The Use of Quantitative Structure Activity Relationships (QSAR) in Traction Fluid Design

Edgar, J. A.; Hurley, S.

doi:10.4271/2004-01-2009

Cited by 3 publications

(3 citation statements)

References 6 publications

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“…Although molecular dynamics simulations enables us to directly analyse the motions of lubricant molecules, [12][13][14] which is a realistic simulation procedure compared with a quantum chemical or statistical approach such as the quantitative structure-property relationship (QSAR), 15,16 they have some restrictions. Because of the large difference in shear viscosity and oil fi lm thickness, the simulations do not directly model the experiments such as ball-on-disk type apparatus.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of elastohydrodynamic lubrication oil film

Washizu

Ohmori

2010

Lubrication Science

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Highlights • A mechanism for the limited shear-stress transition of an elastohydrody-namic lubrication (EHL) oil film is proposed. • The spatial structure and velocity profile showed gradual changes. • Suppression of the fluctuation is found in the EHL regime. Abstract All-atom molecular dynamics simulations of an elastohydrodynamic lubrication oil film are performed to study the effect of pressure. Fluid molecules of n-hexane are confined between two solid plates under a constant normal force of 0.1-8.0 GPa. Traction simulations are performed by applying relative sliding motion to the solid plates. A transition in the traction behavior is observed around 0.5-2.0 GPa, which corresponds to the viscoelastic region to the plastic-elastic region, which are experimentally observed. This phase transition is related to the suppression of the fluctuation in molecular motion.

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Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of elastohydrodynamic lubrication oil film

Washizu

Ohmori

2010

Lubrication Science

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“…High polarity leads to strong repulsive forces between molecules reducing their ability to pack close together. In 2004, Edgar and Hurley showed that quantitative structure activity relationships (QSAR) could be used to predict EHD friction from molecular structure based on friction measurements on other molecular structures [13].…”

Section: Previous Workmentioning

confidence: 99%

Effect of Base Oil Structure on Elastohydrodynamic Friction

2016

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The EHD friction properties of a wide range of base fluids have been measured and compared in mixed sliding-rolling conditions at three temperatures and two pressures. The use of tungsten carbide ball and disc specimens enabled high mean contact pressures of 1.5 and 2.0 GPa to be obtained, comparable to those present in many rolling bearings. The measurements confirm the importance of molecular structure of the base fluid in determining EHD friction. Liquids having linear-shaped molecules with flexible bonds give considerably lower friction than liquids based on molecules with bulky side groups or rings. EHD friction also increases with viscosity for liquids having similar molecular structures. Using pure ester fluids, it is shown that quite small differences in molecular structure can have considerable effects on EHD friction. The importance of temperature rise in reducing EHD friction at slide-roll ratios above about 5% has been shown. By measuring EHD friction at several temperatures and pressures as well as EHD film thickness, approximate corrections to measured EHD friction data have been made to obtain isothermal shear stress and thus EHD friction curves. These show that under the conditions tested most low molecular weight base fluids do not reach a limiting friction coefficient and thus shear stress. However, two high traction base fluids appear to reach limiting values, while three linear polymeric base fluids may also do so. Constants of best fit to a linear/logarithmic isothermal shear stress/strain rate relationship have been provided to enable reconstruction of isothermal EHD friction behaviour for most of the fluids tested.

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“…Tsubouchi identified five key molecular structure features for high-EHD friction to be high molecular stiffness, large size, short alkyl chain length, high melting point and low molecular polarity [7][8][9][10]. Edgar and Hurley applied quantitative structure activity relationships (QSAR) to predict EHD friction based on friction measurements on a learning set of molecules of known structure to aid in the development of new traction fluids [11].…”

Section: Previous Workmentioning

confidence: 99%

Correlation of Elastohydrodynamic Friction with Molecular Structure of Highly Refined Hydrocarbon Base Oils

Kim

Spikes

2020

Tribol Lett

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The molecular compositions of a range of low viscosity hydrocarbon base oils spanning API Groups II to IV have been quantified using 13C NMR and correlated with base oil elastohydrodynamic (EHD) friction. A strong correlation has been found between the proportions of paraffin, linear and branched carbons and EHD friction, with a high proportion of linear and paraffinic carbon atoms contributing to low-EHD friction but branched carbons contributing to high-EHD friction. Correlation equations have been developed to predict EHD friction based on base oil composition. At very high temperature and low pressure, this correlation breaks down as the lubricant in the contact does not reach sufficiently high shear stress for shear thinning to occur. For Group IV polyalphaolefin, the correlation must be extended to account for the very high proportion of linear carbons originating from linear alkene oligomerization. The correlations developed in this study can be used to guide the design of low-EHD friction base oils.

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The Use of Quantitative Structure Activity Relationships (QSAR) in Traction Fluid Design

Cited by 3 publications

References 6 publications

Molecular dynamics simulations of elastohydrodynamic lubrication oil film

Molecular dynamics simulations of elastohydrodynamic lubrication oil film

Effect of Base Oil Structure on Elastohydrodynamic Friction

Correlation of Elastohydrodynamic Friction with Molecular Structure of Highly Refined Hydrocarbon Base Oils

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