The objectives of this research are to improve the design and analysis methods currently used for advanced composite rotary- wing structures. The outcome of the research involves the development of: (1) a refined structural theory for nonhomogeneous anisotropic beams, and (2) an optimum design methodology for loaded- shape-critical applications. The refined beam theory is developed by extending existing one-dimensional anisotropic beam theories to include the effects of nonhomogeneity and transverse shear. This theory, which is an extension of Timoshenko's beam theory, uses an extended set of shear correction factors that are determined by Saint-Venant's elasticity solutions optimization techniques to determine the initial shape of a flexible blade weight is minimized, the stresses and stability boundaries are checked, and the design variables include the blade geometry and material definition. These design methods will impact the future design of rotary-wing structures. Composite materials will be used more intelligently and blade shapes may changes as a result. Major improvements in blade propulsive efficiency are possible, which would result in substantial fuel savings for the next generation of aircraft.
