Aeroelastic Optimization of a Helicopter Rotor
Abstract:Structural optimization of a hingeless rotor is investigated to reduce oscillatory hub loads while maintaining aeroelastic stability in forward flight. Design variables include spanwise distribution of nonstructural mass, chordwise location of blade center of gravity, and blade bending stiffnesses (flap, lag and torsion). An aeroelastic analysis of rotors, based on a finite element method in space and time, is linked with optimization algorithms to perform optimization of rotor blades. Sensitivity derivatives of blade response, hub loads, and eipenvalues with respect to the desien variables are derived using a direct analytical approach, and constitute an integral part of the basic blade response and stability analyses. This approach reduces the computation time substantially; an 80 percent reduction of CPU time to achieve an optimum solution as compared to the widely adopted finite difference approach. Through stiffness and nonstructural mass distributions, a 60–90 percent reduction in all six 4/rev hub loads is achieved for a four‐bladed soft‐inplane rotor.
Document Type: Research Article
Affiliations: Ctr. for Rotorcraft Educ. and Res., Univ. of Maryland, College Park, Md.
Publication date: January 1, 1989
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