Stability analysis of whirl flutter in rotor-nacelle systems with freeplay nonlinearity

Abstract Tiltrotor aircraft are growing in prevalence due to the usefulness of their unique flight envelope. However, aeroelastic stability—particularly whirl flutter stability—is a major design influence that demands accurate prediction. Several nonlinearities may be present tiltrotor systems, such as freeplay, often neglected for simplicity, either modelling or stability analysis. effects can significant, sometimes even invalidating predictions from linear analysis methods. Freeplay is nonlinearity arise nacelle rotation actuators tension–compression loading cycles they undergo. This paper investigates effect freeplay structural pitch degree freedom. Two rotor-nacelle models contrasting complexity studied: one represents classical (propellers) and other captures main aeroelasticity (proprotors). The manifestation systems’ dynamical behaviour mapped out using Continuation Bifurcation Methods, consequently change boundary quantified. Furthermore, on (a) model (b) deadband edge sharpness studied. Ultimately, shown have complex dynamics both creating possibility parameter ranges methods predict stable. While size this additional region finite bounded basic model, it unbounded higher model.