Effect of a local crack on the dynamic characteristics of a rotating grouped blade disc

The effects of a local blade crack and the group arrangement on the mode localization in a rotating turbodisc are studied in this paper. Periodically coupled Euler-Bernoulli beams are used to approximate the grouped and shrouded turboblades. A two-span beam with a torsion spring is used to model the cracked blade. The crack depth characterizes the stiffness of the assumed torsion spring. Galerkin's method is applied to formulate the localization equations of the grouped turbodisc system. Numerical results indicate that the crack depth, crack distribution and rotational speed in a rotating grouped blade disc may significantly affect the localization phenomenon.