Tribology in Industry

431-443

Authors: M.F. Abd Al-Samieh

The mechanism of fluid film lubrication in ultra-thin conjunction under elliptical point contacts is discussed in this paper. The results of changing the ellipticity ratio are highlighted. The operating conditions; load and speed of entraining motion, promote formation of ultra-thin films that are formed under the combined action of Elastohydrodynamic lubrication (EHL), surface contact force of solvation and molecular interactions due to presence of Van der Waals' force. The paper shows that, changing the ellipticity ratio maintain the general behavior of the formation of ultra-thin lubricating film thickness as in the case of circular point contact problem when the contiguous solids are subject to light-to-medium contact loads and the effects of surface forces become significant as the elastic film (i.e. the gap) is reduced to a few nanometers and lubricant discretisation appears.

452-459

Authors: E. Zadorozhnaya, S. Sibiryakov, V. Hudyakov

One of the most urgent issues of the modern world and domestic automobile and tractor production is the problem of the production of efficient and reliable turbochargers. The rotor bearings largely determine the reliable operation of the turbocharger. By increasing the degree of the forcing of the engine the turbocharger rotor speed and the load increases significantly. Working conditions of bearings also complicated because of the temperature rise. In this case the bearing of the turbine and the compressor bearing works in different thermal conditions. The definition of the thermal state of the bearings can be performed experimentally. However, to perform these studies the sophisticated experimental equipment must be used. Researchers can't perform experiments for each type of turbocharger. Therefore, the applying of the theoretical approaches becomes more relevant. The peculiarity of the considered problem is the design of the bearings, which are made in the form of multilayer bearings with floating rings. Such designs increase the number of the parameters that affect the behaviour of the rotor. For the calculation of the multilayer bearings and turbocharger rotor dynamics a method and calculation algorithm was developed. A plan of the experiment based on the orthogonal central composite plan was drawn up. The regression equations for rotor amplitude and bearing temperature were obtained. As variable parameters the clearances (external and internal), rotor speed, pressure and lubricant temperature were used. The results of the calculation were compared with experimental results obtained at the plant. Non-Newtonian properties of the lubricants were taken into account in the calculations. Comparative results showed good agreement. In this way the resulting function can be applied to studies of the similarly multilayer bearings without complicated experimental studies.

471-481

Authors: S.R. More, D.V. Bhatt, J.V. Menghani

Stainless Steel (SS) 304 is commonly used material for slurry handling applications like pipelines, valves, pumps and other equipment's. Slurry erosion wear is a common problem in many engineering applications like process industry, thermal and hydraulic power plants and slurry handling equipments. In this paper, experimental investigation of the influence of solid particle size, impact velocity, impact angle and solid concentration parameters in slurry erosion wear behavior of SS 304 using slurry pot test rig. In this study the design of experiments was considered using Taguchi technique. A comparison has been made for the experimental and Taguchi technique results. The erosion wear morphology was studied using micro-graph obtained by scanning electron microscope (SEM) analysis. At shallow impact angle 30°, the material removal pattern was observed in the form of micro displacing, scratching and ploughing with plastic deformation of the material. At 60° impact angle, mixed type of micro indentations and pitting action is observed. At normal impact angle 90°, the material removal pattern was observed in form of indentation and rounded lips. It is found that particle velocity was the most influence factor than impact angle, size and solid concentration. From this investigation, it can be concluded that the slurry erosion wear is minimized by controlling the slurry flow velocity which improves the service life of the slurry handling equipments. From the comparison of experimental and Taguchi experimental design results it is found that the percentage deviation was very small with a higher correlation coefficient (r2) 0.987 which is agreeable.

487-494

Authors: P. Ilanthirayan, S. Mohanraj, M. Kalayarasan

The piston rings are the most important part in engine which controls the lubricating oil consumption and blowby of the gases. The lubricating film of oil is provided to seal of gases towards crankcase and also to give smooth friction free translatory motion between rings and liner. Of the three rings present top ring is more crucial as it does the main work of restricting gases downwards the crankcase. Boundary lubrication is present at the Top dead centre (TDC) and Bottom dead centre (BDC) of the liner surface. In addition to this, top ring is exposed to high temperature gases which makes the oil present near the top ring to get evaporated and decreasing its viscosity, making metal-metal contact most of the time. Due to this at TDC, excess wear happens on the liner which is termed as Top ring reversal bore wear. The wear rate depends upon many parameters such as lubrication condition, viscosity index, contact type, normal forces acting on ring, geometry of ring face, surface roughness, material property. The present work explores the wear depth for different geometries of barrel ring using Finite Element model with the help of Archard wear law and the same is validated through experimentation. The study reveals that Asymmetric barrel rings have less contact pressure which in turn reduces the wear at Top dead centre.

506-518

Authors: J. Fryza, P. Sperka, I. Krupka, M. Hartl

Consideration of performance, efficiency and energy consumption is nowadays an inherent part of the design of every modern machine. These factors are mainly determined by mechanisms taking place within the lubricated contacts. Unfortunately, the physical origins of these mechanisms have been investigated exclusively for steady conditions that do not occur in actual contacts of machines affected by vibrations. This study presents novel experimental data describing friction in the elastohydrodynamically lubricated contact exposed to the main steady sliding motion along with lateral sliding micro-oscillations. Friction forces were measured simultaneously in two perpendicular directions of point contact. It is shown that the lubricant response in the main direction of motion suffers from shear thinning and thermal effects whereas its lateral response is isothermal Newtonian. Moreover, the lateral friction affects the friction in the main direction, but not vice versa, when the majority of shear flow is maintained in this main direction. These finding are attributed to the perturbation of structural arrangement of lubricant. The results also suggest that a response of mineral oils to shearing is anisotropic. A limiting shear stress is discussed since the total friction was not able to exceed a certain value.

527-535

Authors: E. Surojo, Jamasri, V. Malau, M.N. Ilman

This paper reports on a comparison of the frictional characteristics of three different samples of brake block materials. Two commercial brake blocks (composite and grey iron/metallic) and a non-commercial composite brake block were extracted to form pins (specimens), and then their frictional properties were evaluated using a pin-on-disc apparatus. The non-commercial composite brake block that was investigated in this work was developed as a substitute for the grey iron brake block. The results revealed that the composite brake blocks had a higher wear resistance and were more stable in terms of their coefficient of friction at various contact pressures and sliding speeds compared to the grey iron brake block. The non-commercial composite brake block that was developed in this research had a coefficient of friction that was close to that of the grey iron brake block, and hence, it can be considered as a substitute for the grey iron brake block.

547-558

Authors: R. Majdan, Z. Tkáč, R. Abrahám, K. Kollárová, I. Vitázek, M. Halenár

Three filtration systems using the tractor hydraulic circuit were proposed and verified during the tractors operation. Using the tractor-implement hydraulic system and filter body with accessories the universally useful filtration systems were designed. The designed filtration systems are the second stage of universal oil filtration whereas the first stage is the standard tractor filter. The decrease in the content of iron reached the values 25.53 %, 32.95 % and 41.55 % and the average decrease in oil contamination characterized by average value of decrease in content of iron, copper and silicium reached values 24.3 %, 24.7 % and 35.53 % in dependence on the filtration system and an oil contamination level. The decrease in contamination level verified the ability of designed filtration systems for agricultural tractors.