of the reinforcement ribs, and to determine the indicators that need to be optimized for the structure, including static strength strain index, displacement index, buckling stability safety factor index, and fatigue damage value index; for each indicator of the structure, the various parameters of the reinforcement ribs in the structure are adjusted in turn until the corresponding indicator meets the requirements; when optimizing the indicators in sequence, the indicators that have been optimized before are taken into account.

8. The structural design method of a large-size hollow composite material component according to claim 7, characterized in that: The above indicators are optimized in the order of static strength strain index, displacement index, buckling stability safety factor index, and fatigue damage value index. When adjusting the parameters, the spacing, thickness, material, and cross-sectional shape of the reinforcement are adjusted in turn.

9. The structural design method of a large-size hollow composite material component according to claim 7, characterized in that: When optimizing the fatigue damage value index of the stiffener and adjusting the cross-sectional shape, the angle between the stiffener and the shell skin is increased.

10. The structural design method of a large-size hollow composite material component according to claim 7, characterized in that: When adjusting the cross-sectional shape of the reinforcement, first ensure that the cross-sectional stiffness is replaced equally, and secondly ensure that the cross-sectional size of a single reinforcement is consistent. If multiple cross-sectional mixing of a single reinforcement is required, the conversion connector between the two cross-sectional shapes should be located outside the weak position of the original structure.

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