Landing-gear Impact Response

Landing-gear Impact Response
Author: Tuan H. Tran
Publisher:
Total Pages:
Release: 2019
Genre: Finite element method -- Model -- Testing
ISBN:

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The primary objective of this research is to formulate a methodology of assessing the maximum impact loading condition that will incur onto an aircraft's landing gear system via Finite Element Analysis (FEA) and appropriately determining its corresponding structural and impact responses to minimize potential design failures during hard landing (abnormal impact) and shock absorption testing. Both static and dynamic loading condition were closely analyzed, compared, and derived through the Federal Aviation Administration's (FAA) airworthiness regulations and empirical testing data. In this research, a nonlinear transient dynamic analysis is developed and established via NASTRAN advanced nonlinear finite element model (FEM) to simulate the worst-case loading condition. Under the appropriate loading analysis, the eye-bar and contact patch region theory were then utilized to simulate the tire and nose wheel interface more accurately. The open geometry of the nose landing gear was also optimized to minimize the effect of stress concentration. The result of this research is conformed to the FAA's regulations and bound to have an impact on the design and development of small and large aircraft's landing gear for both near and distant future.

An Overview of Landing Gear Dynamics

An Overview of Landing Gear Dynamics
Author: Jocelyn I. Pritchard
Publisher:
Total Pages: 22
Release: 1999
Genre: Aerodynamics
ISBN:

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On of the problems facing the aircraft community is landing gear dynamics, especially shimmy and brake-induced vibration. Shimmy and brake-induced vibrations can lead to accidents due to excessive wear and shortened life of gear parts and contribute to pilot and passenger discomfort. To increase understanding of these problems, a literature survey was performed. The major focus is on work from the last ten years. Some older publications are included to understand the longevity of the problem and the background from earlier researchers. The literature survey includes analyses, testing, modeling, and simulation of aircraft landing gear; and experimental validation and characterization of shimmy and brake-induced vibration of aircraft landing gear. The paper presents an overview of the problem, background information, and a history of landing gear dynamics problems and solutions. Based on the survey an assessment and recommendations of the most critically needed enhancements to the state of the art will be presented. The status of Langley work contributing to this activity will be given.

A Study of Analytic Modeling Techniques for Landing Gear Dynamics

A Study of Analytic Modeling Techniques for Landing Gear Dynamics
Author:
Publisher:
Total Pages: 86
Release: 1982
Genre: Aircraft
ISBN:

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The ability to accurately predict the dynamic response of an aircraft while it is operating in the taxi mode depends, in part on the correct modeling of the dynamic characteristics of the landing gear system. Traditionally, landing gear have been designed to absorb landing impact ('shock absorber') and their characteristics during periodic, oscillatory response ('spring') have been considered as secondary. With the increased emphasis on the rough or damaged field taxi operation, there is a requirement to determine the best methods for modeling the gear system. This report documents a brief review of the state of the art of gear modeling. A study was then conducted to evaluate important model parameters, using a simple cantilevered gear computer simulation. Also included is the development of a technique for the experimental determination of important gear system parameters. (Author).

Dynamics of Landing Gear Impact, Rebound, and Burnout

Dynamics of Landing Gear Impact, Rebound, and Burnout
Author: William H. Sellers
Publisher:
Total Pages: 163
Release: 1962
Genre:
ISBN:

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A study of aircraft landing gear dynamics is presented from the viewpoint of comparing various methods of treating landing gear dynamic problems. Analytical methods for finding oleo strut forces, tire forces, and for treating the aircraft landing gear dynamics problem, from the simple one degree of freedom system to an equivalent system of six degrees of freedom, are studied and results formulated. One section of this report is devoted to a survey of the known mathematical techniques for treating nonlinear mechanics problems. Also a method of reducing the solution of a set of nonlinear differential equations to the solution of a set of linear equations has been developed. Equations of motion which predict the behavior of the landing aircraft from initial impact, during rebound and to final runout are written, solved, and correlated with an actual landing. Attention is called to the direct simulation analog computer or electric circuit model study of drop testing a gear. Results from this study are compared and correlated with drop test data. A brief account of the physics of rebound phenomena is also presented. (Author).

Landing-Impact Characteristics of Load-Alleviating Struts on a Model of a Winged Space Vehicle

Landing-Impact Characteristics of Load-Alleviating Struts on a Model of a Winged Space Vehicle
Author: Ulysse J. Blanchard
Publisher:
Total Pages: 32
Release: 1960
Genre:
ISBN:

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A brief experimental investigation was made of the landing-impact characteristics of a 1/9-scale dynamic model of a winged space vehicle. The landing tests were made by catapulting a free model onto a hard; surface runway and onto water. The model had a conical fuselage and a flat - plate wing with a basic delta planform and 75 deg sweepback of the leading edge. The use of yielding-metal shock absorbers and various landing-gear arrangements was investigated during landing impact. The basic landing gear consisted of a dual rubber-tired nose wheel and twin main skids aft of the center of gravity near the wing tips. landing motion and acceleration data were obtained over a range of landing attitudes, gross weights, and initial sinking speeds. Brief tests were made with an alternate nose-wheel location. An all-skid configuration also was briefly evaluated for hard-surface and water landings. The landing gear employing yielding struts for impact-energy absorption during hard-surface landings resulted in accelerations of approximately 5 1/2 g near the nose gear over a range of landing parameters. Replacing the nose wheel and tire with a skid did not significantly change the accelerations. Landings in smooth water with rigid struts and adequate planing area at the nose skid resulted in a maximum landing acceleration of approximately 4g.