Rotor System Health Monitoring Using Coupled Rotor-Fuselage Vibration Analysis

A coupled rotor-fuselage vibration analysis is formulated to analyze the effect of rotor system faults on fuselage vibrations and rotor blade displacements in both hover and forward flight conditions. The analysis uses a finite element model in space and time for the rotor system which is coupled with a fully flexible 3-D finite element model of the fuselage. Each rotor blade is modeled individually and can be dissimilar from the others. Two groups of rotor system faults are modeled, adjustable faults and non-adjustable component faults. Results are presented for an SH-60 helicopter and are compared with flight test data. The analysis shows that all of the faults result in increased 1/rev vibration. In general, the analysis predicts the overall trends for vibration magnitude but further refinements of the model are needed to accurately predict phase.