Modeling simulation method for undercarriage shimmy simulation by transport aircraft finite element

Abstract

The invention provides a modeling simulation method for undercarriage shimmy simulation through transport aircraft finite elements. The method comprises the following steps of: 1, constructing an undercarriage model in Abaqus finite element software; step 2, converting the whole aircraft inherent characteristic analysis model in the Nastran finite element software to obtain an aircraft body beam unit model compatible with the Abaqus finite element software; 3, in Abaqus finite element software, an MPC connection module in a Connector connection unit is used for connecting the undercarriage model with the fuselage model, and a full-aircraft shimmy simulation model is obtained. The method has the characteristics of high response sensitivity to excitation and accurate calculation result.

Description

Technical Field

[0001] The invention belongs to the technical field of transport aircraft structural dynamic response analysis, and in particular relates to a modeling and simulation method for transport aircraft finite element landing gear shimmy simulation. Background Art

[0002] Landing gear shimmy refers to a self-excited vibration generated by the front wheels or main wheels when the aircraft is taxiing during takeoff or landing, which deviates from the neutral position of the wheels and couples with each other in the lateral and torsional directions. It can cause severe shaking of the fuselage and affect the pilot's normal operation.

[0003] Large civil aircraft have their own characteristics in terms of aircraft nose wheel control taxiing stability and landing gear anti-shimmy design due to their heavy takeoff and landing weight, large structural size and flexibility, more complex landing gear system design, integrated front wheel steering anti-shimmy system, and the use of new radial tires. This is a more complex problem for the analysis of landing gear shimmy stability and airworthiness verification. Numerical simulation analysis is the main way to study landing gear shimmy. When transport aircraft perform aircraft shimmy calculations, multi-body dynamics software is usually used for modeling, but this modeling method has the disadvantages of low response sensitivity and low calculation result accuracy. Summary of the invention

[0004] The purpose of the present invention is to provide a modeling and simulation method for finite element simulation of landing gear shimmy of a transport aircraft. The present invention has the characteristics of high response sensitivity to excitation and accurate calculation results.

[0005] The technical solution of the present invention is: a modeling method for finite element simulation of landing gear shimmy of a transport aircraft, comprising the following steps:

[0006] Step 1. Build a landing gear model in Abaqus finite element software;

[0007] Step 2. Convert the whole aircraft inherent characteristic analysis model in Nastran finite element software to obtain a fuselage beam unit model compatible with Abaqus finite element software;

[0008] Step 3. In the Abaqus finite element software, use the MPC connection module in the Connector connection unit to connect the landing gear model to the fuselage model to obtain the whole aircraft vibration simulation model.

[0009] In the aforementioned modeling method for finite element simulation of landing gear shimmy of transport aircraft, in step 1, the steps of building the landing gear model are as follows:

[0010] Step 11. Based on the landing gear stiffness matrix obtained from the landing gear static test, the stiffness of the landing gear load-bearing component beam unit model in the Abaqus finite element software is modified;

[0011] Step 12. Based on the tire stiffness test data, the stiffness of the landing gear tire shell unit model in the Abaqus finite element software is modified;

[0012] Step 13. Based on the landing gear drop test data, the buffering performance of the landing gear buffer model in the Abaqus finite element software is modified;

[0013] Step 14. Based on the landing gear front shimmy damper damping test data, modify the damping parameters of the landing gear shimmy damper model in the Abaqus finite element software;

[0014] In the aforementioned modeling method for finite element simulation of landing gear shimmy of transport aircraft, in step 12, the tire stiffness test data includes: tire vertical stiffness, lateral stiffness, heading stiffness and torsional stiffness.

[0015] In the aforementioned modeling method of finite element landing gear shimmy simulation for transport aircraft, in step 13, in the simulation value of the buffering performance of the landing gear buffer model, the pressure of the buffer main oil chamber, return oil chamber, and air chamber are within 5% of the corresponding test values ​​of the drop shock test, and the error of the landing gear ground load is within 5% of the corresponding test value of the drop shock test.

[0016] In the aforementioned transport aircraft finite element modeling method for landing gear shimmy simulation, in step 2, before conversion, the whole aircraft inherent characteristic analysis model is corrected by the whole aircraft ground resonance test results.

[0017] A simulation method for the whole machine shimmy simulation model constructed based on the above modeling method comprises the following steps:

[0018] a. In Abaqus finite element software, create the sliding floor and excitation block;

[0019] b. Establish face-to-face contact between the landing gear tires and the floor and the excitation block;

[0020] c. Adjust the aircraft weight center of gravity and taxiing speed of the full-aircraft shimmy simulation model under various working conditions to obtain the corresponding shimmy simulation results.

[0021] In the above-mentioned simulation method, in step a, the structural parameters of the excitation block section are set to simulate the size of obstacles that the aircraft may encounter during the taxiing process.

[0022] In the above-mentioned simulation method, in step b, the heading motion pair of the aircraft fuselage is restricted, and the relative motion between the aircraft and the floor is controlled by controlling the speed of the floor.

[0023] In the above-mentioned simulation method, in step c, corresponding sub-files are constructed based on the fuselage beam unit model, the landing gear bearing assembly beam unit model, the landing gear tire shell unit model, the landing gear buffer model, and the landing gear shimmy damper model of the whole aircraft shimmy simulation model, and the shimmy simulation results under each working condition are in the sub-file corresponding to the sub-file for easy calling.

[0024] The above-mentioned simulation method also includes step d: generating an analysis main file based on the shimmy simulation results, analyzing whether the aircraft exceeds the aircraft ground load envelope after being excited by the excitation block, and whether the shimmy damper can quickly attenuate the excitation response.

[0025] The advantages of the present invention are as follows: the modeling method of the present invention corrects the parameters of the whole-machine shimmy simulation model based on the stiffness, buffering performance, damping parameters and the whole-machine inherent characteristic analysis model of the landing gear model, uses the Abaqus finite element software to solve the taxiing process of the aircraft, calculates and analyzes the vibration and shimmy response characteristics of the aircraft during the take-off and landing taxiing stages, and compared with the existing multi-body dynamics model, the whole-machine shimmy simulation model constructed by the present invention is more sensitive to excitation and has more accurate calculation results. The simulation method of the present invention also has the ability to batch process data independently, can generate batch processing files according to the type of design working conditions, and batch solve the landing gear response of the model under different weight centers of gravity, different taxiing speeds, and different excitation block profile excitations, which can greatly improve work efficiency.

[0026] The aircraft model is huge. Compared with the traditional multi-body dynamics modeling, the beam unit modeling of the aircraft using Abaqus finite element software can save modeling time. In addition, the calculation formula of the tire model in the multi-body dynamics model is complicated, and hundreds of parameters need to be debugged. The threshold for using the tire model is very high, which is not conducive to the rapid establishment of the shimmy simulation model. The present invention establishes a tire solid model based on Abaqus finite element software. By adjusting the limited structure and material parameters, a tire model that meets the stiffness requirements can be obtained, thereby greatly improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a model diagram of the front landing gear in the example of the present invention.

[0028] Figure 2 It is a main landing gear model diagram in an example of the present invention.

[0029] Figure 3 This is the whole machine vibration model diagram of this invention.

[0030] Figure 4 It is a cross-sectional view of the excitation block of the present invention.

[0031] Figure 5 The front wheel and the excitation block contact diagram in the present invention example

[0032] Figure 6 It is the torsion angle response history of the front landing gear wheel under the action of the excitation block in the example of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0035] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] Example 1: A modeling method for finite element simulation of landing gear shimmy of a transport aircraft, see Figure 1-Figure 6 , including the following steps:

[0037] Step 1. Build a landing gear model in Abaqus finite element software;

[0038] Step 2. Convert the whole aircraft inherent characteristic analysis model in Nastran finite element software to obtain a fuselage beam unit model compatible with Abaqus finite element software;

[0039] Step 3. In the Abaqus finite element software, use the MPC connection module in the Connector connection unit to connect the landing gear model to the fuselage model to obtain the whole aircraft vibration simulation model.

[0040] In the above step 1, the steps for building the landing gear model are as follows:

[0041] Step 11. Based on the landing gear stiffness matrix obtained from the landing gear static test, the stiffness of the landing gear bearing assembly beam unit model in the Abaqus finite element software is modified; the landing gear bearing assembly includes a wheel axle, a piston rod, an outer cylinder, an upper torque arm, a lower torque arm, a locking arm and a rotating shaft, etc.;

[0042] Step 12. Based on the tire stiffness test data, the stiffness of the landing gear tire shell unit model in the Abaqus finite element software is modified;

[0043] Step 13. Based on the landing gear drop test data, the buffer performance of the landing gear buffer model in the Abaqus finite element software is modified; the landing gear buffer model is modified according to the test results of the landing gear drop, and the buffer performance data of each working condition in the drop is modified according to the working condition requirements, and finally a set of general parameters is summarized according to the correction results of each working condition to ensure that the error is within the allowable range under each working condition;

[0044] Step 14. Based on the landing gear front shimmy damper damping test data, modify the damping parameters of the landing gear shimmy damper model in the Abaqus finite element software;

[0045] In the aforementioned step 12, the tire stiffness test data includes: tire vertical stiffness, lateral stiffness, heading stiffness and torsional stiffness. The tire vertical stiffness, lateral stiffness, heading stiffness and torsional stiffness need to be consistent with the test;

[0046] In the aforementioned step 13, in the simulation values ​​of the buffering performance of the landing gear buffer model, the pressures of the buffer main oil chamber, return oil chamber, and air chamber are within 5% of the corresponding test values ​​of the drop test, and the error between the landing gear ground load and the corresponding test value of the drop test is within 5%.

[0047] In the aforementioned step 2, before conversion, the whole-machine inherent characteristic analysis model is corrected by the whole-machine ground resonance test results.

[0048] Taking a typical transport aircraft as an example, Figure 3 When the excitation block shown is excited, how to judge whether the load exceeds the limit and whether the landing gear meets the anti-sway design requirements, the simulation method of the whole machine sway simulation model constructed by the above modeling method includes the following steps:

[0049] a. In Abaqus finite element software, create the sliding floor and excitation block;

[0050] b. Establish face-to-face contact between the landing gear tires and the floor and the excitation block;

[0051] c. Adjust the aircraft weight center of gravity and taxiing speed of the full aircraft shimmy simulation model under various working conditions to obtain the corresponding shimmy simulation results;

[0052] Step d: Generate the main analysis file based on the shimmy simulation results to analyze whether the aircraft exceeds the ground load envelope after being excited by the excitation block, and whether the shimmy damper can quickly attenuate the excitation response. Extract the load, displacement, acceleration of the landing gear under each working condition, and the overload of the center of gravity of the aircraft to ensure that the aircraft limit load is not exceeded during the impact of the excitation block. The dynamic response excited by the excitation block decays to 1 / 3 of the initial vibration amplitude within three cycles, which meets the design requirements.

[0053] In the aforementioned step a, the structural parameters of the excitation block cross section are set to simulate the size of obstacles that the aircraft may encounter during taxiing.

[0054] In the aforementioned step b, the heading motion pair of the aircraft fuselage is limited, and the relative motion between the aircraft and the floor is controlled by controlling the speed of the floor.

[0055] In the aforementioned step c, corresponding sub-files are constructed based on the fuselage beam unit model, the landing gear bearing assembly beam unit model, the landing gear tire shell unit model, the landing gear buffer model, and the landing gear shimmy damper model of the whole aircraft shimmy simulation model, and the shimmy simulation results under each working condition are in the sub-files corresponding to them for easy calling.

[0056] The modeling and simulation method provided by the present invention can obtain more reliable calculation results by correcting the model based on a large amount of test data.

[0057] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A modeling method for finite element simulation of landing gear shimmy of a transport aircraft, characterized in that: The following steps are involved: Step 1. Build a landing gear model in Abaqus finite element software; Step 2. Convert the whole aircraft inherent characteristic analysis model in Nastran finite element software to obtain a fuselage beam unit model compatible with Abaqus finite element software; Step 3. In the Abaqus finite element software, use the MPC connection module in the Connector connection unit to connect the landing gear model to the fuselage model to obtain the whole aircraft vibration simulation model.

2. The modeling method for finite element simulation of landing gear shimmy of a transport aircraft according to claim 1, characterized in that: In step 1, the steps for building the landing gear model are as follows: Step 11. Based on the landing gear stiffness matrix obtained from the landing gear static test, the stiffness of the landing gear load-bearing component beam unit model in the Abaqus finite element software is modified; Step 12. Based on the tire stiffness test data, the stiffness of the landing gear tire shell unit model in the Abaqus finite element software is modified; Step 13. Based on the landing gear drop test data, the buffering performance of the landing gear buffer model in the Abaqus finite element software is modified; Step 14. Based on the landing gear front shimmy damper damping test data, modify the damping parameters of the landing gear shimmy damper model in the Abaqus finite element software.

3. The modeling method for finite element simulation of landing gear shimmy of a transport aircraft according to claim 2, characterized in that: In step 12, the tire stiffness test data includes: tire vertical stiffness, lateral stiffness, heading stiffness and torsional stiffness.

4. The modeling method for finite element simulation of landing gear shimmy of a transport aircraft according to claim 2, characterized in that: In step 13, in the simulation value of the buffering performance of the landing gear buffer model, the pressure of the buffer main oil chamber, return oil chamber, and air chamber are within 5% of the corresponding test values ​​of the drop test, and the error of the landing gear ground load is within 5% of the corresponding test value of the drop test.

5. The modeling method for finite element simulation of landing gear shimmy of a transport aircraft according to claim 1, characterized in that: In step 2, before conversion, the whole-aircraft inherent characteristic analysis model is corrected by the whole-aircraft ground resonance test results.

6. A simulation method for a full machine shimmy simulation model constructed based on the modeling method described in claims 1-5, characterized in that: The following steps are involved: a. In Abaqus finite element software, create the sliding floor and excitation block; b. Establish face-to-face contact between the landing gear tires and the floor and the excitation block; c. Adjust the aircraft weight center of gravity and taxiing speed of the full-aircraft shimmy simulation model under various working conditions to obtain the corresponding shimmy simulation results.

7. The simulation method according to claim 6, characterized in that: In step a, the structural parameters of the excitation block section are set to simulate the size of obstacles that the aircraft may encounter during taxiing.

8. The simulation method according to claim 6, characterized in that: In step b, the heading motion pair of the aircraft fuselage is limited, and the relative motion between the aircraft and the floor is controlled by controlling the speed of the floor.

9. The simulation method according to claim 6, characterized in that: In step c, corresponding sub-files are constructed based on the fuselage beam unit model, the landing gear bearing assembly beam unit model, the landing gear tire shell unit model, the landing gear buffer model, and the landing gear shimmy damper model of the whole aircraft shimmy simulation model, and the shimmy simulation results under each working condition are obtained.

10. The simulation method according to claim 6, characterized in that: The method also includes step d: generating an analysis main file based on the shimmy simulation result, analyzing whether the aircraft exceeds the aircraft ground load envelope after being excited by the excitation block, and whether the shimmy reducer can quickly attenuate the excitation response.

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