Explant analysis of a Maestro™ wrist prosthesis and calculation of its lubrication regime

Internal combustion engines have been improved markedly in recent years through efforts to conserve resources, reduce emissions and improve fuel efficiency. In this regard, the authors have been working to reduce friction and improve the seizure properties of the crankshaft main journal and main bearing. These mechanical components of internal combustion engines incur large friction losses. In order to reduce friction, journals have been coated with a diamond-like carbon (DLC) coating, which has been reported to reduce friction in the fluid lubrication regime in recent years. Another current issue of journals and bearings is the need to improve seizure resistance. Therefore, these properties were evaluated for material combinations of aluminium alloy bearings and DLC-coated journals, which have low affinity. The results revealed that friction was reduced under a fluid lubrication regime and seizure resistance was improved under a mixed lubrication regime.

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Modelling tribochemistry in the mixed lubrication regime

Tribology International ◽

10.1016/j.triboint.2018.12.024 ◽

2019 ◽

Vol 132 ◽

pp. 265-274 ◽

Cited By ~ 5

Author(s):

Abdullah Azam ◽

Ali Ghanbarzadeh ◽

Anne Neville ◽

Ardian Morina ◽

Mark C.T. Wilson

Keyword(s):

Mixed Lubrication ◽

Lubrication Regime ◽

Mixed Lubrication Regime

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Analysis of the Contribution of Adhesion and Hysteresis to Shoe–Floor Lubricated Friction in the Boundary Lubrication Regime

Tribology Letters ◽

10.1007/s11249-012-9989-5 ◽

2012 ◽

Vol 47 (3) ◽

pp. 341-347 ◽

Cited By ~ 20

Author(s):

Caitlin Moore Strobel ◽

Pradeep L. Menezes ◽

Michael R. Lovell ◽

Kurt E. Beschorner

Keyword(s):

Boundary Lubrication ◽

Lubrication Regime

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Evaluation of thermo-oxidized Jatropha bio-oil in lubrication of actual wet clutch materials

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650120981461 ◽

2020 ◽

pp. 135065012098146

Author(s):

Leonardo I Farfan-Cabrera ◽

Ezequiel A Gallardo-Hernández ◽

José Pérez-González ◽

Benjamín M Marín-Santibáñez ◽

Roger Lewis ◽

...

Keyword(s):

Automatic Transmission ◽

Viscosity Index ◽

Jatropha Oil ◽

Oxidative Aging ◽

Lubrication Regime ◽

Viscosity Increase ◽

Bio Oil ◽

Wet Clutch ◽

Transmission Fluid ◽

Pin On Disk

In this work, an assessment of the performance of thermo-oxidated Jatropha oil as a lubricant for actual wet clutch materials was performed and compared with a commercial automatic transmission fluid. For this, Jatropha oil, a commercial automatic transmission fluid and a blend of 20 vol% Jatropha oil–80 vol% automatic transmission fluid were subjected to thermo-oxidative aging at 26 °C and 100 °C, followed by a pin-on-disk testing with disk samples from an actual wet clutch. Evaluation of the film thickness at the sliding interface resulted in a boundary lubrication regime for all the tests. The changes in oxidation, viscosity, and a viscosity index of the samples were evaluated along with friction coefficients at various sliding speeds. Jatropha oil was the most sensitive to thermo-oxidation. Jatropha oil and the blend showed a higher viscosity increase than automatic transmission fluid with thermo-oxidation, while the viscosity index of all oils was decreased considerably, Jatropha oil and the blend being the most reduced. Finally, the anti-shudder property, as measured by the change in the friction coefficient with a sliding speed, of Jatropha oil and automatic transmission fluid was improved by thermo-oxidation at 26 °C but worsened at 100 °C, meanwhile it was barely affected in the blend. Therefore, these results indicate that using pure Jatropha oil as automatic transmission fluid would be unsuitable, but blending it with automatic transmission fluids in specific proportions may be apposite for improving the friction properties of wet clutches even under thermo-oxidative conditions.

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Numerical Modeling of Mixed Lubrication and Flash Temperature in EHL Elliptical Contacts

Journal of Tribology ◽

10.1115/1.2805429 ◽

2007 ◽

Vol 130 (1) ◽

Cited By ~ 17

Author(s):

Neelesh Deolalikar ◽

Farshid Sadeghi ◽

Sean Marble

Keyword(s):

Surface Deformation ◽

Elastohydrodynamic Lubrication ◽

Mixed Lubrication ◽

Asperity Contact ◽

Lubrication Regime ◽

Predicting Performance ◽

Pure Rolling ◽

Rolling Element ◽

Contact Pressures ◽

Film Lubrication

Highly loaded ball and rolling element bearings are often required to operate in the mixed elastohydrodynamic lubrication regime in which surface asperity contact occurs simultaneously during the lubrication process. Predicting performance (i.e., pressure, temperature) of components operating in this regime is important as the high asperity contact pressures can significantly reduce the fatigue life of the interacting components. In this study, a deterministic mixed lubrication model was developed to determine the pressure and temperature of mixed lubricated circular and elliptic contacts for measured and simulated surfaces operating under pure rolling and rolling/sliding condition. In this model, we simultaneously solve for lubricant and asperity contact pressures. The model allows investigation of the condition and transition from boundary to full-film lubrication. The variation of contact area and load ratios is examined for various velocities and slide-to-roll ratios. The mixed lubricated model is also used to predict the transient flash temperatures occurring in contacts due to asperity contact interactions and friction. In order to significantly reduce the computational efforts associated with surface deformation and temperature calculation, the fast Fourier transform algorithm is implemented.

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Percutaneous ablation procedures in cirrhotic patients with hepatocellular carcinoma submitted to liver transplantation: Assessment of efficacy at explant analysis and of safety for tumor recurrence

Liver Transplantation ◽

10.1002/lt.20469 ◽

2005 ◽

Vol 11 (9) ◽

pp. 1117-1126 ◽

Cited By ~ 129

Author(s):

Maurizio Pompili ◽

Vincenzo Giorgio Mirante ◽

Gianfranco Rondinara ◽

Luigi Rainero Fassati ◽

Fabio Piscaglia ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

Liver Transplantation ◽

Tumor Recurrence ◽

Percutaneous Ablation ◽

Cirrhotic Patients ◽

Explant Analysis

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Synergistic Antiwear Effects of Zinc Dialkyl Dithiophosphate and Different Detergents

STLE/ASME 2008 International Joint Tribology Conference ◽

10.1115/ijtc2008-71013 ◽

2008 ◽

Author(s):

G. Pennecot ◽

K. Komvopoulos ◽

E. S. Yamaguchi

Keyword(s):

Wear Rate ◽

Boundary Lubrication ◽

Base Oil ◽

Temperature Range ◽

Zinc Dialkyl Dithiophosphate ◽

Contact Voltage ◽

Lubrication Regime ◽

Steel Surfaces ◽

Dialkyl Dithiophosphate ◽

Insight Into

The effectiveness of blends consisting of base oil, some secondary zinc dialkyl dithiophosphate (ZDDP), and different detergents to form antiwear tribofilms on steel surfaces sliding in the boundary lubrication regime was investigated in the temperature range of 105–125°C. The efficacy of the tribofilms formed from these blends was evaluated in terms of contact voltage and wear rate measurements. The best antiwear performance was demonstrated by the tribofilm formed from the blend containing sulphonate detergent. The results of this study provide insight into competing effects between ZDDP and different detergents that affect significantly the antiwear performance of the formed tribofilms.

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