An Approach for Modeling and Performance Analysis of Three-Leg Landing Gear Mechanisms Based on the Virtual Equivalent Parallel Mechanism

2022 ◽  
Vol 169 ◽  
pp. 104617
Hongyan Tang ◽  
Dan Zhang ◽  
Chunxu Tian
Mohsen Rahmani ◽  
Kamran Behdinan

Abstract Self-induced mechanical oscillation of nose landing gears designated as shimmy is a major safety challenge for aircrafts. The rotational-lateral shimmy vibrations can occur during takeoff, taxiing, and landing and needs to be sufficiently controlled to avoid escalation and catastrophic failure of the landing gear system. Existing solutions for shimmy problem are largely passive control strategies known as shimmy dampers. Despite numerous studies on the source of shimmy and its trends, investigations on the design and performance analysis of shimmy dampers are scarce. From a design perspective, it is crucial to quantify the effective stiffness and damping supplied by the shimmy damper to the system in different operation states. Furthermore, the sensitivity of the damper performance to its design parameters needs to be thoroughly investigated in order to optimize the design for a particular aircraft. In this study, core relationships for three shimmy dampers are presented and used to perform sensitivity studies. These dampers are concepts by Boeing, Collins Aerospace (formerly UTAS), and a new one designated as the Symmetric Torque Link Damper (STLD). The influence of design parameters on the dampers’ performance is studied and observed trends are discussed in the light of inherent trade-offs. Subsequently, a nonlinear Multibody Dynamic model of the landing gear is utilized to obtain sample time histories of oscillations for each shimmy damper in order to highlight the performance differences and to demonstrate the influence of design parameters. Directions for designing future shimmy dampers and recommendations for optimizing them are offered.

2019 ◽  
Vol 13 (2) ◽  
pp. 122-130
Dian ayunita Nugraheni nurmala Dewi

Objectives of this study were analyze fish auction participant satisfaction to auction services in TPI Morodemak, analyze attributes effect, services that fit to service quality measurement, and analyzed fish auction participants perception to performance and importance for fish auction house Morodemak services. Used descriptive method and purposive sampling with 49 respondents consists of commercial fishmongers, traditional fishmongers, purse seine owners, and boat lift net owners as fish auction participant. Satisfication measurement used Customer Satisfication Index (CSI), Importance and Performance Analysis (IPA) and gap analysis. Results from this study were value CSI 20% (0.2) indicate the auction participants dissatisfied with the services provided, IPA show there are four attributes should be develop, two elements have not been completed based on measurement requirements of service satisfaction, gap value average -0.05 means the auction participants were not satisfied with the performance of TPI services because the performance value was lower than the importance value.

2018 ◽  
Vol 2 (01) ◽  
pp. 14
Eddy Supardi

The Tax Payer obidience in fulfiling their taxation obligation will be influenced a lot by the satisfaction level toward the service fiscus. The aim of this observation is to know the response of Tax Payer toward service quality through importance and performance. The population which become the object of this observation is the personal Tax Payer registered in Bogor Tax Service Office and the number of respondents taken as the sample are 100 respondents with Slovin formula. The analysis method used is descriptive analysis and importance-performance analysis.   The result of this observation will be able to be used as one of the input to Bogor Tax Service Office in improving the quality service and for the following observation, especially those who take the same object as the observation in order to improve the quality service to the Tax Payer based on the service of its working way which is felt less. Otherwise it is important for The Tax Payer, maintaining the good work or balancing the service quality based on the working way which is evaluated less important by The Taxe Payer, but has been done reasonably well or very well by The Service Office

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