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This paper presents a study of the tribological properties of two locally developed polymeric composite materials for bearing applications. Unidirectional reinforcements by linen and jute fibres are used, each in turn, in unsaturated polyester resin. Friction and wear tests are carried out, in dry conditions, on a pin-on-disc machine.The experimental results, backed by scanning electron microscope...
Holes were drilled in 6061 T-6 aluminum alloy as well as in a particle reinforced metal matrix composite (MMCp) consisting of 20 vol.% SiC particles, 12 μm in diameter, in a 6061 aluminum matrix (6061/SiC/20p, or Duralcan F3S.20S). HSS (high speed steel) drills of 10 mm diameter were used, and measurements were made of thrust (normal force), torque and flank wear for several feed rates and drill...
An internal finishing system for rectangular tube is simulated mathematically. The finishing pressure on the workpiece is produced by applying a magnetic field to the air-gap between the finishing tool and the magnetic poles, and the tool driving force by moving the magnetic pole. The finishing process is controllable because the finishing pressure is controlled by the input current to the winding...
The formation of ripples on the surface of pure aluminum during solid particle erosion was studied using sharp alumina and spherical glass beads as erodent particles in an air-blast type system. A new laboratory technique controlled the tangential velocity of the erodent particles relative to the samples with their placement on a velocity controlled rotating disk. With this technique, it was possible...
The friction and wear behaviour of ZrO 2 -Y 2 O 3 ,ZrO 2 -Y 2 O 3 -CeO 2 and ZrO 2 -Al 2 O 3 composite ceramics against hardened steel AISI-52100 were investigated using a pin on plate configuration under reciprocating motion. The reproducibility of the results was examined in this configuration. Wear characteristics were...
The impact of particles on a surface can cause severe erosion damage. The erosion of a surface by abrasive particles in an inert fluid should depend on the number of particles striking the surface, their velocity and their direction relative to the surface. These quantities are largely determined by the flow conditions.The importance of knowledge of the flow field surrounding impinging particles and...
A numerical method for the solution of complete or incomplete contact problems is briefly described, together with its application to the problem of indentation of a half space by a tilted circular punch.
The resistance of materials to abrasive wear depends on many factors that can be generally classified as material-based or operating system-based. In the published wear models, the bulk stress state or stress history of worn material do not appear as influencing factors. Following the analogy with stress corrosion and fatigue, as well as with cyclic softening of steel materials, the possible influence...
The microstructural flow behavior of titanium and copper under uniaxial compression has been qualitatively related to the surface morphology and subsurface flow during plane strain abrasion. Uniaxial compression tests were carried out on titanium in the temperature range 298-673 K and copper at 298 K at strain rates in the range 0.1-100 s -1 . Titanium undergoes adiabatic shear banding...
The real bearing capacity of working technical surfaces is one of the parameters which is crucial for the machine exploitation process. The aim of the paper was to analyze the problem of the real bearing development caused by increased quasi-static load. Obtained results of simultaneously measured real approach and real contact area were shown. The analysis of physical test results carried out on...
The cavitation erosion behaviour of a number of metals has been studied using a sea water cavitation tunnel test and a fresh water jet cavitation method. Erosion parameters, including erosion rate and depth of damage, have been obtained for both systems and the data shown to correlate with mechanical properties of the metal, such as plasticity and hardness. Analysis of eroded specimens subjected to...
The rolling or sliding contact of an elastic cylinder and a layered foundation has been investigated. The substrate of the foundation was modeled as a two-dimensional elastic half-space. The one-dimensional Maxwell model was used to describe the normal and tangential compliance of the viscoelastic surface layer bonded to the substrate. Conditions of partial and full slip within the contact area were...
During machining, the cutting edge is subjected to various forms of tool failure such as: progressive wear leading to plastic deformation; chipping; fracture or breakage.Force signals are highly valid carriers of information about the machining process and they are, hence, among the best alternatives for tool monitoring and diagnostic techniques if a proper manipulation technique is devised. A cumulative...
Surface roughness of metal counterface is an important parameter in the wear process of acetal-metal gear pairs. The topic of this paper is whether the results obtained from pin-on-disc or pad-on-disc machines are valid in real operating conditions, i.e. in the machine itself. For this purpose the wear of acetal-metal gear pairs at different counterface roughnesses in a real device was studied. It...
A wedge-shaped hydrodynamic journal bearing is proposed here. The analysis considered the flow in the bearing to be laminar incompressible and the lubricant to be isoviscous. An oblique system of coordinates is used to formulate the Reynolds like equation governing the pressure inside the bearing. An exact solution for the pressure is presented and a perturbed solution valid for small values of the...
The experimental study of heavily loaded lubricated Si 3 N 4 -steel and SiC-steel friction pairs has been carried out. Interfacial conditions were changed from boundary to mixed lubrication with an appreciable effect of elastohydrodynamic separation.It was found that the running-in process in the given friction pair is very sensitive to the initial lubricating conditions. The initial...
Significant progress has been made in the past ten years on deterministic modeling and analysis of lubricated rough contacts operating in the regime of micro-elastohydrodynamic lubrication (EHL). This progress has opened new avenues for analytical-computational studies of tribe-contacts that operate in the mixed regime of micro-EHL and boundary lubrication. Work to this date suggests that deterministic...
This paper presents a systematic approach towards understanding of the tool-wear mechanisms in grooved tool inserts based on chip-flow patterns. It has been observed through high-speed filming experiments and scanning electron microscopy that improper design of chip-groove geometry and/or inappropriate application of the cutting conditions result in @'undesirable@' chip-flow patterns and consequent...
Recent studies at Oak Ridge National Laboratory (ORNL) have shown that ion implantation of polymers can significantly improve wear properties, sometimes dramatically. In several cases, the @'best-wear resistance@' condition for a specific counterface material was associated with the lowest friction coefficient values. To explore the friction behavior of ion implanted polymers further, microfriction...
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