Multibody Modelling of Spalled Rolling Bearings: Effectiveness of Different Contact Algorithms

This study analyses a dynamic multibody model of a deep groove single row ball bearing. The objective of the study is to simulate the dynamic behavior of a bearing under different operational conditions. Typical vibration signals used in bearing diagnostics are simulated using the non-linear Hertzian contact theory. Geometry, material properties, friction and damping coefficients are considered as input while displacements, velocities, accelerations and forces between bearing rings are calculated and validated with the analytical formulations found in literature. Furthermore localized faults are introduced in the simulation in order to extract bearing defect frequencies and to represent the real vibration signal signature in case of fault components. For this purpose, a simplified model is realized using the polygonal contact model. This approach allows to investigate more in detail the effect of localized defects by reproducing the real rolling elements trajectories through a discretization of the contact surfaces. The low computation efficiency compared to the traditional Hertzian approach limits the application of this contact algorithm on the complete bearing model. Nevertheless, the simplified model allows to draw conclusions regarding the influence of the shaft/cage speed on the fault size estimation giving an innovative contribution on bearing diagnostics.