Effects of pretwist and presetting on coupled bending vibrations of rotating thin-walled composite beams

A refined dynamic theory of rotating blades modeled as anisotropic composite thin-walled beams, experiencing the flapping-lagging-transverse shear coupling is presented. The structural model encompasses a number of non-standard features, such as anisotropy and transverse shear, pretwist and presetting angles, the presence of a rigid hub on which the beam is mounted, and the rotatory inertia. The developed theory and the methodology used to determine the eigenfrequency characteristics are validated against the results available in the literature, and new results emphasizing the influence played by the ply-angle, pretwist and presetting, coupled with that of the rotating speed on blade free vibration characteristics are supplied, and pertinent conclusions are outlined.