Robustness Analysis of Intentional Mistuning Patterns in Randomly Mistuned Bladed Disk Assemblies

It is known that bladed disks, which are usually designed as cyclically symmetric structures, undergo considerable amount of forced response amplitude magnification due to the phenomenon called mistuning. Mistuning is inevitable for any cyclically symmetric bladed disk assembly since it is caused by manufacturing tolerances, material properties and operational wear. Since reducing the level of mistuning beyond certain limits is not possible with the current technology, the attempts are rather made to reduce or control the forced response magnification, where intentional mistuning is an alternative., Intentional Mistuning. is to mistune a cyclically symmetric bladed disk with a pre-defined pattern. However, because of the fact that some uncontrolled variation is still unavoidable, it is vital to evaluate any intentional mistuning pattern together with a certain amount of random mistuning. The aim of this study is to statistically compare the robustness of intentional mistuning patterns such as harmonic, linear and pseudo harmonic, with different levels of random mistuning applied on top. Therefore, intentional mistuning patterns will be evaluated without disregarding the effect of uncertainties already present in the system. Two sample bladed disk models are used to gather information on model dependence. Reduced order models of the sample bladed disks are built for this study to reduce computation time. Monte Carlo simulations with selected intentional and random mistuning pairs are then performed under pre-defined excitations to compare the performance of the intentional mistuning patterns applied.