Dynamic Modeling of Helicopter Rotor Blades

This paper is concerned with the dynamic analysis of a pre-twisted rotating composite rotor blade. General kinematical relations for a beam theory that treated finite rotation were established. Two sets of analyses were extracted from the 3-D nonlinear blade analysis: one is the 2-D linear cross section analysis, and the other is the 1-D nonlinear blade analysis. The Danielson-Hodges generalized measurement and Green strain were introduced to calculate strain-displacement relations. In addition, rotor structural dynamics was developed with multi-body formulation. The Hartenberg-Denavit method was introduced and the recursive computation method for the position vector of a generic point in an inertial frame was derived. In comparison with measurements from Minguet's experiment and blade-droop stop impact tests, the results are in good agreement with that the finite rotation treatment is better than the common moderate rotation hypothesis in dealing with blades under large deflections and the recursive computation method makes it easier to deal with arbitrary rotor configurations.