Analytic Insight into the Structural Couplings and Nonlinear Formulation of Solid and Thin-Walled Composite Blades

A model for the structural behavior of solid and thin-walled composite blades is presented. The model is designed to handle arbitrary thick solid cross-sections or general thin-walled geometries, and includes three-dimensional out-of-plane warping. The formulation enables to derive closed-form analytic solutions for various basic geometries and lamination modes that explicitly identify the origin of the elastic couplings. In addition, the analytic solutions provide detailed distributions of the out-of-plane warping, that may be used as the basic shear deformation shape functions in numerical analyses of complex composite beams. The nonlinear scheme enables the inclusion of large initial twist and is based on three-dimensional formulation that preserves warping continuity. A study of the combined influence of initial twist and elastic couplings is also presented.