Helicopter Rotor Load Prediction Using a Geometrically Exact Beam with Multicomponent Model

Abstract

In this paper, an accurate structural dynamic analysis was developed for a helicopter rotor system including rotor control components, which was coupled to various aerodynamic and wake models in order to predict an aeroelastic response and the loads acting on the rotor. Its blade analysis was based on an intrinsic formulation of moving beams implemented in the time domain. The rotor control system was modeled as a combination of rigid and elastic components. A multicomponent analysis was then developed by coupling the beam finite element model with the rotor control system model to obtain a complete rotor-blade/control-system aeroelastic analysis. The rotor blade analysis was in good agreement and validated by comparing with DYMORE. Numerical results were obtained for a four-bladed, small-scale, articulated rotor rotating in vacuum and in a wind tunnel to simulate forward-flight conditions and its aerodynamic effects. The complete rotor-blade/control-system model was loosely coupled with various inflow and wake models in order to simulate both hover and forward-flight conditions. The resulting rotor blade response and pitch link loads are in good agreement with those predicted by CAMRAD II. The present analysis features both model compactness and robustness in its solution procedure while capturing the sophisticated behavior of individual rotor components. The analysis is expected to be part of a framework useful in the preliminary design phase for helicopters.