Pivot Rolling Motion Effect in Rocker Back Tilting Pad Journal Bearings: First Comparison Between Experiment and Simulation

The theoretical contact point of the pivot in Rocker Back (RB) tilting pad journal bearings (TPJB) is normally considered fixed in common software programs for the study of the bearing rotordynamic behavior. In a previous paper the authors proposed an equivalent pivot rotational stiffness to be implemented in commercial software to simulate the effect of the variation of the circumferential coordinate of the theoretical contact point due to the pad rolling motion in RB TPJB. This work is devoted to a preliminary comparison of the predicted performance and the experimental one for a 280 mm diameter RB TPJB in different operating conditions in order to validate the proposed approach. The inclusion of a pivot rotational stiffness among the data for simulation affects especially the cross-coupled dynamic coefficients. The latter, predicted as negligible without the new implementation, were closer, in order of magnitude, to the experimental results.