Effect of Defect Size and Load on the Performance of Thermoplastic Bearings

Abstract

The dynamic performance of thermoplastic bearing with respect to defect size, location, applied load, and speed was investigated in this article. A fatigue test rig was developed in house to test the thermoplastic bearing. The vibration signals are measured continuously using a piezoelectric accelerometer to investigate the influence of the size and location of the defects of both polypropylene (PP) and polyoxymethylene (POM) bearings. Vibration signatures of metallic bearings are investigated and compared with thermoplastic bearings. Test results reveal that POM bearings exhibit less vibration amplitude compared to that of PP and metal. Peak vibration amplitudes of shaft harmonics and Fast Fourier Transform increase with respect to the load levels and are more pronounced in inner race defects compared to outer race defects and are found to increase with the increase in defect size. A statistical indicator kurtosis shows the sensitivity to bearing damage by analyzing the vibration signals of the thermoplastic ball bearing. Thermoplastic bearing failure under high loads reveals wear and smearing as the important failure modes.

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

“…14 b). 28 As shown in the Fig. 14 b, the plastic bearing expands thus the clearance between the shaft and the inner race is reduced due to the increase of the frictional heat, leading to additional wear.…”

“…Under conditions of heavy loads smearing occurs, an accumulation of the melted retainer and races are formed on inner ring's path. 28 Figure 14 c shows a large, smeared area in the path of rolling elements which stops the bearing rotation. Then, the failure occurs, when the whole bearing assembly collapses.…”

“…Recently, N. Gaaliche et al investigated experimentally the impact of the location and size of the defects on the dynamic performance of ball bearings made of polyoxymethylene (POM) and polypropylene (PP). 28 Vibration responses of steel ball bearing were gathered using a piezoelectric accelerometer and compared to their plastic counterparts. The obtained results showed that metal and PP bearings reveal less vibration amplitude compared to that of POM.…”

“…Even though the previous studies had been performed on the simulation of vibration responses for metal bearings, only few experimental studies have been carried out to analyze the dynamic behavior of thermoplastic bearings. 27,28 In this work, a rolling bearing system using the implicit finite element method is investigated to compute FFT spectrums of the vibration signals and the Von Mises stress distribution of thermoplastic bearing.…”