Abstract

Existing studies primarily focus on stiffness and damping under full-film lubrication or dry contact conditions. However, most lubricated transmission components operate in the mixed lubrication region, indicating that both the asperity contact and film lubrication exist on the rubbing surfaces. Herein, a novel method is proposed to evaluate the time-varying contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions. This method is sufficiently robust for addressing any mixed lubrication state regardless of the severity of the asperity contact. Based on this method, the transient mixed contact stiffness and damping of spiral bevel gears are investigated systematically. The results show a significant difference between the transient mixed contact stiffness and damping and the results from Hertz (dry) contact. In addition, the roughness significantly changes the contact stiffness and damping, indicating the importance of film lubrication and asperity contact. The transient mixed contact stiffness and damping change significantly along the meshing path from an engaging-in to an engaging-out point, and both of them are affected by the applied torque and rotational speed. In addition, the middle contact path is recommended because of its comprehensive high stiffness and damping, which maintained the stability of spiral bevel gear transmission.

Highlights

  • As crucial mechanical transmission parts, spiral bevel gears are widely used in aviation, automobile, and mining

  • This investigation highlights the effect of mixed lubrication on the stiffness and damping of spiral bevel gears, and reveals the effects of the operating conditions

  • Owing to the lack of a comprehensive analysis regarding the transient mixed lubrication of spiral bevel gears, the stiffness and damping are typically expressed by the simplified Hertz contact, which may result in considerable errors because the effects of direct contact of asperities, squeezing effect of lubricant, and the interaction between them are not considered

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Summary

Introduction

As crucial mechanical transmission parts, spiral bevel gears are widely used in aviation, automobile, and mining. Zhu and Hu [8, 9] established the first unified mixed lubrication numerical simulation model coupled with 3D machined rough surfaces in point contact. Pu et al [27] presented a mixed lubrication model considering both the 3D machined roughness and velocity angle between two contact surfaces; based on the numerical simulation results, the friction and flash temperature were further predicted. Shi [24] presented a stiffness and damping model in point contact transient non-Newtonian thermal EHL for crowned herringbone gears, and the effects of the operating conditions and contact parameters on the stiffness and damping of oil films were revealed. Systematic research was performed to reveal the effects of roughness, transmission torque, rotational speed, and contact trajectory on the transient mixed contact stiffness and damping

Transient mixed lubrication theory
Transient mixed contact stiffness and damping model
Stiffness in transient mixed lubrication
Damping in transient mixed lubrication
Results and discussion
Comparison with Hertz contact
Effect of roughness
Effect of rotational speed
Conclusions
Full Text
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