| dc.description.abstract | Acoustic emission is the release of high frequency sound energy in a material under strain. It is the result of microscopic changes in material structure and is associated with deformation and defect growth. Until about 1973, acoustic emission technology was primarily employed in the non-destructive testing of such structures as pipelines, heat exchangers, storage tanks, pressure vessels, and coolant circuits of nuclear reactor plants. However, the applicability of this technique to the detection of defects in rotating equipment bearings was recognized and the results of prototype testing were published in 1973. These tests led to the development of a plant-wide, computerized acoustic incipient failure detection (IFD) system which was leased from a major aerospace contractor in 1975 and evaluated until early 1977. In late 1977, advanced, second generation IFD systems were employed. These systems incorporate features which greatly enhance component reliability and usefulness to plant operators. Automated acoustic emission sensing has proven to be indispensable for dependable surveillance of machinery condition. Design concepts and field experience with advanced, second generation acoustic IFD systems are described and many actual incipient failure warning events illustrated in detail. | en |
