Large-scale finite element simulation model simplification method

Abstract

The invention relates to the field of simulation model simplification, in particular to a large-scale finite element simulation model simplification method, which comprises the following steps of: establishing a basic model, splitting the basic model into a plurality of sub-models, determining the resolution ratio of each sub-model, and performing secondary modeling on a structure model according to the resolution ratios of the sub-models. A simulation refining model and an abstraction model are respectively generated for each secondary modeling according to the actual structure corresponding to the structure, a corresponding simulation refining model is generated, and underwater vibration noise calculation is performed on the structure, so that the number of grid units of a finite element model is greatly reduced, the modeling difficulty is reduced, the calculation efficiency is improved, and the calculation efficiency is improved. And underwater vibration noise calculation of a large-scale complex structure is realized.

Description

Technical Field

[0001] The present invention relates to the field of simulation model simplification, and in particular to a large-scale finite element simulation model simplification method. Background Art

[0002] The finite element method is a commonly used method for calculating the vibration and noise of underwater structures. However, for objects with large size and complex internal structure, the number of finite element grid units is very large, often reaching more than one million. Not only is the grid division difficult, the simulation process has extremely high requirements on the computer's computing performance, and the calculation time is very long, the calculation is difficult, and it is easy to make mistakes.

[0003] In order to realize the underwater vibration and noise calculation of large-scale complex structures, it is necessary to control the number of finite element grid units, that is, to simplify the finite element model. However, the simplification of the model is bound to cause a decrease in the accuracy of the simulation results. Therefore, it is crucial to simplify the finite element simulation model while ensuring that the simulation results are quite accurate.

[0004] Chinese patent authorization announcement number: CN112257307B discloses a simulation calculation method and system for the walking resistance of underwater tracked equipment, including: establishing a three-dimensional solid model of track plates, underwater tracked equipment and water environment; based on the three-dimensional solid model of track plates, establishing a discrete unit model of underwater soil, calculating the mechanical properties of soil particles and the dynamic response data of track plates; based on the three-dimensional solid model of underwater tracked equipment and water environment, establishing a finite element model of water environment, calculating the dynamic response data of underwater tracked equipment at different flow rates; based on the simulation calculation results of soil mechanics and fluid mechanics, establishing the dynamic equation of underwater tracked equipment walking; solving the dynamic equation to obtain a three-dimensional schematic diagram of the environmental resistance of underwater tracked equipment when walking under the combined action of different soil environments and water environments. The invention can accurately calculate the walking resistance of underwater tracked equipment in complex environments.

[0005] However, the above method has the following problems: the number of mesh elements in the finite element model is large and the calculation efficiency is low. Summary of the invention

[0006] To this end, the present invention provides a large-scale finite element simulation model simplification method to overcome the problems of a large number of grid units and low calculation efficiency in the finite element model in the prior art.

[0007] To achieve the above object, the present invention provides a large-scale finite element simulation model simplification method, comprising:

[0008] Establish a basic model and split the basic model into several sub-models;

[0009] Determine the resolution of each sub-model, and perform secondary modeling on the structural model according to the resolution of the sub-model;

[0010] Generate simulation refined models and abstract models for each secondary modeling according to the actual structure corresponding to the structure;

[0011] According to the basic model, each sub-model is subjected to secondary modeling to generate a finite element model including at least a beam unit and a structure, and the end points of the beam unit and the cross section of the tail structure model are rigidly constrained to form a secondary basic model;

[0012] Performing finite element modeling on the secondary basic model, and adding the total mass to the axial segment of the model accordingly, to generate a corresponding simulation refined model;

[0013] Performing underwater vibration and noise calculation on the structure;

[0014] Wherein, the structure at least includes a tail structure and a cylindrical shell structure;

[0015] The front cylindrical shell structure of the structure is simplified into the beam unit having the same length, diameter and thickness as the original structure.

[0016] Furthermore, when calculating the underwater vibration noise generated by the structure, the structure is simulated and refined according to the actual structural composition.

[0017] The simulation refined model at least includes a model of the tail structure and a model of the beam unit formed with a cylindrical shell as the main structural body.

[0018] Furthermore, the rigid constraint is to impose hard limits on the physical quantities of the tail structure and the cylindrical shell structure so that the physical quantities remain unchanged during the simulation process;

[0019] The physical quantities include relative position, velocity and / or acceleration.

[0020] Furthermore, the simulation refinement model is fitted, and a number of data are generated according to a number of indicator characteristics.

[0021] Wherein, the indicator characteristics include the shape, mass and / or relative position of the structure.

[0022] Furthermore, when performing the underwater vibration noise calculation, the calculated total mass includes the structural mass of the structure itself, the mass of the water between the double-layer shells, and the mass of the water attached to the outside of the shells.

[0023] Furthermore, the structural mass of the structure itself is calculated,

[0024] Wherein, when calculating the structural mass, the non-structural mass is added to the corresponding beam unit.

[0025] Furthermore, the non-structural mass is the difference between the mass of the beam unit and the structural mass of the cylindrical shell.

[0026] Furthermore, the mass of the water between the double-layer shells is calculated, and the mass of the water between the double-layer shells is added to the corresponding beam unit model.

[0027] Further, the mass of the water attached to the outside of the shell is calculated, and the mass of the water attached to the outside of the shell is added to the corresponding beam unit model.

[0028] Furthermore, the structure is modeled by finite element, and the structural mass of the structure itself, the mass of the water between the double-layer shells, and the mass of the water attached to the outside of the shells are added to the axial segments of the model accordingly.

[0029] Compared with the prior art, the present invention establishes a basic model and splits it into several sub-models, determines the resolution of each sub-model, and performs secondary modeling on the structure model according to the resolution of the sub-model, and generates a simulation refined model and an abstract model for each secondary model according to the actual structure corresponding to the structure, performs secondary modeling on each sub-model according to the basic model to generate a finite element model including at least a beam unit and a structure, and rigidly constrains the end points of the beam unit and the cross-section of the tail structure model to form a secondary basic model, performs finite element modeling on the secondary basic model, and adds the total mass to the axial segment of the model to generate a corresponding simulation refined model, and performs underwater vibration and noise calculation on the structure, which greatly reduces the number of grid units in the finite element model, reduces the difficulty of modeling, improves the efficiency of calculation, and realizes the underwater vibration and noise calculation of large-scale complex structures.

[0030] Furthermore, by establishing the tail structure model and the simplified beam unit model of the cylindrical shell structure, the difficulty of meshing is reduced and the number of mesh elements in the finite element model is greatly reduced.

[0031] Furthermore, by rigidly constraining the end points of the beam unit and the cross-section of the tail structure model, the deformation consistency of the connection points is achieved, which improves the accuracy of the calculation.

[0032] Furthermore, by fitting the simulation refinement model and generating a number of data according to a number of indicator characteristics, the difficulty of calculation is reduced and the efficiency of underwater vibration and noise calculation is improved.

[0033] Furthermore, by adding the structural mass of the structure itself, the mass of the water between the double-layer shells, and the mass of the water attached to the outside of the shells when calculating the underwater vibration noise, the accuracy of the simplified simulation calculation results is guaranteed.

[0034] Furthermore, by adding non-structural mass, the mass of water between the double-layer shell, and the mass of water attached to the outside of the shell to the corresponding beam element model, the beam element part is simplified, and the underwater vibration and noise calculation of large-scale complex structures is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A flowchart of a large-scale finite element simulation model simplification method of the present invention;

[0036] Figure 2 It is a schematic diagram of the simulation refinement model of the present invention;

[0037] Figure 3 This is a schematic diagram of the actual axial mass distribution of a double-layer cylindrical shell structure simplified as a beam unit in the present invention;

[0038] Figure 4 A schematic diagram of the mass distribution of water between the double-layer cylindrical shell structures simplified as beam units of the present invention;

[0039] Among them: 1. Tail structure model; 2. Simplified beam unit model of cylindrical shell structure. DETAILED DESCRIPTION

[0040] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0042] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is only for description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0043] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] See also Figure 1 As shown, it is a flow chart of a large-scale finite element simulation model simplification method of the present invention, including:

[0045] Step S1, establishing a basic model and splitting the basic model into several sub-models;

[0046] Step S2, determining the resolution of each sub-model, and performing secondary modeling on the structural model according to the resolution of the sub-model;

[0047] Step S3, generating a simulation refined model and an abstract model for each secondary modeling according to the actual structure corresponding to the structure;

[0048] Step S4, based on the basic model, secondary modeling is performed on each sub-model to generate a finite element model including at least a beam unit and a structure, and the end points of the beam unit and the cross section of the tail structure model are rigidly constrained to form a secondary basic model;

[0049] Step S5, performing finite element modeling on the secondary basic model, and adding the total mass to the axial segment of the model to generate a corresponding simulation refined model;

[0050] Step S6, calculating underwater vibration noise of the structure;

[0051] Wherein, the structure comprises at least a tail structure and a cylindrical shell structure;

[0052] The front cylindrical shell structure of the structure is simplified into a beam element with the same length, diameter and thickness as the original structure.

[0053] In specific implementation, the vibration of the tail structure in the form of a conical shell is an important component of the vibration noise of the double-layer cylindrical-conical combined structure. Therefore, when studying the calculation of underwater vibration noise caused by the tail structure, the focus part of the tail structure can be simulated and refined according to the actual structural composition, while the front cylindrical shell structure can be simplified to a beam unit with the same length, diameter and thickness as the original structure.

[0054] A basic model is established and split into several sub-models, the resolution of each sub-model is determined, and the structural model is secondary modeled according to the resolution of the sub-model. Each secondary model is generated into a simulation refined model and an abstract model according to the actual structure corresponding to the structure. According to the basic model, each sub-model is secondary modeled to generate a finite element model including at least a beam unit and a structure, and the end points of the beam unit and the cross-section of the tail structure model are rigidly constrained to form a secondary basic model. Finite element modeling is performed on the secondary basic model, and the total mass is added to the axial segment of the model to generate the corresponding simulation refined model. The underwater vibration and noise calculation of the structure is performed, which greatly reduces the number of grid units in the finite element model, reduces the difficulty of modeling, improves the efficiency of calculation, and realizes the underwater vibration and noise calculation of large-scale complex structures.

[0055] See also Figure 2 As shown, it is a schematic diagram of the simulation refinement model of the present invention. When calculating the underwater vibration noise generated by the structure, each secondary model is composed of the simulation refinement model according to the actual structure corresponding to the structure.

[0056] The simulation refined model at least includes a tail structure model 1 and a cylindrical shell structure simplified beam unit model 2.

[0057] By establishing the tail structure model and the simplified beam unit model of the cylindrical shell structure, the difficulty of meshing is reduced and the number of mesh elements in the finite element model is greatly reduced.

[0058] Specifically, the rigid constraints are to impose hard limits on the physical quantities of the tail structure and cylindrical shell structure so that the physical quantities remain unchanged during the simulation;

[0059] Physical quantities include relative position, velocity and / or acceleration.

[0060] By rigidly constraining the end points of the beam unit and the cross-section of the tail structure model, the deformation consistency of the connection point is achieved, which improves the accuracy of the calculation.

[0061] Specifically, the simulation refinement model is fitted and several data are generated according to several indicator characteristics.

[0062] The indicator features include the shape, mass and / or relative position of the structure.

[0063] Embodiment 1:

[0064] If the shape of the structure is selected as the indicator feature, if structure A is a cylindrical shell, structure B is a cylindrical shell, and structure C is a rectangular parallelepiped, then structures A and B are in one group, and structure C is in another group.

[0065] Embodiment 2:

[0066] If the mass of the structure is selected as the indicator feature, if the mass of structure A is 30kg, the mass of structure B is 30kg, and the mass of structure C is 200kg, then structures A and B are in one group, and structure C is in another group.

[0067] Embodiment 3:

[0068] If the relative position of the structures is selected as the indicator feature, if the relative position of structure A is front-to-back connection, the relative position of structure B is front-to-back connection, and the relative position of structure C is side-by-side connection, then structures A and B are in one group, and structure C is in another group.

[0069] By fitting the simulation refined model and generating a number of data according to a number of indicator characteristics, the difficulty of calculation is reduced and the efficiency of underwater vibration and noise calculation is improved.

[0070] Specifically, when calculating underwater vibration noise, the total mass calculated includes the structural mass of the structure itself, the mass of the water between the double-layer hulls, and the mass of the water attached to the outside of the hulls.

[0071] In specific implementation, when calculating the underwater vibration and noise of a structure, the total mass involved in the vibration includes not only the structural mass of the structure itself, but also the mass of the water between the double-layer shell and the mass of the water attached to the outside of the shell. Therefore, in order to ensure the accuracy of the simplified simulation calculation results, the simplified finite element model needs to take all the above three mass components into account according to the axial distribution.

[0072] Embodiment 4:

[0073] If the mass of the structure itself is 5kg, the mass of the water between the double shells is 50kg, and the mass of the water attached to the outside of the shells is 60kg, the total mass is 115kg.

[0074] By adding the structural mass of the structure itself, the mass of the water between the double-layer shells, and the mass of the water attached to the outside of the shells when calculating underwater vibration and noise, the accuracy of the simplified simulation calculation results is guaranteed.

[0075] Specifically, the structural mass of the structure itself is calculated.

[0076] Among them, when calculating the structural mass, the non-structural mass is added to the corresponding beam element.

[0077] Specifically, the nonstructural mass is the difference between the mass of the beam element and the structural mass of the cylindrical shell.

[0078] During modeling, the unsimplified part is an accurate three-dimensional model, and its own structural mass can be taken into account by setting material parameters. However, for the part simplified into beam elements, since the mass of the simplified beam elements is usually different from the actual mass of the double-layer cylindrical shell structure, when calculating underwater vibration and noise, this part of the mass difference needs to be added to the corresponding beam elements in the form of non-structural mass.

[0079] The actual mass of the double-layer cylindrical structure of the beam element minus the mass of the corresponding beam element itself is the non-structural mass that needs to be added to the corresponding beam element when calculating the underwater vibration and noise of the structure.

[0080] Embodiment 5:

[0081] If the mass of the beam element is 10kg and the mass of the cylindrical shell structure is 5kg, then the non-structural mass is 5kg.

[0082] Embodiment 6:

[0083] If the mass of the beam element is 80kg and the mass of the cylindrical shell structure is 5kg, the non-structural mass is 75kg.

[0084] See also Figure 3 and Figure 4 As shown, they are respectively a schematic diagram of the actual axial mass distribution of the double-layer cylindrical shell structure simplified as a beam unit in the present invention and a schematic diagram of the mass distribution of water between the double-layer cylindrical shell structures simplified as beam units in the present invention. The mass of the water between the double-layer shells is calculated, and the mass of the water between the double-layer shells is added to the corresponding beam unit model.

[0085] When moving underwater, the cavity between the double-layer shell is filled with seawater. In the simplified model, the cylindrical shell structure at the front end is simplified to a beam unit. When calculating underwater vibration and noise, the effect of this part of water cannot be simulated. Therefore, the mass of this part of water must be added to the corresponding beam unit model.

[0086] Specifically, the mass of the water attached to the outside of the shell is calculated, and the mass of the water attached to the outside of the shell is added to the corresponding beam element model.

[0087] During modeling, the unsimplified part is an accurate three-dimensional model. When using finite element software to calculate the underwater vibration and noise of the structure, the effect of attached water can generally be directly considered by setting the fluid domain and parameters. Therefore, there is no need to specifically add the mass of attached water. However, for the part simplified into a beam unit, its attached water mass must be calculated separately and added to the beam unit as a non-structural mass.

[0088] On the basis of the above model simplification method, a large-scale double-layer cylindrical-conical combined structure is modeled by finite element method, and the above three masses are added to the axial segments of the model accordingly to obtain a simplified finite element model for underwater vibration and noise calculation.

[0089] Specifically, the structure is modeled by finite element, and the structural mass of the structure itself, the mass of the water between the double-layer shells, and the mass of the water attached to the outside of the shells are added to the axial segments of the model accordingly.

[0090] By adding non-structural mass, the mass of water between the double-layer shell, and the mass of water attached to the outside of the shell to the corresponding beam element model, the beam element part is simplified, and the underwater vibration and noise calculation of large-scale complex structures is realized.

[0091] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A large-scale finite element simulation model simplification method, characterized in that: include: Establish a basic model and split the basic model into several sub-models; Determine the resolution of each sub-model, and perform secondary modeling on the structural model according to the resolution of the sub-model; Generate simulation refined models and abstract models for each secondary modeling according to the actual structure corresponding to the structure; According to the basic model, each sub-model is subjected to secondary modeling to generate a finite element model including at least a beam unit and a structure, and the end points of the beam unit and the cross section of the tail structure model are rigidly constrained to form a secondary basic model; Performing finite element modeling on the secondary basic model, and adding the total mass to the axial segment of the model accordingly, to generate a corresponding simulation refined model; Performing underwater vibration and noise calculation on the structure; Wherein, the structure at least includes a tail structure and a cylindrical shell structure; The front cylindrical shell structure of the structure is simplified into the beam unit having the same length, diameter and thickness as the original structure.

2. The large-scale finite element simulation model simplification method according to claim 1, characterized in that: When calculating the underwater vibration noise generated by the structure, the structure is simulated and refined according to the actual structural composition. The simulation refined model at least includes a model of the tail structure and a model of the beam unit formed with a cylindrical shell as the main structural body.

3. The large-scale finite element simulation model simplification method according to claim 2, characterized in that: The rigid constraint is to impose hard limits on the physical quantities of the tail structure and the cylindrical shell structure so that the physical quantities remain unchanged during the simulation process; The physical quantities include relative position, velocity and / or acceleration.

4. The large-scale finite element simulation model simplification method according to claim 3, characterized in that: Fitting the simulation refinement model and generating a number of data according to a number of indicator characteristics, Wherein, the indicator characteristics include the shape, mass and / or relative position of the structure.

5. The large-scale finite element simulation model simplification method according to claim 4, characterized in that: When calculating the underwater vibration noise, the total mass calculated includes the structural mass of the structure itself, the mass of the water between the double-layer shells, and the mass of the water attached to the outside of the shells.

6. The large-scale finite element simulation model simplification method according to claim 5, characterized in that: Calculate the structural mass of the structure itself, Wherein, when calculating the structural mass, the non-structural mass is added to the corresponding beam unit.

7. The large-scale finite element simulation model simplification method according to claim 6, characterized in that: The non-structural mass is the difference between the mass of the beam unit and the structural mass of the cylindrical shell.

8. The large-scale finite element simulation model simplification method according to claim 7, characterized in that: The mass of the water between the double-layer shells is calculated, and the mass of the water between the double-layer shells is added to the corresponding beam unit model.

9. The large-scale finite element simulation model simplification method according to claim 8, characterized in that: The mass of the water attached to the outside of the shell is calculated, and the mass of the water attached to the outside of the shell is added to the corresponding beam element model.

10. The large-scale finite element simulation model simplification method according to claim 9, characterized in that: Finite element modeling is performed on the structure, and the structural mass of the structure itself, the mass of the water between the double-layer shells, and the mass of the water attached to the outside of the shells are added to the axial segments of the model accordingly.

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