Almost-sure asymptotic stability of rotor blades flapping motion in forward flight in turbulent flow

This paper examines the almost-sure asymptotic stability of uncoupled flapping motion of rotor blades in forward flight under the effect of atmospheric turbulence. Under these conditions, the equation of motion of the rotor blade system contains both harmonic and stochastic excitations. The intensities of these excitations are assumed small in order to approximate the physical process by a diffusive Markov process defined by a set of Itô equations. Explicit almost-sure stability conditions are derived for the equivalent Itô equations and are compared with the mean square stability conditions obtained using Itô differential rule.