CN112623258A - Undercarriage shimmy analysis method - Google Patents
Undercarriage shimmy analysis method Download PDFInfo
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- CN112623258A CN112623258A CN202011610450.4A CN202011610450A CN112623258A CN 112623258 A CN112623258 A CN 112623258A CN 202011610450 A CN202011610450 A CN 202011610450A CN 112623258 A CN112623258 A CN 112623258A
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- gap
- shimmy
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
- B64F5/00—Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C25/00—Alighting gear
- B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface
- B64C25/50—Steerable undercarriages; Shimmy-damping
- B64C25/505—Shimmy damping
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/15—Vehicle, aircraft or watercraft design
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2111/00—Details relating to CAD techniques
- G06F2111/04—Constraint-based CAD
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
Abstract
The invention belongs to the technical field of strength design of an aircraft landing gear, and particularly relates to a landing gear shimmy analysis method. The method comprises the following steps: establishing a landing gear shimmy analysis simulation model; finding a structure to be analyzed from the simulation model; modifying the motion constraint of the structure to be analyzed; determining the precise distance between two components with gaps in the structure to be analyzed; determining a gap between the two components; adding a compression spring between the two parts; and adjusting the gap between the two parts by adjusting the free length of the spring to obtain the relationship between the related parameters of the shimmy characteristics of the undercarriage and the size of the gap, wherein the gap adjustment range is from 0 to the maximum value of the gap in the overhaul range, and the free length of the spring is obtained by subtracting the gap between the parts from the accurate distance between the geometric characteristic points. The method can quickly realize the setting and adjustment of the structural clearance and effectively simulate the influence analysis of the structural clearance change on the shimmy characteristic of the undercarriage.
Description
Technical Field
The invention belongs to the technical field of strength design of an aircraft landing gear, and particularly relates to a landing gear shimmy analysis method.
Background
Landing gear shimmy is a serious failure in aircraft development and use. Once the airplane generates shimmy phenomenon in the sliding process, the shimmy phenomenon can not only cause the shaking of the airplane body or the resonance of a local part to influence the normal operation of a pilot, but also can cause the breakdowns of the deflector rod, the transmission mechanism, the shell and the fixing device thereof, the landing gear and the airplane body structure to be broken, the damage of the airplane wheels and the tires, and even the accident of the airplane.
Gaps inevitably exist among all moving parts of the undercarriage, and the gaps can be gradually increased along with the increase of the retraction times of the undercarriage, so that the shimmy characteristic is changed.
Structural clearances cause load and motion discontinuities during landing gear motion, which are non-linear parameters. The discontinuous phenomenon of the motion is difficult to describe by using a shimmy motion differential equation, a linear shimmy motion differential equation set is mostly adopted to carry out shimmy analysis work in the past, the research and analysis on nonlinear parameters are mostly concentrated on coulomb friction and nonlinear damping coefficients, and the analysis work of the influence of structural gaps on shimmy characteristics is less.
For example, in multi-body dynamics simulation, a contact method is used to realize structure motion, force transmission relation and structure gap definition in a model, solid parameters need to be added, the definition of a contact surface and contact parameters needs to be carried out, and because connecting structures such as bushings possibly exist between different parts, the parts are generally simplified in simulation analysis, so that the phenomenon that the structure gap of the two parts in the model is inconsistent with the actual condition is caused, the parts need to be modified in CAE software, the structure gap is consistent with the actual condition, the operation is complex, the gap parameter setting and adjusting difficulty is high, the modeling workload is large, and the calculation efficiency is low.
Disclosure of Invention
The purpose of the invention is as follows: the landing gear shimmy analysis method is provided to solve the technical problem of aircraft landing gear shimmy analysis and calculation.
The technical scheme is as follows:
in a first aspect, a method for analyzing shimmy of a landing gear is provided, which includes: establishing a landing gear shimmy analysis simulation model; finding a structure to be analyzed from the simulation model; modifying the motion constraint of the structure to be analyzed; determining the precise distance between two components with gaps in the structure to be analyzed; determining a gap between the two components; adding a compression spring between the two parts; and adjusting the gap between the two parts by adjusting the free length of the spring to obtain the relationship between the related parameters of the shimmy characteristics of the undercarriage and the size of the gap, wherein the gap adjustment range is from 0 to the maximum value of the gap in the overhaul range, and the free length of the spring is obtained by subtracting the gap between the parts from the accurate distance between the geometric characteristic points.
Further, the structure to be analyzed is a structure having an influence on the shimmy characteristics.
Further, modifying the motion constraint of the structure to be analyzed specifically as follows: the freedom of movement in the gap direction is released.
Further, determining the precise distance between two components with gaps in the structure to be analyzed specifically comprises: and respectively searching respective characteristic points on the two parts, and taking the distance between the characteristic points on the two parts as an accurate distance.
Further, the clearance between the two parts is a designed installation clearance, and the adjustment range is not less than the maximum clearance of the structure in the maintenance period.
Further, a compression spring is added between the two components, in particular between the characteristic points of the two components.
Further, the stiffness of the spring is greater than 107N/mm。
Further, the feature point is a center point of the feature structure.
Has the advantages that:
the method can quickly realize the setting and adjustment of the structural clearance, can effectively simulate the influence analysis of the structural clearance change on the shimmy characteristic of the undercarriage, can effectively set and adjust the structural clearance, and has high calculation efficiency.
Drawings
FIG. 1 is a schematic view of the gap between the front anti-twisting arms
FIG. 2 is a schematic view of a double-sided spring arrangement;
FIG. 3 is a schematic view of a single-sided spring arrangement;
FIG. 4 simplified model of anti-torsion arm structure gap.
Detailed Description
According to the embodiment of the invention, the method for analyzing the shimmy of the undercarriage comprises the following steps: the method comprises the steps that a landing gear shimmy analysis simulation model is built in multi-body power software, the model comprises main force bearing structures and moving parts, such as buffer struts, support rods, torsion-proof arms, rotary hoops, tires and the like, and other parts can be omitted to reduce the scale of the simulation model; finding a structure to be analyzed concerned in shimmy research from the simulation model, wherein in the shimmy analysis of the undercarriage, the gap between the upper torsion-proof arm and the lower torsion-proof arm and the gap between the main intersection points have large influence on shimmy characteristics and need to be concerned; modifying the motion constraint of the structure to be analyzed according to the real motion relation of the structure and the motion direction of the gap influence; determining the precise distance between two components with gaps in the structure to be analyzed; determining the gap between the two parts, wherein the size of the initial gap can be determined according to the technical requirements of structural assembly; a compression spring is added between the two parts, and the direction of the spring is the relative movement direction between the two parts; and adjusting the gap between the two parts by adjusting the free length of the spring to obtain the relationship between the related parameters of the shimmy characteristics of the undercarriage and the size of the gap, wherein the gap adjustment range is from 0 to the maximum value of the gap in the overhaul range, and the free length of the spring is obtained by subtracting the gap between the parts from the accurate distance between the geometric characteristic points.
Wherein the structure to be analyzed is a structure having an influence on the shimmy characteristics.
Modifying the motion constraint of the structure to be analyzed, specifically: the freedom of movement in the gap direction is released.
Determining the precise distance between two components with gaps in the structure to be analyzed, specifically comprising: and respectively searching respective characteristic points on the two parts, and taking the distance between the characteristic points on the two parts as an accurate distance.
The initial clearance of the two components is a design installation clearance, and the adjustment range is not less than the maximum clearance of the structure in the maintenance period.
And adding a compression spring between the two parts, specifically adding the compression spring between the characteristic points of the two parts.
The feature points may be, but are not limited to, geometric centers of features, connection points, and the like.
The following detailed description is made with reference to the accompanying drawings.
1. Building undercarriage shimmy analysis simulation model
The landing gear shimmy analysis simulation model can be established in multi-body dynamics simulation software.
2. Determining the precise distance between individual components
Firstly, the theoretical distance between two parts which are required to be subjected to clearance setting is determined according to the actual landing gear structural design. This distance may be defined as the distance between feature points between two parts.
Taking the structure shown in fig. 1 as an example, the relative distance between the centers of the ear holes may be the distance between the two parts, and the structure in the figure is arranged symmetrically, so the distances between the ear piece of the middle part and the ear pieces on the left and right sides are both L1.
3. By adding springs between two parts only under pressure
A spring is added between the characteristic points of the two parts, only under pressure, in a particular form with reference to figures 2 and 3.
4. Spring parameter setting
Free length of spring:
free length (L) ═ part theoretical distance (L1) — structural gap (t)/2 (double-sided setup)
Or:
free length (L) ═ part theoretical distance (L1) -structural gap (t) (single sided setup)
Spring rate:
spring rate (K) is recommended to be more than or equal to 10E +7N/mm
3. Structural clearance adjustment
The adjustment of the structural clearance can be completed by adjusting the free length of the spring, and the simplified model of the structural clearance of the torsion-proof arm is shown in figure 4.
Claims (8)
1. A method of analyzing drag shimmy of a landing gear, comprising:
establishing a landing gear shimmy analysis simulation model;
finding a structure to be analyzed from the simulation model;
modifying the motion constraint of the structure to be analyzed;
determining the precise distance between two components with gaps in the structure to be analyzed;
determining a gap between the two components;
adding a compression spring between the two parts;
and adjusting the gap between the two parts by adjusting the free length of the spring to obtain the relationship between the related parameters of the shimmy characteristics of the undercarriage and the size of the gap, wherein the gap adjustment range is from 0 to the maximum value of the gap in the overhaul range, and the free length of the spring is obtained by subtracting the gap between the parts from the accurate distance between the geometric characteristic points.
2. The method according to claim 1, characterized in that the structure to be analyzed is a structure having an influence on the shimmy behavior.
3. The method according to claim 1, characterized in that the motion constraints of the structure to be analyzed are modified, in particular: the freedom of movement in the gap direction is released.
4. The method according to claim 1, characterized in that determining the precise distance between two components of the structure to be analyzed in which a gap exists comprises in particular:
respectively searching for respective characteristic points on the two parts,
the distance between the feature points on the two parts is taken as the precise distance.
5. The method of claim 1, wherein the clearance of the two components is a design installation clearance and the adjustment range is no less than a maximum clearance of the structure during the service period.
6. Method according to claim 4, characterized in that a compression spring is added between the two components, in particular between the characteristic points of the two components.
7. The method of claim 1, wherein the spring has a stiffness greater than 107N/mm。
8. The method of claim 1, wherein the feature point is a center point of the feature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011610450.4A CN112623258B (en) | 2020-12-29 | 2020-12-29 | Landing gear shimmy analysis method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011610450.4A CN112623258B (en) | 2020-12-29 | 2020-12-29 | Landing gear shimmy analysis method |
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| CN112623258A true CN112623258A (en) | 2021-04-09 |
| CN112623258B CN112623258B (en) | 2022-09-20 |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090224100A1 (en) * | 2008-03-05 | 2009-09-10 | Goodrich Corporation | Shimmy damper for aircraft landing gear |
| US20150151835A1 (en) * | 2013-12-04 | 2015-06-04 | Isaiah W. Cox | Load Transfer in a Powered Aircraft Drive Wheel |
| CN105480431A (en) * | 2014-10-11 | 2016-04-13 | 中国航空工业集团公司西安飞机设计研究所 | Method for avoiding excessive vibration of undercarriage in overhead state |
| CN106599466A (en) * | 2016-12-14 | 2017-04-26 | 中国人民解放军空军工程大学 | Road runway flatness evaluation method based on vibration accelerations |
| CN108791827A (en) * | 2018-06-25 | 2018-11-13 | 中国民航大学 | A kind of controller and control method for undercarriage magnetorheological shimmy damper |
| CN109711034A (en) * | 2018-12-24 | 2019-05-03 | 西北工业大学 | A kind of undercarriage health monitor method |
-
2020
- 2020-12-29 CN CN202011610450.4A patent/CN112623258B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090224100A1 (en) * | 2008-03-05 | 2009-09-10 | Goodrich Corporation | Shimmy damper for aircraft landing gear |
| US20150151835A1 (en) * | 2013-12-04 | 2015-06-04 | Isaiah W. Cox | Load Transfer in a Powered Aircraft Drive Wheel |
| CN105480431A (en) * | 2014-10-11 | 2016-04-13 | 中国航空工业集团公司西安飞机设计研究所 | Method for avoiding excessive vibration of undercarriage in overhead state |
| CN106599466A (en) * | 2016-12-14 | 2017-04-26 | 中国人民解放军空军工程大学 | Road runway flatness evaluation method based on vibration accelerations |
| CN108791827A (en) * | 2018-06-25 | 2018-11-13 | 中国民航大学 | A kind of controller and control method for undercarriage magnetorheological shimmy damper |
| CN109711034A (en) * | 2018-12-24 | 2019-05-03 | 西北工业大学 | A kind of undercarriage health monitor method |
Non-Patent Citations (2)
| Title |
|---|
| 严志刚等: "飞机起落架结构振动的非线性动力学研究现状及展望", 《科学技术与工程》 * |
| 张严等: "考虑间隙特性的起落架摆振非线性分岔分析", 《航空计算技术》 * |
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