Characteristics of Dynamic Coefficients on Stability for Herringbone-Grooved Journal Bearings

Abstract

This work proposes a novel approach to analyze the stability characteristics for the dynamic coefficients of a herringbone- grooved journal bearing. Based on the perturbation method at the equilibrium position of a journal bearing, this study expresses the variation of critical mass as the derivation of eight dynamic coefficients: four stiffness and four damping coefficients. Since the relationship between the critical mass and the eight dynamic coefficients is very complicated, it is difficult to judge the influence in previous studies of an individual dynamic coefficient on stability. The method presented in this paper can investigate quantitatively which dynamic coefficients dominate stability. The results show that the coefficients Kxx and Kyx increase and improve the stability as the eccentricity ratio increases. As the groove geometry changes, the coefficients governing stability depend on the parameters of groove geometry: groove depth, groove width, and groove angle. When the groove angle changes, variations in Kxy always exert negative influences on stability. When the groove depth or the groove width increases, the change in Dyy exerts a significant negative influence on stability. With an increase in the groove angle or groove pattern, the negative effect of Dyy on the bearing decreases. Accordingly, the influence of variations in the groove depth is similar to that of variations in the groove width.