Dynamic modeling of high-speed helical gear transmission system with multiple geometric deviations and non-uniform contact

Existing helical gear dynamic models remain limited in providing a unified state-dependent description of the combined effects of multiple geometric deviations on non-uniform contact. To address this problem, this study develops a dynamic model in which pitch, profile, and helix deviations are mapped as normal perturbations into a common time-varying backlash field and coupled with the dynamic transmission error to determine the instantaneous contact state and load-bearing configuration. The improved mesh element is directly coupled with the shafting, bearings, and casing, establishing a consistent pathway from geometric deviations to system vibration response. The results show that pitch deviation changes the tooth-pair load-bearing sequence and mainly enhances rotational-frequency sideband components around the gear mesh frequency (GMF). Helix deviation enhances sideband modulation through contact position migration along the face width direction, whereas profile deviation primarily increases the GMF main-peak energy by changing the local stiffness of the main load-bearing region. As gear accuracy grade deteriorates, sideband related indices show higher sensitivity to accuracy degradation than the GMF main peak alone. Experimental validation shows good agreement between simulation and experiment in terms of time-domain amplitude, GMF main peak energy, and rotational-frequency sideband components. These results provide a practical basis for linking operational vibration features with geometric deviation related manufacturing accuracy assessment, assembly quality control, and sideband-based condition monitoring.