Equivalent thin layer unit simulation method and system of eVTOL aircraft threaded connection structure
By using the equivalent thin-layer element simulation method, the problem of low simulation accuracy of threaded connections in eVTOL aircraft was solved, achieving high-precision nonlinear response simulation, improving aircraft performance and safety, shortening the R&D cycle and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI LAIWEI NEW AVIATION TECHNOLOGY CO LTD
- Filing Date
- 2026-01-19
- Publication Date
- 2026-05-01
AI Technical Summary
Existing technologies for numerical simulation of threaded connections in eVTOL aircraft suffer from low simulation accuracy and high dynamic response error. They are unable to accurately simulate the nonlinear behavior of threads under various working conditions, such as gap closure and preload relaxation under impact loads, which restricts aircraft lightweighting and performance improvement.
The equivalent thin-layer element simulation method is adopted. By obtaining the geometric and material parameters of the threaded connection, calculating the axial and radial stiffness, establishing thin-layer elements and assigning them moduli, and combining preload and dynamic load, a simulation model is constructed to simulate the nonlinear response of the threaded connection under dynamic load.
It improves simulation accuracy, reduces dynamic response error, accurately simulates gap changes and stiffness nonlinearity of threaded connections, reduces the number of physical prototype iterations, shortens the R&D cycle, reduces R&D costs, and enhances equipment operational safety.
Smart Images
Figure CN121959751A_ABST
Abstract
Description
A simulation method and system for equivalent thin-layer elements of threaded connection structures in eVTOL aircraft Technical Field
[0001] This application relates to the field of threaded connection simulation, specifically to an equivalent thin-layer element simulation method and system for the threaded connection structure of an eVTOL aircraft. Background Technology
[0002] As a new type of aviation equipment, eVTOL (Electric Vertical Take-Off and Landing) aircraft need to meet the strength, rigidity and dynamic response requirements of various operating conditions such as vertical take-off and landing, hovering, and high-speed cruise. Threaded connection is a key connection form of the core load-bearing structure of VTOL aircraft and is widely used in key parts such as the connection between the fuselage and the wing, the connection between the power module and the fuselage flange, the connection between the landing gear and the fuselage support, and the connection between the battery compartment and the fuselage frame.
[0003] In the field of numerical simulation analysis of threaded connections in eVTOL aircraft, the industry generally adopts a simplified processing method consistent with the simulation of threaded connections in traditional mechanical structures. This method is mainly divided into two categories: rigid connection simplification method: the two components of the threaded connection (such as the fuselage frame and the wing joint) are regarded as a completely rigid connection, which is achieved through "node fusion" or "binding constraint" in the finite element model. The geometric features, fit clearance and mechanical properties of the thread itself are ignored, and the connection area is directly defined as an integrated structure without relative deformation.
[0004] Simple solid contact method: only simplifies the partial contact interface of the simulated thread, adopts "face-to-face contact" or "point-to-face contact" settings, only considers the normal contact pressure and the tangential friction of the foundation, and does not involve the stiffness nonlinearity of the threaded connection, the influence of preload, and the impact transmission characteristics between multiple threads.
[0005] The above methods suffer from low simulation accuracy, high dynamic response error, and inability to accurately simulate the nonlinear behavior of threads under various working conditions, such as gap closure and preload relaxation under impact loads, which restricts the lightweighting and performance improvement of eVTOL aircraft. Summary of the Invention
[0006] In view of the above problems, this application provides an equivalent thin-layer element simulation method and system for the threaded connection structure of eVTOL aircraft, which overcomes or at least partially solves the problems of low simulation accuracy, high dynamic response error, and inability to accurately simulate the nonlinear behavior of threads under multiple working conditions in the above-mentioned prior art simulation methods.
[0007] A first aspect of this application provides a simulation method for equivalent thin-layer elements of a threaded connection structure in an eVTOL aircraft, comprising: acquiring the geometric parameters, material parameters, and structural parameters of the threaded connection; calculating, based on the geometric and material parameters, the axial stiffness, radial stiffness, axial stiffness, and radial stiffness of the internal thread per unit length, and the external thread per unit length, respectively; calculating, based on the axial and radial stiffness of the internal thread per unit length, the axial and radial stiffness of the external thread per unit length, and the structural parameters, calculating, respectively, the total axial stiffness and total radial stiffness of the threaded connection; determining, based on the total axial and radial stiffness, the axial modulus and radial modulus of the equivalent thin-layer material; establishing a thin-layer element at the threaded connection interface in the finite element model and assigning it axial and radial moduli; connecting the thin-layer element to the two components of the threaded connection through binding constraints, and applying preload and dynamic loads to complete the construction of the simulation model.
[0008] In this embodiment, calculations are performed based on the geometric and material parameters of the threaded connection. The stiffness of the threaded connection per unit length in both the axial and radial directions is established in the simulation, providing fundamental parameters for simulating stiffness nonlinearity. By introducing structural parameters, the stiffness per unit length is integrated into the total axial and radial stiffness of the threaded connection. The calculated total axial and radial stiffness of the threaded connection are then mapped to the axial and radial moduli of the thin-layer element. This allows the thin-layer element to realistically reflect the differences in the mechanical response of the threaded connection in different directions during simulation, thereby simulating gap changes and stiffness nonlinearity under dynamic loads, improving simulation accuracy, and reducing dynamic response errors.
[0009] Furthermore, the thin-layer element setting replaces the traditional rigid connection or simple contact model. It possesses independent material properties and can undergo elastic deformation in the simulation, thereby simulating the minute displacement, gap closing and opening behavior of the threaded connection under dynamic loads. Explicitly applying preload in the model can simulate the prestress distribution of the threaded connection in its initial state; the application of dynamic loads directly corresponds to actual working conditions such as vertical take-off and landing impacts and gusts of wind, making the simulation model exhibit a time-varying nonlinear response.
[0010] In one alternative approach, calculating the total axial stiffness of the threaded connection includes: determining an axial load distribution coefficient based on the axial stiffness of the internal thread per unit length, the axial stiffness of the external thread per unit length, and structural parameters; determining the axial thread stiffness of the internal thread based on the axial load distribution coefficient and the axial stiffness of the internal thread per unit length; determining the axial thread stiffness of the external thread based on the axial load distribution coefficient and the axial stiffness of the external thread per unit length; and determining the total axial stiffness of the threaded connection based on the axial thread stiffness of both the internal and external threads.
[0011] In one alternative approach, calculating the total radial stiffness of the threaded connection includes: determining a radial load distribution coefficient based on the radial stiffness of the internal thread per unit length, the radial stiffness of the external thread per unit length, and structural parameters; determining the radial thread stiffness of the internal thread based on the radial load distribution coefficient and the radial stiffness of the internal thread per unit length; determining the radial thread stiffness of the external thread based on the radial load distribution coefficient and the radial stiffness of the external thread per unit length; and determining the total radial stiffness of the threaded connection based on the radial thread stiffness of both the internal and external threads.
[0012] In one alternative approach, the geometric parameters include: pitch, thread engagement length, flank angle, bolt diameter, nut outer diameter, and helix angle.
[0013] In one alternative approach, the material parameters include: the elastic modulus of the internal thread material, the Poisson's ratio of the internal thread material, the elastic modulus of the external thread material, and the Poisson's ratio of the external thread material.
[0014] In one alternative approach, the structural parameters include: the cross-sectional area of the internal thread and the cross-sectional area of the external thread.
[0015] In one alternative approach, the length of the thin-layer unit is the same as the thread engagement length, the width of the thin-layer unit is the same as the circumference length of the threaded connection, and the thickness of the thin-layer unit is 0.3 times the thread pitch.
[0016] In one alternative approach, determining the axial modulus of the equivalent thin-layer material includes: calculating the axial modulus based on the total axial stiffness, the thickness of the thin-layer element, and the contact area of the thin-layer element; wherein the contact area of the thin-layer element is the product of the length and width of the thin-layer element.
[0017] In one alternative approach, determining the radial modulus of the equivalent thin-layer material includes: calculating the radial modulus based on the total radial stiffness, the thickness of the thin-layer element, and the contact area of the thin-layer element; wherein the contact area of the thin-layer element is the product of the length and width of the thin-layer element.
[0018] Another aspect of this application provides an equivalent thin-layer element simulation system for an eVTOL aircraft threaded connection structure, comprising: a parameter acquisition module for acquiring geometric parameters, material parameters, and structural parameters of the threaded connection; a first stiffness calculation module for calculating, based on the geometric parameters and material parameters, the axial stiffness of the internal thread per unit length, the radial stiffness of the internal thread per unit length, the axial stiffness of the external thread per unit length, and the radial stiffness of the external thread per unit length; and a second stiffness calculation module for calculating, based on the geometric parameters and material parameters, the axial stiffness of the internal thread per unit length, the radial stiffness of the internal thread per unit length, and the radial stiffness of the external thread per unit length. The system employs several methods: a axial stiffness and a radial stiffness per unit length of the external thread, along with structural parameters, to calculate the total axial and radial stiffness of the threaded connection; a modulus calculation module to determine the axial and radial moduli of the equivalent thin-layer material based on the total axial and radial stiffness; a first modeling module to create thin-layer elements at the threaded connection interface in the finite element model and assign them axial and radial moduli; and a second modeling module to connect the thin-layer elements to the two threaded components through binding constraints and apply preload and dynamic loads to complete the simulation model construction.
[0019] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 is a flowchart of an equivalent thin-layer unit simulation method for an eVTOL aircraft threaded connection structure provided in some embodiments of this application.
[0022] Figure 2 is a schematic diagram of the principle of the thin-layer unit constitutive model provided in some embodiments of this application.
[0023] Figure 3 is a schematic diagram of the equivalent thin-layer material of the threaded connection structure provided in some embodiments of this application.
[0024] Figure 4 is a schematic diagram of the computing interface provided in some embodiments of this application.
[0025] Figure 5 is a schematic diagram of the equivalent thin-layer unit simulation system of the eVTOL aircraft threaded connection structure provided in some embodiments of this application. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
[0028] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and drawings of this application are intended to cover without excluding other meanings. The words "a" or "an" do not exclude the presence of multiples.
[0029] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0030] Furthermore, the terms "first," "second," etc., in the specification and claims of this application or in the aforementioned drawings are used to distinguish different objects rather than to describe a specific order, and may explicitly or implicitly include one or more of the features.
[0031] In the description of this application, unless otherwise stated, "multiple" means two or more (including two), and similarly, "multiple groups" means two or more (including two groups).
[0032] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, "connection" or "linkage" in mechanical structures can refer to a physical connection, such as a fixed connection, for example, a connection fixed by fasteners, such as a connection fixed by screws, bolts, or other fasteners; a physical connection can also be a detachable connection, such as a snap-fit or interlocking connection; a physical connection can also be an integral connection, such as a connection formed by welding, bonding, or integral molding. In circuit structures, "connection" or "linkage" can refer not only to a physical connection but also to an electrical connection or a signal connection. For example, it can be a direct connection, i.e., a physical connection, or an indirect connection through at least one intermediate component, as long as the circuit is connected; it can also refer to the internal connection of two components. Signal connection can refer not only to signal connection through a circuit but also to signal connection through a media, such as radio waves. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0033] Figure 1 is a flowchart of an equivalent thin-layer element simulation method for an eVTOL aircraft threaded connection structure provided by some embodiments of this application. As shown in Figure 1, the equivalent thin-layer element simulation method for an eVTOL aircraft threaded connection structure provided by this application includes the following steps 101 to 106: Step 101: Obtain the geometric parameters, material parameters and structural parameters of the threaded connection.
[0034] Geometric parameters may include: pitch Thread engagement length Tooth lateral angle Bolt diameter Nut outer diameter and rise angle The geometric parameters mentioned above can be seen in Figure 4.
[0035] Material parameters may include: the elastic modulus of the internal thread material. Poisson's ratio of internal thread material , elastic modulus of external thread material Poisson's ratio of the external thread material .
[0036] Structural parameters may include: cross-sectional area of the internal thread. and the cross-sectional area of the external thread Cross-sectional area of internal thread Right now Cross-sectional area of external thread Right now .
[0037] Step 102: Based on the geometric and material parameters, calculate the axial stiffness of the internal thread per unit length, the radial stiffness of the internal thread per unit length, the axial stiffness of the external thread per unit length, and the radial stiffness of the external thread per unit length.
[0038] Step 103: Based on the axial stiffness of the internal thread per unit length, the radial stiffness of the internal thread per unit length, the axial stiffness of the external thread per unit length, the radial stiffness of the external thread per unit length, and the structural parameters, calculate the total axial stiffness and total radial stiffness of the threaded connection respectively.
[0039] Step 104: Based on the total axial stiffness and total radial stiffness, determine the axial modulus and radial modulus of the equivalent thin-layer material.
[0040] Step 105: In the finite element model, create a thin-layer element at the threaded connection interface and assign it axial and radial moduli.
[0041] Step 106: Connect the thin-layer unit to the two threaded components through binding constraints, and apply preload and dynamic load to complete the simulation model construction.
[0042] In this embodiment, calculations are performed based on the geometric and material parameters of the threaded connection. The stiffness of the threaded connection per unit length in both the axial and radial directions is established in the simulation, providing fundamental parameters for simulating stiffness nonlinearity. By introducing structural parameters, the stiffness per unit length is integrated into the total axial and radial stiffness of the threaded connection. The calculated total axial and radial stiffness of the threaded connection are then mapped to the axial and radial moduli of the thin-layer element. This allows the thin-layer element to realistically reflect the differences in the mechanical response of the threaded connection in different directions during simulation, thereby simulating gap changes and stiffness nonlinearity under dynamic loads, improving simulation accuracy, and reducing dynamic response errors.
[0043] Furthermore, the thin-layer element setting replaces the traditional rigid connection or simple contact model. It possesses independent material properties and can undergo elastic deformation in the simulation, thereby simulating the minute displacement, gap closing and opening behavior of the threaded connection under dynamic loads. Explicitly applying preload in the model can simulate the prestress distribution of the threaded connection in its initial state; the application of dynamic loads directly corresponds to actual working conditions such as vertical take-off and landing impacts and gusts of wind, making the simulation model exhibit a time-varying nonlinear response.
[0044] In some embodiments, calculating the total axial stiffness of a threaded connection includes: determining an axial load distribution coefficient based on the axial stiffness of the internal thread per unit length, the axial stiffness of the external thread per unit length, and structural parameters; determining the axial thread stiffness of the internal thread based on the axial load distribution coefficient and the axial stiffness of the internal thread per unit length; determining the axial thread stiffness of the external thread based on the axial load distribution coefficient and the axial stiffness of the external thread per unit length; and determining the total axial stiffness of the threaded connection based on the axial thread stiffness of both the internal and external threads.
[0045] In some embodiments, calculating the total radial stiffness of a threaded connection includes: determining a radial load distribution coefficient based on the radial stiffness of the internal thread per unit length, the radial stiffness of the external thread per unit length, and structural parameters; determining the radial thread stiffness of the internal thread based on the radial load distribution coefficient and the radial stiffness of the internal thread per unit length; determining the radial thread stiffness of the external thread based on the radial load distribution coefficient and the radial stiffness of the external thread per unit length; and determining the total radial stiffness of the threaded connection based on the radial thread stiffness of both the internal and external threads.
[0046] Specifically, based on the theory of thread mechanics, given a force F acting on a unit length of thread, the elastic deformation of internal and external threads per unit length is calculated separately. This deformation is divided into axial and radial deformation. The total axial deformation of the external and internal threads per unit length is defined as... and The total radial deformation is defined as and In this context, the subscript 'a' represents the axial correlation parameter, and the subscript 'r' represents the radial correlation parameter.
[0047] The total axial deformation per unit length of a thread includes bending moment deformation, shear deformation, root tilting deformation, root shear deformation, and radial expansion and contraction deformation. The formula is as follows: Total axial deformation per unit length of internal thread ,in: ; ; ; ; .in, , , , and These represent the bending moment deformation, shear deformation, root tilting deformation, root shear deformation, and radial expansion and contraction deformation corresponding to the internal thread.
[0048] Total axial deformation per unit length of external thread: ,in: ; ; ; ; .in, , , , and These represent the bending moment deformation, shear deformation, root tilting deformation, root shear deformation, and radial expansion and contraction deformation corresponding to the external thread.
[0049] By decomposing the multi-dimensional deflection of the thread (bending moment, shear, radial expansion and contraction, etc.), a quantitative correlation between stiffness parameters and thread geometric parameters and material parameters is achieved, solving the problem of the "stiffness black box" in existing methods.
[0050] Total radial deformation per unit length of internal thread: Total radial deformation per unit length of external thread: .
[0051] Axial stiffness of internal threads per unit length: Axial stiffness of external threads per unit length: Radial stiffness of internal threads per unit length: Radial stiffness of external threads per unit length: .
[0052] Define load distribution factor Substitute the values calculated above into the equations. , , , The axial load distribution coefficient can then be obtained. and radial load distribution coefficient .
[0053] Axial thread stiffness of internal thread: Axial thread stiffness of external thread: Since the external and internal threads in a threaded connection are connected in series, the total axial stiffness of the threaded connection is: .
[0054] Similarly: Radial thread stiffness of internal threads: External thread radial thread stiffness: Total radial stiffness of threaded connections: .
[0055] In some embodiments, determining the axial modulus of an equivalent thin-layer material includes: calculating the axial modulus based on the total axial stiffness, the thickness of the thin-layer element, and the contact area of the thin-layer element; wherein the contact area of the thin-layer element is the product of the length and width of the thin-layer element.
[0056] In some embodiments, determining the radial modulus of an equivalent thin-layer material includes: calculating the radial modulus based on the total radial stiffness, the thickness of the thin-layer element, and the contact area of the thin-layer element; wherein the contact area of the thin-layer element is the product of the length and width of the thin-layer element.
[0057] Figure 2 is a schematic diagram of the constitutive model principle of thin-layer unit provided in some embodiments of this application. Referring to Figure 2, after the thin-layer unit is introduced into the threaded connection structure, the threaded connection structure is subjected to axial force under the action of force F. and radial force Its axial and radial deformations are shown in Figure 2. Figure 2(a) shows a schematic diagram of axial deformation, and Figure 2(b) shows a schematic diagram of radial deformation. The parameters describing the axial stress-strain relationship are based on the total axial stiffness of the thread. The axial modulus, derived and calculated, is defined in the equivalent thin-film material. The parameters describing the radial stress-strain relationship are based on the total radial stiffness of the thread. The radial modulus, derived and calculated, is defined in the equivalent thin-film material. The specific calculation process is as follows: Refer to Figure 2(a), The shear stress generated after being subjected to axial force can be expressed as: ,in, The shear angle in radians (when this angle) When the value is very small, it can be approximated by its tangent, that is... , This represents the contact area of the thin-layer unit. This is axial displacement. This represents the thickness of the thin-layer unit. The contact area of the thin-layer unit. It is the product of the length l and the width s of the thin-layer element.
[0058] Transforming the previous equation, we get: .in, This represents the total axial stiffness.
[0059] The axial modulus of the equivalent thin-layer material It can be represented as: .
[0060] Referring to Figure 2(b), The normal stress generated after being subjected to radial force can be expressed as: ,in For normal strain (under small deformation conditions), ), This represents the normal displacement.
[0061] Transforming the previous equation, we get: ,in, This represents the total radial stiffness.
[0062] Then the radial modulus of the equivalent thin-layer material It can be represented as: .
[0063] In some embodiments, the length l of the thin-layer unit is consistent with the thread engagement length. The width 's' of the thin-layer unit is consistent with the circumference length of the threaded connection, and the thickness of the thin-layer unit... 0.3 times the pitch The circumference length of the threaded connection is... 0.3 is based on the tooth flank angle The calculated proportionality coefficient.
[0064] In practical applications, thin-layer elements are connected to two threaded components (such as fuselage frame and wing joint) through "binding constraints". The material properties of the thin-layer elements are given a defined axial modulus and radial modulus. Based on the Desai thin-layer element theory, the Poisson's ratio of the thin-layer element is set to 0. The preload is applied through the "temperature load equivalent method", that is, the equivalent environmental temperature change is calculated based on the preload. Dynamic loads (such as impact and gusts) are applied according to the actual working conditions to complete the construction of the simulation model.
[0065] By setting the Poisson's ratio νs=0 for thin-layer units, the different mechanical responses of threaded connections in the axial, radial, and shear directions can be accurately reflected.
[0066] In practical applications, when the eVTOL threaded connection is a thin-walled structure (such as the aluminum alloy frame connection of the battery compartment), a 4-node tetrahedral thin-layer unit can be used instead of an 8-node hexahedral unit. The calculation method of its material parameters remains unchanged, and only the size of the thin-layer unit needs to be adjusted, for example, the thickness of the thin-layer unit.
[0067] For threaded connections of composite materials (such as carbon fiber reinforced resin matrix composite fuselage joints), the "laminate stiffness theory" can be used to modify the thread deflection calculation formula, replacing the axial modulus and radial modulus with the laminated equivalent elastic modulus of the composite material.
[0068] Preload application alternative: When the thread diameter is greater than M20 (such as landing gear connecting bolts), the "direct force load application method" can be used, which replaces the temperature load method by applying an equivalent preload load to both ends of the thin-layer unit.
[0069] Figure 3 is a schematic diagram of the equivalent thin-layer material of the threaded connection structure provided in some embodiments of this application. Figure 4 is a schematic diagram of the calculation interface provided in some embodiments of this application. Referring to Figures 3 and 4, input the thread engagement length. Tooth lateral angle Angle of elevation pitch Bolt diameter Nut outer diameter The elastic modulus of internal thread material Poisson's ratio The elastic modulus of the external thread material Poisson's ratio It can output: the thickness t of the thin-layer unit and the axial modulus of the equivalent thin-layer material. With radial modulus .
[0070] Another embodiment of this application provides an equivalent thin-layer element simulation system for the threaded connection structure of an eVTOL aircraft. Figure 5 is a schematic diagram of the structure of the equivalent thin-layer element simulation system for the threaded connection structure of an eVTOL aircraft provided in some embodiments of this application. Referring to Figure 5, the system includes: a parameter acquisition module 51, used to acquire the geometric parameters, material parameters, and structural parameters of the threaded connection; a first stiffness calculation module 52, used to calculate the axial stiffness, radial stiffness, axial stiffness, and radial stiffness of the internal thread per unit length, and the external thread per unit length, respectively, based on the geometric parameters and material parameters; a second stiffness calculation module 53, used to calculate the total axial stiffness and total radial stiffness of the threaded connection, respectively, based on the axial stiffness, radial stiffness, axial stiffness, and radial stiffness of the internal thread per unit length, and the structural parameters; and a modulus calculation module 54, used to determine the axial modulus and radial modulus of the equivalent thin-layer material based on the total axial stiffness and total radial stiffness. The first modeling module 55 is used to create thin-layer elements at the threaded connection interface in the finite element model and assign them axial and radial moduli. The second modeling module 56 is used to connect the thin-layer elements to the two threaded components through binding constraints and apply preload and dynamic loads to complete the construction of the simulation model.
[0071] This embodiment provides an equivalent thin-layer element simulation system for the threaded connection structure of an eVTOL aircraft. The simulation error for key dynamic response parameters such as modal frequencies and impact overload transfer coefficients can be reduced to within 2.6%, an order of magnitude improvement over existing methods (15%-25% error). For example, the maximum deviation between the simulated and experimental values of the first three modal frequencies of the fuselage-wing connection is 2.54%, meeting the engineering design accuracy requirement of "error ≤ 5%". It can accurately simulate nonlinear behaviors such as vertical takeoff and landing impacts (peak overload 50-100G), preload relaxation (relaxation rate ≤ 8% after 1000 cycles), and thread collisions, with a simulation deviation of ≤ 3% for overload transfer under dynamic loads. This reduces the number of physical prototype iterations due to inaccurate simulations (an average reduction of 2-3 iterations), shortens the single-aircraft development cycle by 3-6 months, and reduces development costs by 15%-20%. Simulation tests can accurately predict the fatigue life and failure risk of threaded connections, reducing the probability of threaded connection failure during eVTOL flight and improving equipment operational safety. Establish a "precision-efficiency" balance scheme for eVTOL threaded connection simulation, and provide a standardized method for the simulation of connection structures of new energy aviation equipment.
[0072] Another embodiment of this application also provides a computer device, including: a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the equivalent thin-layer unit simulation method for an eVTOL aircraft threaded connection structure shown in FIG1 of this application embodiment.
[0073] Another embodiment of this application also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it can implement the equivalent thin-layer unit simulation method for an eVTOL aircraft threaded connection structure shown in Figure 1 of this application embodiment.
[0074] Those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.
[0075] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A simulation method for equivalent thin-layer elements of threaded connection structures in eVTOL aircraft, characterized in that, The method includes: obtaining the geometric parameters, material parameters, and structural parameters of the threaded connection; calculating the axial stiffness, radial stiffness, and external stiffness per unit length of the internal thread, based on the geometric parameters and material parameters; calculating the total axial stiffness and total radial stiffness of the threaded connection based on the axial stiffness, radial stiffness, and external stiffness per unit length of the internal thread, radial stiffness, and external stiffness per unit length of the external thread, as well as the structural parameters; determining the axial modulus and radial modulus of the equivalent thin-layer material based on the total axial stiffness and total radial stiffness; establishing a thin-layer element at the threaded connection interface in the finite element model and assigning it the axial modulus and radial modulus; connecting the thin-layer element to the two components of the threaded connection through binding constraints and applying preload and dynamic load to complete the simulation model construction.
2. The method according to claim 1, characterized in that, The calculation of the total axial stiffness of the threaded connection includes: determining an axial load distribution coefficient based on the axial stiffness of the internal thread per unit length, the axial stiffness of the external thread per unit length, and the structural parameters; determining the axial thread stiffness of the internal thread based on the axial load distribution coefficient and the axial stiffness of the internal thread per unit length; determining the axial thread stiffness of the external thread based on the axial load distribution coefficient and the axial stiffness of the external thread per unit length; and determining the total axial stiffness of the threaded connection based on the axial thread stiffness of the internal thread and the axial thread stiffness of the external thread.
3. The method according to claim 1, characterized in that, The calculation of the total radial stiffness of the threaded connection includes: determining a radial load distribution coefficient based on the radial stiffness of the internal thread per unit length, the radial stiffness of the external thread per unit length, and the structural parameters; determining the radial thread stiffness of the internal thread based on the radial load distribution coefficient and the radial stiffness of the internal thread per unit length; determining the radial thread stiffness of the external thread based on the radial load distribution coefficient and the radial stiffness of the external thread per unit length; and determining the total radial stiffness of the threaded connection based on the radial thread stiffness of the internal thread and the radial thread stiffness of the external thread.
4. The method according to claim 1, characterized in that, The geometric parameters include: pitch, thread engagement length, flank angle, bolt diameter, nut outer diameter, and helix angle.
5. The method according to claim 1, characterized in that, The material parameters include: the elastic modulus of the internal thread material, the Poisson's ratio of the internal thread material, the elastic modulus of the external thread material, and the Poisson's ratio of the external thread material.
6. The method according to claim 1, characterized in that, The structural parameters include: the cross-sectional area of the internal thread and the cross-sectional area of the external thread.
7. The method according to claim 1, characterized in that, The length of the thin-layer unit is the same as the thread engagement length, the width of the thin-layer unit is the same as the circumference length of the threaded connection, and the thickness of the thin-layer unit is 0.3 times the thread pitch.
8. The method according to claim 7, characterized in that, Determining the axial modulus of the equivalent thin-layer material includes: calculating the axial modulus based on the total axial stiffness, the thickness of the thin-layer unit, and the contact area of the thin-layer unit; wherein the contact area of the thin-layer unit is the product of the length and the width of the thin-layer unit.
9. The method according to claim 7, characterized in that, Determining the radial modulus of the equivalent thin-layer material includes: calculating the radial modulus based on the total radial stiffness, the thickness of the thin-layer unit, and the contact area of the thin-layer unit; wherein the contact area of the thin-layer unit is the product of the length and the width of the thin-layer unit.
10. An equivalent thin-layer element simulation system for the threaded connection structure of an eVTOL aircraft, characterized in that, The system includes: a parameter acquisition module for acquiring geometric parameters, material parameters, and structural parameters of the threaded connection; a first stiffness calculation module for calculating, based on the geometric parameters and material parameters, the axial stiffness of the internal thread per unit length, the radial stiffness of the internal thread per unit length, the axial stiffness of the external thread per unit length, and the radial stiffness of the external thread per unit length; and a second stiffness calculation module for calculating, based on the axial stiffness of the internal thread per unit length, the radial stiffness of the internal thread per unit length, the axial stiffness of the external thread per unit length, and the radial stiffness of the external thread per unit length, respectively. The radial stiffness of the thread per unit length and the structural parameters are used to calculate the total axial stiffness and total radial stiffness of the threaded connection, respectively. A modulus calculation module is used to determine the axial and radial moduli of the equivalent thin-layer material based on the total axial and radial stiffness. A first modeling module is used to establish a thin-layer element at the threaded connection interface in the finite element model and assign it the axial and radial moduli. A second modeling module is used to connect the thin-layer element to the two components of the threaded connection through binding constraints and apply preload and dynamic loads to complete the simulation model construction.