This study investigates the feasibility of micro-groove cross hatched textures on Ti6Al4V articulating with Ultra High Molecular Weight Polyethylene (UHMWPE) for a Metal-on-Polymer (MoP) hip implant to improve biotribological performance. Keeping 10% texture area density with 10 µm groove depth, micro-grooves ranging from 50 µm to 250 µm in width are fabricated by Laser Surface Texturing (LST) technique over polished Ti6Al4V samples. Tribological performance of UHMWPE pins against Ti6Al4V plate is tested for the different loading conditions under biological environment using linear reciprocating tribometer. Worn out pin samples are examined for their surface interactions, wear mechanism, and morphology using Scanning Electron Microscope (SEM). The result shows that the selection of micro-groove texture width is critical for obtaining the maximum tribological benefits. Texture width equal or more than the Hertzian contact is reducing friction and wear up to 14% and 57%, respectively, at the tribo-pair and similarly decrease in pitch also enhances tribological performance.

In this paper, a novel multi-objective optimization of a two-stage spur gearbox is carried out with a comprehensive range of constraints. The first objective function aims to reduce the weight/volume...

This article presents the findings from a parametric study examining the effect of four contaminants (soot, oxidation, moisture, and sulphuric acid) at varying levels (four for each). It was observed that all contaminants and contaminant levels reduce the conductivity of the oil. Oxidation and soot contaminants produced large increases in viscosity. The wear rate was mainly influenced by acid and soot additions, while the coefficient of friction was increased by all contaminants and contaminant levels. The steady-state charge levels changed for some contaminants. The best correlation of steady-state charge with the other measured tribological parameters of wear rate, friction, and temperature is seen for the series of oxidized oils. The multi-contaminated oil (L4 × 4) shows remarkably little degradation in tribological performance. Analysis of the wear mechanisms shows that soot and oxidation produced abrasion and polishing wear, respectively, while sulphuric acid and moisture produced corrosive wear.

Minimum weight and high-efficiency gearboxes with the maximum service life are the prime necessity of today’s high-performance power transmission systems such as automotive and aerospace. Therefore, the problem to optimize the gearboxes is subjected to a considerable amount of interest. To accomplish these objectives, in this paper, two generalized objective functions for two stage spur-gearbox are formulated; first objective function aims to minimize the volume of gearbox material, while the second aims to maximize the power transmitted by the gearbox. For the optimization purpose, regular mechanical and critical tribological constraints (scuffing and wear) are considered. These objective functions are optimized to obtain a Pareto front for the two-stage gearbox using a specially formulated discrete version of non-dominated sorting genetic algorithm (NSGA-II) code written MATLAB. Two cases are considered, in the first with the regular mechanical constraints. However, the second case, power loss and the tribological constraints (scuffing and wear constraints), are included to obtain a Pareto front. Finally, the two cases are compared and the results reveal that there is a high probability of wear failure of gear pairs if tribological constraints neglected. When considered power losses in the objective function along with the tribological constraints, the efficiency of the gearbox is improved. However, the volume of the gearbox is slightly increased.