A study of the mechanisms of cracking-induced mistuning in bladed disks is presented in this paper. An analytical model for a bladed disk was formulated using lumped-mass-beams, and a cracked blade was represented by a beam with a through-crack at the root. Local stiffness reduction due to cracking was incorporated using a flexibility matrix method. The dynamic characteristics of the bladed disk were analysed for the tuned system and then for the mistuned system with cracks of various depths

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... roduced at the root of a blade. The dynamic characteristics of the mistuned system with a cracked blade were evaluated and the mistuning pattern due to blade cracking was investigated. The mechanisms of cracking-induced mistuning were elucidated by analysing the mode localisations and the reductions in natural frequency for different coupling ratios between the disk and blades. The results show that the occurrence of a cracked blade significantly increases the response amplitude of the other uncracked blades and therefore gives rise to enhanced HCF damage for all coupling ratios studied. In the present study, the relationship between the cracked blade and its vibration response signature is established, hence providing the essential guidance required for blade crack detection procedures and for blade failure investigations. Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. See also ADM202115, RTO-MP-AVT-121. Evaluation, Control and Prevention of High Cycle Fatigue in Gas Turbine Engines for Land, Sea and Air Vehicles., The original document contains color images. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 12 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98)