الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
All rotating machinery uses bearing elements to support the load and maintain the clearances between rotating and stationary parts; most of the machines have rolling element bearing. In this study, The theory of operation for the roller element bearing was clarified precisely, which demonstrates the elastohydrodynamic lubrication between the rollers and raceways and how the EHL film thickness is affected by increasing the pressure in the load zone of the bearing. The surfaces of the bearing components that deforms elasticity and plasticity suffer from the surface and sub-surface fatigue due to repeated cycles of operation, this surface damage happen underneath the surfaces and can’t be seen by visual inspection. There are various failure modes of rolling-element bearing in the industry, such as bearing wear, corrosion, flaking, indentations, bearing misalignment, inadequate lubrication, smearing, improper fits and clearances and bearing cracks. Those failure modes shorten the life of the bearing and alter them to be unserviceable. There are many condition monitoring techniques that were developed to diagnose the bearing wear rate during the operation, the most effective method is the vibration analysis which is discussed briefly in this thesis. Various bearing frequencies were determined and clarified according to the bearing geometry and speed, in which wear rate in the bearing can be clarified by the modern vibration analysis techniques. The bearing wear is classified to four stages, which depend on the level of the defects and its severity. Each stage has different behavior in various vibration techniques and some related to early subsurface damages which generate stress waves that can be detected only with special measurement such as enveloping and demodulation, and other may be related to a real defect in the bearing components that is obvious in the normal vibration measurement. The case studies are demonstrated to confirm the Importance of the vibration analysis techniques in saving the bearing and the machine from catastrophic failures as well as the cost of the labors, spare parts and unplanned shutdown.