A new quasi-static multi-degree of freedom tapered roller bearing model to accurately consider non-Hertzian contact pressures in time-domain simulations

Abstract

The accuracy of the fatigue life calculations in rolling bearing simulations is highly dependent on the precision of the roller-raceway contact simulations and the ability to accurately include structural deflections of the supporting structure. Several different methods exist to simulate the pressure distributions, and in time-domain bearing simulations, where many contacts need evaluation, the simple and time efficient methods are more popular. These methods underestimate the fatigue life reduction due to roller end effects, overload and misalignments. Furthermore, existing time-domain rolling bearing models assume that the bearing rings remain circular, which can be a poor approximation, especially for large and flexible supported bearings. This paper presents a new multi-degree of freedom frictionless quasi-static time-domain tapered roller bearing model that uses high precision elastic half-space theory to simulate the contact pressures and allows for an arbitrary stiffness of the outer ring supporting structure. The potentially higher computational demand using the advanced contact calculations is addressed by pre-processing series of contacts at different centreline approaches and roller tilt angles, which are used for interpolating contact results during time-domain simulations. The stiffness of the outer ring supporting structure is included by condensing a FE-model using an assumed modes method also known as modal flexibility. It is demonstrated that this new model allows for simulation of bearing misalignments and structural deflections, and that the effect of these conditions is directly evaluated in a detailed fatigue life analysis.