Hydrodynamic bearing applications of micro-electro-mechanical systems
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Microdynamical systems have been studied for a number of years, with concentration on sensors and, more recently, actuators. Only limited work has been completed on integrating microdynamical components into systems that satisfy mechanical tasks on macroscopic scales. In this paper, we describe microdynamical components that are needed to produce a surface which is actively deformable on local scales. The focus of this effort is on creating micron-scale surface deformations of critical machine elements. In particular, we consider the design and demonstration of smart journal and thrust bearings capable of using embedded sensors and actuators to dynamically change the surface geometry. The ability to actively deform bearing surfaces allows for the design of bearings which are less prone to failure, the design of bearings with greater load carrying abilities, and a fundamental study of the effect of surface geometries and fluid conditions on bearing performance, such as start-up and shut-down conditions. At this juncture in the research, we have chosen silicon membrane structures for the actuators and sensors, with in-plane dimensions ranging from 50x50 square microns to lOOOxlOOO square microns and out-of-plane deflections from 0.1-50 microns. Four primary research tasks are implemented to support the development of the membrane elements: bearing modeling; sensor and actuator modeling, fabrication, and experiments; and macroscopic bearing experiments. Results of each of these tasks are presented, focusing on numerical bearing models, sensor and actuator design and fabrication, and physical experimentation.