Acoustic Emission from Stress Rupture and Fatigue of an Organic Fiber Composite

Abstract

A series of tests was carried out to determine the scatter in acoustic emission data gathered during stress rupture and fatigue testing of a simple fiber-reinforced epoxy composite. Single-end organic fiber-epoxy strands were monitored for acoustic emission during tension tests to failure, stress rupture tests, and dynamic fatigue tests. During the stress rupture and fatigue tests, the plots of summation of acoustic emission counts versus time were found to resemble metal creep curves in that primary, secondary, and tertiary regions could be distinguished. Because of a significant amount of scatter, only a limited correlation can be made between the slope of the summation of acoustic emission in the steadystate region and the specimen life during stress rupture and fatigue testing. In addition, flawed specimens were easily sorted out during the tension tests. These results indicate that acoustic emission data gathered during composite fatigue and stress rupture testing might be useful for life prediction.