Random vibration and reliability of a damped thick rotating blade of generally orthotropic material

A finite element model is employed to investigate the mean square response and reliability of a rotating composite blade with external and internal damping under stationary or nonstationary 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 reliability in deflection failure or stress failure criteria is included. The numerical results indicate that the increment of rotational speed will reduce the mean square response and lead to increased reliability. 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 and reliability of an orthotropic blade under random excitations.