Exploration of coupled-vibration phenomena in multi-disk rotor with blades with multi-cracks

Abstract

Based on previous research results obtained in the authors’ laboratory, in this article, we develop, refine, and summarize the disk-transverse, blade-bending, and shaft-torsion coupled-vibration phenomena of a multi-disk rotor with blades with multiple cracks. Three methods are used to explore these phenomena, namely, the finite element method, experimental method, and assumed mode method. The assumed mode method is primary, and the others play subsidiary roles. Some beneficial and interesting results are presented in this article. First, the authors used the assumed mode method and finite element method (ANSYS) to explore and compare the change rules of the natural frequencies and mode shapes in a rotor. Second, it is pointed out how multi-cracks affect the coupled-vibration phenomena of a single-/multi-disk(s) system. Numerical calculation results also show that the crack depth, number of crack blades, as well as the symmetry of the crack blades, affect the natural frequencies. Finally, the experimental results are discussed and the advantages and limitations of using each of the three methods are given. While the experimental measurement method advanced herein may have some limitations, the results should guide future research.