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In the current research, oil derived from several Brassica species, and related oilseeds, was investigated for use as a lubricant base-oil. Oils obtained from B. rapa L. were selected because of their superior cold temperature performance over Sinapis alba L., B. carinata A., B. napus, and B. juncea L. The commercial antiwear additive zinc dialkyl dithiophosphate (ZDDP) was added (800 ppm) to B. rapa oils to determine the impact on oxidative stability and lubricity. It was found that the B. rapa oil ACS-C7 had a low cloud and pour point. B. rapa oils had poor oxidative stability at 97.8 °C when compared to a mineral oil (petroleum-based) standard. ZDDP had little effect on oxidative stability and cloud point. It was concluded that B. rapa oils have sufficient low temperature performance for use as a lubricant base oil. However, for continued use in a motor oil formulation, further modification of the oxidative stability will be necessary. All B. rapa oils with and without ZDDP were subjected to lubricity testing in a Plint High Frequency Wear Tester (TE-77). Lubricity testing simulates the high temperature and pressure in a motor system. The coefficient of friction and resultant wear scar width were measured. B. rapa oils lower coefficients of friction and decrease wear scar widths when compared with a mineral oil standard. Addition of ZDDP to B. rapa oils slightly increased lubricity performance of the oils. The wear scars produced on the polished stainless steel disk were subjected to X-ray Absorption Near Edge Structure (XANES) analysis using two synchrotron beamlines at the Canadian Light Source. XANES analysis confirmed the presence of a lubricating tribofilm on the surface of the stainless steel disks following B. rapa lubricity testing. These results indicate that B. rapa oils are suitable candidates as lubricant base oils for motor oil formulation.

This thesis is concerned with the development of a nunerical technique for the computational analysis of ruptured liquid films in both steadily and dynamically loaded bearings. The approach is based on the principle of oil flow continuity. A cavitation algorithm, proposed by H. G. Elrod, was implemented for studies of hydrodynamic lubrication in infinitely long cylinder/plane bearings (i.e. non-conformal contacts) under combined sliding, rolling and normal motion. Difficulties involved in the implementation of this algorithm were investigated in great depth. A new 'improved' method of solution, which is well-suited to the computational analyses of steadily and dynamically loaded bearings, was developed. The improved technique involves the solution of the hydrodynamic lubrication problem for oil film pressures or degrees of lubricant filling in the full film and cavitated regions of a bearing. Detailed studies of cylinder/plane under conditions of both instantaneous and sinusoidal normal motion were performed. The improved solution was shown to facilitate the implicit implementation of the Jakobsson-Floberg-011son boundary conditions (i.e. the inclusion of 'oil film history' phencinena) in dynamically loaded bearing analyses. Detailed comparisons between the oil film history and classical solutions, and published experimental studies were made. Computer programs based on the classical Reynolds equation and the improved method of solution were developed for the analysis of circuTiferentially grooved, finite journal bearings operating under steady-state and dynamic loading conditions. The improved method of solution produced more realistic predictions of performance characteristics, particularly oil film extent, oil flow and bearing power loss. Comprehensive comparisons with published theoretical and experimental studies were made. Encouraging agrenent was obtained between the oil flow continuity analyses and experiments. Journal centre orbit analyses of dynamically loaded bearings, typically found in reciprocating engines, indicated that the oil film history solution may reveal a nunber of new features of time-varying performance characteristics not previously predicted by the classical Reynolds solution.

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Yes / Droplet flows, termed misting, are significant lubrication flow mechanisms to, in and around the piston assembly. Therefore, these are important in piston assembly tribology and engine performance. Crankcase lubricant degradation rate has been hypothesised to be influenced by lubricant droplet flows through the piston assembly and crankcase, but not previously confirmed. Lubricant was sampled from the sump, top ring zone (TRZ), and mist and aerosol from the crankcase during an extend-ed run. The physical and chemical degradation of these samples was characterised. Droplet flows were intermediate in degradation and fuel dilution between TRZ and sump. Flows with smaller droplet sizes were more degraded that those with larger droplets. The degradation of polymers was dependent on their molecular architecture.

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