Nonlinear dynamic properties of disk-bolt rotor with interfacial cutting faults on assembly surfaces

Interfacial cutting faults on assembly surfaces are considered in a three-dimensional (3D) disk-bolt rotor system. The traditional finite element method is used to establish the 3D model of faulted disk-bolt rotor. A contact algorithm is applied to calculate the static features of this combined rotor. It is revealed that interfacial cutting faults produce rotor bending which is gradually strengthened as rotational speed increases besides disk’s mass eccentricity. The 3D dynamic equations of a faulted disk-bolt rotor system include these cutting faults’ static influences. The nonlinear dynamic properties are investigated by Poincaré mapping, Newton iteration and a prediction-correction algorithm. As a result, the rotor bending due to cutting faults reduces the global stability of the complicated rotor and enlarges the vibration amplitude obviously. This speed-variant bending also decides the feature that rotor vibration increases again after critical speed no matter whether dynamic balance is carried out. The maximum allowable fault depth is obtained and it gives an explanation as to why the machining precision of assembly surfaces should be strictly controlled in the disk-bolt rotor. Generally, this paper originally tries to provide a feasible approach to consider a 3D interfacial cutting fault with specific shape and to analyze the static–dynamic coupling characteristics for a disk-bolt rotor.