Development of an Experimental System to Measure Stresses in a Bearing Using Photo-elasticity

Although stress analysis of the bearing contact problem has been a subject of significant interest, it is rare to find experimental studies on the topic. The problem is attributed to the difficulty in designing an experimental system, which can apply radial and axial loads and permit direct measurement of the bearing contact stresses. A novel experimental configuration is presented which simultaneously applies radial and axial ball bearing loads on a bearing housing into which an assembled photoelastic model of the bearing is mounted. The technique is demonstrated and validated by measuring contact stresses of angular contact ball bearings using the “frozen stress” photoelastic experimental hybrid method (PEHM). Experimental results reveal that ball deformations are mainly concentrated at the contact points. Ball 0, positioned at the base of the bearing housing, experienced the highest magnitude of stresses located near the geometric center of the contact region. Stresses are observed to progressively decrease with increased distance from ball 0 along the circular bearing groove toward balls 4 L and 4R (near the three and nine o-clock positions) where the lowest stress magnitudes were observed. It was also shown that the most highly loaded balls were located in the lower semi-circular section. PEHM measurements are found to be in very good agreement with finite element analysis.