Vibration characteristics of a pretwisted multi-blade-shaft system with blade stiffness mismatch

The substructure mode synthesis method is employed to establish a mathematical model in this paper. The main body is represented by shaft, while the branching components are represented by blades. By solving this model, accurate frequency results of the rotating blade-shaft system are obtained at a high computational speed that meets engineering requirements. The resulting mode diagram aligns with that of the finite element model. Utilizing this model, the stiffness detuning of the rotating blade shaft system is investigated through a combination of surrogate modeling and ant colony algorithm, leading to several significant findings. It is observed that an increase in the standard deviation of stiffness detuning amplifies the length of frequency interval while minimally affecting the frequency mean value. Moreover, an increase in average stiffness expands the interval length for system frequencies. Additionally, higher rotational speeds reduce the interval length for blade-dominant vibrations but extend it for shaft-dominant vibrations.