An Improved Mesh Stiffness Model for Cracked Spur Gears Considering Tooth Surface Contact Characteristics

Abstract

Abstract

Tooth crack, as a typical fault, directly affects the meshing characteristics of gears, which causes abnormal vibration and noise during the gear meshing process, with some even threatening the operational safety of the mechanical device. Meanwhile, the mapping relation between the tooth crack and the actual meshing characteristics is still unclear under the tooth surface morphology and lubrication properties. Aiming at this issue, an integrated time-varying meshing stiffness (I-TVMS) model with cracks is proposed under the complex and variable working conditions. Based on the potential energy method, the analytical expressions with cracks are derived and calculated, and, then, the variation laws of I-TVMS under different crack parameters, tooth surface morphology, and structural and excitation parameters are investigated. Combined with the healthy tooth, the crack increases the contact load on the tooth surface, and reduces the oil film thickness, which decreases the I-TVMS of the cracked tooth. The greater the crack depth and torque is, the smaller the oil film thickness, and the weaker the I-TVMS fluctuation will be. The influence of the crack angle depends on the crack type and meshing region. The tooth-root crack is more sensitive in the single-tooth region, whereas the tooth surface crack shows a larger change only in the double-tooth mean value. When the crack location transitions from the tooth root to the tooth top, the stiffness attenuation gradually weakens.