Random response of a rotating composite blade with flexure¯torsion coupling effect by the finite element method

A finite element model is employed to investigate the mean square response of a damped rotating composite blade with flexure¯torsion interaction under stationary or non-stationary random excitation. The effects of transverse shear deformation and rotary inertia are considered. The finite element model can satisfy all the geometric and natural boundary conditions of a thick blade. The blade is considered to be subjected to white noise, band-limited white noise or filtered white noise excitation. The numerical results indicate that the increment of rotational speed will reduce the mean square response. It is also found that the mean square response decreases when the low natural frequency of base decreases. Inversely, the mean square response increases when the high natural frequency of base decreases. It is also shown that the fiber orientations have a significant effect on the mean square response of an orthotropic blade under random excitations. Moreover, the flexure¯torsion coupling effect on the mean square response is changed by different fiber orientations.