SBIR-STTR Award

This Small Business Innovation Research Phase I project involves a parametric study of a "Self Sensing Active Control Foil Bearing" (SSACFB) concept. Through the use of stacks of piezoelectric ceramic elements (PZT) attached along the foil element, the load applied onto the foil element can be determined using the voltage generated by the piezoelectric elements. At the same time, the piezoelectric stacks also act as an actuator to push / pull the foil element towards/from the shaft to increase the loading capacity of the bearing and/or to ensure foil lift off at low shaft rotating speed. The foil element instrumented with PZT piezoelectric ceramics becomes in effect a smart structure that can be continuously controlled in order to optimize system performance during rapid, intense transients. The novelty of this concept resides in the introduction of a "smart bearing", which has the sensing and actuating system integrated into one single unit. The other innovations to the application are an elastic bed and diamond like coating of the foil element. The active control of the bearing will provide long life, lower power loss, and operational regime tuned loading capacity. Phase I of the project will concentrate on the parametric study of the piezoelectric application on a foil element demonstrate the feasibility of the concept. According to Frost and Sullivan, the bearing market is growing at about 11 % a year and is forecast to see moderate growth in several areas in the future. In the year 2000, the total bearing market revenue is expected to reach $1.45 billion. The successful development of the self sensing active control foil bearing will have great impact on high speed bearing applications, especially in the high speed precision manufacturing industries as well as in the aerospace industry.

This Small Business Innovation and Research (SBIR) Phase II project will develop a 'Self-Sensing Active Control Foil Bearing' (SSACFB). Through the use of a stack of piezoelectric ceramic elements attached at the lower side of foil elements, the load on the foil element can be determined from the voltage generated by the piezoelectric elements. At the same time, the piezoelectric stack also acts as an actuator to push/pull the foil element from the shaft to increase the loading capacity of the bearing and/or to ensure lift-off at low shaft rotational speeds. The novelty of the concept is in elimination of the sensing system, the integration of sensing and control in a single unit, and the active control of the bearing to provide long-life, lower power loss, and larger loading capacity. In addition, elastic bed and diamond-like coatings on the foil element will be addressed in this proposal. Phase I found the self-sensing and controllability in this bearing to be feasible. Construction and testing of a fully instrumented, prototype self-sensing controllable foil bearing will be performed in Phase II. Potential commercial applications are planned in the $1.5 billion bearing market, which is growing presently at about 11% annually with moderate growth forecasted in the future. The SSACFB technology is aimed at commercial needs for oilless high-speed controllable bearings. Successful development of SSACFB will impact high speed bearing applications, especially in the aerospace/aeronautic and other high speed precision manufacturing industries.