| Robust maximum mistuned forced response of turbine engine bladed disks is investigated. The physical phenomena associated with mistuning, frequency splitting and mode distortion, are explored using a continuous model formulation of bladed disk structural dynamics, and maximum forced response is associated with mode distortion. Maximum response occurs when the harmonic components of a distorted mode are in phase at some location on the disk. This result is applied to a lumped parameter model of bladed disk structural dynamics, and a theory is developed for predicting the maximum forced response in a bladed disk due to distortion of a structural mode. The theory results in a closed-form expression for the maximum response in terms of the participation of the tuned modes in the mistuned response. Mode localization is described in the context of this theory. In addition, the theory predicts that when a system is intentionally mistuned to achieve maximum response, the response is robust, or insensitive to small, unintentional random mistuning.; The theory on robust maximum mistuned forced response is verified numerically and experimentally. A method for calculating the mistuning needed to obtain the mode with maximum response is developed. This method is applied to numerical lumped parameter models, and the predicted maximum forced response is demonstrated. In addition, the robustness of the intentionally mistuned system is shown using Monte Carlo simulations. The methods described in this thesis are also applied to an experimental bladed disk. The experimental bladed disk is intentionally mistuned to obtain the mode that results in maximum response. An engine order traveling wave excitation is used to excite the bladed disk, and the predicted maximum forced response in the bladed disk is demonstrated. The robustness of the maximum response is also shown experimentally. These results represent the first numerical and experimental demonstrations of a theory on maximum forced response in mistuned turbine engine bladed disks. |
