To Study the Effect of Loading on Defect Signature by Using Statistical Parameters

Loading can make defect to propagate abnormally in the bearing, and in such circumstances, bearing life estimation can become a difficult task. To deal with this, it is important to understand the effect of variable loading conditions on signature characteristics and later further analysis can be made in this field. In this work, effect of variable loading was studied on vibration signature characteristics originated from defect by carrying out the statistical analysis. Two different sizes of axial groove defects present on the outer race of taper roller bearing were used for the purpose of the study with three different loading conditions in the form of additional mass on the shaft. The trend of different statistical parameters was plotted and investigated for different loading conditions. The analysis reveals that only standard deviation and Shannon entropy (SE) were showing downward trend with an increase in loading. Torsional damping of the shaft increases with an increase in weight (load) on the shaft and that may be the cause of trend shown by standard deviation and SE. To comprehend this relation, statistical analysis was also carried out on theoretically constructed signals with three different damping characteristics and on single burst with having different loading conditions. In both the analysis, same trend was observed for the parameter’s standard deviation and SE, which signifies that loading and damping are having commensurate relation. Simple sensitivity index (SSI) was calculated from the responded parameters to find the most sensitive parameter to the loading and the results revealed that SE supersedes standard deviation in dealing with loading conditions.