Muchammad

Numerical study of the load-carrying capacity of lubricated parallel sliding textured surfaces including wall slip

This article analyzes the combined effect of surface texturing and wall slip on the load-carrying capacity of parallel sliding systems. A new modified Reynolds equation with slip is proposed, based on the critical shear stress model, to reveal the hydrodynamic load-carrying capacity. A range of parameters such as texturing zone, texture cell aspect ratio, critical shear stress, and slip length are analyzed. It is shown that the optimal texturing zone length oscillates around 75% of the slider length. A slight shift of the optimized texturing zone toward the inlet of the contact is observed when the critical shear stress is increased. The numerical analysis also shows that there is a unique threshold value of the critical shear stress for every texture cell aspect ratio. When this ratio is increased, the threshold value increases, thus influencing the slip considerably. Slip has a positive effect on the load-carrying capacity for critical shear stress lower than the threshold value, whereas it has no effect on higher values. It is also found that in comparison with a solely textured surface, the load-carrying capacity of the combined textured/wall slip pattern can be increased by around 300% using the optimized slip parameters.

Wear Analysis of Spherical Graphite Cast Iron Using Pin-on Disc Tribotester

Cast iron is widely used due to low price, good machining and good damping capability. However, it has huge friction. In certain automotive components such as cylindrical liner, cast iron is used. The biggest challenge in cylinder liner is obtaining lower friction and wear. The main aim of the paper is to experimentally investigate the characteristics of wear induced by the sliding contact piston ring cylinder liner without lubrication. The modified material of spherical graphite cast iron has been explored. The indenter load, hardness and wear are of main particular interest. The pin on disk tribotester is used to obtain the characteristics of wear volume, wear width and wear depth. The other purpose of this research is to observe the characteristics of cylinder liner wear of spheroidal graphite cast iron from Klaten, Indonesia. The results show that low indenter load causes wear depth and volume. This finding is in a good agreement with published works. In addition, it is found that the material hardness also greatly affects the wear depth, wear volume and wear width.

Numerical investigation of pocketed slip slider bearing with non-Newtonian lubricant

Boundary slip as well as surface texturing is an effective method to improve the tribological performance of lubricated mechanical components. This article analyzes the combined effect of single texturing (pocketing) and wall slip on pressure that strongly related to the load-carrying capacity of slider bearing. The modified Reynolds equation for lubrication with non-Newtonian power-law fluid is proposed. The equation was solved numerically using a finite difference equation obtained by means of the micro-control volume approach. Further, numerical computations for slider bearing with several power-law indexes were compared with the presence of the pocket and slip. The numerical results showed that the characteristic of non-Newtonian is similar to Newtonian fluid with respect to hydrodynamic pressure distribution. The maximum load support is achieved when the pocket depth is equal to the film thickness.