Vibration characteristics of a gear system incorporating spatial crack propagation on an idler tooth

Abstract

Tooth crack (TC) represents a predominant mode of failure in gears. Existing studies commonly simplify the crack propagation path as the planar crack propagation path (PCPP), while largely neglecting the more complex spatial crack propagation path (SCPP), which extends simultaneously along the tooth thickness direction (TTD), tooth width direction (TWD) and tooth height direction (THD). To detect and identify the spatial crack propagation (SCP) on idler gears, a gear-rotor-housing coupled dynamic model (DM) is established to investigate its influences on dynamic characteristics and fault features of the idler transmission system. First, the idler tooth model incorporating SCPP is established, and the corresponding method for calculating meshing stiffness (MS) is proposed to examine the effect of representative SCPPs on MS. Subsequently, a finite element-based gear-rotor-housing coupled DM is constructed to analyze influences of SCP on the system’s vibration characteristics. Finally, experimental validation confirms the accuracy of the proposed model and the analytical findings. Notable divergences in MS, vibration characteristics and fault features have been identified among different SCPPs. Feature indicators sensitive to SCP are identified to monitor the progression of idler tooth cracks.