Bearing is a generic name for a mechanical device that handles load and, in parallel, reduces friction between moving components in a mechanical assembly or sub-assembly. It is this reduction in friction that allows a bearing to aid a system in either rotational or linear movement. Hydrodynamic bearings perform this function by forcing a dynamic lubricant through converging surfaces in relative motion. This action develops an oil film between the two mating surfaces preventing metal to metal contact and drastically reduces the friction. The ideal condition is achieved when two surfaces are kept fully separated by the lubrication film. Fixed Tapered-land hydrodynamic thrust bearings are designed to function within a defined set of conditions. To adequately design a fixed tapered-land hydrodynamic thrust bearing, loads, speeds, temperatures and lubricant properties must be known. In-field loading data collected over time shows that applied loads can vary in certain applications such as engines, turbocharges, wind turbines, to name a few. Tapered sections of the hydrodynamic thrust bearing allow for the formation of the hydrodynamic wedge. The wedge creates fluid film pressure separating the thrust bearing and contact surfaces. This action decreases the friction and wear generated from applied loading. As the applied load on the hydrodynamic bearing increases, oil film thickness decreases. Oil film thickness is a key parameter to ensure that the bearing does not fail due to excess load capacity. In order to maintain proper oil film thickness, taper angle needs to be changed. However, in traditional fixed pad hydrodynamic bearings, taper angle is machined using milling and turning centers and cannot be changed for the entire service life of the bearing. Therefore, hydrodynamic thrust bearings operate optimally for a very small range of load and speed for a given pad taper angle. As the load and speed changes, hydrodynamic bearing performance deviates from its optimal values. On the other hand, instead of permanently machining, pad taper can be achieved (depending on load and speed) by exploiting the anisotropic nature of composite materials. The work presented here investigates composite lamina formulation in taper-land composite hydrodynamic thrust bearings as a means of controlling taper depth via thermal expansion so that optimum bearing functionality is maintained during load fluctuation. Thermal expansion of specific composite lamina formulation is analyzed using ABAQUS/CAE and composite module. The analysis shows that composite tapered-land hydrodynamic thrust bearings can be tailored to operate successfully within a larger range of applied load variance.


Thermal Expansion Simulation of Composite Hydrodynamic Thrust Bearings

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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