Abstrakt

Polymer lined tilting-pad bearings demonstrate many advantages over traditional bearing systems. Bearings with a polymer layer in comparison with a babbitted layer show, for example: lower value of friction coefficient (important during start/stops), higher fatigue strength of the coating, better distribution of the load on individual pads due to lower elasticity of the polymers, wider range of operational temperatures or the ability to carry higher specific loads. Polymer lined bearings are, of course, not free from some disadvantages, as for example some problems with reliable temperature monitoring of the bearing surface due to low thermal conductance of the polymer or necessity of a special additional intermediate layer to fix the polymer to a steel pad body. PTFE and PEEK based composites are most often used in bearing engineering practise. Both materials have a low value of thermal conductance, but differ from the each other in mechanical properties. Stiffness (Young modulus) of the PEEK is about an order of magnitude higher than that of PTFE. The influence of the polymer lining mechanical properties on the bearing performance has not been systematically studied for thrust bearing so far. In this paper, the effect of mechanical properties of the coating material on a tilting-pad thrust bearing performance was investigated. Three coating material properties were considered: Babbitt, PEEK and PTFE. Analysis was carried out with the use of an experimentally verified TEHD model of the bearing pad, which utilized FEM and CFD in one task. The results of calculations (temperature, pressure and oil film thickness profiles) were compared. The results show significant differences in bearing performance depending on coating properties. In general, this analysis allowed the authors to show and assess the changes in flow phenomena caused by changes in coating material properties.

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