Numerical investigation of a mistuned industrial bladed disk dynamics with structural contacts using time and frequency methods

Abstract

This work focuses on the numerical investigation of mistuned bladed disk dynamics undergoing blade-tip/casing contact events. The effect of mistuning on the bladed disk dynamics is evaluated as it undergoes structural blade-tip/casing contacts in the vicinity of its nominal angular speed. It is first underlined that the interaction of interest is in essence a rubbing interaction involving all the blades with no significant disk response. Indeed, results obtained with a single blade model and the full bladed disk suggest that both contact stiffening and maximum displacements are similar for both models. Then, an in-depth analysis of the tuned bladed disk interaction is carried out using both time and frequency solution methods. The analysis of the tuned bladed disk highlights that contact stiffening and maximum amplitudes may be underestimated by time integration strategies. Numerical challenges inherent to frequency methods are then underlined on mistuned bladed disks. A stochastic analysis on the influence of mistuning in a nonlinear context is carried out using time integration strategy. Amplification and localization factors are computed to quantify the effect several degrees of mistuning on the bladed disk dynamics with contact nonlinearities. Due to the inherent restrictions associated with the employed time integration methods, the analysis is centered on localization factors. It is evidenced that two areas of high localization stand out, all located close to sudden changes of amplitudes, thus suggesting the possible coexistence of distinct stable solutions featuring very distinct levels of localization.