Investigation on dynamic rubbing characteristics of a bladed rotor system with multi-mode rubbing fault

Dynamic behavior analysis of blades under high cycle fatigue with rubbing fault is vital for estimating the reliability of rotating machinery. This paper focuses on a novel rubbing model and the flexible dynamic characteristics of a shaft-blade-disk system (SBDS) model with considerations of various forms of rub-impacts. Firstly, the deformation relations and the motion equations of the SBDS model in steady state are derived using Lagrange's principle. Secondly, a new quasi-static blade rubbing model involving shaft deformation and blade coupling effect is established, and the influence of rub-impact correlation parameters on rubbing force is further explored. Then, both the effect of shaft-disk coupling on the blades at various states and the dynamic characteristics of numerous rubbing modes are also investigated. The results revealed that the asymmetric form of rub-impact will induce more complex vibrational behavior (such as frequency components and trajectory differences), while the symmetrical rubbing modes can keep the system relatively stable.