Eventos Anais de eventos
DINAME 2017
XVII International Symposium on Dynamic Problems of Mechanics
Influence of Fuselage and Rotor Damping and Robustness Analysis of a Dynamic Vibration Absorber Applied to a Helicopter
Submission Author:
Diogo Bertolini Profeta de Oliveira , SP
Co-Authors:
Diogo Bertolini Profeta de Oliveira, Leonardo Sanches, Joao Flavio PAFUME COELHO, Guilhem MICHON
Presenter: Leonardo Sanches
doi://10.26678/ABCM.DINAME2017.DIN17-0084
Abstract
This paper presents the evaluation of a spring-mass-damping vibration system (SMDVS) attached to the fuselage of a helicopter with hinged blades. The dynamic behavior of the system is altered by the SMDVS, which consequently changes the stability characteristics of the aircraft when it is on the ground, i.e.: ground resonance instabilities. The SMDVS has potential use in helping alleviate the exponential growth of the aircraft dynamic response at the unstable regions if considered as a dynamic vibration absorber (DVA). The system is considered stable if its dynamic behavior has a negative exponential growth. The DVA parameters (mass, stiffness, and damping) are of great relevance for the system stability (helicopter+DVA), and can contribute to the mitigation of ground resonance instabilities. The helicopter parameters, specially the rotor and fuselage damping, can help mitigate the instabilities. The first purpose of this work is to use Coleman's Method to assess the influence of fuselage and rotor damping on ground resonance instabilities. The stability of the system is evaluated with different combinations of fuselage and rotor damping for two different helicopters: a helicopter without DVA and a helicopter with DVA. The results showed that in order to vanish the instabilities, the system must have a proper combination of damping. The second purpose of this work is to introduce uncertainties in the dynamic system related to hinge stiffness of one rotor blade and to use the -analysis to predict the smallest perturbations that make the system unstable for the two helicopter types. The results showed that for both helicopters, the proper combination of fuselage and rotor damping can produce a system so robust that it can lose one of its rotor blade stiffness and still remain stable. Also, the analysis showed that adding the DVA to the system does not change its robustness.
Keywords
Coleman's Method, helicopter ground resonance, dynamic vibration absorber, robustness analysis
