CN106295061B - Design method and simplified structure of main undercarriage of full-aircraft dynamic model - Google Patents
Design method and simplified structure of main undercarriage of full-aircraft dynamic model Download PDFInfo
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- CN106295061B CN106295061B CN201610708288.7A CN201610708288A CN106295061B CN 106295061 B CN106295061 B CN 106295061B CN 201610708288 A CN201610708288 A CN 201610708288A CN 106295061 B CN106295061 B CN 106295061B
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Abstract
The invention relates to a design method of a main undercarriage of a full-aircraft dynamic model, which comprises the following steps: obtaining the design size of the main undercarriage of the full-aircraft dynamic model according to the size of the real main undercarriage and a preset scaling; step two: obtaining a force transmission structure of a model main undercarriage according to the force transmission structure of the real main undercarriage, and performing simulation calculation on the mechanical property of the simplified force transmission structure of the main undercarriage; step three: fitting according to a hydraulic buffer and tire performance parameters in the real main undercarriage to obtain a spring stiffness coefficient and tire performance parameters in the simplified structure of the main undercarriage; step four: recalculating the dimensions of the spring and the tire according to the mechanical property obtained in the step two, the spring stiffness coefficient and the tire performance parameter obtained in the step three; step five: and (5) obtaining the optimal size of the main landing gear of the full-aircraft dynamic model through iterative optimization. The design method of the main landing gear of the full-aircraft dynamic model completely ensures that the force transmission structure and the force transmission characteristic can be designed to meet the requirements of dynamic tests.
Description
Technical Field
The invention belongs to the technical field of airplane structural strength tests, and particularly relates to a design method and a simplified structure of a main undercarriage of a full-airplane dynamic model.
Background
The main landing gear is a medium for the action of an airplane and the ground, and in the previous dynamic model design, the main landing gear buffer is designed with the following methods:
(1) the design of the model main landing gear is completely consistent with that of a real airplane, and the main landing gear buffer is high in cost and complex in structure; meanwhile, the size space of the model main landing gear is limited, so that the processing requirement is extremely high;
(2) the model main landing gear is a combination of a single rod and a tire, a buffer part is not arranged, and the main landing gear only provides a supporting function in a test and cannot meet the requirement of a mechanical property curve in the test.
Disclosure of Invention
The invention aims to provide a design method of a main undercarriage of a full-aircraft dynamic model, which solves the problem of the defects of the design of the main undercarriage in the existing dynamic model.
In order to achieve the purpose, the invention adopts the technical scheme that: a design method for a main landing gear of a full-aircraft dynamic model comprises the following steps
The method comprises the following steps: obtaining the design size of the main undercarriage of the full-aircraft dynamic model according to the size of the real main undercarriage and a preset scaling;
step two: obtaining a force transmission structure of a main undercarriage of the full-aircraft dynamic model according to the force transmission structure of the real main undercarriage, and performing simulation calculation on the mechanical property of the simplified force transmission structure of the main undercarriage of the full-aircraft dynamic model;
wherein, the power transmission structure is changed into:
the main force transmission route is changed from a machine body, an outer cylinder, a hydraulic buffer, an inner cylinder and a tire into the main force transmission route, namely, the machine body, the outer cylinder, a spring buffer, the inner cylinder and the tire;
the force transmission path of a brace rod-machine body-outer cylinder in the original structure is eliminated, and the connection form of the machine body and the outer cylinder is converted into fixed connection by hinging;
step three: fitting according to a hydraulic buffer and tire performance parameters in the real main undercarriage to obtain a spring stiffness coefficient and tire performance parameters in a simplified structure of the main undercarriage of the full-aircraft dynamic model;
step four: recalculating the dimensions of the spring and the tire according to the mechanical property obtained in the step two, the spring stiffness coefficient and the tire performance parameter obtained in the step three;
step five: and (5) performing iterative optimization to obtain the optimal size of the main undercarriage of the full-aircraft dynamic model.
Further, the predetermined scaling is a ratio of a real main landing gear size to a full-aircraft dynamic model size.
The invention also provides a simplified structure of the main undercarriage of the full-machine dynamic model, which comprises an outer cylinder, a spring, an inner cylinder, an upper anti-torsion arm, a lower anti-torsion arm, a tire, an end head, a hoop and a bush, wherein the tire is arranged on a wheel axle, the bush is sleeved outside the inner cylinder, one end of the inner cylinder is fixed on the wheel axle, the other end of the inner cylinder extends into the outer cylinder, the inner cylinder is fixed with the end head, the outer cylinder is fixed with a machine body, the hoop (8) is arranged at one end of the outer cylinder connected with the inner cylinder, the spring is sleeved outside the inner cylinder and is arranged between the hoop and the wheel axle, one end of the upper anti-torsion arm is hinged with the outer.
The design method of the full-aircraft dynamic model main landing gear and the simplified structure of the invention are complete, and the force transmission structure and the force transmission characteristic are ensured; under given parameters, the structure of the main landing gear is optimally simplified, the structure is simple, the constraint requirements among parts are clear, and the test parameter requirements are easily met; the manufacturing cost and the process requirement are low; through test verification, the landing gear structure design meets the requirements of a dynamic test.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
FIG. 1 is a schematic diagram of the force transfer of a real main landing gear structure according to one embodiment of the present invention.
FIG. 2 is a simplified structural force transfer diagram of a full-aircraft-dynamics-model main landing gear according to an embodiment of the invention.
FIG. 3 is a diagram illustrating a fitting of spring rate coefficients according to an embodiment of the present invention.
FIG. 4 is a schematic diagram of a full-machine dynamics model according to an embodiment of the present invention.
5-1 to 5-3 are simplified structural schematic diagrams of the main landing gear of the full-aircraft dynamic model according to an embodiment of the invention.
Detailed Description
In order to make the implementation objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, but not all embodiments of the invention. The embodiments described below with reference to the drawings are exemplary and intended to be illustrative of the invention and are not to be construed as limiting the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the scope of the present invention.
The invention discloses a design method of a main undercarriage of a full-aircraft dynamic model, which comprises the following specific steps of:
the method comprises the following steps: obtaining the design size (or called scaling size) of a main undercarriage of a full-aircraft dynamic model according to the size of a real main undercarriage and a preset scaling, wherein the preset scaling is the ratio of the size of the real nose undercarriage to the size of the full-aircraft dynamic model, and the examples of the size of a structural parameter, the relational expression of the structural parameter and a scaling factor and the specific structural parameter of a certain nose undercarriage, which are related in the nose undercarriage, are shown in tables 1 and 2;
TABLE 1 scaling parameters
TABLE 2 example scaling parameters
Step two: simplifying and changing the force transmission structure of the front landing gear of the full-aircraft dynamic model according to the force transmission structure of the real front landing gear, and carrying out simulation calculation on the mechanical property of the changed force transmission structure of the front landing gear of the full-aircraft dynamic model;
however, before simplification, the actual main landing gear force transfer structure is first studied, as shown in fig. 1, and the force transfer path is as follows:
(1) the machine body is hinged with the outer cylinder, is hinged with the stay bar and transfers force downwards, and a triangular stabilizing mechanism formed by the machine body, the stay bar and the outer cylinder transfers 6 space force elements through the outer cylinder;
(2) the machine body force is transmitted to the hydraulic buffer through the lower end of the outer cylinder, and is transmitted to the inner cylinder and finally transmitted to the tire after the action of the hydraulic buffer;
(3) the antitorque arm prevents the inner and outer cylinders from twisting and does not participate in the force transmission.
Then simplifying and changing the real main landing gear force transmission structure, and simulating and calculating the mechanical property, specifically
(1) The main force transmission route is simplified and changed into 'machine body-outer cylinder-spring buffer-inner cylinder-tyre';
(2) the connection form of the machine body and the outer cylinder is converted from hinging to fixing, and the machine body can transmit six spatial force elements through the joint of the outer cylinder;
(3) because the weight of the model in the embodiment is about 60kg, the material property is enough to meet the ground load, a force transmission path of a strut connecting the fuselage and an outer cylinder (the upper part of the undercarriage) in the original structure is eliminated, namely, the fuselage is hinged with the outer cylinder, and a triangular stabilizing mechanism hinged with the strut is converted into a single force transmission path of the fuselage and the outer cylinder;
(4) the buffer part is converted into spring buffering by a hydraulic cylinder, so that the structural size and the processing cost are greatly reduced;
(5) the upper and lower through holes of the end head prevent the air spring force from generating in the closed space when the inner and outer cylinders move relatively to each other, and the mechanical property is not affected.
Step three: and fitting according to the hydraulic buffer and the tire performance parameters in the real nose landing gear to obtain the spring stiffness coefficient and the tire performance parameters (namely calculating the buffer and the tire performance parameters) in the simplified structure of the nose landing gear of the full-aircraft dynamic model.
Since the real main landing gear bumper is a hydraulic bumper, it is simplified to a spring bumper. The mechanical property of the hydraulic buffer is a curve, and the mechanical property of the spring is a straight line, so that the mechanical property curve of the buffer needs to be fitted to obtain the stiffness coefficient K of the spring.
Tire performance parameters generally result in a maximum load F and a k that is fit to a true tire curve according to test task requirements.
Step four: and recalculating the size parameters of the spring and the tire according to the mechanical property obtained in the step two, the spring stiffness coefficient and the tire performance parameter obtained in the step three.
And under the frame of the design size of the buffer and the mechanical property of the spring, the spring buffer is designed according to the design requirement of the spring.
The scaling model undercarriage is based on a real main undercarriage 1: 6.5, so the inner diameter, free length and rigidity of the spring are determined. The spring material 60SiMn was selected under the current conditions of the spring processing plant. Thus, the initial limiting constraints of the spring design are obtained.
The maximum allowable load is taken as a design target of 150% of working load, and spring parameters are designed according to a navigation mark HB 3-51-2008 carbon element and alloy steel wire cylindrical spiral compression spring.
According to the maximum load F and k obtained by fitting a real tire curve, the radius d of the tire is larger than F/k, and then according to the layout size of the undercarriage, the tire size parameter is obtained.
Step five: and (5) performing iterative optimization to obtain the optimal size of the nose landing gear of the full-aircraft dynamic model.
According to the determined initial parameters of the undercarriage force transmission structure, a dynamic model is established, and the target is optimized: the vertical acceleration of the center of gravity of the model is minimal. With this iterative optimization, the landing gear is obtained as shown in table 3 below.
TABLE 3 parameters after iterative optimization
| Serial number | Parameter(s) | Numerical value |
| 1 | Free extension of main starting spring | 117.5111mm |
| 2 | Size of the inner barrel of the main opener | 195mm |
| 3 | Size of the main starting outer cylinder | 181.5mm |
| 4 | Radius of leading tire | 90mm |
| 5 | Vertical stiffness of the leading tire | 32000N/m |
| 6 | Damping coefficient of main starting tire | 100kg/s |
| 7 | The stiffness coefficient of the main starting spring is 100 percent | 12050N/m |
| 8 | Damping coefficient of main spring | 400kg/s |
Finally, the simplified structure of the main landing gear of the full-aircraft dynamic model of the invention is further illustrated, as shown in fig. 5-1 to 5-3, wherein fig. 5-2 is a front view, fig. 5-1 and fig. 5-3 are a right view and a cross-sectional view, respectively, and comprises an outer cylinder, a spring, an inner cylinder, an upper antitorque arm, a lower antitorque arm, a tire, a tip, a hoop and a bush, wherein the tire is mounted on an axle, one end of the inner cylinder is fixed on the axle, the other end of the inner cylinder is sleeved with the bush and fixed with the tip, and then extends into the inner cylinder from one end of the outer cylinder, the other end of the outer cylinder is fixed with the aircraft body, one end of the outer cylinder connected with the inner cylinder is provided with the hoop, the spring is sleeved outside the inner cylinder and between the hoop and the axle, one end of the upper.
The design method and the simplified structure of the full-aircraft dynamic model main landing gear take a real main landing gear as a reference, and a force transmission structure of the main landing gear is reserved to the maximum extent; the performance of the tire is scaled according to the performance parameters of the real main undercarriage; the hydraulic buffer is simplified into a spring mechanism and is designed according to a mechanical curve of the hydraulic buffer. On the premise of ensuring the mechanical property and the model size of the main landing gear, the main landing gear is simplified to the greatest extent. The aircraft dynamic model landing gear is designed in the most real mode, the design and processing cost is reduced, and the dynamic requirements and the similarity requirements are met.
The above description is only for the best mode of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (2)
1. A design method for a main undercarriage of a full-aircraft dynamic model is characterized by comprising the following steps
The method comprises the following steps: obtaining the design size of the main undercarriage of the full-aircraft dynamic model according to the size of the real main undercarriage and a preset scaling;
step two: obtaining a force transmission structure of a main undercarriage of the full-aircraft dynamic model according to the force transmission structure of the real main undercarriage, and performing simulation calculation on the mechanical property of the simplified force transmission structure of the main undercarriage of the full-aircraft dynamic model;
wherein, the power transmission structure is changed into:
the main force transmission route is simplified from 'machine body-outer cylinder-hydraulic buffer-inner cylinder-tire' to 'machine body-outer cylinder-spring buffer-inner cylinder-tire';
the force transmission path of a brace rod, a machine body and an outer cylinder is cancelled, and the connection form of the machine body and the outer cylinder is converted into fixed connection by hinging;
step three: fitting is respectively carried out according to the hydraulic buffer and the tire performance parameters in the real main undercarriage, and the spring stiffness coefficient and the tire performance parameters in the simplified structure of the main undercarriage of the full-aircraft dynamic model are obtained;
step four: recalculating the dimensions of the spring and the tire according to the mechanical property obtained in the step two, the spring stiffness coefficient and the tire performance parameter obtained in the step three;
step five: and (5) performing iterative optimization to obtain the optimal size of the main undercarriage of the full-aircraft dynamic model.
2. The full aircraft dynamic model main landing gear design method according to claim 1, wherein the predetermined scaling is a ratio of a real main landing gear size to a full aircraft dynamic model size.
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| CN109522636B (en) * | 2018-11-09 | 2022-12-30 | 中国直升机设计研究所 | Wheel type undercarriage simplifying method for helicopter crash-resistant analysis |
| CN112069712B (en) * | 2020-09-07 | 2022-10-11 | 中国航空工业集团公司成都飞机设计研究所 | Method for rapidly analyzing landing load of support arm type undercarriage |
| CN112793805B (en) * | 2020-12-29 | 2022-11-22 | 中国航空工业集团公司西安飞机设计研究所 | Full-machine drop shock shrinkage ratio model test method |
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