Development of load distribution model and micro-geometry optimization of four-point contact ball bearings

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2018

Öğrenci: SİNAN YILMAZ

Danışman: METİN AKKÖK

Özet:

The unique kinematic characteristics and load-carrying capabilities of four-point contact ball bearings make these bearings being widely used in demanding applications. Particularly, four-point contact ball bearings are preferred due to their reverse axial load carrying capability and high level of stability. In this study, micro and macro geometrical aspects of these bearings are investigated and compared with the conventional ball bearings. Once the geometry and internal kinematics of four-point contact ball bearing are examined and formulated, a comprehensive mathematical model is established to define the load distribution characteristics of four-point contact ball bearings by implementing existing models in literature. The contact between each individual rolling element and raceway are considered in accordance with Hertzian contact theory and formulated with numerical approximation methods. Centrifugal body forces are taken into account in the model in order to capture the behavior of these bearings under high rotational speeds. Moreover, the contact stress and contact truncation formulations are provided for the performance evaluation of four-point contact ball bearings. The developed model is then employed to explore the consistency with the recent FEA studies and software packages under specified load and speed conditions. After the verification of the model, an optimization subroutine is developed in order to optimize the micro-geometry of custom design bearings for different load and speed conditions as well as for different optimization targets. Several constraints are to be implemented in this optimization subroutine in order not to converge to an infeasible design. Thus, this efficient optimization subroutine is to be a guidance in the design of the custom design bearings for demanding applications. At the end, several optimization results and the corresponding custom design bearing geometries are investigated in terms of the effects of these geometrical parameters on maximum contact stresses, contact truncations and load distributions.