Robustness Analysis of Helicopter Ground Resonance with Parametric Uncertainties in Blade Properties

Leonardo Sanches (1) , Daniel Alazard (1) , Guilhem Michon (2) , Alain Berlioz (2)

1 DMIA - Département de Mathématiques, Informatique, Automatique
2 ICA - Institut Clément Ader

This paper presents a stability robustness analysis of the helicopter ground-resonance phenomenon. By using the lifting procedure the uncertain linear-time-periodic model of the helicopter is transformed into an augmented uncertain linear-time-invariant model that allows the application of μ-analysis tools. The lifting procedure involves a periodic switching linear-time-invariant piecewise model computed using oversampling of the system period. The representativeness of the lifted model for various oversampling period values and methods is discussed and compared with a Floquet analysis for several parametric discretization configurations. A μ-analysis is then applied to find the worst-case parametric configuration for a given rotor angular rate. The parametric uncertainties taken into account are the dynamic characteristics (stiffness and damping) of each blade hinge. A significant advantage of the proposed approach is that it enables performing ground-resonance analysis for a rotor with dissimilar blade properties due to aging effects. Considering uncertainties on the four blade hinge stiffnesses and damping factors, the μ-analysis performed on the lifted model leads to the conclusion that the worst case for degraded rotor stability corresponds to the symmetric perturbation of all the blades.

Mots clés: Ground resonance; Time-periodic system; Parametric robustness

Domaines: Génie des procédés

Leonardo Sanches, Daniel Alazard, Guilhem Michon, Alain Berlioz. Robustness Analysis of Helicopter Ground Resonance with Parametric Uncertainties in Blade Properties. Journal of Guidance, Control, and Dynamics, 2013, 36 (1), pp.272-281. ⟨10.2514/1.55627⟩. ⟨hal-01851606⟩