ACOUSTIC EMISSION DETECTION OF FATIGUE CRACK INITIATION AND PROPAGATION IN NOTCHED AND UNNOTCHED TITANIUM SPECIMENS

摘要

The purpose of this program is twofold. First, to assemble, check and demonstrate the operation of an acoustic emission instrumentation system for early detection of fatigue test specimen cracks, and to evaluate it as a tool for detecting the initiation and propagation of cracks in titanium fatigue specimens. This method has been selected because the acoustic emission technique has unique abilities in the detection of crack initiation in specimens during the application of static or dynamic loads, and in monitoring material internal changes under these loads. Second, to seek the development of relationships between the acoustic emissions of the specimen and the degree of damage due to crack presence and growth for titanium fatigue specimens. The development of these relationships would lead directly to a further understanding of the mechanisms of failure of these specimens. Of specific interest is the relationship of crack initiation and growth to the fatigue life cycle.