Dynamic Analysis of Outer and Inner Race Defects on Thermoplastic Rolling Bearing System Using Implicit Finite Element Method

This paper proposes an improved finite element dynamic model to analyze the vibration response of a rolling bearing system. The vibration responses of defect free and defective polypropylene (PP) bearings are analyzed using the finite element analysis and compared with the experimental results using the in house developed bearing fatigue test rig. The boundary conditions of this model are imposed to ensure an adequate homogeneity with the experimental apparatus. This study considers the viscoelastic property of thermoplastic to investigate the effect of the flexibility and damping viscosity of material. The three-dimensional dynamic analysis detects the vibrations produced in a rolling bearing system. Modal frequencies and the vibration modes shapes which must be avoided had been determined. Monitoring the evolution of vibration signatures as a function of defect location is also carried out using Finite Element Analysis (FEM). Test results reveal that peak vibration amplitudes are more pronounced in an inner ring defect than in an outer ring defect. Vibration signals of stainless-steel bearings are investigated to compare the performance of the thermoplastic bearings with its metallic counterparts. Both test and simulation results reveal that a lower level of vibration is observed with PP bearings compared to that of metal. The PP bearings not only dampen vibrations, but also accommodate shaft misalignments unlike their steel counterparts. Once overall vibration spectrums results are validated, Von Mises stresses within the rings are evaluated under excessive loading conditions. The simulation results show that stress is high in raceways where the balls are compressed between the raceways. Computational results agree well with the experimental tests for the test scenarios.