Mitigating Vibration Levels of Mistuned Cyclic Structures by Use of Contact Nonlinearities

In cyclic systems, manufacture tolerances and possible wear of the structure lead to small random variations (also called random mistuning) of the nominal (tuned) cyclic symmetric mechanical system. Most of the time, these imperfections result in systems with vibration levels higher than the tuned one and are thus detrimental. Friction nonlinearities are used in the nominal design as a damping mechanism to dissipate the vibrational energy. This paper combines the latest development of nonlinear reduction methodologies to assess the influence of friction and contact mechanism on a high-fidelity finite-element model of a bladed disk subjected to random mistuning. Through statistical studies, it is shown that the nonlinearities at stake tend to mitigate the negative influence of random mistuning on the amplification factor.