Date

2022-6-03

Author

Naghizadeh, Ehsan

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High computation costs imposed by a large number of degrees of freedom hamper the vibration analysis for blade disk systems. Moreover, mistuning, which necessitates the solution of the problem numerous times, and contact surfaces which require displacement data on shroud Degrees of Freedom (DOFs) with high accuracy, highlight the demand for an efficient reduced-order model. Consequently, aiming at deriving results with acceptable accuracy while minimizing computational cost, researchers have proposed different reduction techniques. In this context, Component Mode Synthesis (CMS) methods that follow the famous divide and conquer theory are approved to be very effective. In this study, first, the most famous reduction techniques based on CMS, namely, Rubin, Hurty/Craig-Bampton, Dual Craig-Bampton, and Mixed interface methods, are implemented for reducing the computational cost of an academic bladed disk system with shrouds. A new reduction method is proposed by capitalizing on the information derived from the proceeding comparison study, which is a generalized case for Rubin and Hurty/Craig-Bampton methods. Subsequently, the efficiency of the proposed method is compared with its rivals available in the literature in both tuned and mistuned case studies. It is concluded that the proposed method can provide superior accuracy while maintaining a relatively low computational cost when appropriately used with the cyclic symmetry property and Rubin method for a tuned bladed disk system. For the mistuned case, the reduction of the blade sector is analogous to the tuned case. Therefore, special attention is paid to the disk assembly for the mistuned case. Three different reduction approaches are proposed for the disk segment. Moreover, an interface reduction method is implemented to reduce the size of the model further. Finally, each of these methods is implemented on the disk sector and coupled with the reduced blade segment to create a reduced-order model of the entire bladed disk assembly. The Reduced Order Model (ROM) performance is investigated for different mistuning patterns. It is concluded that the reduction measure proposed in this work can bring excellent results and drastically reduce the computational time for the analysis of mistuned bladed disk.

Subject Keywords

Reduced-Order Modeling, Component Mode Synthesis (CMS), Bladed Disk Systems, Mistuning, Shrouds

URI

https://hdl.handle.net/11511/97743

Collections

Graduate School of Natural and Applied Sciences, Thesis