Multilevel Decomposition Approach To Integrated Aerodynamic/Dynamic/Structural Optimization Of Helicopter Rotor Blades

This paper describes an integrated aerodynamic /dynamic/structural (IADS) optimization procedure for helicopter rotor blades. The procedure combines performance, dynamics, and structural analyses with a general purpose optimizer using multilevel decomposition techniques. At the upper level, the blade structure and response are represented in terms of global quantities (stiffnesses, mass, and average strains). At the lower level, the blade structure and response are represented in terms of local quantities (detailed dimensions and stresses). The upper level objective function is a linear combination of performance and dynamic measures. Upper level design variables include pretwist, point of taper initiation, taper ratio, root chord, blade stiffnesses, tuning masses, and tuning mass locations. Upper level constraints consist of limits on power required in hover, forward flight, and maneuve