Structural Modeling and Free Vibration Analysis of Rotating Composite Thin‐Walled Beams

A refined theory of rotating blades modeled as thin‐walled compasite beams of arbitrary closed cross‐sections is presented and used to study their free vibration behavior. The structural model encompasses a number of non‐classical features such as the anisotropy and heterogeneity of constituent materials, transverse shear, primary and secondary warpings and includes the effects of the centrifugal and Coriolis force fields. It is shown that in the context of a special ply angle configuration and when Coriolis effects are discarded, the governing system of equations splits exactly into two independent systems, describing the flap‐lag‐transverse shear and extension‐twist motions. It is also revealed that the structural model developed in this paper contains, as special cases, a number of cases described in the literature. The excellent agreement between the results available in the literature and the ones obtained in the context of the present developed model is reported. Numerical illustrations showing the influence of the ply orientation and angular velocity on the flap‐lag‐transverse shear and twist‐extension coupled free vibration eigencharacteristics are presented and the benefilts of exploiting the induced elastic couplings are highlighted.