Lightweight integrated shell structure and design method suitable for high-speed unmanned aerial vehicle

Abstract

The application discloses a lightweight integrated shell structure and design method suitable for high-speed unmanned aerial vehicle, relates to the technical field of unmanned aerial vehicle structure design and modular assembly, and constructs a 400km / h high-speed unmanned aerial vehicle aerodynamic load-environment constraint-structure boundary coupling model; based on CFD simulation and formula optimization, low-resistance streamline shape design of the shell is completed; based on composite material mechanics and topological optimization, a skin-skeleton-sandwich integrated lightweight structure is designed; impact-resistant protective structure, anti-turbulence structure, heat dissipation and sealing structure, electromagnetic wave-transparent structure, and dynamic self-adaptive parameter optimization module and multi-objective performance weighted trade-off mechanism are integrated; modular assembly design and multi-dimensional performance verification are carried out, and process files of the shell structure capable of mass production are output. By using the above method, formula aerodynamic optimization, composite topological structure design, multi-functional integration and modular assembly are adopted, and the full performance of the shell under the 400km / h working condition is optimized.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) structural design and modular assembly technology, and in particular to a lightweight integrated shell structure and design method suitable for high-speed UAVs. Background Technology

[0002] With the advancement of low-altitude airspace opening policies and the iteration of drone technology, 400km / h-class high-speed drones have become the core direction of industry development. Their flight speed far exceeds that of traditional multi-rotor (≤60km / h) and conventional fixed-wing (≤150km / h) drones. As the core load-bearing component that directly interacts with high-speed airflow, the aerodynamic performance, structural strength, lightweight level, and protection capabilities of the shell directly determine the drone's flight efficiency, endurance, control stability, and service life.

[0003] Current traditional drone shell technology cannot adapt to high-speed conditions of 400km / h, and has five major technical defects: High-speed aerodynamic performance deteriorates, leading to a surge in drag and energy consumption; Traditional low-speed drones often employ simplified ellipsoidal, cylindrical, or angular shapes for their outer shells, failing to optimize aerodynamic characteristics before transonic speeds (Mach numbers 0.3-0.4). At high speeds, airflow separation, vortex generation, and the emergence of shock waves lead to an exponential increase in aerodynamic drag, significantly reducing the lift-to-drag ratio. Actual measurements show that traditional shells exhibit a drag coefficient ≥0.25 at 400 km / h, exceeding the drag of optimal shapes by over 100%, directly resulting in a 40-60% reduction in drone range and excessive load on the power system.

[0004] There is a serious imbalance between structural strength and lightweighting; existing shells either use metal materials such as aluminum alloys or stainless steel, with a surface density ≥ Excessive weight hinders high-speed flight; or a single-layer carbon fiber composite material without topological reinforcement is used, which, under aerodynamic loads of 400 km / h, gust impacts, and high-frequency vibrations, will have a bending deformation of ≥3 mm, making it prone to cracking, debonding, and local collapse, and thus cannot meet the stiffness requirements of high-speed structures.

[0005] Lacks resistance to turbulence and impact. High-frequency turbulence and vibration are easily generated at the gaps in the lower shell, servo interface, and skin splicing points during high-speed flight, leading to flight attitude drift. At the same time, the impact energy of foreign objects such as raindrops, dust, and birds increases by 3 to 5 times. Traditional shells do not have a dedicated impact-resistant layer, and the impact damage rate is ≥80%, which cannot guarantee the safety of high-speed flight.

[0006] Low functional integration and poor system adaptability; Traditional shells only have basic protective functions and do not integrate functions such as power cooling, electromagnetic wave transmission, waterproof sealing, vibration reduction and noise reduction. At high speeds, the engine compartment temperature exceeds the standard by ≥20℃, the sealing rating is ≤IP54, and the aircraft cannot fly in rainy or snowy weather. The signal attenuation of the payload equipment is ≥30%.

[0007] The assembly and maintenance efficiency is low and does not meet the requirements for mass production. Traditional shells are integrally molded without modular design, and the disassembly and assembly time is ≥30 minutes. Repairs require complete replacement, which is costly and time-consuming, and cannot meet the needs of mass production and rapid maintenance of high-speed drones.

[0008] Existing drone shell patents all focus on low-speed / medium-speed scenarios, and have not carried out integrated aerodynamic-structural-material-functional-assembly design for high-speed conditions of 400km / h. There is no complete formulaic design system and performance verification standard, which cannot solve the core technical pain points of the shell under high-speed flight. Summary of the Invention

[0009] The purpose of this invention is to provide a lightweight integrated shell structure and design method suitable for high-speed unmanned aerial vehicles (UAVs) to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, the present invention provides a design method for a lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles, comprising: S1. Construct a coupled model of aerodynamic load, environmental constraints, and structural boundary for a 400km / h high-speed UAV; S2. Based on CFD simulation and formula optimization, complete the low-resistance streamlined shape design of the shell; S6. Based on composite material mechanics and topology optimization, design an integrated lightweight structure of skin-skeleton-sandwich; S4 integrates an impact-resistant protection structure, an anti-turbulence structure, a heat dissipation and sealing structure, an electromagnetic wave-transmitting structure, as well as a dynamic adaptive parameter optimization module and a multi-objective performance weighted trade-off mechanism. S5, modular assembly design and multi-dimensional performance verification, outputting mass-producible shell structure and process documents.

[0011] Preferably, when the flight speed is 400 km / h, step S1 is as follows: S11. Calculate high-speed aerodynamic loads, including: Dynamic pressure calculation formula: ; Where: ρ = 1.225 kg / m 3 (Standard sea level air density) The flight speed corresponding to 400 km / h is V = 111.11 m / s; Formula for calculating aerodynamic drag: ; In the formula: S is the drag coefficient of the shell (optimization target ≤ 0.12), and S is the windward area of ​​the UAV (S = 0.28m in this invention). 2 ); Aerodynamic lift calculation formula: ; In the formula: The lift coefficient (optimization target ≥ 0.95); Formula for calculating fuselage torsional moment: ; Where: H is the height of the outer shell's center of mass (0.35m); S12, Calculate external environmental constraints; Formula for calculating the impact energy of a foreign object: ; In the formula: m is the mass of the bird / dust (0.5 kg for bird, 0.01 kg for dust). For the speed of birds and dust, =111.11m / s (The drone's high-speed movement is about 111m / s. Based on relative motion, the speed of the bird and the dust are ignored, that is, the bird and the dust are approaching at a speed of 111m / s).

[0012] The ambient temperature is -40℃ to 80℃, the power of the engine compartment heat dissipation power is P=600W, and the temperature of the inner wall of the outer shell is ≤70℃. S13. Define structural boundary constraints: total length 2.8m, maximum width 0.62m, maximum height 0.52m, installation tolerance ±0.1mm, sealing surface flatness ≤0.05mm, electromagnetic loss ≤0.5dB; S14. Perform pre-verification of structural boundary feasibility, including spatial boundary verification, interface verification, and functional verification.

[0013] Preferably, step S2 includes: S21. The outer shell is divided into three parts: upper shell, middle shell, and bottom shell. The shape is defined using the variable curvature streamlined formula. Formula for the ellipsoid of the upper shell: ; In the formula: the length-to-diameter ratio a / b = 1.8:1, a = 0.36m, b = 0.2m, to avoid the drag of the sharp-head shock wave.

[0014] Formula for a medium-shell variable curvature surface: ; In the formula: The curvature coefficient is determined through simulation iteration to ensure that the middle shell has no sharp edges or steps.

[0015] Bottom shell tapering formula: ; In the formula: θ is the angle of inclination of the bottom shell on one side, that is, the angle between the inclined plane of the shell sidewall that contracts inward and the axis. The width of the larger end of the tapered section (total lateral width of the shell inlet end). =0.62m, The width of the narrow end of the tapered section (the total transverse width of the outlet end after the shell has contracted). =0.18m, It is the total axial length of the tapered section (the distance from the large end to the small end along the central axis of the shell). =0.8m; S22. Aerodynamic performance optimization, including lift-to-drag ratio optimization, surface friction drag optimization, and airflow separation determination, where the lift-to-drag ratio optimization objective is: ; S23. CFD simulation verification was performed using the Reynolds-averaged Navier-Stokes equations.

[0016] Preferably, step S3 contains the following: Lightweight calculation, areal density calculation formula: ; In the formula: =0.96kg (skin). =0.18kg (skeleton) =0.12kg (lining) For the outer shell surface area, ; Structural strength calculation, bending strength formula: ; In the formula: The bending moment is the moment on the cross-section of a component caused by an external force. , The distance is the perpendicular distance from the outermost fiber of the cross section to the neutral axis, and the distance is the distance between the farthest points on the upper and lower edges of the cross section. , Let be the moment of inertia of the cross section about the neutral axis (the second moment of the cross section), which characterizes the geometric property of the cross section in resisting bending deformation. ; .

[0017] Shear strength formula: ; In the formula: The shear force is the resultant of transverse external forces perpendicular to the cross-section. , Static moment (area moment): the first moment of the local area from the shear position to the edge of the section about the neutral axis. , To calculate the cross-sectional width (cross-sectional thickness parallel to the neutral axis) at the location. .

[0018] Deformation constraint formula: ; In the formula: (Elastic modulus of composite materials) The total length of the cantilever beam (length from the fixed end to the free end) is L = 0.5m.

[0019] Topology optimization objective function: ; In the formula: Cellular volume fraction, after optimization =0.28.

[0020] Preferably, step S4 contains the following: The impact-resistant protective structure includes a 1.2mm thick skin laid on the leading edge of the upper shell and the windward side of the middle shell, with an energy absorption rate of [missing information]. It can completely absorb the impact energy of birds flying at a high speed of 400km / h; The anti-turbulence structure uses embedded sealing strips to eliminate gap eddy currents, with a turbulence suppression rate of ≥65%; combined with micro vibration damping ribs spaced 80mm apart, the high-speed vibration amplitude is ≤0.1mm; The heat dissipation structure adopts a biomimetic fish scale heat dissipation channel, with a ventilation volume of... The heat dissipation efficiency is improved by 42%, and the temperature of the engine compartment wall can be controlled at ≤70℃. The sealing structure uses an integrated silicone rubber seal, achieving an IP67 protection rating and sealing pressure. To achieve a leak-free seal; The load-bearing area of ​​the electromagnetic wave-transparent structure is covered with quartz fiber skin, and the electromagnetic wave transmittance is [missing information]. Electromagnetic loss ≤0.5dB, no signal attenuation of the task payload; Dynamic adaptive parameter optimization can automatically adjust aerodynamic, structural, and heat dissipation parameters according to flight altitude, speed, and ambient temperature to maintain stable performance under all operating conditions. A multi-objective performance weighted trade-off mechanism is used to construct a lightweight, low-drag, high-rigidity, and strong-protection weighted fitness function. The weight coefficients can be dynamically adjusted according to mission scenarios such as long-range cruise and reconnaissance patrol to achieve optimal overall performance.

[0021] Preferably, step S5 includes modular assembly design, shell failure constraint repair mechanism, multi-dimensional performance verification, iterative optimization and performance convergence verification, standardized output file and system adaptation; Modular assembly design, with assembly tolerances of the upper shell, middle shell, and bottom shell ≤ ±0.1mm, assembly time ≤ 8min, and connection strength. ; Shell failure constraint repair mechanism: includes structural deformation repair, assembly misalignment repair, and functional failure repair. After repair, all items are retested and verified, with a repair success rate of ≥95%. Multi-dimensional performance verification meets the following conditions: aerodynamic performance And the rise-to-drag ratio Structural performance: flexural strength ≥350MPa, deformation... Protective properties absorb energy. J. Sealing grade transmittance Lightweight surface density ; Iterative optimization and performance convergence verification: The maximum number of iterations is 200, and the inertia weight is linearly reduced from 0.95 to 0.35; convergence is determined when there is no improvement in the index for 30 consecutive iterations. This structure converges to the optimum in 156 iterations. Standardized output files and system adaptation: Outputs STEP / IGS 3D models, process documents, and performance reports; standardized interfaces, compatible with mainstream flight control, power, and mission payload systems, ready to use immediately after installation.

[0022] A lightweight integrated shell structure suitable for high-speed drones includes an upper shell, a middle shell connected to the upper shell, and a bottom shell connected to the middle shell by screws. The outer layers of the upper shell, middle shell, and bottom shell are all provided with skins. The skeleton is an aramid paper honeycomb structure, and the inner lining is polyimide foam. A locating pin is provided on the upper shell near the middle shell, and a buckle matching the locating pin is provided on the middle shell near the upper shell.

[0023] Preferably, an image transmission camera is installed on the top of the upper shell, and an AI image transmission module mounting cavity is provided inside.

[0024] Preferably, the middle shell has a battery mounting cavity inside, a flight controller and ESC mounting cavity is located below the battery mounting cavity, and multiple motor and propeller mounting cavities are arranged around the middle shell.

[0025] Preferably, an antenna mounting cavity is provided inside the bottom shell.

[0026] Therefore, the present invention, by adopting the above-mentioned lightweight integrated shell structure and design method suitable for high-speed UAVs, has the following beneficial effects: (1) For the first time, a quantitative calculation model of shell aerodynamic load, drag and lift-to-drag ratio under 400km / h working condition was established to solve the problem of no basis for high-speed shape optimization.

[0027] (2) The optimal stiffness-to-weight ratio is achieved through composite material mechanics formulas, with a surface density of only 1.12 kg / m³. 2 The structural strength is increased by 80%.

[0028] (3) It integrates an impact-resistant protection structure, an anti-turbulence structure, a heat dissipation and sealing structure, an electromagnetic wave transmission structure, as well as a dynamic adaptive parameter optimization module and a multi-objective performance weighting mechanism to adapt to high-speed full-scene applications.

[0029] (4) Disassembly and assembly time ≤ 8 min, batch production efficiency increased by 60%.

[0030] (5) Add three levels of safety margin, failure classification repair, and multi-objective weighted optimization to improve structural reliability and maintainability.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating an embodiment of the design method for a lightweight integrated shell structure applicable to high-speed unmanned aerial vehicles (UAVs) according to the present invention. Figure 2 This is an overall three-dimensional view of an embodiment of the lightweight integrated shell structure of the present invention applicable to high-speed unmanned aerial vehicles; Figure 3 This is a side view of an embodiment of the lightweight integrated shell structure of the present invention applicable to high-speed unmanned aerial vehicles; Figure 4 This is a cross-sectional view of an embodiment of the lightweight integrated shell structure of the present invention applicable to high-speed unmanned aerial vehicles; Figure label: 1. Top shell; 2. Middle shell; 3. Bottom shell; 4. Clip; 5. Image transmission camera; 6. AI image transmission module mounting cavity; 7. Battery mounting cavity; 8. Flight controller and ESC mounting cavity; 9. Motor and propeller mounting cavity; 10. Antenna mounting cavity. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] Please see Figure 1 This invention provides a design method for a lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles, including: Step 1: Construct a coupled model of aerodynamic loads, environmental constraints, and structural boundaries for a 400km / h high-speed UAV. This provides precise quantitative constraints for the shell design, and the aerodynamic loads, environmental impact loads, and structural installation boundaries under high-speed flight are determined through formula calculations, avoiding design blind spots.

[0036] High-speed aerodynamic load calculation: 400km / h corresponds to a flight speed of ,Mach number (The speed of sound at standard atmospheric pressure is c = 340 m / s).

[0037] 1.1 Formula for calculating dynamic pressure: ; In the formula: (Standard sea level air density) .

[0038] Substitute into the calculation: .

[0039] Formula for calculating aerodynamic drag: ; In the formula: The drag coefficient is the outer shell coefficient (optimization target ≤ 0.12). The windward area of ​​the drone (S=0.28m in this invention) 2 ).

[0040] Substitute into the calculation: .

[0041] Aerodynamic lift calculation formula: ; In the formula: The lift coefficient (optimization target ≥ 0.95).

[0042] Substitute into the calculation: .

[0043] Formula for calculating fuselage torsional moment: ; In the formula: H is the height of the outer shell's center of mass (0.35m).

[0044] Substitute into the calculation: .

[0045] 1.2 Calculation of external environmental constraints.

[0046] Formula for calculating the impact energy of a foreign object: ; In the formula: The mass of birds / dust (0.5 kg for birds, 0.01 kg for dust) is given. For the speed of birds and dust, =111.11m / s (The drone's high-speed movement is about 111m / s. Based on relative motion, the speed of the bird and the dust are ignored, that is, the bird and the dust are approaching at a speed of 111m / s). .

[0047] Impact energy of birds: ; Dust impact energy: .

[0048] Temperature constraints: Ambient temperature -40℃ to 80℃, engine compartment heat dissipation power The temperature of the inner wall of the outer shell is ≤70℃.

[0049] 1.3 Structural boundary constraints.

[0050] Define the enclosure mounting reference: total length L = 2.8m, maximum width Maximum height Installation tolerance ±0.1mm, sealing surface flatness ≤0.05mm, electromagnetic loss in the wave-transparent area ≤0.5dB.

[0051] 1.4 Pre-verification of structural boundary feasibility.

[0052] In the early stages of enclosure design, pre-verification of 3D boundaries, mounting interfaces, and functional compatibility is performed to avoid rework in later stages. Spatial boundary verification: Verify that the shell dimensions (2.8m × 0.62m × 0.52m) conform to the installation space of the drone fuselage and there is no interference; Interface verification: Verify that the tolerance of the flight controller, power, and load mounting interfaces is ±0.1mm, and the flatness of the sealing surface is ≤0.05mm; Functional verification: Pre-verification showed no conflicts or design flaws in the wave transmission, heat dissipation, and sealing functions; Verification results: Only after all standards are met can the detailed structural design proceed, ensuring that the design scheme is 100% feasible.

[0053] Step 2: Based on CFD simulation and formulaic optimization, complete the low-drag streamlined shape design of the outer shell. Through parametric modeling, formulaic optimization, and CFD simulation, determine the optimal shape of the outer shell to minimize aerodynamic drag at 400km / h.

[0054] 2.1 Parametric modeling of shell segments.

[0055] The outer shell is divided into three parts: upper shell 1, middle shell 2, and bottom shell 3. The shape is defined using a variable curvature streamlined formula. Formula for the ellipsoid of the upper shell 1: ; Where: length-to-diameter ratio , , To avoid the drag of sharp-headed shock waves.

[0056] Formula for the variable curvature surface of the middle shell: ; In the formula: The curvature coefficient is determined through simulation iteration to ensure that the middle shell has no sharp edges or steps.

[0057] Bottom case 3 tapering formula: ; In the formula: (Optimal taper angle) , , θ is the angle of inclination of the bottom shell, which is the angle between the inwardly contracting slope of the shell sidewall and the axis. The width of the larger end of the tapered section (total transverse width of the shell inlet end); The width of the narrow end of the tapered section (the total transverse width of the outlet end after the shell has contracted). It is the total axial length of the tapered section (the distance from the large end to the small end along the central axis of the shell).

[0058] 2.2 Aerodynamic performance optimization formula.

[0059] Formula for calculating the lift-to-drag ratio: ; Optimization goal: .

[0060] Formula for calculating surface friction resistance: ; In the formula: For wall shear stress, The outer shell surface area (3.8m²) 2 ); Surface roughness , .

[0061] Airflow separation determination formula: ; In the formula: (Aerodynamic viscosity) This ensures that the airflow remains unseparated.

[0062] 2.3 CFD simulation verification.

[0063] Simulations were performed using Reynolds-averaged Navier-Stokes equations: Continuity equation: ; Momentum equation: ; Simulation results: Shell drag coefficient Lift coefficient Rise-to-drag ratio It meets the requirements for high speed and low resistance at 400km / h.

[0064] Step 3: Based on composite material mechanics and topology optimization, design an integrated lightweight structure of skin-skeleton-sandwich layer. Through composite material lamination theory and topology optimization formulas, achieve a balance between lightweight shell and high stiffness. The core is a three-layer composite structure of skin, topological skeleton, and sandwich layer.

[0065] 3.1 Structural Stratification Parameter Design.

[0066] Outer skin: T700 carbon fiber / epoxy resin composite material, layup angle [0° / ±45° / 90°]s, thickness .

[0067] Intermediate topological framework: aramid paper honeycomb structure, pore size Wall thickness ,high .

[0068] Inner lining: polyimide foam, density ,thickness .

[0069] 3.2 Lightweight Calculation Formula.

[0070] Formula for calculating areal density: ; In the formula: (Skin) (skeleton), (lining), .

[0071] Substitute into the calculation: .

[0072] 3.3 Structural strength calculation formula.

[0073] Bending strength formula: ; In the formula: , , . The bending moment on the cross-section is the moment by which an external force causes a member to bend. The distance is the perpendicular distance from the outermost fiber of the cross section to the neutral axis, and the distance is the distance between the farthest points of the upper and lower edges of the cross section. Let be the moment of inertia of the cross section about the neutral axis (the second moment of the cross section), which characterizes the geometric property of the cross section in resisting bending deformation.

[0074] Substitute into the calculation: It meets the requirement of ≥350MPa.

[0075] Shear strength formula: ; In the formula: , , . Shear force is the resultant of transverse external forces perpendicular to the cross section. Static moment (area moment): the first moment of the local area from the shear position to the edge of the section about the neutral axis; To calculate the cross-sectional width (cross-sectional thickness parallel to the neutral axis) at the location.

[0076] Substitute into the calculation: It meets the requirement of ≥20MPa.

[0077] Deformation constraint formula: ; In the formula: (Elastic modulus of composite materials) This is the total length of the cantilever beam (length from the fixed end to the free end). .

[0078] Substitute into the calculation: It meets the requirement of ≤0.5mm.

[0079] 3.4 Topology optimization objective function.

[0080] ; In the formula: Cellular volume fraction, after optimization =0.28.

[0081] 3.5 Structural safety margin and redundancy design.

[0082] Based on extreme operating conditions such as high-speed aerodynamic loads of 400 km / h, external object impacts, and temperature deformation, a three-level safety margin is added to the outer shell of this invention to avoid design boundary failure: Aerodynamic safety margin: A 20% safety factor is reserved for the calculated values ​​of dynamic pressure, drag, and lift. The actual design load = theoretical calculation value × 1.2 to ensure that the structure does not fail under sudden aerodynamic loads such as gusts and sudden winds.

[0083] Structural strength margin: 15% redundancy is reserved for the design values ​​of bending strength, shear strength, and deformation. Actual strength index = theoretical threshold × 1.15, to cope with the molding tolerance of composite materials and long-term vibration fatigue loss.

[0084] Sealing / heat dissipation safety margin: A 25% margin is reserved for sealing pressure and heat dissipation ventilation volume, and the upper limit of engine compartment temperature control is reduced by 5°C compared with the design value, which is suitable for high temperature and high humidity extreme environments.

[0085] Safety margin verification: All structural components were subjected to extreme overload tests, with a load of 1.5 times the design load applied. The shell showed no cracking, no delamination, and no excessive deformation, meeting the safety redundancy requirements for high-speed flight.

[0086] Step 4: Integrate a multi-functional protective structure that is shock-resistant, turbulence-resistant, heat-dissipating, sealing, and wave-transparent. Through a standardized functional design, it integrates five core protective functions to meet the needs of all high-speed flight scenarios.

[0087] 4.1 Impact-resistant protective structure.

[0088] Impact-resistant layer: Aramid fiber / polyethylene composite layer, thickness t=1.2mm, laid on the leading edge of the upper shell and the windward side of the middle shell.

[0089] Energy absorption formula: ; In the formula: (Energy absorption rate) , It can completely absorb the impact energy of birds.

[0090] 4.2 Anti-turbulence structure.

[0091] Embedded sealing strips: eliminate gap eddy currents; turbulence suppression rate formula: ; In the formula: , , .

[0092] Miniature vibration damping ribs: spacing 80mm, high-speed vibration amplitude ≤0.1mm.

[0093] 4.3 Heat dissipation and sealing structure.

[0094] Bionic fish scale heat dissipation channel: Ventilation volume formula: ; In the formula: , , , Heat dissipation efficiency is improved by 42%.

[0095] Silicone rubber integrated seal: Protection rating IP67, sealing pressure formula: In the formula: , , To ensure no leakage.

[0096] 4.4 Electromagnetic wave-transmitting structure.

[0097] The load-bearing area uses quartz fiber skin, and the transmittance formula is: In the formula: , , The signal is not attenuated.

[0098] 4.5 Dynamic adaptive parameter optimization.

[0099] The shell design parameters support dynamic adaptive adjustment to accommodate different flight altitudes, speeds, and ambient temperatures, making it suitable for high-speed flight in all scenarios. Adaptive aerodynamic parameters: The outer shell angle of attack and the bottom shell taper angle are automatically adjusted according to the flight altitude (changes in air density) to ensure that the lift-to-drag ratio is always ≥8.5; Adaptive structural parameters: The topological frame support strength is adaptively adjusted according to the flight speed, balancing high-speed rigidity and low-speed lightweight. Adaptive heat dissipation parameters: When the engine compartment temperature exceeds the threshold, the ventilation volume of the biomimetic fish scale heat dissipation channel automatically increases, and the temperature is controlled to ≤70℃.

[0100] 4.6 Multi-objective performance weighted trade-off mechanism.

[0101] A multi-objective weighted fitness function is constructed to achieve optimal overall performance, encompassing lightweight, low drag, high stiffness, and strong protection of the outer shell. Weighted function formula: ; In the formula: Weighting coefficients ( (This can be dynamically adjusted according to the task scenario); Scene weight configuration: Remote cruise: (Lightweight) = 0.35 (Low resistance) = 0.4; Reconnaissance Patrol: (High stiffness) = 0.3, (Strong protection) = 0.35; Optimization goal: To avoid overall performance imbalance caused by a single optimal performance outcome through weighted trade-offs.

[0102] Step 5: Modular assembly design + multi-dimensional performance verification, outputting a mass-producible shell structure. This enables rapid shell assembly and full performance verification, meeting the needs of mass production and engineering applications.

[0103] 5.1 Modular assembly design.

[0104] Segmented structure: upper shell 1, middle shell 2 and bottom shell 3. Upper shell 1 and middle shell 2 are connected to positioning pins by quick-release buckles 4.

[0105] Assembly tolerance formula: ; constraint: ≤±0.1mm, assembly time ≤8min.

[0106] Connection strength formula: ; In the formula: 4 clips each. =150N / piece =1800N, which meets the requirements for high-speed loads.

[0107] 5.2. Outer shell failure constraint repair mechanism.

[0108] For structural deformation, assembly misalignment, and functional failure issues that occur during the production, assembly, and use of the casing, instead of direct scrapping, a tiered repair process is implemented: Structural deformation repair: When the skin bending deformation exceeds the tolerance, hot pressing is performed along the composite material layup direction to correct it, or local topological reinforcing ribs are added to the deformation area to restore the stiffness index.

[0109] Assembly misalignment repair: When the tolerance of modular connection exceeds the tolerance, fine adjustment of positioning pins and compensation of sealing strips are used to ensure that the assembly tolerance is ≤±0.1mm and the flatness of the sealing surface meets the standard.

[0110] Functional failure repair: When heat dissipation / wave transmission / sealing performance is substandard, the heat dissipation channel, wave transmission skin or seal can be replaced locally without replacing the entire shell, thus reducing maintenance costs.

[0111] Post-repair verification: The repaired shell undergoes aerodynamic, mechanical, and protective tests again. It can only be used after all tests are passed. The repair success rate is ≥95%.

[0112] 5.3 Multi-dimensional performance verification formula.

[0113] Aerodynamic performance assessment: ; Structural performance assessment: ; Protection performance assessment: ; Lightweight determination: ; 5.4 Iterative optimization and performance convergence verification.

[0114] Optimization iteration settings: Maximum number of iterations for shell aerodynamics, structure, and function optimization = 200 generations, with inertia weight decreasing linearly from 0.95 to 0.35; Convergence criteria: If the shell drag coefficient, areal density, and strength indicators do not improve for 30 consecutive generations, it is considered to have reached the global optimum. Convergence Result: Performance converged after 156 iterations, with the final drag coefficient... =0.108, surface density 1.12 kg / m³ 2 This achieves the optimal design solution.

[0115] 5.5 Standardized output files and system compatibility.

[0116] After the outer shell of this invention is designed and manufactured, standardized engineering documents are output, which can be directly connected to the mass production line of UAVs and the flight control / payload system: 3D model files: STEP and IGS formats, compatible with industrial design software such as UG, SolidWorks, and CATIA; Process documents: Composite material layup process card, autoclave molding parameter table, modular assembly operation instructions; Performance reports: aerodynamic CFD simulation report, mechanical test report, protection performance test report, wind tunnel flight verification report; System compatibility: The shell interface is standardized and compatible with mainstream high-speed UAV flight controllers (Pixhawk Pro), power systems (turbojet / hybrid), and mission payloads (electro-optical / radar), allowing for immediate use.

[0117] Example This embodiment takes a 400km / h high-speed long-range reconnaissance compound wing UAV as the application object, and elaborates on the entire process of design, manufacturing and verification of the shell structure. All parameters are verified by formula calculation and actual measurement.

[0118] 1. Complete the construction of the coupling model to implement the solution in step 1.

[0119] Flight parameters: , , ; Aerodynamic loads: , , ; Environmental constraints: bird impact Power cooling ; Structural boundaries: L=2.8m, W=0.62m, H=0.52m, installation tolerance ±0.1mm.

[0120] 2. Carry out low-resistance shape optimization design and implement the solution in step 2.

[0121] Upper shell 1: ellipsoidal, a=0.36m, b=0.2m, major-to-diameter ratio 1.8:1; Shell 2: Variable curvature surface, without sharp edges or steps; Bottom shell 3: tapering angle approximately 28.81°, tail width 0.18m; CFD simulation: , K=9.17 There is no separation of airflow.

[0122] 3. Complete the manufacturing of the lightweight composite structure and implement the solution in step 3.

[0123] Material selection: Skin: T700 carbon fiber composite material, layup [0° / ±45° / 90°]s, 0.8mm; Framework: Aramid honeycomb, pore size 5mm, 10mm; Liner: Polyimide foam, 2mm.

[0124] Performance calculation: areal density: ; Bending strength: ; Deformation variables: ; Shear strength: .

[0125] Molding process: autoclave molding, temperature 180℃, pressure 0.6MPa, heat preservation for 2 hours.

[0126] 4. Complete the multi-functional protection integrated design and implement the technical solution in step 4.

[0127] Impact resistance: The upper shell has a 1.2mm aramid layer with an energy absorption rate of 92%, and passed the 3086.4J impact test without damage; Anti-turbulence: Sealing strip + vibration damping ribs, vibration suppression rate of 65%, no attitude drift at high speed; Heat dissipation and sealing: Fish-scale channel ventilation volume 0.086m 3 / s, IP67 sealing, engine compartment temperature ≤68℃; Wave transmission: The quartz skin has a wave transmission rate of 95.6%, and there is no signal attenuation of the reconnaissance equipment.

[0128] 5. Carry out modular assembly implementation and performance verification to complete the application of step 5 of the overall solution.

[0129] Assembly: Three-module quick-release buckle 4-connection, assembly time 7.5min, tolerance ±0.08mm; Wind tunnel test: at 400km / h =0.108, K=9.17, meets the standard; Mechanical tests: Bending, compression, and torsional strengths all meet design requirements; Protection tests: Impact, sealing, heat dissipation, and wave transmission performance all passed 100%.

[0130] like Figures 2-4 It also provides a lightweight integrated shell structure suitable for high-speed drones, including an upper shell 1, a middle shell 2 connected to the upper shell 1, and a bottom shell 3 connected to the middle shell 2 by screws. The outer layers of the upper shell 1, the middle shell 2, and the bottom shell 3 are all provided with skins, the skeleton is an aramid paper honeycomb structure, and the inner lining is a polyimide foam.

[0131] A positioning pin is provided on the upper shell 1 near the middle shell 2, and a buckle 4 matching the positioning pin is provided on the middle shell 2 near the upper shell 1.

[0132] The top of the upper shell 1 is equipped with an image transmission camera 5, and the interior is equipped with an AI image transmission module mounting cavity 6.

[0133] The middle shell 2 has a battery mounting cavity 7 inside, and a flight controller and ESC mounting cavity 8 is located below the battery mounting cavity 7. Multiple motor and propeller mounting cavities 9 are arranged around the middle shell 2. The bottom shell has an antenna mounting cavity 10 inside.

[0134] Therefore, the present invention adopts the above-mentioned lightweight integrated shell structure and design method suitable for high-speed UAVs, which can simultaneously achieve a high-speed UAV shell structure and a complete process design and manufacturing method with low aerodynamic drag, high structural rigidity, lightweight, resistance to aerodynamic disturbance, resistance to foreign object impact, efficient heat dissipation, high sealing level and quick assembly and disassembly. It is especially suitable for 400km / h class high-speed fixed-wing / compound-wing UAVs, covering high-end UAV application scenarios with extreme requirements for flight speed, endurance, structural reliability, environmental adaptability and maintenance efficiency, such as high-speed reconnaissance, long-distance logistics delivery, border patrol, emergency rescue, and meteorological detection.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A design method for a lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles, characterized in that, include: S1. Construct a coupled model of aerodynamic load, environmental constraints, and structural boundary for a 400km / h high-speed UAV; S2. Based on CFD simulation and formulaic optimization, complete the low-resistance streamlined shape design of the outer shell; including: S21. The outer shell is divided into three parts: upper shell, middle shell, and bottom shell. The shape is defined using the variable curvature streamlined formula. Formula for the ellipsoid of the upper shell: ； In the formula, the length-to-diameter ratio a / b = 1.8:1, a = 0.36m, and b = 0.2m; Formula for a medium-shell variable curvature surface: ； In the formula, The curvature coefficient; Bottom shell tapering formula: ； In the formula, θ is the angle of inclination of the bottom shell on one side. The width of the larger end of the tapered section. =0.62m, The width of the smaller end of the tapered section. =0.18m, This is the total axial length of the tapered section. =0.8m; S22. Aerodynamic performance optimization, including lift-to-drag ratio optimization, surface friction drag optimization, and airflow separation determination, where the lift-to-drag ratio optimization objective is: ; S23. CFD simulation verification was performed using the Reynolds-averaged Navier-Stokes equations. S3. Based on composite material mechanics and topology optimization, design an integrated lightweight structure of skin-skeleton-sandwich layer; S4 integrates an impact-resistant protection structure, an anti-turbulence structure, a heat dissipation and sealing structure, an electromagnetic wave-transmitting structure, as well as a dynamic adaptive parameter optimization module and a multi-objective performance weighted trade-off mechanism. S5, modular assembly design and multi-dimensional performance verification, outputting mass-producible shell structure and process documents.

2. The design method for a lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles according to claim 1, characterized in that, At a flight speed of 400 km / h, step S1 is as follows: S11. Calculate high-speed aerodynamic loads, including: Dynamic pressure calculation formula: ； In the formula, The air density at standard sea level, , The flight speed corresponding to 400 km / h ; Formula for calculating aerodynamic drag: ； In the formula, S is the drag coefficient of the shell, and S is the frontal area of ​​the UAV. Aerodynamic lift calculation formula: ； In the formula, The lift coefficient; Formula for calculating fuselage torsional moment: ； In the formula, H is the height of the outer shell's center of mass; S12, Calculate external environmental constraints; Formula for calculating the impact energy of a foreign object: ； In the formula, m is the mass of the bird or dust. For the speed of birds and dust, ; The ambient temperature is -40℃ to 80℃, the power of the engine compartment heat dissipation power is P=600W, and the temperature of the inner wall of the outer shell is ≤70℃. S13. Define structural boundary constraints: total length 2.8m, maximum width 0.62m, maximum height 0.52m, installation tolerance ±0.1mm, sealing surface flatness ≤0.05mm, electromagnetic loss ≤0.5dB; S14. Perform pre-verification of structural boundary feasibility, including spatial boundary verification, interface verification, and functional verification.

3. The design method for a lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles according to claim 1, characterized in that, Step S3 is as follows: Lightweight calculation, areal density calculation formula: ； In the formula, =0.96kg, =0.18kg, =0.12kg, For the outer shell surface area, ; , and These are the weights of the skin, frame, and liner, respectively. Structural strength calculation, bending strength formula: ； In the formula, The bending moment on the cross section, , The distance is the perpendicular distance from the outermost fiber of the cross section to the neutral axis, and the distance is the distance between the farthest points on the upper and lower edges of the cross section. , Let be the moment of inertia of the cross section about the neutral axis. ; Shear strength formula: ； In the formula, For cross-sectional shear force, , For static moment, , To calculate the cross-sectional width at the location, ; Deformation constraint formula: ； In the formula, The elastic modulus of the composite material. L is the total length of the cantilever beam, L=0.5m; Topology optimization objective function: ； In the formula, Cellular volume fraction, after optimization =0.

28.

4. The design method for a lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles according to claim 3, characterized in that, Step S4 is as follows: The impact-resistant protective structure includes a 1.2mm thick skin laid on the leading edge of the upper shell and the windward side of the middle shell, with an energy absorption rate of [missing information]. ; The anti-turbulence structure uses embedded sealing strips to eliminate gap eddy currents, with a turbulence suppression rate of ≥65%; combined with micro vibration damping ribs spaced 80mm apart, the high-speed vibration amplitude is ≤0.1mm; The heat dissipation structure adopts a biomimetic fish scale heat dissipation channel, with a ventilation volume of... The temperature of the engine compartment interior wall is controlled at ≤70℃; The sealing structure uses an integrated silicone rubber seal, achieving an IP67 protection rating and sealing pressure. ; The load-bearing area of ​​the electromagnetic wave-transparent structure is covered with quartz fiber skin, and the electromagnetic wave transmittance is [missing information]. Electromagnetic loss ≤0.5dB; Dynamic adaptive parameter optimization automatically adjusts aerodynamic, structural, and heat dissipation parameters according to flight altitude, speed, and ambient temperature to maintain stable performance under all operating conditions. A multi-objective performance weighted trade-off mechanism is implemented, constructing a lightweight, low-drag, high-rigidity, and strong-protection weighted fitness function. The weight coefficients are dynamically adjusted according to the task scenario to achieve optimal overall performance.

5. The design method for a lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles according to claim 4, characterized in that: Step S5 includes modular assembly design, shell failure constraint repair mechanism, multi-dimensional performance verification, iterative optimization and performance convergence verification, standardized output files and system adaptation; Modular assembly design, assembly tolerance of upper shell, middle shell and bottom shell ≤ ±0.1mm, assembly time ≤ 8min, connection strength ; The shell failure constraint repair mechanism includes structural deformation repair, assembly misalignment repair, and functional failure repair. After repair, all items are retested and verified, with a repair success rate of ≥95%. Multi-dimensional performance verification meets the following conditions: aerodynamic performance And the rise-to-drag ratio Structural performance: flexural strength ≥350MPa, deformation... Protective properties absorb energy. J. Sealing grade transmittance Lightweight surface density ; Iterative optimization and performance convergence verification: The maximum number of iterations is 200, and the inertia weight is linearly reduced from 0.95 to 0.35; convergence is determined if there is no improvement in the index for 30 consecutive iterations. Standardized output files and system adaptation: Output STEP / IGS 3D models, process documents, and performance reports; standardized interfaces, compatible with mainstream flight control, power, and mission payload systems.

6. A lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles (UAVs), employing the design method for a lightweight integrated shell structure suitable for high-speed UAVs as described in any one of claims 1-5, characterized in that: It includes an upper shell, a middle shell connected to the upper shell, and a bottom shell connected to the middle shell by screws. The outer layers of the upper shell, middle shell, and bottom shell are all provided with skins. The skeleton is an aramid paper honeycomb structure, and the inner lining is polyimide foam. A locating pin is provided on the upper shell near the middle shell, and a buckle matching the locating pin is provided on the middle shell near the upper shell.

7. The lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles according to claim 6, characterized in that: The top of the upper shell is equipped with an image transmission camera, and the interior has an AI image transmission module mounting cavity.

8. The lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles according to claim 6, characterized in that: The middle shell has a battery mounting cavity, below which is a flight controller and ESC mounting cavity, and around the middle shell are multiple motor and propeller mounting cavities.

9. The lightweight integrated shell structure suitable for high-speed unmanned aerial vehicles according to claim 6, characterized in that: An antenna mounting cavity is provided inside the bottom shell.

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