Linear finite element formulation and analysis of high speed Pretwisted rotating blades

This paper presents a linear finite element model formulation that incorporates the effects of rotary inertia, tip-mass, maneuver speed, the blade pitch angle, and the hub tilting on dynamic responses of high-speed rotating blade experiencing a spin-up maneuver operation. To make the system realistic, a linear finite element beam model is derived by using the Hamilton and variational formulation. The proposed finite element approach enables the study of the maneuver dynamics at various spin-up operations. A state space transformation is employed to convert the dynamic equations into a state space model for dynamic response analysis. Numerical experiments are performed to study the dynamic characteristics of the structure contributed by rotary inertia, tip-mass, maneuver speed, the blade pitch angle and the hub tilting. The dynamics of the rotating blade at different flight conditions are studied and reported. The inadequacy of linear finite element formulation is discussed. A further study by using nonlinear finite element formulation is suggested.