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|Title:||Analytical Study of Thermal Variation Impact on Dynamics of a Spindle Bearing System||Authors:||Omar Saleem||Supervisor:||Dr. Mohammad Alfares||Keywords:||Thermal : Spindle Bearing||Issue Date:||2017||Publisher:||Kuwait university - college of graduate studies||Abstract:||Most major industries today use rotating machinery. Many of these rotating machinery contain ball bearings as supports. Changes in the thermal status of the ball bearing can have a noticeable effect on the performance of the machine itself, and therefore studying the thermal effect on the performance ball bearing during service is important. For this purpose, a study is carried out where a simple rotating shaft system is supported by two single row, deep groove ball bearings is taken into consideration. The heat is generated due to the contact between the balls and rings of the bearing. This thermal effect is studied using a transient thermal model. Also, the affect of this thermal behavior on dynamics of the system is studied. The system is divided into nodes; each is assumed to be a uniform temperature. Thermal energy balance is used on each node to obtain a set of differential equations. ODE solver (ODE 45) in MATLAB is used to solve the resulting system of differential equations. The thermal model takes into account an initial preload as well as the thermal preload that is caused by the uneven expansion of bearing components. Five degrees of freedom dynamic model is combined with transient thermal effect is used to study the change in dynamics of the system.. The temperature outputs depend on different system parameters such as speed of rotation, type of bearing, ambient temperature, type of oil, initial preload, and many others. Varying any of these parameters within the model will cause the temperature profile to change. Therefore, the effect of these parameters has been studied to fully understand the thermal behavior. It is seen from results that the heat generation rate is directly proportional to the rotational speed of the shaft which is expected. The study shows that higher thermally induced preload is reached at higher speeds. Temperature is found to be directly proportional to the speed of rotation. It is also noticed that initial preload has a small effect on the heat generation, thermally induced preload, and temperature of the bearing. The resulting displacement values in the axial and radial directions of the shaft tend to move closer to the initial zero center of the shaft with increasing thermally induced preload. Also, the dominant frequency values generally increases with increasing time with changing thermally induced preload values.||URI:||http://hdl.handle.net/123456789/662|
|Appears in Programs:||0630 Mechanical Engineering|
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checked on Nov 12, 2019
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