Design Automation and Hertzian Stress Analysis of Spherical Roller Bearing

Abstract

Rolling bearing is a commonly used mechanical component wherever relative rotary motion takes place between parts of the system. Modern 3D modeling technique has to be used for satisfactory representation of the complex rolling bearing components because of better adaptability compared to traditional 2D drafting. In case of specific product variants where basic features and relations between them are in a constant fashion, parametric modeling automation makes this task easy and less time consuming. 3D parametric modeling automation has been done by integrating Microsoft Excel spreadsheet with Pro/E software. New bearing model has been generated by updating the Excel spreadsheet as per required bearing dimensions.

Motion and load transmission in spherical roller bearing occurs within the assembly by various curved contacting surfaces. The stress produced by the transmitted load would be very high due to least contacting area. For such contacting problems, Heinrich Hertz has derived a specific theory. An attempt has been made to study the stress behaviour in spherical roller bearing particularly within rollers and inner ring using analytical method described in Hertzian theory. The same contact stress behaviour has been studied by using FEM in ANSYS. Cyclic loading reduces the bearing life than design life. Here it is also attempted to predict the bearing fatigue life based on actual loading conditions using results obtained by Hertz theory in ANSYS.

In spherical roller bearing, inner race is the most critical and complex feature because load transmission takes place between inner ring and roller at inner race only. As it has complex angular curvature, manufacturers provide high tolerance for it. The effect of positive and negative tolerance on the contact stress has been studied by static structural analysis using ANSYS. It has found that negative tolerance gives better result in terms of induced stress and fatigue life.