Dynamics and reliability design of rotor-nacelle-wing coupled structures under non-white random gusts

This paper investigates the dynamics and reliability of rotor-nacelle-wing coupled structures with cubic nonlinearity under non-white random gusts. Random gusts will induce the coupled structures to exhibit unexpected high-amplitude limit-cycle oscillations or catastrophic instability, directly shortening the service life and threatening flight safety. By modeling non-white random gusts as Gaussian colored noises with correlation time, this study reveals the impact of correlation time on structural reliability. We observe that a shorter correlation time and larger intensity significantly increases the risk of stochastic jumping, structural fatigue damage and catastrophic instability. The current work proposes a reliability framework that integrates first passage criteria for sudden overload and fatigue failure criteria for cumulative damage. Two nonlinear energy sink structures are put forward to reduce vibrations by redirecting energy flow. Indeed, the parameters of the nonlinear energy sinks in the rotor-nacelle-wing coupled structure are optimized using a multi-objective particle swarm method. Compared to merely tuning structural parameters, our vibration control strategy achieves at least a 54.68% improvement in reliability, with maximum enhancements exceeding 95.32% in a certain parameter domain. This research is the first to consider bistable stochastic dynamics of rotor nacelle-wing coupled structures under non-white random gusts to improve reliability, which will provide new insights into the structural safety design of tilt-rotor aircraft.