Stochastic Analysis of Asymmetric Tilting-Pad Journal Bearings

Tilting-pad journal bearings (TPJBs) are symmetric from design. However, the machining and assembling tolerances of a TPJB can result in asymmetries of the pad position that strongly affect the final dynamic characteristics of the system. In this work, a numerical study is devised to analyze the stiffness and damping coefficients of an asymmetric TPJB with load-on-pad (LOP), evaluated by a thermo-hydrodynamic (THD) model for a wide range of Sommerfeld numbers. The uncertainty in the TPJB geometry is included in the model by varying the nominal bearing gap (assembled clearance) according to a distribution ruled by the Monte Carlo Method. The results show that, in most of the cases, the asymmetry represents a detrimental effect on the bearing characteristics. However, there are some cases where the asymmetry of the TPJB is beneficial, resulting in higher stiffness and damping than expected from designing a symmetric bearing.