CN-122021123-A - Finite element modeling method for flight simulation turntable frame

CN122021123ACN 122021123 ACN122021123 ACN 122021123ACN-122021123-A

Abstract

The invention provides a finite element modeling method for a flight simulation turntable frame, which relates to the technical field of flight simulation turntable simulation and comprises the following steps: the method comprises the steps of S1, modeling a mixed bias shell unit of a turntable frame, S3, modeling multi-rule equivalent of a shell unit of a thin-wall structure and a reinforcing rib, and S4 model integration and application, wherein the configurability of model precision and efficiency is realized by respectively setting differential bias rules and multi-rule equivalents for a cylindrical component, a thin wall and the reinforcing rib, the complexity and calculation task requirements of the model are optimally matched under mechanical equivalent by adopting various rules from high fidelity to high efficiency according to a design stage and an analysis target, and the equivalent simplification of bending resistance and torsional rigidity of a reinforcing rib-thin wall composite section is realized by setting the geometric characteristics of the reinforcing rib with the normal bias parameters of a neutral plane and the reference plane.

Inventors

CHEN YANYAN
GAO FENG
JIN QINGHUA
GAO XIAOKUN
DONG XIAOYAN
ZHAO KUN

Assignees

北京长城航空测控技术研究所有限公司
中国航空工业集团公司北京长城航空测控技术研究所

Dates

Publication Date: 20260512
Application Date: 20251229

Claims (9)

1.A finite element modeling method for a flight simulation turntable frame is characterized by comprising the following steps: S1, identifying geometric characteristics and mechanical characteristic parameters of a turntable frame, wherein the turntable frame comprises a support end and load end cylinder assembly and a thin-wall-reinforcing rib composite assembly; s2, setting a mixed representation surface bias rule of a support end and a load end cylindrical component, wherein the wall thickness of the cylindrical component is represented by a thickness parameter of a shell unit, and the mixed representation surface bias rule comprises that a neutral surface of the shell unit is biased to a cylindrical component connection surface at a cylindrical component part connected with an adjacent thin wall, and the neutral surface of the shell unit is biased to the surface of the cylindrical component for a free end and a bearing assembly surface of the cylindrical component; S3, simulating a thin-wall-reinforcing rib composite assembly, wherein the thin wall is simulated by adopting a shell unit, a neutral plane is positioned by setting a bias reference plane of the shell unit as an outer surface, a middle surface or an inner surface, and the reinforcing rib is simulated by adopting the shell unit or a beam unit respectively and is mechanically connected with the thin-wall shell unit; S4, integrating the established structural model of the support end and load end cylindrical assemblies and the thin-wall-reinforcing rib composite assemblies, and configuring connection constraint among units, so that a finite element model for modal analysis, rigidity analysis and structural topology and size optimization of the turntable frame is obtained.
2. The method for modeling finite elements of a flight simulation turntable frame according to claim 1, wherein in the step S3, the reinforcing ribs are simulated by adopting shell units, the method comprises the steps of establishing the shell units perpendicular to the thin-wall shell units, forming T-shaped joint structures at the joints of the reinforcing ribs and the thin walls, and realizing mechanical coupling of the reinforcing ribs and the thin walls by configuring common nodes and connection constraints.
3. The method for modeling finite elements of a flight simulation turntable frame according to claim 1, wherein in the step S3, the reinforcing rib is simulated by adopting a shell unit, the method comprises the steps of establishing a shell unit coplanar with the thin-wall shell unit, and characterizing the geometric form of the convex and concave thin-wall surface of the reinforcing rib by setting the section attribute and the normal offset of a neutral plane relative to a geometric centroid of the shell unit, wherein the thickness, the section height and the normal offset of the coplanar shell unit are set in association with the offset reference plane of the thin-wall shell unit, so that the mechanical attribute of a composite section formed by the thin-wall shell unit and the coplanar shell unit is equivalent to the geometric structure.
4. The method according to claim 1, wherein in step S3, the stiffener is modeled by using a beam unit, including extracting a path center line of the stiffener as a geometric line of the beam unit, and giving geometric properties by setting a cross-sectional shape and a dimension parameter in a cross-sectional library, wherein the stiffener beam unit and the thin-walled shell unit are constrained by using multi-point constraint and rigid region coupling at a junction.
5. The finite element modeling method for the flight simulation turntable frame according to claim 4, wherein in the step S3, the reinforcing rib is simulated by adopting a beam unit, the method comprises the steps of establishing a beam unit local coordinate system, establishing a geometric datum line of the beam unit along a path center line of the reinforcing rib, and establishing a displacement constraint equation between corresponding nodes of the beam unit and the shell unit based on the beam unit local coordinate system, wherein the displacement constraint equation is specifically: ; In the formula, And J-direction displacements of the P node and the Q node of the beam unit are respectively j=1, 2 and 3, j=4, 5 and 6 are respectively translational degrees of freedom in the X, Y, Z-axis direction, j=4, 5 and 6 are respectively rotational degrees of freedom in the X, Y, Z-axis direction, and d is the distance between the geometric centroid of the beam unit and the shell unit.
6. The method of finite element modeling of a flight simulation turntable frame according to claim 1, wherein in the mixed representation surface bias rule of step S2, for a bearing interference fit and a support end and load end cylindrical assembly of a mounting surface, a cylindrical assembly shell element neutral plane is biased to a theoretical reference plane of the mounting surface, and for a non-mounting surface, a cylindrical assembly shell element neutral plane is biased to a cylindrical assembly inner surface.
7. The method of finite element modeling of a flight simulation turntable frame according to claim 1, wherein in the modeling of the cylindrical component of the mixed characterization surface bias rule in the step S2, the isotropic line elastic material property is given to the shell unit, and the size of the shell unit is determined based on the size of the turntable frame, the modal frequencies of each order, and the bending wave wavelength.
8. The method for modeling finite elements of a flight simulation turntable frame according to claim 1, wherein in the step S3, the reinforcing ribs are simulated by beam units, the connection between the beam units and the thin-wall shell units is integrated through coupling nodes, the end nodes of the beam units and the node groups in the corresponding connection areas of the shell units are associated through a motion coupling equation, the connection areas meet the assumption of a flat section, and the composite bending effect between the reinforcing ribs and the thin wall is simulated.
9. The method for modeling finite elements of a flight simulation turntable frame according to claim 1, further comprising a model verification step of comparing the natural frequency and the static deformation of a key point, which are calculated by a finite element model of the turntable frame under the same boundary condition, with a standard finite element model modal analysis result established based on a solid structure, and optimizing unit bias rules, connection setting and attribute parameters in a mixed characterization surface bias rule through frequency relative error and displacement confidence factors.

Description

Finite element modeling method for flight simulation turntable frame Technical Field The invention relates to the technical field of flight simulation turntable simulation, in particular to a finite element modeling method for a flight simulation turntable frame. Background The turntable frame is a key bearing component for supporting the flight simulation internal components and the tested load and transmitting motion and power. The static and dynamic mechanical properties, particularly rigidity and resonance modes, directly determine the motion precision, bandwidth and dynamic controllability of the turntable. In order to meet the requirements of high precision and high dynamic response, and meanwhile, light weight is achieved, a hollow thin-wall cylindrical structure is generally adopted as a main body of the turntable frame, and criss-cross reinforcing ribs are arranged at key positions so as to improve local rigidity and overall modal frequency. Therefore, the overall size, the local chamfer angle, the wall thickness parameter, the arrangement density, the cross-sectional shape, the geometric dimension and the like of the reinforcing ribs of the frame are important variables of the structural optimization design. Finite element analysis FEA is an indispensable tool for performing performance evaluation and optimization design of such complex structures. However, from preliminary conceptual design to detailed parameter optimization, the overall process requires balancing the contradiction of computational accuracy and modeling/solution efficiency. In the optimization design stage, iteration trial calculation is needed for massive design variable combinations, and the calculated amount is extremely large. At this time, a simplified finite element model which can ensure the prediction precision of key mechanical properties and minimize the grid scale is established, and is important for shortening the design period and improving the optimization efficiency. Currently, in the existing research of thin-wall structures and turntable designs, selection of specific unit types such as solid units, shell units and beam units or a simplified method of local connection structure are discussed, but research focuses are relatively scattered. A set of systematic, differentiated simplified modeling rules for typical detail configurations of flight simulation turret frames, such as support end/load end cylinder assemblies for mounting bearings/motors, and thin-walled-stiffener composite cylindrical arms connecting the two, have not been formed. Meanwhile, the model precision and the calculation efficiency after different simplification rules, such as different unit types, bias methods and connection processing combination application, are not systematically quantitatively evaluated and preferably guided. The lack of systematic methods and quantitative evaluation results in the fact that the model is simplified by experience, the simplified process is random, and a scientific and repeatable optimal balance between the complexity of the model and the calculation accuracy is difficult to achieve. The optimization iteration is slow due to the fact that the model is too fine, the overall design progress is tired, key mechanical characteristics are lost due to overgrowth, the optimization result deviates from the actual, and the quality and performance of the turntable frame are affected. It is therefore necessary to propose a method for finite element modeling of a flight simulation turret frame. Disclosure of Invention In order to solve the defects in the prior art, the invention aims to provide a finite element modeling method of a flight simulation turntable frame, which realizes the configurability of model precision and efficiency by respectively setting differential bias rules and multi-rule equivalents for a cylindrical component, a thin wall and a reinforcing rib, can adopt various rules from high fidelity to high efficiency according to a design stage and an analysis target, optimally matches the complexity of the model and the requirement of a calculation task under the mechanical equivalent, and realizes the equivalent simplification of bending resistance and torsional rigidity of the reinforcing rib-thin wall composite section by performing relevance setting on the geometric characteristic of the reinforcing rib with a normal bias vector parameter of a neutral plane and a thin wall reference plane, thereby providing a high-efficiency simulation basis for the size, shape and topology optimization of the turntable frame and obviously improving the design efficiency of simulation driving. The invention provides a finite element modeling method of a flight simulation turntable frame, which comprises the following steps: S1, identifying geometric characteristics and mechanical characteristic parameters of a turntable frame, wherein the turntable frame comprises a support end and load end cylinder assembly and a thin-