Effect of Static and Dynamic Misalignment on Ball Bearing Radial Stiffness

The primary objective was to determine, through experimental testing and rotordynamic computer simulations, the radial stiffness of an angular contact ball bearing with inner race static misalignment and outer race dynamic misalignment under various axial loads. Two different testing methods were used to determine the radial stiffness of the ball bearing: 1) eigenvalue frequency analysis and 2) critical speed transition tests. Each method used experimental measurements in conjunction with computer simulation to determine the radial ball bearing spring rate. Experimental measurements of the forward eigenvalues, backward eigenvalues, backward critical speeds, and forward critical speeds were matched with computer model simulations to determine the stiffness values for each of the cases. The rotordynamic characteristics of the rotating assembly suggested significant nonlinearity of the test bearings and also revealed signs of bifurcation for higher degrees of static misalignment.