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Thermo-elastic Development of Cylindrical and Spherical Superelements and Introduce a New Gigh Speed Angular Contact Bearing Superelement Model

Shamloofard, Mansoor | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43956 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Movahhedy, Mohammad Reza
  7. Abstract:
  8. Angular contact bearings are utilized in many industrial types of machinery, including machine tools’ spindle. Spindle is one of the most important parts of a machine tool, which has a substantial impact on dynamic properties and stability of machining processes. Spindles’ motion takes place under guidance of bearings, which are mainly angular contact type. Since bearings’ loading under forces that are resulted from angular velocity and temperature increment are intensified, it is required to control the applied forces in operating situation, in order to predict the hardness, accuracy, efficiency, and life time of spindle. Thus, determining the dynamic performance of machine tool’s spindle, bearings are of great importance. Once, two degrees of freedom model was used to simulate bearings, in which the effects of nonlinear contact and high velocity loads had been neglected. In recent years, simulating the bearings, five degrees of freedom model for each ring was used. The mentioned model was capable of considering nonlinear contact and loading due to high velocity. In present work, a novel method for modeling the angular contact bearings is presented. In this trend, thermo-mechanical analysis of angular contact bearings is conducted via finite element method, using cylindrical and spherical super-elements. Super-elements make it possible to solve finite element problems by using less elements and more accurate. In present investigation, the presented bearing model is a structural super-element consisted of cylindrical and spherical super-elements and capable of considering effects of nonlinearity (contact, rolling friction), high velocity (centrifugal force, gyroscopic torque, variation of contact angle), temperature field, structural field, thermal stresses, produced heat in the contact zone, heat transfer and its effects on temperature distribution of system and component expansion, etc. Simulating the contact between shots and rings, analytical relations are used. Consequently, thermo-mechanical analysis of angular contact bearings is conducted through two different methods, one by using bearing super-element model and the other by using typical three dimensional elements in ANSYS software. The results of these methods are compared to experimental reports of references. The result comparison between proposed super-element model and cubical elements model of ANSYS software and empirical reports, suggests higher accuracy, lower solution time, and verity of super-element model compared to cubical elements of ANSYS
  9. Keywords:
  10. Angular Contact Ball Bearing ; Finite Element Method ; Cylindrical Superelement ; Spherical Super Element ; Thermal Stress

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