Dynamic analysis for a spur geared rotor system with tooth tip chipping based on an improved time-varying mesh stiffness model

Abstract This study conducts a comprehensive analysis of a spur geared rotor system with tooth tip chipping from the viewpoints of dynamic modeling and fault detection. An improved tooth tip chipping model is proposed, and analytical equations of time-varying mesh stiffness (TVMS) for a chipped tooth is derived. A new term called “torsional stiffness” is introduced into the overall TVMS due to the chipping defect. On this basis, a finite element dynamic model of a spur geared rotor system is established. The mass unbalance caused by the chipping defect is emphasized in the dynamic model. The nonlinear frequency responses of the geared rotor system are obtained to study the system vibration behaviors. The influences of chipping defects on the TVMS, time histories and frequency spectrums of vibration signals are revealed. Several statistic indicators are applied to evaluate the fault conditions under different rotational speeds. Finally, a comparative study is carried out to show the effects of unbalance excitations caused by chipping defects on the system vibration responses. This study could provide a comprehensive methodology and some meaningful references for the modeling, dynamic analysis and fault diagnosis of gear transmission systems with local defects.