An elastohydrodynamic analysis of a misaligned sterntube bearing

Abstract

Steady load performance data are presented for a sterntube bearing lined with an elastic material, which is contained in a rigid housing and subject to angular misalignment. The analysis is thus applicable to oil-lubricated sterntube bearings in which reinforced resin liners are used as an alternative to conventional white metal lining. The hydrodynamic analysis method used satisfies flow continuity throughout the cavitation zone. A rigorous elastic model, accounting for inter-element and element-to-housing forces was developed. Results showed that a simplified approach neglecting element interaction was of acceptable accuracy. An effective oil viscosity based on a simple thermal balance calculation was used. A relaxation method was employed for the combined hydrodynamic and elastic deflection solutions, with over-relaxation applied to the former. The application of under-relaxation to the elastic deflection solution was necessary in order to obtain convergence. The most significant results are those for minimum film thickness which is shown to be reduced by liner elasticity in all cases. This reduction is shown to be a direct function of both specific bearing pressure and misalignment angle. The rigid bearing assumption is confirmed to be acceptable for white-metal-lined sterntube bearings.