A dynamic model is reported herein for the study of vibrations of deep groove ball bearings having single and multiple defects on surfaces of inner and outer races. Masses of shaft, housing, races, and balls are considered in the modeling. The coupled solution of governing equations of motions is obtained using Runge–Kutta method. The model provides the vibrations of shaft, balls, and housing in time and frequency domains. Computed results from the model are validated with experimental results, which are generated using healthy and defective deep groove ball bearings. Characteristic defect frequencies and its harmonics are broadly investigated using both theoretical and experimental results. Comparison of vibration spectra for the cases having single and two defects on races reveals relatively higher velocity amplitudes with two defects. Good correlations between theoretical and experimental results are observed. Authors believe that this dynamic model can be used with confidence for the study and prediction of vibrations of healthy and defective deep groove ball bearings.
Benefits of surface textures for improving the performance behaviors of tribo-contacts are being explored and established by the investigators across the globe. But the consolidated information of findings of such explorations are spread. Therefore, the objective of this paper is to summarize the information available related to the preparation of surface textures and performance outcomes in the presence of surface textures at the concentrated contacts. Mainly, recent research findings and practices followed for the study of friction, wear, lubrication, contact fatigue, vibration, and noise at the generic concentrated contacts in presence of surface textures are reviewed for current status of research in the area and outlining the future prospects.
Research is being focused on to find the influence of surface variations such as texturing or grooving on the bearing performances. Though, earlier it was restricted to the theoretical aspects alone, however, with the help of advance manufacturing techniques (laser surface texturing, etching, special grinding process, etc.), it has become possible to produce micro-textures or grooves on the surface of journal bearing. The objective of the present study is to numerically compare the influence of spherical texture and micro-grooving (longitudinal and transverse) on friction coefficient and average temperature of journal bearing at low and high eccentricity ratios. From the findings, it has been observed that the micro-grooving reduces the friction coefficient and average temperature is maximum in comparison with spherical texture.
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