FRICTION EVALUATION OF LUBRICATED LASER TEXTURED SURFACES

1. Adrian Predescu1), Mircea D. Pascovici1), Traian Cicone1), Cristian S. Popescu1),Constantin Grigoriu2), Dumitru Dragulinescu2)1) Department of Machine Elements and Tribology, University POLITEHNICA of Bucharest 2) National Institute for Laser, Plasma and Radiation Physics, Bucharest FRICTION EVALUATION OF LUBRICATED LASER TEXTURED SURFACES World Tribology Congress 2009, 6 – 11 September, Kyoto

2. PAPERS World Tribology Congress 2009, 6 – 11 September, Kyoto

3. experimental assessment of hydrodynamic performances (load capacity and friction force) for parallel, partially textured, sliders and comparison with a similar step slider the comparison of the experimental data with numerical simulations and with the results obtained by the others in order to establish the new research directions OBJECTIVES World Tribology Congress 2009, 6 – 11 September, Kyoto

4. LST TECHNOLOGY 1. Laser Nd:YVO4; 2. Microscope objective mount; 3. Microscope objective; 4. X axis linear table; 5. Y axis linear table. World Tribology Congress 2009, 6 – 11 September, Kyoto

5. TEST RIG AND SPECIMENS World Tribology Congress 2009, 6 – 11 September, Kyoto

6. EXPERIMENTAL PROCEDURE Constant film thickness tests Pin-on-disk testing arrangement World Tribology Congress 2009, 6 – 11 September, Kyoto

7. THE MODEL Data used in experiments and numerical simulations World Tribology Congress 2009, 6 – 11 September, Kyoto

8. RESULTS Experiment Load capacity variation vs. time Friction force variation vs. time World Tribology Congress 2009, 6 – 11 September, Kyoto

9. RESULTS Experiment Friction coefficient variation vs. time World Tribology Congress 2009, 6 – 11 September, Kyoto

10. Experiment RESULTS Dimensionless friction force vs. dimensionless film thickness Dimensionless load capacity vs. dimensionless film thickness World Tribology Congress 2009, 6 – 11 September, Kyoto

11. RESULTS Experiment Friction coefficient vs. dimensionless film thickness World Tribology Congress 2009, 6 – 11 September, Kyoto

12. RESULTS Numerical simulations 265822 Pa p -3.15 mm z -25327 Pa 3.15 mm 3.15 mm -3.15 mm x Pressure distribution at h=0.01 mm, and U=0.314 m/s The vectorial velocity distribution in film World Tribology Congress 2009, 6 – 11 September, Kyoto

13. RESULTS Experiment vs. Numerical Friction force vs. film thickness, experiment and numerical Load capacity vs. film thickness, experiment and numerical World Tribology Congress 2009, 6 – 11 September, Kyoto

14. Original experimental setup for testing lubricated textured surfaces using a standard pin-on-disc machine specially instrumented. Original tests with a textured (grooved) pin on a flat disc. The preliminary results have clearly put in evidence the cumulative hydrodynamic effect of partially textured surfaces. Sources of differences between the numerical simulations and experiments: relative positioning of the pin and the disc; the accuracy of the film thickness measurement; “wave effect”. The experimental results fairly agree with previously reported results. New tests will be performed for different configurations with improved surface accuracy. Stepped slider is better than grooved slider. CONCLUSIONS World Tribology Congress 2009, 6 – 11 September, Kyoto

15. Thank you, magic Kyoto! World Tribology Congress 2009, 6 – 11 September, Kyoto