Torotrak Imperial Consultants Traction Modelling For a Toroidal

Torotrak – Imperial Consultants Traction Modelling For a Toroidal CVT George Nikas 11 July 2002

Project objectives

What was achieved Developed generalised Reynolds equation. n Non-Newtonian modelling. n Spin effects. n Residual stresses. n Life computations based on the I-H model. n Computer software developed and tested. n Dramatic reduction of CPU time. n

Effect of the contact load

Effect of the slide-roll ratio

Contour map of the film thickness

Effect of the ellipticity ratio

Effect of surface roughness

Effect of the traction-fluid temperature

Overall traction - example

Traction over limiting shear stress

Subsurface normal stress xx Depth: 5. 5 m Minimum xx: 1. 25 GPa Maximum xx: +0. 28 GPa

Subsurface normal stress yy Depth: 5. 5 m Minimum yy: 1. 16 GPa Maximum yy: +0. 16 GPa

Subsurface normal stress zz Depth: 5. 5 m Minimum zz: 1. 50 GPa Maximum zz: 0. 00 GPa

Subsurface shear stress xy Depth: 5. 5 m Minimum xy: 0. 21 GPa Maximum xy: +0. 20 GPa

Subsurface shear stress zx Depth: 55. 0 m Minimum zx: 0. 14 GPa Maximum zx: +0. 20 GPa

Subsurface shear stress zy Depth: 55. 0 m Minimum zy: 0. 15 GPa Maximum zy: +0. 16 GPa

Residual stresses and life expectancy

Subsurface stress concentration Depth: 55 m

Publication “Fatigue Life and Traction Modeling of Continuously Variable Transmissions” Author: G. K. Nikas Where: ASME Journal of Tribology. Scheduled to appear in the October 2002 issue.