Seawater lubricated polymer journal bearings for use in wave energy converters

This study investigates the wear characteristics of polymeric journal bearings while immersed in seawater, and their applicability towards wave energy conversion. A block on ring wear machine was used to test four commercially available bearing materials under unidirectional and oscillatory sliding conditions at low pressure. It was observed that wear generally increases with counterface roughness; however, major deviations to this trend exist, depending on the bearing’s composition. Stable wear rates were shown to vary widely depending on velocity profile, though a general trend could not be established for the sample group as a whole. It was shown that polymer wear rates cannot be attributed to any one parameter, and that detailed testing at several characteristic pressures and velocities is needed to determine a material’s applicability towards wave energy converters operating in real seas.

► Polymer journal bearing wear in seawater cannot be attributed to any one parameter.
► Great differences in wear rate were observed for linear versus oscillatory sliding.
► Wear rate increases with counterface roughness for fabric-reinforced bearings.
► UHMWPE exhibits good resistance to abrasive wear, especially during linear sliding.
► Tests must be devised to accurately simulate bearing conditions in deployed WECs.