Loughborough University
Non-linear vibro-impact phenomenon....pdf (1.93 MB)

Non-linear vibro-impact phenomenon belying transmission idle rattle

Download (1.93 MB)
journal contribution
posted on 2009-05-22, 13:08 authored by Osman A.M. Tangasawi, Stephanos TheodossiadesStephanos Theodossiades, Homer Rahnejat, P. Kelly
This paper investigates automotive transmission gear rattle. Specifically, idle gear rattle, where the repetitive impacts of teeth are subject to light loads is investigated. Hydrodynamic regime of lubrication prevails in lightly loaded impact of teeth pairs. Formation of a lubricant film is due to the combined entraining motion of the lubricant and squeeze film effect. A lumped parameter inertial dynamic model, comprising hydrodynamic impact and flank friction for pairs of simultaneous teeth pairs of loose gears is developed. The overall dynamic model includes seven loose gear pairs and rigid body lateral motions of input and output transmission shafts. Therefore, the influence of fluid film behaviour on idle gear rattle is determined, which has hitherto not attracted sufficient research studies. Gear rattle is manifested by a vibration signature, which corresponds to the bands of frequencies due to torsional engine oscillations, meshing frequencies, and impact characteristics of lubricated conjunctions. The spectral contributions are affected by lubricant rheology, specifically its bulk viscosity variation with temperature. It has been found that spectral disposition tends towards lower frequency contributions with reducing lubricant viscosity because of rising temperatures and lowering lubricant stiffness. The findings conform with the experimental results, also reported in the paper. It has also been shown that squeeze film motion plays a significant role in the propensity of transmission system to rattle.



  • Mechanical, Electrical and Manufacturing Engineering


TANGASAWI, O. ... et al., 2008. Non-linear vibro-impact phenomenon belying transmission idle rattle. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 222 (10), pp. 1909-1923


Professional Engineering Publishing / © IMECHE


  • VoR (Version of Record)

Publication date



This article was published in the Journal, Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science [© IMECHE]. The definitive version is available at: http://www.pepublishing.com/




  • en