Kee Y., Kim D., Kim S., Joo G.

In aeronautical and aerospace engineering, rotating blades are the main structural members of turbo-machines. Because these blades must perform efficiently with high specific strength, they must undergo vibration analysis. Thus, the vibration analysis of turbo-machinery blades has been widely investigated, and has been a part of investigations in numerous published references. In early works, many research workers have assumed the turbo-machinery blade as a beam, while it may be adequate for blade with high aspect ratios. As a matter of fact, the chord-wise bending modes becomes involved in the vibration due to the effect of decrease in blade aspect ratio. Therefore, the beam-type model can not represent those modes. During the recent years, more rigorous methods of analysis have been developed based on the plate theory. The plate-type model can consider the chord-wise bending effects, and obtain accurate results. Nowadays, shell-type structures are widely used as a part of the turbo-machines. These structures have different curvatures, which are the main feature relative to the beam and plate models. Thus, shell models are preferable to plate models because the shell models consider the effect of surface curvature. The purpose of this study is to analyze the free vibration characteristics of a rotating blade subjected to the centrifugal force, Coriolis acceleration and thermal loads. In this study, general formulation is proposed to analyze the initially twisted rotating shell-type blades in thermal environment. For a thick shell, we must consider the transverse shear deformation, as well as rotary inertia. Thus, based on the concept of degenerated shell element with the Reissner-Mindlin's assumptions, the finite element method is adopted for solving the governing equations. Additionally, simplified equations are derived for the case of open circular cylindrical panels.