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.