High strength propeller blade structure based on bionics

Abstract

The utility model discloses a high -strength propeller blade type structure based on bionics aims at solving the problem of traditional propeller insufficient strength, low propelling efficiency, easy to be worn and corroded, is applicable to the ship scene. The structure includes blade main part, the bionic skeleton of embedding blade main part inside and the composite surface strengthening layer coated in the blade main part outer surface, the blade main part is gradually thick along the length direction design, and the root thickness adapts high load demand, and the thickness gradually reduces from the root to the tip to optimize the fluid characteristic, the bionic skeleton is by the main vein along the blade length direction distribution, the secondary vein along the width direction and the main vein vertical interlaced and the branch vein that is triangularly distributed in the main vein and secondary vein grid is formed, the utility model greatly promotes the bending -resistant, the torsion -resistant and the impact -resistant ability of propeller, avoids the fracture deformation caused by stress concentration, prolongs the fatigue life, on the other hand effectively reduces the fluid resistance, and promotes the propelling efficiency.

Description

Technical Field

[0001] This utility model relates to the field of propeller technology, specifically to a high-strength propeller blade structure based on bionics. Background Technology

[0002] As is well known, when large ships navigate in the ocean environment, the propeller, as the core propulsion component, must operate under complex and harsh conditions for extended periods. In marine navigation scenarios, the propeller not only bears the enormous propulsive reaction force required for the ship's forward movement, but also withstands the centrifugal force generated by its own rotation and the torque transmitted by the hub. The blade root is constantly under high stress, making it a critical part of the structure susceptible to damage. Simultaneously, the marine environment presents multiple challenges: seawater is highly corrosive, continuously eroding the propeller surface; underwater, there may be sand, gravel, and debris, which can cause impact and friction to the blades during propeller rotation.

[0003] Traditional large ship propellers often employ a single metal material or a simple streamlined structure design, making it difficult to simultaneously meet the requirements of high strength, corrosion resistance, wear resistance, and high propulsion efficiency. In practical applications, traditional propellers frequently experience cracking and breakage due to stress concentration at the blade roots, directly threatening ship navigation safety and requiring frequent downtime for maintenance or replacement, significantly increasing ship operating costs. Furthermore, the surface of metal blades is susceptible to seawater corrosion and lacks sufficient wear resistance. Prolonged use leads to accelerated surface wear, resulting in increased fluid resistance, a significant decrease in propulsion efficiency, and consequently, increased fuel consumption, failing to meet the practical needs of large ships for long-term stable navigation and low operating costs. Utility Model Content

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a high-strength propeller blade structure based on bionics.

[0005] (II) Technical Solution To achieve the above objectives, this utility model provides the following technical solution: a high-strength propeller blade structure based on bionics, comprising a blade body, an embedded bionic skeleton, a surface reinforcement layer coated on the outer surface of the blade body, the blade body having a gradually varying thickness along the blade length direction, the thickness at the blade root being 1.5 to 2 times the average blade thickness, and the thickness gradually decreasing from the root to the tip, the bionic skeleton including a main vein, secondary veins and a branch vein mesh structure, the main veins being distributed along the blade length direction, the secondary veins being perpendicular to the main veins and having multiple secondary veins along the blade width direction, the branch veins being distributed between the mesh formed by the main veins and secondary veins and having a triangular structure, and the surface reinforcement layer being a composite coating of polytetrafluoroethylene and alumina ceramic particles.

[0006] Furthermore, the blade body is made of carbon fiber reinforced composite material, and the interior of the blade body is filled with lightweight foam core material. The carbon fiber arrangement is as follows: 70% of the carbon fiber is arranged along the blade length direction, and 30% of the carbon fiber is arranged alternately along the blade width direction. The carbon fibers are filled with a flexible epoxy resin matrix and are bonded by hot pressing molding process.

[0007] Furthermore, the bionic skeleton is made of high-strength titanium alloy or carbon fiber reinforced composite material, the thickness of the bionic skeleton is 0.5~1mm, accounting for 10%~15% of the total thickness of the blade, and the bionic skeleton is bonded and fixed to the lightweight foam core material of the blade body by epoxy resin.

[0008] Furthermore, in the biomimetic skeleton, there are 2 to 3 main veins with a diameter of 1 to 2 mm and an elliptical cross-section with the major axis along the thickness direction of the leaf; the secondary veins have a diameter of 0.5 to 1 mm and the spacing between the secondary veins is 1 / 5 to 1 / 4 of the width of the leaf; the branch veins have a diameter of 0.3 to 0.5 mm and conform to the curved shape of the leaf surface.

[0009] Furthermore, the blade tip of the blade body adopts a rounded transition design, and the radius of curvature of the rounded arc is 0.3 to 0.5 times the width of the blade tip.

[0010] Furthermore, the thickness of the surface strengthening layer is 0.1~0.2mm, the content of alumina ceramic particles is 30%, and the bonding strength between the surface strengthening layer and the blade body is ≥5MPa.

[0011] Furthermore, the lightweight foam core material of the blade body is polyurethane foam core material with a density of 0.2 g / cm³; the parameters of the hot pressing molding process are: temperature 120℃, pressure 0.5 MPa, and heat preservation time 2 h.

[0012] (III) Beneficial Effects Compared with the prior art, this utility model provides a high-strength propeller blade structure based on bionics, which has the following beneficial effects: This biomimetic high-strength propeller blade structure features a biomimetic skeleton embedded within the blade body. Through a three-tiered force-bearing system consisting of main veins, secondary veins, and branch veins, it transforms the concentrated load borne by the propeller into a distributed load, efficiently transferring and distributing it to various areas of the blade. This structure significantly enhances the overall strength and impact resistance of the blade. Even when encountering underwater sand and debris in the ocean, it effectively reduces the risk of blade dents, deformation, or even breakage, ensuring the continuity of navigation for large ships and reducing the frequency of downtime and maintenance due to sudden malfunctions.

[0013] The composite coating of polytetrafluoroethylene (PTFE) and alumina ceramic particles on the outer surface of the blade is well-suited to the corrosive and abrasive environment of the ocean. PTFE effectively resists the corrosive effects of seawater, preventing damage to the blade surface from prolonged contact with seawater; while the alumina ceramic particles enhance the wear resistance of the blade surface, reducing wear caused by seawater erosion and friction from underwater impurities. Simultaneously, this coating reduces the viscous drag of the fluid on the blade surface, improving propeller propulsion efficiency, helping to reduce fuel consumption in large vessels, and further lowering operating costs. Attached Figure Description

[0014] Figure 1 This is a first-view structural diagram of the present invention; Figure 2 This is a schematic diagram of the second-view structure of the present invention; Figure 3 This is a front half-sectional view of the structure of this utility model; Figure 4 This utility model Figure 1 Left half-section view of the enlarged partial structure of the main body of the middle blade.

[0015] In the diagram: 1. Blade body; 2. Main vein; 3. Secondary vein; 4. Branch vein; 5. Lightweight foam core material; 6. Surface reinforcement layer. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Please see Figures 1 to 4This utility model is a high-strength propeller blade structure based on bionics, including a blade body 1, a bionic skeleton embedded inside the blade body 1, and a surface reinforcement layer 6 coated on the outer surface of the blade body 1. The blade body 1 has a gradually changing thickness design along the blade length direction, with the thickness at the blade root being 1.5 to 2 times the average thickness of the blade, and the thickness gradually decreasing from the root to the blade tip. The bionic skeleton includes a mesh structure of main veins 2, secondary veins 3, and branch veins 4. The main veins 2 are distributed along the blade length direction, the secondary veins 3 are perpendicular to the main veins 2 and are arranged in multiples along the blade width direction, and the branch veins 4 are distributed between the mesh formed by the main veins 2 and the secondary veins 3 and are in a triangular structure. The surface reinforcement layer 6 is a composite coating of polytetrafluoroethylene and alumina ceramic particles. In this embodiment, when the propeller rotates, the force on the blades is distributed in a clear gradient. The root bears the maximum load (including the centrifugal force generated by the propeller rotation, the torque transmitted by the hub, and the reaction force of the fluid propulsion), and the stress value is 3 to 5 times that of the blade tip; while the blade tip only needs to bear the impact of local airflow / water flow, and the load is relatively small. Main vein 2 is distributed along the blade length direction: Since the main load transmission path when the propeller rotates is the hub, blade root, blade length direction, and blade tip, the main vein 2 is arranged along this direction and can directly bear and transmit more than 70% of the longitudinal load (such as centrifugal force and propulsion reaction force), which is equivalent to the main beam of the blade. When the longitudinal load is transmitted through the main vein 2, it will spread to the blade width direction (such as the lateral force generated by the lateral impact of the airflow). The secondary vein 3 can disperse the lateral load to the main vein 2 to avoid local load accumulation, which is equivalent to the crossbeam. Branch vein 4 is distributed in a triangular pattern in the grid of main vein 2 and secondary vein 3: Utilizing the geometric stability of the triangular structure (triangles have no risk of geometric deformation and their shear resistance is better than that of mesh, rectangular and other structures), it fills the load gap between the main vein 2 and secondary vein 3 and prevents the grid area from being dented or deformed due to local impact (such as underwater debris collision and airflow turbulence). The biomimetic skeleton forms a three-tiered force-bearing system: the main vein 2 bears the load, the secondary vein 3 disperses the load, and the branch vein 4 reinforces the load. This system transforms concentrated loads (such as root torque and tip impact) into distributed loads, which are then transmitted to various areas of the blade body 1 through the skeleton network, preventing overload in a single part. The low surface energy of polytetrafluoroethylene (PTFE)—its coefficient of friction ≤0.04 (far lower than the 0.15~0.2 of traditional metal blade surfaces)—reduces viscous resistance of airflow / water flow on the blade surface and possesses excellent chemical stability, resisting corrosion from seawater and humid air. The high hardness of alumina ceramic particles—hardness ≥HV800 (3~4 times that of aluminum alloys)—allows them to be embedded in PTFE as a wear-resistant skeleton, resisting frictional wear from impurities in airflow / water flow (such as dust and gravel), avoiding the insufficient wear resistance of PTFE when used alone. The composite coating, through the synergistic effect of the wear-resistant ceramic particles and the corrosion-reducing properties of PTFE, simultaneously solves the two major problems of blade surface wear and fluid resistance, achieving a balance between protection and efficiency. In this design, the blade body is made of carbon fiber reinforced composite material, and the interior of the blade body is filled with lightweight foam core material. The carbon fiber arrangement is as follows: 70% of the carbon fibers are arranged along the blade length direction, and 30% of the carbon fibers are arranged alternately along the blade width direction. The carbon fibers are filled with a flexible epoxy resin matrix and bonded together by a hot pressing molding process. The composite structure employs carbon fiber reinforced composite material with a lightweight foam core. The high specific strength (strength-to-weight ratio) of carbon fiber bears the main tensile / bending loads, while the foam core fills the internal voids, avoiding localized stress concentration caused by direct contact between the carbon fiber materials and reducing overall weight. 70% of the carbon fiber is arranged along the blade length (corresponding to the radial load and propulsive reaction force during propeller rotation), and 30% is staggered along the width (corresponding to lateral shear force, such as the lateral impact of airflow / water flow), achieving "load direction matching with reinforcement material direction" and reducing ineffective material consumption. A flexible epoxy resin matrix fills the gaps between the carbon fibers, and hot-pressing (high temperature cures the resin, high pressure binds the materials tightly) ensures no voids between the carbon fiber, foam core, and resin, forming an "integrated load-bearing structure" and preventing delamination failure. Compared to traditional all-metal blades, the overall weight is reduced by 30%-40%, and the power consumption of the equipment is reduced by more than 15%. The blade's bending strength is increased by 40%, and its shear strength is increased by 35%. It does not have significant deformation when rotating at high speed, thus resolving the contradiction of "lightweight and high strength cannot be achieved at the same time". The hot pressing process makes the blade structure consistent with more than 98%, ensuring stable performance during mass production and reducing the defect rate. In this design, the biomimetic skeleton is made of high-strength titanium alloy or carbon fiber reinforced composite material. The thickness of the biomimetic skeleton is 0.5~1mm, accounting for 10%~15% of the total blade thickness. The biomimetic skeleton is bonded to the lightweight foam core material 5 of the blade body 1 with epoxy resin. High-strength titanium alloy (tensile strength ≥900MPa) or carbon fiber reinforced composite material (tensile strength ≥1500MPa) is selected as the biomimetic skeleton, as its strength is much higher than that of the foam core material of the blade body 1. It can serve as an internal support beam for the blade, bearing localized concentrated loads. The skeleton thickness is controlled at 0.5-1mm, accounting for 10%-15% of the total blade thickness, ensuring both the support rigidity of the skeleton and avoiding an increase in the overall weight of the blade due to excessive skeleton thickness (skeleton weight percentage ≤8%). The shear strength of the epoxy resin adhesive is ≥15MPa, allowing the skeleton and foam core material to form a "cooperative stress-bearing interface," preventing relative sliding between the skeleton and the body during rotation, which would lead to localized stress concentration. The support provided by the biomimetic skeleton increases the torsional strength of the blades by 30%. When a ship's propeller is impacted by underwater debris, the skeleton can disperse more than 70% of the impact load, preventing the blades from cracking. The skeleton material can be selected to suit different scenarios: titanium alloy skeletons are suitable for ships (resistant to seawater corrosion), and epoxy resin bonding ensures that the bond life between the skeleton and the main body is ≥5000 hours, with no risk of falling off, thus extending the overall service life of the blades. In this design, the biomimetic skeleton has 2 to 3 main veins 2 with a diameter of 1 to 2 mm and an elliptical cross-section with its major axis along the thickness of the leaf; secondary veins 3 with a diameter of 0.5 to 1 mm and a spacing of 1 / 5 to 1 / 4 of the leaf width; and branch veins 4 with a diameter of 0.3 to 0.5 mm, which conform to the curved shape of the leaf surface. Two to three main veins 2 (adapted to the blade width), with a diameter of 1-2 mm, can cover the main stress area of ​​the blade. The elliptical cross-section (major axis along the thickness direction) increases the bending section modulus by 25% compared to a circle, making it easier to resist the radial bending force when the blade rotates. The spacing of the secondary veins 3 is 1 / 5 to 1 / 4 of the blade width, which can evenly distribute the load transmitted by the main veins 2 to the blade edge, avoiding stress concentration in the main veins 2 and edge areas due to excessive spacing, or redundant weight of the skeleton due to insufficient spacing. The branch veins 4 conform to the curved shape of the blade, which can avoid the formation of "gaps" between the skeleton and the blade body 1, reducing internal airflow / water flow disturbance during rotation. At the same time, the triangular branch vein structure 4 (compared to the mesh) has higher stability and can disperse local shear stress. The elliptical structure of the main vein 2 increases the bending resistance of the blade root by 20%, solving the problem of "easy breakage" of the traditional circular main vein 2; the reasonable spacing of the secondary veins 3 increases the uniformity of stress distribution on the blade surface by 50%, with no local stress peaks (≤80% of the allowable stress of the material); the branch veins 4 that fit the curved surface reduce the airflow disturbance inside the blade by 15%, indirectly improving the propulsion efficiency by 3%-5%.

[0018] In this design, the blade tip of the blade body 1 adopts a rounded transition design, with the radius of curvature of the rounded transition being 0.3 to 0.5 times the blade tip width. The rounded transition at the blade tip (radius of curvature 0.3-0.5 times the blade tip width) avoids the tip vortices generated during high-speed rotation of traditional sharp blade tips (vortices increase fluid resistance and reduce propulsion efficiency), while also reducing air / water separation at the blade tip. Sharp blade tips are prone to stress concentration due to a sudden reduction in thickness (stress concentration factor ≥ 1.5), while the rounded transition reduces the stress concentration factor to below 1.1, preventing blade tip fracture due to fatigue loads (such as long-term rotation). Blade fluid resistance is reduced by 20%, and propulsion efficiency is increased by 15%-20%.

[0019] In this design, the surface reinforcement layer 6 has a thickness of 0.1~0.2mm, containing 30% alumina ceramic particles, and the bonding strength between the surface reinforcement layer 6 and the blade body 1 is ≥5MPa. The alumina ceramic particles (hardness HV800 or higher) are uniformly dispersed in polytetrafluoroethylene (PTFE), resisting friction from impurities (such as dust and sand) in the airflow / water flow, preventing direct wear on the blade body 1 material (carbon fiber). PTFE has a coefficient of friction ≤0.04, reducing the "viscous resistance" of the fluid to the blade surface, and its high chemical stability resists corrosion from seawater and humid air. The 0.1-0.2mm thickness balances wear resistance and weight increase (reinforcement layer weight percentage ≤3%), and the bonding strength ≥5MPa prevents the reinforcement layer from detaching during high-speed rotation (detachment leads to localized corrosion / accelerated wear). The blade surface wear resistance is improved by 50%.

[0020] In this design, the lightweight foam core material 5 of the blade body 1 is polyurethane foam with a density of 0.2 g / cm³. The parameters of the hot-pressing process are: temperature 120℃, pressure 0.5 MPa, and holding time 2 hours. The compressive strength of the polyurethane foam core material (density 0.2 g / cm³) is ≥0.5 MPa, which can support the shape of the carbon fiber layer. At the same time, its density is only 1 / 20 of that of metal, ensuring the lightweight of the blade. The 120℃ temperature allows the epoxy resin to fully cure (curing degree ≥95%), the 0.5 MPa pressure can eliminate air in the gaps between materials (porosity ≤1%), and the 2-hour holding time can ensure that the thick-walled area (blade root) is completely cured, avoiding strength reduction caused by internal uncured areas. The supporting effect of the foam core material improves the blade forming accuracy by 40%, with a surface error ≤0.1 mm, ensuring stable propulsion efficiency. Precise hot-pressing parameters ensure that the tensile strength fluctuation range of the blade is ≤5%, resulting in high performance consistency during mass production.

[0021] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-strength propeller blade structure based on bionics, comprising a blade body (1), characterized in that, The blade body (1) has a biomimetic skeleton embedded inside. The outer surface of the blade body (1) is coated with a surface strengthening layer (6). The blade body (1) has a gradually changing thickness design along the blade length direction. The thickness at the root of the blade is 1.5 to 2 times the average thickness of the blade. The thickness gradually decreases from the root to the tip of the blade. The biomimetic skeleton includes a mesh structure of main veins (2), secondary veins (3) and branch veins (4). The main veins (2) are distributed along the blade length direction. The secondary veins (3) are perpendicular to the main veins (2) and are provided in multiples along the blade width direction. The branch veins (4) are distributed between the mesh formed by the main veins (2) and the secondary veins (3) and are in a triangular structure. The surface strengthening layer (6) is a composite coating of polytetrafluoroethylene and alumina ceramic particles.

2. The high-strength propeller blade structure based on bionics according to claim 1, characterized in that, The blade body (1) is made of carbon fiber reinforced composite material. The interior of the blade body (1) is filled with lightweight foam core material (5). The carbon fiber arrangement is as follows: 70% of the carbon fiber is arranged along the blade length direction, and 30% of the carbon fiber is arranged alternately along the blade width direction. The carbon fibers are filled with a flexible epoxy resin matrix and are combined by hot pressing molding process.

3. The high-strength propeller blade structure based on bionics according to claim 1, characterized in that, The bionic skeleton is made of high-strength titanium alloy or carbon fiber reinforced composite material. The thickness of the bionic skeleton is 0.5~1mm, accounting for 10%~15% of the total thickness of the blade. The bionic skeleton is bonded and fixed to the lightweight foam core material (5) of the blade body (1) by epoxy resin.

4. The high-strength propeller blade structure based on bionics according to any one of claims 1-3, characterized in that, In the biomimetic skeleton, there are 2 to 3 main veins (2), the diameter of the main veins (2) is 1 to 2 mm, the cross-section is elliptical and the long axis is along the thickness direction of the leaf; the diameter of the secondary veins (3) is 0.5 to 1 mm, the spacing of the secondary veins (3) is 1 / 5 to 1 / 4 of the width of the leaf; the diameter of the branch veins (4) is 0.3 to 0.5 mm, and the branch veins (4) conform to the curved shape of the leaf surface.

5. The high-strength propeller blade structure based on bionics according to any one of claims 1-3, characterized in that, The blade body (1) adopts a rounded transition design at the blade tip, and the radius of curvature of the rounded arc is 0.3 to 0.5 times the width of the blade tip.

6. The high-strength propeller blade structure based on bionics according to any one of claims 1-3, characterized in that, The thickness of the surface strengthening layer (6) is 0.1~0.2mm, the content of alumina ceramic particles is 30%, and the bonding strength between the surface strengthening layer (6) and the blade body (1) is ≥5MPa.

7. The high-strength propeller blade structure based on bionics according to claim 2, characterized in that, The lightweight foam core material (5) of the blade body (1) is a polyurethane foam core material with a density of 0.2 g / cm³.

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