Structural Dynamics Analysis of Thin-Walled, Pretwisted Composite Blades with Spanwise Taper

In this study, a mixed-based approach that combines the classical stiffness and flexibility methods is developed to analyze the rotating dynamic behavior of thin-walled, tapered composite blades with built-in twist angles. The analysis model includes the effects of elastic couplings, shell wall thickness, transverse shear couplings, torsion warping, and constrained warping. The resulting theory describes the beam kinematics in terms of the axial, flap and lag bending, flap and lag shear, torsion, and torsion-warping deformations. The equations of motion for the beam are obtained by using Hamilton's principle. The analysis is validated against experimental test data and detailed finite element analysis results for pretwisted and tapered beams with different material distributions and cross-section shapes. Good correlation is achieved for various configuration cases considered in this study. The influence of pretwist, taper and fiber orientation angles on the structural dynamic response of rotating composite beams are investigated.