Release of acoustic energy during the fatiguing of a rolling-element bearing

A simple theoretical model has been developed to describe the acoustic energy Agenerated when a fine crack grows in a fatiguing rolling-element steel-bearing Ain the gearbox of a helicopter during flight. The acoustic-impulseʹs amplitude A(at the bearing) and duration increase from 9.8 x 10(-12) to 29.0 x 10(-12) m, Aand from 0.1 to MUs, respectively, as the crack growth becomes critical. The Adetection and measurement of this acoustic energy can lead to the prediction of Athe associated crack-growth. (c) 1999 Elsevier Science Ltd. All rights reserved.