A launch platform dynamics model correction method, device and storage medium

Abstract

The application discloses a launch vehicle launch platform dynamics model correction method and device and a storage medium, belongs to the technical field of launch vehicle launch platform modeling, and comprises the following steps: establishing a launch vehicle launch platform structure dynamics model and reserving correction parameters; building a launch platform modal test system and performing physical modal test; and automatically correcting the model based on modal test data and error identification. The application can realize the establishment and correction of the launch vehicle launch platform, has good modeling effect, and the connection relationship between various components of the launch vehicle launch platform is more reasonable.

Description

Technical Field

[0001] This invention relates to the field of launch vehicle launch platform modeling technology, and in particular to a method, device and storage medium for correcting the dynamic model of a launch vehicle launch platform. Background Technology

[0002] The launch platform is the ground support equipment that ensures the normal operation of the rocket body during the transportation, propellant loading, and launch phases. Functionally, it can be divided into structural subsystems, propellant loading and gas supply subsystems, and electrical and measurement subsystems. The structural subsystem ensures effective force transmission and the structural safety of the launch pad while the rocket body is on it. The propellant loading and gas supply subsystem is responsible for pressurizing the propellant loading tanks and related structures. The electrical and measurement subsystem is responsible for powering onboard components and measuring relevant parameters.

[0003] In the design of launch pads, particular attention is paid to the dynamic response of the platform under external excitations, as the magnitude of the dynamic response affects the normal operation and service life of the launch platform. The finite element method is currently the primary method for calculating the dynamic response of the launch platform, and the foundation of the finite element method is obtaining an accurate structural dynamic model.

[0004] In daily practice, the existing technical solutions have been found to have the following problems: Existing structural dynamics models for launch platforms lack a complete and efficient modeling process. Furthermore, the internal structures of launch platforms often employ idealized rigid body connections, which fail to reflect real-world connection relationships.

[0005] Therefore, it is necessary to provide a new technical solution to solve the above problems. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a method, device, and storage medium for correcting the dynamic model of a launch vehicle platform, which can establish an accurate structural dynamic model.

[0007] A method for correcting the dynamic model of a launch vehicle platform includes: S1. Establish a structural dynamics model of the launch platform for the carrier rocket and reserve correction parameters; S2. Build a launch platform modal testing system and conduct physical modal testing; S3. Automatically correct the model based on modal test data and error identification.

[0008] Preferably, step S1 includes: S11. Model the bottom support legs; S12. Model the upper and lower platforms of the launch pad; S13. Model the support legs of the arrow body; S14. Assemble the bottom support leg model, upper and lower platform models, and rocket body support leg model into a launch platform model according to their positional relationship. S15. Perform modal analysis on the assembled launch platform model and check for any anomalies in the model. Save the model if no anomalies are found.

[0009] Preferably, step S11 includes: In CAD software, perform geometric preprocessing on the bottom support legs, remove chamfers, bolts and bolt holes that have little impact on the simulation, and save them in a general geometric file format; Import the bottom leg geometry file into HyperMesh software. After cutting the complex geometry into a combination of simpler geometry, use the 3D solid element C3D8 to complete the bottom leg mesh generation. Assign material properties to the bottom leg and export it in a format that can be imported into ABAQUS software.

[0010] Preferably, step S12 includes: In CAD software, perform geometric preprocessing on the upper and lower platforms of the launch pad, remove chamfers, bolts and bolt holes that have little impact on the simulation, and save them in a general geometric file format. Import the geometry files of the upper and lower platforms into HyperMesh software, and extract the mid-surface of the steel plates and flanges in the upper and lower platforms as geometric feature surfaces. Divide the geometric feature surface into 2D elements, assign thickness to the element containing the steel plate and the element containing the flange plate according to the actual thickness, and assign material properties and element section properties. Tie constraints are applied to steel plates with flange connections, with the tolerance set to be greater than the flange plate thickness, and no initial clearance elimination is set. Export to a format that can be input into ABAQUS software.

[0011] Preferably, step S13 includes: In CAD software, perform geometric preprocessing on the rocket body legs, remove chamfers, bolts and bolt holes that have little impact on the simulation, and save them in a general geometric file format; Import the rocket body and leg geometry files into HyperMesh software. After cutting the complex geometry into a combination of simple geometry, use the 3D solid element C3D8 to complete the bottom leg mesh generation. Then, assign material properties to the rocket body and legs, assign element section properties, and export them into a format that can be imported into ABAQUS software.

[0012] Preferably, step S14 includes: Import the upper and lower platform models into ABAQUS software as the basic structure, and import the bottom support legs and arrow body support legs as branch structures. The bottom support legs and the arrow body support legs are arrayed and copied according to their quantity, and the arrayed parts are translated and rotated according to their actual positional relationship; Establish a set of nodes on the upper surface of the upper platform and the lower surface of the rocket body legs. Use Tie constraints to constrain the upper platform and rocket body legs. The master node is the upper surface of the upper platform and the slave node is the lower surface of the rocket body legs. Set the tolerance according to the gap distance. The nodes in the connection area between the lower surface of the platform and the bottom support leg are coupled to the center node, which serves as the interface node for connection with the bottom support leg. The nodes in the upper surface area of ​​the bottom support leg are coupled to the center node, which serves as the interface node for connection with the lower platform. The rotational degree of freedom between the center node of the lower platform and the center node of the bottom support leg is constrained by springs, while the translational and torsional degrees of freedom are coupled. The stiffness of the rotational spring was established as the core parameter for model correction.

[0013] Preferably, the launch platform modal testing system built in step S2 includes an excitation subsystem and a testing subsystem; the excitation subsystem includes an exciter, a force hammer, a power amplifier, and supporting cables; the testing subsystem includes a force sensor, an acceleration sensor, a data acquisition chassis, and supporting cables.

[0014] Preferably, step S3 includes: establishing an objective function to evaluate the similarity between modal frequencies and mode shapes in measured and simulated results, obtaining the optimal rotational stiffness, and using the optimal rotational stiffness as a correction parameter to correct the dynamic model of the launch vehicle platform.

[0015] According to another aspect of this application, a computing device is also provided, comprising: a processor and a memory storing a computer program, wherein the computer program, when executed by the processor, performs the aforementioned method for correcting the dynamic model of a launch vehicle platform.

[0016] According to another aspect of this application, a computer-readable storage medium is also provided, on which computer instructions are stored, which, when executed on a computer, cause the computer to perform the aforementioned method for correcting the dynamic model of a launch vehicle platform.

[0017] Compared with the prior art, this application has at least the following beneficial effects: 1. This invention can realize the establishment and correction of the launch vehicle platform, and the modeling effect is good, and the connection relationship between the various components of the launch vehicle platform is more reasonable.

[0018] 2. In this invention, the connection between the lower platform and the bottom support legs in the dynamic model of the launch vehicle platform is changed from a rigid connection to a rotational spring connection, and the spring stiffness is used as the core correction parameter of the model to accurately reflect the real connection relationship.

[0019] 3. This invention constructs an error identification method between modal test and simulation results based on the modal similarity function (MAC), which solves the problem of a single model evaluation index. Attached Figure Description

[0020] The following sections will describe some specific embodiments of the invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic diagram of the overall process of the present invention; Figure 2 This is a schematic diagram of the launch platform modal testing system of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] like Figure 1 As shown, a method for correcting the dynamic model of a launch vehicle platform includes: S1. Establish a structural dynamics model of the launch platform for the carrier rocket and reserve correction parameters.

[0023] The main load-bearing structure of a launch vehicle platform includes upper and lower platforms, launch pad bottom supports, and rocket body supports. This embodiment uses a launch platform with 8 bottom supports and 4 rocket body supports as an example to illustrate the process of establishing the structural dynamics model of the launch vehicle platform.

[0024] Step S11: Model the bottom support leg.

[0025] Specifically, in CAD software, the bottom support leg is pre-processed geometrically, removing chamfers, bolts, bolt holes, etc., which have little impact on the simulation, and saved as a general geometric file format "*.x_t".

[0026] Import the bottom support leg geometry file into HyperMesh software. After breaking down the complex geometry into a combination of simpler geometries, the bottom support leg mesh is generated using the 3D solid element C3D8. Then, material properties are assigned to the bottom support leg, with a density of 7850 kg / m³. 3 The elastic modulus is 210 GPa, the Poisson's ratio is 0.3, and the element section property is assigned the name "SOLIDSECTION".

[0027] Export the data as an ABAQUS software input file "*.inp" for later use.

[0028] Model the upper and lower platforms of the launch pad.

[0029] In CAD software, perform geometric preprocessing on the upper and lower platforms of the launch pad, removing chamfers, bolts, bolt holes, etc., which have little impact on the simulation, and save them as a general geometric file format "*.x_t".

[0030] Import the geometry files of the upper and lower platforms into HyperMesh software, and extract the mid-surface of the steel plates and flanges in the upper and lower platforms as geometric feature surfaces.

[0031] The geometric feature surfaces are divided into 2d elements of type S4R. Thickness is assigned to the elements containing the steel plate and the flange plate according to their actual thickness, along with material and element section properties. For example, when assigning material properties, the density is set to 7850 kg / m³. 3 The elastic modulus is 210 GPa and the Poisson's ratio is 0.3. The element section property is assigned the name "SHELLSECTION".

[0032] Tie constraints are applied to steel plates with flange connections, with a tolerance set to 1.5 times the flange plate thickness. Initial gap elimination is not set to avoid mesh distortion.

[0033] Export as an ABAQUS calculation input file "*.inp" for later use.

[0034] Step 13: Model the rocket's outriggers.

[0035] Specifically, in CAD software, the rocket body legs are geometrically preprocessed, removing chamfers, bolts, bolt holes, etc., which have little impact on the simulation, and saved as a general geometric file format "*.x_t".

[0036] The geometry file of the rocket's outriggers was imported into HyperMesh software. After breaking down the complex geometry into a combination of simpler geometries, the bottom outrigger mesh was created using 3D solid elements (C3D8). Material properties were then assigned to the outriggers, with a density of 7850 kg / m³. 3The elastic modulus is 210 GPa, the Poisson's ratio is 0.3, and the element section property is assigned the name "SOLIDSECTION".

[0037] Export the data as a calculation input file "*.inp" for ABAQUS software and keep it for later use.

[0038] Step 14: Assemble the bottom support leg model, the upper and lower platform models, and the rocket body support leg model according to their positional relationship.

[0039] Specifically, the upper and lower platform models are imported into the ABAQUS software as the basic structure, and the bottom support legs and arrow body support legs are imported as branch structures.

[0040] The bottom support legs and the arrow body support legs are arrayed and copied in order of quantity, and the arrayed parts are translated and rotated according to their actual positional relationship.

[0041] A set of nodes is established for the upper surface of the upper platform and the lower surface of the rocket's outriggers. Tie constraints are used to constrain the upper platform and the rocket's outriggers. The master node is the upper surface of the upper platform, and the slave node is the lower surface of the rocket's outriggers. Tolerances are set according to the gap distance.

[0042] The nodes in the connection area between the lower surface of the platform and the bottom support leg are coupled to the center node, which serves as the interface node connecting to the bottom support leg. Similarly, the nodes on the upper surface of the bottom support leg are coupled to the center node, which also serves as the interface node connecting to the lower platform. The rotational degree of freedom between the center node of the lower platform and the center node of the bottom support leg is constrained by a spring, while the translational and torsional degrees of freedom are coupled. The rotational spring stiffness is established as the core parameter for model correction.

[0043] The connection relationships of a launch pad are divided into the connection between the support leg and the launch pad, and the connection between the launch pads. The stiffness of the connection between the launch pads is relatively certain, but the stiffness of the connection between the launch pad and the support leg is difficult to model accurately. Therefore, it is necessary to model it using a parametric method. The specific parameter is the rotational spring stiffness, and the parameter is corrected based on the actual measurement results. The corrected result can ensure that the model is consistent with the actual connection state.

[0044] Step 15: Perform modal analysis on the assembled launch platform model. The purpose of this analysis is to check for any abnormalities in the model. After confirming that the model is correct, save it as a "FST.inp" file for later use.

[0045] S2. Build a launch platform modal testing system and conduct physical modal testing.

[0046] like Figure 2As shown, the modal testing system consists of two parts: an excitation subsystem and a testing subsystem. The excitation subsystem includes: an exciter, a force hammer, a power amplifier, and matching cables. The testing subsystem includes: a force sensor, an accelerometer, a data acquisition chassis, and matching cables.

[0047] After the launch platform is transported and its state changes from electric pulley drive to outrigger fixed support, a specific location on the platform is excited using a vibrator or hammer. During the test, the excitation force signal and sensor acceleration signal are transmitted via cable to the software for real-time identification of modal parameters, including modal frequencies, mode shapes, and damping ratios. The launch platform only needs to measure the first three low-frequency modes in the outrigger fixed support state.

[0048] S3. Automatically correct the model based on modal test data and error identification.

[0049] Since the rotational spring stiffness is a parameterized representation of the connection between the outrigger and the launch pad, the rotational spring stiffness was obtained here based on the optimization method. The modal results calculated using this stiffness are consistent with the actual measurement results, which shows that the model has been consistent with the actual launch pad state, that is, automatic correction has been achieved.

[0050] When automatically correcting the structural dynamics model, the similarity between the modal frequencies and mode shapes in the measured and simulation results is considered. The similarity of the mode shapes is evaluated using the modal similarity function (MAC).

[0051] The established objective function is: ; In the formula, Modal contribution coefficient; The frequency value is the simulated frequency value of the i-th modality. The frequency value of the i-th modal test; The MAC value of the simulated and measured modal shape of the i-th order mode; in, ; In the formula, The measured mode shape of the i-th mode; Calculate the mode shape for the i-th mode.

[0052] Since the objective function cannot be written in analytical form, the optimal solution cannot be obtained by the derivative-based method. In this embodiment, the golden section search method is used to find the optimal rotational stiffness.

[0053] The search range for rotational stiffness is taken as Because the range is large, therefore the independent variable... Take the logarithm to the base 10, that is: ; in, For rotational stiffness.

[0054] This results in a wider range of rotational stiffness. Transform into a smaller range of independent variables The optimization problem, with values ​​ranging from... .

[0055] Take a trial point in the middle of this range: ; ; ; ; Will , Replace the corresponding rotational spring stiffness parameters in the assembled launch platform model and calculate the objective function value. and The contribution coefficients for the first-order modes are 0.5, the second-order modes are 0.3, and the third-order modes are 0.2.

[0056] Compare and Keep the interval with the smaller objective function and repeat the above process until... .

[0057] The above formula means that after repeatedly performing the above process, the initially selected range of k values ​​is continuously reduced until the absolute value of the difference between the maximum and minimum values ​​of the range is less than a certain preset value. This indicates that the accuracy of the k value is high enough that the iteration process can be stopped.

[0058] The final optimized rotational stiffness parameters are as follows: .

[0059] It should be noted that other optimization methods capable of solving for the optimal rotational stiffness can also yield the final result.

[0060] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0061] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for correcting the dynamic model of a launch vehicle platform, characterized in that, include: S1. Establish a structural dynamics model of the launch platform for the carrier rocket and reserve correction parameters; S2. Build a launch platform modal testing system and conduct physical modal testing; S3. Automatically correct the model based on modal test data and error identification.

2. The method for correcting the dynamic model of a launch platform for a carrier rocket as described in claim 1, characterized in that, Step S1 includes: S11. Model the bottom support legs; S12. Model the upper and lower platforms of the launch pad; S13. Model the support legs of the arrow body; S14. Assemble the bottom support leg model, upper and lower platform models, and rocket body support leg model into a launch platform model according to their positional relationship. S15. Perform modal analysis on the assembled launch platform model and check for any anomalies in the model. Save the model if no anomalies are found.

3. The method for correcting the dynamic model of a launch platform for a carrier rocket as described in claim 2, characterized in that, Step S11 includes: In CAD software, perform geometric preprocessing on the bottom support legs, remove chamfers, bolts and bolt holes that have little impact on the simulation, and save them in a general geometric file format; Import the bottom leg geometry file into HyperMesh software. After cutting the complex geometry into a combination of simpler geometry, use the 3D solid element C3D8 to complete the bottom leg mesh generation. Assign material properties to the bottom leg and export it in a format that can be imported into ABAQUS software.

4. The method for correcting the dynamic model of a launch platform for a carrier rocket as described in claim 3, characterized in that, Step S12 includes: In CAD software, perform geometric preprocessing on the upper and lower platforms of the launch pad, remove chamfers, bolts and bolt holes that have little impact on the simulation, and save them in a general geometric file format. Import the geometry files of the upper and lower platforms into HyperMesh software, and extract the mid-surface of the steel plates and flanges in the upper and lower platforms as geometric feature surfaces. Divide the geometric feature surface into 2D elements, assign thickness to the element containing the steel plate and the element containing the flange plate according to the actual thickness, and assign material properties and element section properties. Tie constraints are applied to steel plates with flange connections, with the tolerance set to be greater than the flange plate thickness, and no initial clearance elimination is set. Export to a format that can be input into ABAQUS software.

5. The method for correcting the dynamic model of a launch platform for a carrier rocket as described in claim 4, characterized in that, Step S13 includes: In CAD software, perform geometric preprocessing on the rocket body legs, remove chamfers, bolts and bolt holes that have little impact on the simulation, and save them in a general geometric file format; Import the rocket body and leg geometry files into HyperMesh software. After cutting the complex geometry into a combination of simple geometry, use the 3D solid element C3D8 to complete the bottom leg mesh generation. Then, assign material properties to the rocket body and legs, assign element section properties, and export them into a format that can be imported into ABAQUS software.

6. The method for correcting the dynamic model of a launch platform for a carrier rocket as described in claim 5, characterized in that, Step S14 includes: Import the upper and lower platform models into ABAQUS software as the basic structure, and import the bottom support legs and arrow body support legs as branch structures. The bottom support legs and the arrow body support legs are arrayed and copied according to their quantity, and the arrayed parts are translated and rotated according to their actual positional relationship; Establish a set of nodes on the upper surface of the upper platform and the lower surface of the rocket body legs. Use Tie constraints to constrain the upper platform and rocket body legs. The master node is the upper surface of the upper platform and the slave node is the lower surface of the rocket body legs. Set the tolerance according to the gap distance. The nodes in the connection area between the lower surface of the platform and the bottom support leg are coupled to the center node, which serves as the interface node for connection with the bottom support leg. The nodes in the upper surface area of ​​the bottom support leg are coupled to the center node, which serves as the interface node for connection with the lower platform. The rotational degree of freedom between the center node of the lower platform and the center node of the bottom support leg is constrained by springs, while the translational and torsional degrees of freedom are coupled. The stiffness of the rotational spring was established as the core parameter for model correction.

7. The method for correcting the dynamic model of a launch platform for a carrier rocket as described in claim 6, characterized in that, The launch platform modal testing system built in step S2 includes an excitation subsystem and a testing subsystem; the excitation subsystem includes an exciter, a force hammer, a power amplifier and supporting cables; the testing subsystem includes a force sensor, an acceleration sensor, a data acquisition chassis and supporting cables.

8. The method for correcting the dynamic model of a launch platform for a carrier rocket as described in claim 7, characterized in that, Step S3 includes: establishing an objective function to evaluate the similarity between modal frequencies and mode shapes in measured and simulated results, obtaining the optimal rotational stiffness, and using the optimal rotational stiffness as a correction parameter to correct the dynamic model of the launch vehicle platform.

9. A computing device, characterized in that, include: The processor and the memory storing a computer program, wherein the computer program, when executed by the processor, performs the method for correcting the dynamic model of a launch platform as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed on a computer, cause the computer to perform the method for correcting the dynamic model of a launch platform as described in any one of claims 1 to 8.

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