Papers by Author: Jerzy T. Sawicki

Abstract: In the last twenty years, there has been significant progress in the design of rotating machinery equipped with smart components and embedded functions. This was accompanied by developments in actuators, sensors and power electronics technologies, advances in data acquisition and signal processing, as well as developments in control theory. This paper will provide a brief overview of the current state of art and it will illustrate examples of the applications of smart technologies applied to rotating machines. Several technologies, either most recently developed or under development will be presented, which involve active control and are relevant to smart solutions applied to rotating machinery.

Abstract: Well-established procedures exist to monitor and diagnose fairly severe problems with rotating machinery but little progress has been made in developing techniques to detect subtle changes in machine condition for both improved diagnostics, and to develop prognostic procedures for determining remaining service life. Of all machine faults, crack initiated problems present probably the most significant safety and loss hazard in modern turbomachinery, including aircraft engines and power generation units. Different approaches are used to model, detect, and localize crack-induced damage in rotating structures. This paper presents novel application of active magnetic bearings (AMBs) for on-line rotor crack detection. AMB-actuators provide convenient means to apply a broad spectrum of known dynamic forces and monitor responses in a rotor-bearing system, which facilitates more sensitive and precise diagnostics. The paper presents theoretical modeling and description of the experimental facility for proof-of-concept testing.

Abstract: This paper describes initial results from a project expanding the field of rotor health monitoring by using Active Magnetic Bearings (AMBs) as actuators for applying a variety of known force inputs to a spinning rotor in order to monitor and evaluate response signals resulting from these inputs on-line. Similar to modal analysis and other nondestructive evaluation (NDE) techniques which apply input signals to static structures in order to monitor responses; this approach allows for the measurement of both input and output response in a rotating system for evaluation. However, unlike these techniques, the new procedure allows for multiple forms of force input signals to be applied to a rotating structure. This technique is being developed for use on rotating equipment supported in conventional bearings where an AMB actuator is added to a system for improved health monitoring. This paper presents initial results from this project including a demonstration of the system identification capability of the procedure during the commissioning of a test rig, and a summary of a technique developed for identifying breathing-cracks in rotors using the new technique.