Hanger fairing optimization method based on modal method

Abstract

The invention belongs to the field of hanger fairing design, and particularly relates to a hanger fairing optimization method based on a modal method. If a fault occurs in an experiment or use, redesign and improvement are needed, the development cost is greatly increased, and the development progress is influenced. According to the hanger fairing optimization method based on the modal method, according to the structural characteristics of the hanger fairing and the connection characteristics of the hanger fairing and a framework, the modal method is used for analyzing the first 10-order modals of the hanger fairing, and according to modal deformation, optimization constraint, the shell size and the supporting structure, the hanger fairing is optimized, the requirements for pneumatic shaping, strength and weight are met, and the hanger fairing is optimized. The method effectively reduces the complexity of the model, eliminates the influence of a load condition, improves the development efficiency, achieves a better optimization effect, and has a very high engineering application value.

Description

Technical Field

[0001] The invention belongs to the design field of a pylon fairing, and in particular relates to a pylon fairing optimization method based on a modal method. Background Art

[0002] The pylon fairing is an important functional component of the pylon, generally installed at the front and rear of the pylon. Most of them are conical or polygonal in shape. They play a role of rectification during flight and reduce the resistance and disturbance of the flow field to the pylon.

[0003] During flight, the pylon fairing is generally subjected to aerodynamic disturbances and vibration excitation from the pylon. The pylon fairing consists of three parts: a shell, a connecting assembly, and a support. The shell is the main load-bearing structure of the pylon fairing. The shell is connected to the support by a connecting assembly. The support is used to increase the strength and rigidity of the pylon fairing to meet the strength, rigidity, and life requirements of the pylon fairing. As an accessory of the pylon, the pylon fairing is generally designed based on experience and its function is verified through environmental tests such as vibration and impact. If a malfunction occurs during the experiment or use, it needs to be redesigned and improved, which greatly increases the development cost and affects the development progress.

[0004] With the rapid development of computer technology, the use of finite element software ANSYS for dynamic stress and fatigue analysis of pylon fairings has become an important means. As an accessory of the pylon, the pylon fairing needs to be modeled and analyzed as a whole with the pylon when performing dynamic stress analysis. The pylon structure is complex and large in size. The finite element model is huge in scale, the calculation cycle is long, and the calculation accuracy is poor when modeling and analyzing the whole. If problems occur in the pylon fairing during testing and use, the iteration cycle is long when using such a model to optimize and design the pylon fairing. Moreover, the vibration environment of the pylon is complex. When performing dynamic stress analysis, it is necessary to consider the excitations in the heading, vertical, and lateral directions. When optimizing and designing the pylon fairing, the weak positions of several load states are not completely consistent, and multiple iterations are required to find a better solution.

[0005] Therefore, it is necessary to design an optimization method for the pylon fairing model itself and eliminate the influence of load conditions. Summary of the invention

[0006] The purpose of the present invention is to provide a method for optimizing a pylon fairing based on a modal method.

[0007] The present invention proposes a method for optimizing a pylon fairing based on a modal method, the method comprising the following steps:

[0008] S1. Perform three-dimensional modeling on the pylon fairing to obtain a simulation model;

[0009] S2. Perform pre-processing on the simulation model, add part materials, constraint relationships, and set modal analysis conditions before simulation;

[0010] S3. According to the modal deformation, optimization of constraint relationship, pylon fairing size and support parts are performed;

[0011] The constraint relationship optimization includes: when the modal frequency of the analysis result is coupled with the working frequency of the bracket, or when the modal deformation area at the constraint position occupies ≥ 0.5 of the shortest side length of the geometric surface, adding a constraint relationship to the modal deformation area at the constraint position;

[0012] The optimization of the fairing size of the pylon includes: observing each modal deformation, selecting the torsion mode with the largest deformation, and when the modal frequency of the analysis result is coupled with the operating frequency of the pylon, or when the modal deformation area at the constraint position occupies ≥0.5 of the shortest side length of the geometric surface, adjusting the shell size according to the stiffness of the side torsion stiffness W1 and the upper and lower torsion stiffness W2 close to 1:1 to increase the torsion stiffness;

[0013] Support optimization includes: observing each modal deformation, selecting two bending modes and one torsion mode with the largest deformation, and when the modal frequency of the analysis result is coupled with the operating frequency of the bracket, or when the modal deformation area at the constraint position occupies ≥0.5 of the shortest side length of the geometric surface, determining the number of supports and related positions according to the position and number of modal deformations, requiring the bending stiffness I1 of the support itself to be ≥0.2 times the bending stiffness I2 of the shell in the same direction;

[0014] S4. For the simulation model of the optimized pylon fairing, the constraint relationship is re-determined and the modal analysis conditions are set for simulation. When the modal frequency of the analysis result is not coupled with the pylon operating frequency and the maximum modal deformation is reduced by more than 30%, the optimization is terminated.

[0015] Advantageously, the simulation model is created in the SolidWorks software environment.

[0016] Advantageously, the simulation model of the pylon fairing is imported into ansys software for modal analysis.

[0017] Advantageously, the constraint comprises that the connection relationship between the shell and the skeleton is set as a fixed constraint.

[0018] Advantageously, the modal analysis includes setting to perform a 10th order modal analysis without considering damping, and the solver type is controlled by a program.

[0019] Advantageously, the connecting components are bolts, the spacing between the connecting components is ≥2 times the diameter of the connecting components, and the distance between the connecting components and the edge is ≥2 times the diameter of the connecting components.

[0020] Advantageously, for a rectangular cross section, the torsional stiffness W = 0.3ht 2 , h is the height of the rectangular section, and t is the width of the rectangular section.

[0021] Advantageously, the support member is a thin plate with a rectangular cross section, a U-shaped channel, an I-beam or a combined frame.

[0022] Advantageously, for a pylon fairing and support of rectangular cross-section, the bending stiffness I = 0.16h 2 t, h are the height of the rectangular section, and t is the width of the rectangular section.

[0023] Beneficial effects: The present invention uses the modal method to analyze the first 10 modes of the pylon fairing according to the structural characteristics of the pylon fairing and the connection characteristics with the skeleton, and optimizes the constraints, shell size, and supporting structure according to the modal deformation, thereby optimizing the pylon fairing to meet the requirements of aerodynamic shaping, strength, and weight, effectively reduce the complexity of the model, eliminate the influence of load conditions, improve the development efficiency, achieve better optimization effects, and have high engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the pylon fairing model of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure with added support;

[0026] Figure 3 It is an analysis chart for adding support. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings, but the specific implementation of the present invention is not limited thereto. The method includes the following steps:

[0028] S1. In the SolidWorks software environment, three-dimensional modeling of the pylon fairing is performed, such as Figure 1 shown.

[0029] S2. Import the simulation model of the pylon fairing into the ANSYS software, perform pre-processing on the simulation model, add the part material as alloy aluminum, add constraint relationships and set modal analysis conditions, and then perform simulation analysis.

[0030] The constraints include: the connection relationship between the shell and the skeleton is set as a fixed constraint.

[0031] Modal analysis includes: setting up 10th-order modal analysis, ignoring damping, and the solver type is controlled by the program.

[0032] S3. According to the modal deformation of the 10th-order mode, the constraint relationship optimization, the size optimization of the pylon fairing and the support optimization are carried out.

[0033] Constraint relationship optimization includes: when the modal frequency of the analysis result is coupled with the operating frequency of the bracket, or when the modal deformation area at the constraint position occupies ≥ 0.5 of the shortest side length of the geometric surface, add a constraint relationship to the modal deformation area at the constraint position, that is, add a connection component, see Figure 2 , and requires that the spacing of the connecting components (bolts are used in this embodiment) is ≥ 2 times the diameter of the connecting components (the bolt diameter in this embodiment), and the distance between the connecting components and the edge is ≥ 2 times the diameter of the connecting components (the bolt diameter in this embodiment).

[0034] The optimization of the fairing size of the pylon includes: observing each modal deformation, selecting the torsion mode with the largest deformation, and when the modal frequency of the analysis result is coupled with the operating frequency of the pylon, or when the modal deformation area at the constraint position occupies ≥0.5 of the shortest side length of the geometric surface, the side torsion stiffness W1 and the upper and lower torsion stiffness W2 are close to 1:1, changing the shell size and increasing the torsion stiffness. Among them, for rectangular cross-sections, torsion stiffness W = 0.3ht 2 , h is the height of the rectangular section, t is the width of the rectangular section, determine the side torsional stiffness W1 and design the dimensions.

[0035] The support optimization includes: observing each order of modal deformation, selecting two bending modes and one torsion mode with the largest deformation, when the modal frequency of the analysis result is coupled with the operating frequency of the pylon, or when the modal deformation area at the constraint position occupies ≥ 0.5 of the shortest side length of the geometric surface, according to the position and number of modal deformation, determine the number of supports and related positions, and require the support (this embodiment uses a rectangular cross-section thin plate, and others are not limited to U-shaped grooves, I-beams, combined frames, etc.) The bending stiffness I1 of the support itself is ≥ 0.2 times the bending stiffness I2 of the shell in the same direction. Among them, for the pylon fairing and support with a rectangular cross-section, the bending stiffness I = 0.16h 2 t, h are the heights of the rectangular section, and t is the width of the rectangular section. Based on the known dimensions of the pylon fairing, the bending stiffness I1 of the support is determined and the dimensions are designed.

[0036] S4. For the simulation model of the optimized pylon fairing, redefine the constraint relationship and set the modal analysis conditions for simulation. Figure 3 , the optimization is terminated when the modal frequency of the analysis result is not coupled with the operating frequency of the bracket and the maximum modal deformation is reduced by more than 30%.

Claims

1. A method for optimizing a pylon fairing based on a modal method, characterized in that: The method comprises the following steps: S1. Perform three-dimensional modeling on the pylon fairing to obtain a simulation model; S2. Perform pre-processing on the simulation model, add part materials, constraint relationships, and set modal analysis conditions before simulation; S3. According to the modal deformation, optimization of constraint relationship, pylon fairing size and support parts are performed; The constraint relationship optimization includes: when the modal frequency of the analysis result is coupled with the working frequency of the bracket, or when the modal deformation area at the constraint position occupies ≥ 0.5 of the shortest side length of the geometric surface, adding a constraint relationship to the modal deformation area at the constraint position; The optimization of the fairing size of the pylon includes: observing each modal deformation, selecting the torsion mode with the largest deformation, and when the modal frequency of the analysis result is coupled with the operating frequency of the pylon, or when the modal deformation area at the constraint position occupies ≥0.5 of the shortest side length of the geometric surface, adjusting the shell size according to the stiffness of the side torsion stiffness W1 and the upper and lower torsion stiffness W2 close to 1:1 to increase the torsion stiffness; Support optimization includes: observing each modal deformation, selecting two bending modes and one torsion mode with the largest deformation, and when the modal frequency of the analysis result is coupled with the operating frequency of the bracket, or when the modal deformation area at the constraint position occupies ≥0.5 of the shortest side length of the geometric surface, determining the number of supports and related positions according to the position and number of modal deformations, requiring the bending stiffness I1 of the support itself to be ≥0.2 times the bending stiffness I2 of the shell in the same direction; S4. For the simulation model of the optimized pylon fairing, the constraint relationship is re-determined and the modal analysis conditions are set for simulation. When the modal frequency of the analysis result is not coupled with the pylon operating frequency and the maximum modal deformation is reduced by more than 30%, the optimization is terminated.

2. The method for optimizing the pylon fairing according to claim 1, characterized in that: The simulation model was established in SolidWorks software environment.

3. The method for optimizing the pylon fairing according to claim 1, characterized in that: Import the simulation model of the pylon fairing into ANSYS software for modal analysis.

4. The method for optimizing the pylon fairing according to claim 1, characterized in that: The constraint includes setting the connection relationship between the shell and the skeleton as a fixed constraint.

5. The method for optimizing the pylon fairing according to claim 1, characterized in that: The modal analysis includes setting up a 10th-order modal analysis without considering damping, and the solver type is controlled by the program.

6. The method for optimizing the pylon fairing according to claim 1, characterized in that: The connecting components adopt bolts, the spacing between the connecting components is ≥ 2 times the diameter of the connecting components, and the distance between the connecting components and the edge is ≥ 2 times the diameter of the connecting components.

7. The method for optimizing the pylon fairing according to claim 6, characterized in that: For rectangular cross-sections, torsional stiffness W = 0.3ht 2 , h is the height of the rectangular section, and t is the width of the rectangular section.

8. The method for optimizing the pylon fairing according to claim 1, characterized in that: The supporting members are made of rectangular cross-section thin plates, U-shaped grooves, I-beams or combined frames.

9. The method for optimizing the pylon fairing according to claim 8, characterized in that: For the rectangular cross-section pylon fairing and support, the bending stiffness I = 0.16h 2 t, h are the height of the rectangular section, and t is the width of the rectangular section.

Images