Variation in the stability of a rotating blade disk with a local crack defect

• Published in: Journal of sound and vibration Vol. 294; no. 3; pp. 486 - 502
• Main Authors: Huang, Bo-Wun, Kuang, Jao-Hwa
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.06.2006; Elsevier
• Subjects: Exact sciences and technology; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Physics; Solid mechanics; Structural and continuum mechanics; Vibration, mechanical wave, dynamic stability (aeroelasticity, vibration control...); Longitudinal crack; Localized mode; Blade shroud; Rotation speed; Modeling; Varying speed; Cantilever beam; Periodic structure; Longitudinal vibration; Multiscale method; Rotating disk; Crack length; Turbine blade; Defect; Galerkin method; Bending vibration; Rotating beam(mechanics)
• ISSN: 0022-460X; 1095-8568
• DOI: 10.1016/j.jsv.2005.11.028

The effect of a near root local blade crack on the stability of a grouped blade disk is investigated in this paper. A bladed disk comprised of periodically shrouded blades is used to simulate the coupled periodic structure. The blade crack is modeled using the local flexibility with coupling terms. The mode localization phenomenon introduced by the blade crack on the longitudinal and bending vibrations in the rotating blades has also been considered. Using the Galerkin's method, the imperturbation equations of a bladed disk in which one of the blades is cracked, subject to fluctuations in the rotation speed, can be derived. Employing the multiple scales method, the boundaries of the instability zones in the mistuned turbo blade system are approximated. Numerical results indicate that an additional unstable zone is introduced near the localization frequency and the regions of unstable zones are varied with the crack size and fluctuations in disk speed.