A high-precision fluid-solid coupling simulation method based on flexible multi-body dynamics

Abstract

The application discloses a high-precision fluid-solid coupling simulation method based on flexible multi-body dynamics, and belongs to the technical field of fluid-solid coupling simulation. The method comprises the following steps: establishing a finite element model of a simulation object, establishing a flexible body by using a modal matrix, creating a frame and a force element object in batches, compiling a user-defined subroutine UDF1 into a dynamic link library connected to a calculation model to form a solid solution server; dividing a fluid dynamics calculation grid, compiling a UDF2 and connecting the UDF2 to the calculation model after compilation to form a fluid solution server; alternately generating two identification files by a master control module at each simulation time step for solid and fluid solutions, performing data exchange and interpolation mapping of fluid-solid coupling, and finally obtaining a high-precision fluid-solid coupling simulation result. The application realizes function expansion and system integration in a non-invasive development mode, each component can be independently upgraded or replaced with different solver kernels, is convenient for upgrading and maintenance, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of fluid-structure interaction simulation technology and provides a high-precision fluid-structure interaction simulation method based on flexible multibody dynamics. Background Technology

[0002] In the aerospace field, fluid-structure interaction (FSI) has significant scientific and engineering implications. This phenomenon refers to the dynamic interaction between the elastic structure of an aircraft and the surrounding fluid (such as air or water). This interaction has a profound impact on the design, performance, and safety of aircraft, particularly in areas such as aeroelastic stability, structural optimization design, and control system design.

[0003] With the continuous advancement of aircraft design technology, a new type of aircraft has emerged—the morphing aircraft. Its characteristic is that it can achieve continuous and smooth changes in its shape through mechanical movement and structural deformation, depending on the flight environment and mission requirements. This form of change greatly improves the aircraft's flight performance and stealth capabilities, thus attracting widespread attention from researchers worldwide.

[0004] However, because the structural design of morphing aircraft involves the coupling of rigid body motion and elastic deformation over a wide range, traditional fluid-structure interaction (FSI) analysis methods are no longer sufficient to meet the requirements of its design and analysis. This coupled dynamics, commonly referred to as flexible multibody dynamics in academia, has become a hot topic of research in the new century.

[0005] Furthermore, this fluid-structure interaction analysis method based on flexible multibody dynamics has significant application value for the design of biomimetic aircraft and biomimetic submarines. This is because the design of these biomimetic devices often requires simulating the structure and movement of living organisms, such as the flapping of a bird's wings or the waving of a fish's fins, all of which necessitate considering the coupling effect between rigid body motion and elastic deformation.

[0006] Therefore, developing a high-precision fluid-structure interaction simulation method based on flexible multibody dynamics to meet the design needs of morphing aircraft and biomimetic devices has become an important task in current scientific research. Summary of the Invention

[0007] To address the aforementioned needs, this invention provides a high-precision fluid-structure interaction simulation method based on flexible multibody dynamics. This method enables functional expansion and system integration through non-intrusive development, meeting the design requirements of morphing aircraft and biomimetic devices. Each component can be independently upgraded or replaced with different solver kernels, facilitating maintenance.

[0008] The present invention discloses a fluid-structure interaction (FSI) simulation method based on flexible multibody dynamics. The corresponding computer instructions are stored in a readable storage medium. The processor executes the computer instructions to start the main control module. The main control module is used to control the FSI simulation process and the data exchange and interpolation mapping of the FSI interface, including the following steps:

[0009] (i) Construct a solid-state solver server to perform structural initialization on the simulation object; the solid-state solver server is implemented based on flexible multibody dynamics software.

[0010] The structure initialization includes: (1) establishing finite element models of each independent component according to the geometric shape of the simulation object, setting the connection points of each independent component in the finite element model with multi-point constraint conditions, performing modal calculations on the finite element models of each component using finite element analysis software, and exporting the modal matrix; (2) establishing a flexible body in the flexible multibody dynamics software through the modal matrix, using scripts to create frames and force element objects in batches at the finite element nodes where the interpolation points are located, and exporting the calculation model, which includes model files, instruction files and matrix files; (3) writing a user-defined subroutine UDF1, which includes: monitoring whether there is an identifier file 1 in the working directory file, and if it is detected, performing a one-step simulation calculation of the flexible multibody dynamics response, reading the force vector of the finite element node of the selected force element object before execution, writing the displacement of the finite element node of the selected frame after execution, and finally deleting the identifier file; compiling UDF1 into a dynamic link library and connecting it to the calculation model exported in (2) to form a servo-type solid solver server that can be called.

[0011] (ii) Construct a fluid solution server and perform aerodynamic initialization on the simulation object; the fluid solution server is implemented based on computational fluid dynamics software;

[0012] The aerodynamic initialization includes: (4) dividing the fluid dynamics calculation grid, setting the solution, and exporting the calculation model. The calculation model includes the example setting file, the grid file, the coordinates of the corner points of the initial aerodynamic grid on the object surface, and the coordinates of the center point of the first layer of the initial object surface grid; (5) writing a user-defined subroutine UDF2. UDF2 includes: monitoring whether there is an identifier file 2 in the working directory file. If it is detected, a one-step simulation calculation of the fluid dynamics response is performed. Before execution, the displacement of the corner points of the aerodynamic grid on the object surface at the current moment is read in. After execution, the force vector of the center point of the aerodynamic grid on the object surface at the current moment is exported. Finally, the identifier file 2 is deleted. UDF2 is compiled into a dynamic link library and linked to the calculation model exported in (4) to form a servo-type fluid solution server that can be called.

[0013] (iii) The main control module uses the interpolation matrix G to transmit data between the aerodynamics and structure of the simulation object;

[0014] Interpolate the displacement x of the finite element node to the corner displacement h = Gx of the aerodynamic mesh on the object surface;

[0015] The force vector F at the center point of the aerodynamic grid h Force vector F interpolated to the equivalent finite element node a =G T F h The superscript T indicates transpose.

[0016] (iv) The main control module alternately generates identifier file 1 and identifier file 2 in each simulation time step and puts them into the working directory file. After the solid solution server and fluid solution server detect the corresponding identifier file, they will perform a simulation calculation. Then the main control module uses the interpolation matrix G to transfer data between aerodynamics and structure, and then continues to the next simulation time step. The main control module saves the data solved by the solid solution server and fluid solution server in each simulation time step, as well as the nodal displacement matrix and force vector matrix of the fluid-structure interaction interface.

[0017] The beneficial effects of this invention are as follows:

[0018] (1) This invention realizes a general fluid-structure interaction simulation method. The simulation process and file reading and writing are controlled by user-defined subroutines without changing the solver kernel. Functional expansion and system integration are realized in a non-intrusive development manner. Each component can be independently upgraded or replaced with different solver kernels, which is convenient for maintenance.

[0019] (2) This invention establishes a flexible multibody dynamic fluid-structure interaction method for engineering. Most simulation software commonly used by engineering units cannot directly modify the source code, but generally provides user-defined sub-functions. Therefore, this solution has good scalability.

[0020] (3) The fluid-structure interaction simulation method of the present invention can perform high-precision fluid-structure interaction analysis on complex objects with large displacement and large deformation coupling, which has great application value and can greatly improve the design and analysis level of engineering units. Attached Figure Description

[0021] Figure 1 This is a flowchart of the high-precision fluid-structure interaction simulation method based on flexible multibody dynamics of the present invention;

[0022] Figure 2 This is a schematic diagram of the implementation framework of the high-precision fluid-structure interaction simulation method based on flexible multibody dynamics of the present invention.

[0023] Figure 3 This is a schematic diagram of the model components and constraint relationships in an embodiment of the present invention;

[0024] Figure 4This is a diagram of the wing moment response according to an embodiment of the present invention;

[0025] Figure 5 This is a longitudinal displacement response curve of the wing hinge displacement according to an embodiment of the present invention. Detailed Implementation

[0026] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] This invention uses the calculation of the fluid-structure interaction dynamic response of a flexible folding wing as an example to illustrate the high-precision fluid-structure interaction simulation method based on flexible multibody dynamics of this invention. An implementation process is as follows: Figure 1 As shown, the following seven steps will be used to explain the fluid-structure interaction simulation method of this invention. The simulation process and file reading / writing are controlled by a user-defined subroutine. Necessary information from the solid solution server and the fluid solution server is exported to a common folder, and then read, interpolated, and written using an independent control program, ultimately forming a complete simulation framework, such as... Figure 2 As shown.

[0028] Step 1: Perform structural initialization. The solid-state solver server of this invention is implemented based on flexible multibody dynamics software. In this embodiment, the flexible multibody dynamics software used is ADAMS, but it is not limited to this software.

[0029] 1) First, based on the geometric shape of the simulation object, establish the finite element model of each independent component.

[0030] To achieve flexible multibody dynamics simulation, finite element modeling is required for each moving component. Furthermore, before finite element modeling, the global coordinates of each component need to be predefined, and the connection relationships need to be specified so that boundary conditions and reserved connection points can be defined during finite element modeling. The structural model of the flexible folding wing in this embodiment is as follows: Figure 3 As shown, the wingtip span accounts for 1 / 4 of the wing, and the wingtip spread angle is 20°.

[0031] The system momentum equation of a flexible multibody system is:

[0032]

[0033] Where, n b M represents the number of components in a flexible multibody system. i K is the mass matrix of the i-th component. i q is the stiffness matrix of the i-th component. i It is the generalized coordinate vector of the i-th component. It is the constraint matrix, and λ is the Lagrange multiplier. and These represent elastic force and external force, respectively. The superscript T indicates transpose. q i The second derivative of .

[0034] If component i vibrates freely in a floating coordinate system, then

[0035]

[0036] in, Let i be the generalized coordinate vector of component i in the floating coordinate system. This is the mass matrix of component i in the floating coordinate system. It is the stiffness matrix of component i in the floating coordinate system.

[0037] This is a classic vibration equation, the solution of which can be written as: Where j is the imaginary unit, a i Let be the coefficient matrix, and ω be the angular frequency of vibration. Substituting into the equation, we get... This is a typical generalized eigenvalue problem. The mode transformation matrix can be obtained by solving. in It is the mode shape matrix composed of the first m modal vibrations. These are modal coordinates. Substituting them into the system's momentum equation yields...

[0038]

[0039] In this context, the subscripts r and f represent the rigid and flexible components, respectively, and the hyphens above the characters indicate their relationship to the mode shape matrix. The operation was performed, and the coordinates were transformed to the modal coordinate system; It divides the mass matrix of component i in the modal coordinate system into four parts. It is the mass matrix corresponding to the rigid part in modal coordinates. It is the mass matrix corresponding to the elastic component in modal coordinates. It is the mass matrix corresponding to the coupling effect of the rigid and elastic parts in the modal coordinate system.

[0040] 2) Perform modal calculations on the finite element models of each component and export the modal neutral files.

[0041] In the finite element model, the connection points of each independent component are set with multi-point constraints. Modal calculations are performed on the finite element models of each component, and the modal matrix, i.e., the mode shape matrix, is derived. Many finite element analysis software programs support exporting modal neutral files required by ADAMS. This example uses the finite element analysis software MSC.Patran. First, ensure that finite element modeling is complete and a valid f06 file has been successfully calculated. Then, execute the following command in MSC Patran:

[0042] 1. Ensure the analysis type is Normal Modes, i.e., call Nastran's SOL103;

[0043] 2. Select the connection node, and choose the DOF List created during the previous modeling process;

[0044] 3. Click Solution Parameters to access detailed settings;

[0045] 4. In the pop-up menu, click the ADAMS Preparation button to enter the export MNF settings;

[0046] 5. Select the output file; generally, Full Run+MNF is preferred.

[0047] 6. Set the unit system. It is recommended to keep the MMKS unit system in both finite element method and ADAMS. Then click the OK button in each submenu step by step to save the settings.

[0048] 7. (Optional) If you need to analyze the stress state of the finite element model in ADAMS, you can add Grid Points Stresses in Output Requests under Subcases in the Patran analysis card to output nodal force information. It is recommended to select this option in critical components. If the number of nodes in the finite element model is large, the output MNF file will also be very large, affecting simulation speed.

[0049] Step 2: In the flexible multibody dynamics software, a flexible body is established using modal matrices. A script is used to create frames and force element objects in batches at the finite element nodes where the interpolation points are located, and these are numbered according to a specific pattern. After making the necessary solution settings, the computational model is exported. The computational model includes a model file, an instruction file, and a matrix file. The interpolation points are pre-set and consist of selected finite element mesh nodes, generally chosen at the main load-bearing components of the structure, to receive the force vectors interpolated from the fluid mesh.

[0050] This invention uses the multibody dynamics and motion analysis software MSC.ADAMS, and specifically executes the following process:

[0051] 1) Create a flexible body in MSC.ADAMS software using a modal neutral file;

[0052] In the MSC.ADAMS software, use the Adams Flex module to import the MNF files obtained in the previous step to obtain four flexible body parts. Then, set the corresponding hinge constraints at the connection points and add the corresponding motion.

[0053] 2) Use a Python script to create Marker and VForce objects in batches at the finite element nodes where the interpolation points are located, and number the frame and force element objects according to a set pattern. Marker represents the frame, and VForce represents the force element object.

[0054] 3) After making the necessary solver settings in MSC.ADAMS, export the model file, instruction file, and matrix file. The model file (Model.adm) contains all the parameter information and solver settings of the simulation model, the matrix file (Part1.mtx, Part2.mtx…) contains the modal characteristics of all flexible bodies, and the instruction file (Model.acf) contains all the simulation steps that the solver needs to execute. In this example, only the user-defined program needs to be executed.

[0055] Step 3: Write and compile a user-defined subroutine to control the execution of the solid-state solver server. Link the compiled dynamic link library into the computational model exported in Step 2.

[0056] 1) Write an ADAMS user-defined subroutine (UDF), marked as the first subroutine. Its functions include: monitoring the status of the identifier file (1) to control the simulation process; if the identifier file (1) is detected, execute one step; and before execution, read the three-dimensional force vector matrix of the selected VForce object, i.e. Figure 2 The interpolation point force vector matrix is ​​written into the node coordinate matrix of the selected Marker after execution. Figure 2 The interpolation point displacement matrix in the file is then deleted, and finally the identifier file (1) is deleted.

[0057] The main functions of the first subroutine implemented in this embodiment of the invention are described in detail below:

[0058] 1. Define the Consub function, whose input is a pointer to an sAdamsControl structure, which contains parameters such as simulation deadline and total number of simulation steps;

[0059] 2. Initialize variables, including: whether it is the first simulation (iniflg), number of states (nstates), status value returned by ADAMS function call (status), force magnitude (sforce), ADAMS command string (cmd), error flag (errflg), node number range (ipar), etc.

[0060] 3. Read the simulation deadline and total number of steps from the input parameters, and calculate the time step size for each step;

[0061] 4. Enter a loop, and in each loop, determine whether the simulation needs to be stopped. If so, exit the loop.

[0062] 5. If the identifier file adams_run exists, read in the magnitude of the external force, construct the ADAMS command string, call the c_modify function to modify the force magnitude in the ADAMS model, and call the c_analys function to perform a one-step simulation calculation;

[0063] 6. After the simulation calculation is complete, call the c_datout function to output the simulation results to a file;

[0064] 7. Call the c_sysary function again to calculate the node displacements and output the results to a file;

[0065] 8. Delete the identifier file adams_run.

[0066] 2) Compile the UDF into a dynamic link library and link it to the computational model exported in step two, forming a callable server-based solver. Figure 2 The solid-state solver server is shown. This embodiment of the invention requires the Microsoft Visual Studio compiler. In the directory terminal, type `adams[version number]cr-user` and follow the prompts to select the UDF source code for compilation and linking. At this point, the main control program can start the solid-state solver server using the command line command "adams[version number]ru-user dynamic link library.dll instruction file.acf".

[0067] Step 4: Divide the CFD calculation grid, perform necessary solution settings such as dynamic mesh and turbulence model, and export the calculation model. The calculation model includes the example settings file, the grid file, the coordinates of the corner points of the aerodynamic grid on the initial surface, and the coordinates of the center points of the first layer of the initial surface grid.

[0068] Step 5: 1) Write a user-defined subroutine for FLUENT, referred to as the second subroutine. Its function is to process data related to computational fluid dynamics. FLUENT is a general-purpose computational fluid dynamics (CFD) software. The fluid solver server in this embodiment is based on the computational fluid dynamics software FLUENT, but it is not required to use this software.

[0069] In the main body of the code, the second subroutine contains the following UDF function definitions and function calls:

[0070] The `DEFINE_ON_DEMAND(global_local_id_matching)` function performs specific operations during computation. It first reads a file named "center0.txt", which contains the global ID and node count for each grid cell. Then, it iterates through the grid cells in each node, matching them against the global ID, and storing the matching results in the `position` and `total_f_node_para` arrays.

[0071] The functions Cx_output, Cy_output, and Cz_output are used to calculate and output Cx, Cy, and Cz data in fluid dynamics, i.e., torques in fluid dynamics. Specifically, they calculate the centroid coordinates and forces of each grid cell, calculate the torque at each node, and output the results to the files "Cx.txt", "Cy.txt", and "Cz.txt".

[0072] The Fx_output, Fy_output, and Fz_output functions are used to calculate and output Fx, Fy, and Fz data in fluid dynamics, which are the components of force in the X, Y, and Z directions.

[0073] This code reads the mesh and node information from the fluid dynamics calculation, matches the global ID and local ID, and calculates and outputs the torque and force component data.

[0074] 2) Compile the second subroutine code into a dynamic link library and link it to the computational model exported in step four to form a callable servo-type fluid solver server, such as... Figure 2 As shown, its function is to monitor the working directory file. If a new time step input of the object surface aerodynamic mesh corner displacement matrix is ​​detected, it will read it in and calculate the one-step hydrodynamic response. Finally, it will output the object surface aerodynamic mesh center point displacement matrix and force vector matrix.

[0075] Step Six: Write the main control program, i.e., the main control module. Its main functions are: controlling the simulation process and the data exchange and interpolation mapping of the fluid-structure interaction interface, such as... Figure 2 As shown.

[0076] This program implements a multiphysics simulation of fluid-structure interaction, where ADAMS is used for structural simulation and Fluent is used for fluid simulation. The code generates simulation results by alternately running ADAMS and Fluent, exchanging and interpolating data at each time step.

[0077] The main control program will alternately generate identification files (1) and (2) to tell the solid solution server and the fluid solution server that a one-step simulation calculation can be performed, and delete the corresponding identification file after solving a time step. In this way, the process control problem of different solution software across platforms is solved by designing two identification files.

[0078] The main control program also pre-calculates the interpolation matrix G to solve the problem of physical quantity exchange between fluid simulation and structural simulation, realizing data transfer between the two platforms. The interpolation matrix G, based on the principle of virtual work and energy conservation, interpolates the force vectors on the fluid mesh of the finite volume method to the nodes of the solid finite element units, and interpolates the displacement vectors of the solid finite element unit nodes to the points of the fluid mesh. Specifically, the interpolation matrix G can be obtained using interpolation methods such as IPS (spline interpolation) and TPS (thin plate spline interpolation).

[0079] The relationship between the displacement h of the fluid control point and the displacement x of the structural node can be expressed by the interpolation matrix h = Gx. The displacement x of the structural node is... Figure 2 The interpolation point displacement matrix in the equation, and the displacement h of the fluid control point are... Figure 2 The displacement matrix of the corner points of the aerodynamic mesh on the object surface.

[0080] According to the principle of virtual work, the force F on the aerodynamic grid is... h and the force F on the equivalent structural node a For the corresponding displacement, the same amount of virtual work must be done, i.e., δh T F h =δx T F a , where δh T and δx T It is a virtual displacement. Therefore, we have δx T (F a -G T F h Since ) = 0, due to the arbitrariness of the virtual displacement, we can obtain F a =G T F h Force F on the aerodynamic grid h Right now Figure 2 Force vector matrix at the center point of the aerodynamic mesh on the object surface, and force F at the structural nodes. a Right now Figure 2 The force vector matrix of the interpolation points in the matrix.

[0081] The main control program then uses h = Gx and F a =G T F h Data transfer between the aerodynamics and structure of the simulated object is performed. After displacement interpolation, the aerodynamic mesh deforms, and the boundary conditions are updated.

[0082] Step 7: 1) Start the main control program, sequentially open the solid solution server for flexible multibody dynamics formed in step 3 and the fluid solution server for computational fluid dynamics formed in step 5, then alternately generate identification files (1) and (2), and complete the force vector interpolation from the center point of the aerodynamic mesh on the object surface to the force vector interpolation node of the structure and the interpolation from the displacement of the structure interpolation node to the displacement of the corner point of the aerodynamic mesh on the object surface within each simulation time step.

[0083] 2) Save the simulation results and exit the main control program. Under the condition of a wind speed of 25 m / s and a wingtip folding motion with an amplitude of 20° following a sinusoidal law, the simulated torque response results are as follows: Figure 4 As shown, the displacement response results are as follows: Figure 5 As shown.

[0084] At each simulation time step, the displacement of the finite element nodes calculated by the solid solver server is saved to the working directory file, and the force vector of the center point of the aerodynamic mesh of the object surface calculated by the fluid solver server is saved to the working directory file. The main control module interpolates the data between aerodynamics and structure and saves it to the working directory file.

[0085] Except for the technical features described in the specification, all other technologies are known to those skilled in the art. Descriptions of well-known components and technologies are omitted in this invention to avoid redundancy and unnecessary limitation.

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A fluid-structure interaction simulation method based on flexible multibody dynamics, characterized in that, The method is stored as computer instructions in a readable storage medium. When the processor executes the computer instructions, it starts the main control module. The main control module is used to control the fluid-structure interaction simulation process and the data exchange and interpolation mapping of the fluid-structure interaction interface, including the following steps: (i) Construct a solid-state solver server to perform structural initialization on the simulation object; the solid-state solver server is implemented based on flexible multibody dynamics software. The structure initialization includes: (1) establishing finite element models of each independent component according to the geometric shape of the simulation object, setting the connection points of each independent component in the finite element model with multi-point constraint conditions, performing modal calculations on the finite element models of each component using finite element analysis software, and exporting the modal matrix; (2) establishing a flexible body in the flexible multibody dynamics software through the modal matrix, using a script to create frames and force element objects in batches at the finite element nodes where the interpolation points are located, and exporting the calculation model, which includes model files, instruction files and matrix files; (3) writing a user-defined subroutine UDF1, which includes: monitoring whether there is an identifier file 1 in the working directory file, and if it is detected, performing a flexible multibody dynamics simulation calculation, reading the force vector of the finite element node of the selected force element object before execution, writing the displacement of the finite element node of the selected frame after execution, and finally deleting the identifier file; compiling UDF1 into a dynamic link library and connecting it to the calculation model exported in (2) to form a solid solver server; (ii) Construct a fluid solution server and perform aerodynamic initialization on the simulation object; the fluid solution server is implemented based on computational fluid dynamics software; The aerodynamic initialization includes: (4) dividing the fluid dynamics calculation grid, setting the solution, and exporting the calculation model. The calculation model includes the example setting file, the grid file, the coordinates of the corner points of the initial aerodynamic grid on the object surface, and the coordinates of the center point of the first layer of the initial object surface grid; (5) writing a user-defined subroutine UDF2. UDF2 includes: monitoring whether there is an identifier file 2 in the working directory file. If it is detected, a fluid dynamics simulation calculation is performed. Before execution, the displacement of the corner points of the aerodynamic grid on the object surface at the current moment is read in. After execution, the force vector of the center point of the aerodynamic grid on the object surface at the current moment is exported. Finally, the identifier file 2 is deleted; UDF2 is compiled into a dynamic link library and linked to the calculation model exported in (4) to form a fluid solution server; (iii) The main control module uses the interpolation matrix G to transmit data between the aerodynamics and structure of the simulation object; Interpolate the displacement x of the finite element node to the corner displacement h = Gx of the aerodynamic mesh on the object surface; The force vector F at the center point of the aerodynamic grid on the surface. h Force vector F interpolated to the equivalent finite element node a =G T F h The superscript T indicates transpose. (iv) The main control module alternately generates identifier file 1 and identifier file 2 at each simulation time step and puts them into the working directory file. After the solid solution server and fluid solution server detect the corresponding identifier file, they will perform a simulation calculation. Then the main control module uses the interpolation matrix G to transfer data between aerodynamics and structure, and then continues to the next simulation time step.

2. The method according to claim 1, characterized in that, In step one, the system momentum equation for component i of the flexible multibody system is established as follows: Where, n b M represents the number of components in a flexible multibody system. i K is the mass matrix of the i-th component. i q is the stiffness matrix of the i-th component. i It is the generalized coordinate vector of the i-th component. It is the constraint matrix, and λ is the Lagrange multiplier. It is elastic force. It is an external force; q i The second derivative; If component i vibrates freely in a floating coordinate system, then the vibration equation is obtained: in, It is the generalized coordinate vector of component i in the floating coordinate system. This is the mass matrix of component i in the floating coordinate system. This is the stiffness matrix of component i in the floating coordinate system; The solution to the vibration equation is as follows: Where j is the imaginary unit, a i Let ω be the coefficient matrix, and ω be the angular frequency of vibration; substituting into the vibration equation, we have... The mode transformation matrix is ​​obtained by solving. Where the mode matrix The mode shape matrix is ​​composed of the first m modal vibrations; p i f These are modal coordinates. Substituting them into the system momentum equation yields: In this context, the subscripts r and f represent the rigid and elastic components, respectively, and the hyphens above the characters indicate the corresponding physical quantities and mode shapes. The operation was performed and transformed into the modal coordinate system; The mass matrix of component i in the modal coordinate system is divided into 4 parts.

3. The method according to claim 1, characterized in that, In step four, at each simulation time step, the displacement of the finite element nodes calculated by the solid solver server is saved to the working directory file, and the force vector of the center point of the aerodynamic mesh of the object surface calculated by the fluid solver server is saved to the working directory file. The main control module interpolates the data between aerodynamics and structure and saves it in the working directory file.

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