Effects of Mistuning on the Forced Response of Bladed Discs with Friction Dampers

摘要

A method recently developed by the authors allows efficient calculation of the periodic forced response to be performed for bladed discs with arbitrary nonlinearities, including friction contacts and gaps. The method can be used with large finite element models and includes friction contact models, allowing for variable normal stresses at the friction contact interfaces, such as underplatform dampers, blade-root joints and others. A multiharmonic representation of the forced response enables analysis to be undertaken with the required accuracy and under arbitrary distributed and multiharmonic excitation. In this paper, the effects of friction dampers on the multiharmonic forced response of large-scale finite element models of practical mistuned bladed discs are studied for the first time. Maximum forced response levels of mistuned systems are explored and compared with those for tuned assemblies. The effects of parameter values for the friction dampers on the amplification factors and distribution of the maximum amplitudes over the bladed disc assembly are investigated. Conditions are found when the amplification factors can be decreased as a result of mistuning, in direct contrast to the conventional results obtained using linear models.