Some Characteristics of Rolling-Element Bearings under Oscillating Conditions. Part 1: Theory and Rig Design

Rolling-element bearings are among the most common components of modern machinery and yet little is known about their characteristics under working and oscillating conditions. Thus, when spindle systems are designed and their dynamic stiffness is important, it is very difficult to find suitable characteristics to use in the modelling. It is the purpose of this paper to indicate why these characteristics are difficult to measure and to discuss the results that are available in the literature. It is also the case that very few models have been developed to represent the stiffness and damping of rolling-element bearings. In the 1980s, some models were developed, but these were in confidential, limited-circulation publications. However, permission has now been given to present these models in the open literature. The principles of a rig are described that allow the stiffness and damping properties of rolling-element bearings to be measured under rotating conditions. A theoretical analysis is presented that allows the characteristics of the rolling contacts to be predicted. In addition, the effect of the necessary joints that arise when using bearings is analysed. A detailed description is given of the rig and its initial calibration and testing. The extensive results obtained are described in parts 2 and 3 of this work.