Effect of number of blades and distribution of cracks on vibration localization in a cracked pre-twisted blade system

A number of several blades can be grouped at their tips to increase their stiffness. This work examines how the effect of number of grouped blades and distribution of cracks affect the mode localization of a mistuned blade system. The pre-twisted blade and the effect of twist angle on localization are also considered in this article. Dynamic characteristics of blades in a blade system are focused to study. Periodically coupled pre-twisted beams were used to approximate shrouded blades. The Euler-Bernoulli beam model was employed to characterize the tapered pre-twisted blade. The mode localization equations associated with the local blade crack defects in the rotating grouped blade system were formulated using Hamilton's principle. The Galerkin method was used to discretize the localization equations of the mistuned system. The numerical results herein reveal that the number of grouped blades and the distribution of multi-disorders in a rotating blade system may markedly affect the localization phenomenon. (c) 2005 Elsevier Ltd. All rights reserved.