Acoustic Emission from Boron-Aluminum Composites during Tensile Fracture and Fatigue.

Severe deformation of boron-aluminum composite material produces acoustic emission events that are useful in evaluating the degree of damage and in predicting imminent failure. When boron filaments are fractured the resultant acoustic emissions are quite energetic and can usually be detected even in noisey environments such as those associated with fatigue testing. During the fatigue of composites with unidirectionally aligned filaments, it is relatively common to obtain shear cracks which become sources of fretting noise. Such fretting noise is not always an indication of continuing damage and it can obscure acoustic emission events of more interest unless some form of isolation or discrimination is used. One technique for accomplishing this task is discussed. Author