MULTILEVEL DECOMPOSITION PROCEDURE FOR EFFICIENT DESIGN OPTIMIZATION OF HELICOPTER ROTOR BLADES

This paper addresses a multilevel decomposition procedure, for efficie nt design optimization of helicopter blades, with the coupling of aero dynamics, blade dynamics, aeroelasticity, and structures. The multidis ciplinary optimization problem is decomposed into three levels. The ro tor is optimized for improved aerodynamic performance at the first lev el. At the second level, the objective is to improve the dynamic and a eroelastic characteristics of the rotor. A structural optimization is performed at the third level. Interdisciplinary coupling is establishe d through the use of optimal sensitivity derivatives. The Kreisselmeie r-Steinhauser function approach is used to formulate the optimization problem when multiple design objectives are involved, A nonlinear prog ramming technique and an approximate analysis procedure are used for o ptimization. Results obtained show significant improvements in the rot or aerodynamic, dynamic, and structural characteristics, when compared with a reference or baseline rotor.