유한 요소 해석을 통해 계산된 틸팅 패드 베어링의 피봇강성과 Hertzian 접촉 모델 해석 결과 비교

Abstract

Recent studies emphasize the importance of pivot stiffness in the analysis of tilting pad bearings (TPBs). The present paper develops a finite element model of the pad pivot and compares the predicted pivot stiffness tothe results of Hertzian contact model calculations. Specifically, a finite element analysis generates tetrahedral meshmodels with ~40,000 nodes for a ball-socket pivot and ~50,000 nodes for a rocker-back pivot. These models assumea frictionless boundary condition in the contact area. Increasing the applied loads on the pad in conjunction withincreasing time steps ensures rapid convergence during the nonlinear numerical analysis. Predictions are performedusing the developed finite element model for increasing the differential diameters between the pad pivot (or ball)and the bearing housing (or socket). The predictions show that the pivot contact area increases with decreasing differentialdiameters and increasing applied loads. Further, the maximum deformation occurring at the pivot centerincreases with increasing differential diameters and increasing applied loads. The pivot stiffness increases nonlinearlywith decreasing differential diameters and increasing applied loads. Comparisons of results of the developedfinite element model to those of Hertzian contact model calculations assuming a small contact area show that thelatter model underestimates the pivot stiffnesses predicted by the finite element models of the ball-socket and rockerbackpivots, particularly for small differential diameters. This result implies the need for cautionduring the designof pivot stiffness by the Hertzian contact model.