Considerations on Acoustic Emissions in Ti Grade 5 during Fatigue Test

In this paper the behavior of Ti grade 5 specimens during fatigue tests, subjected to uniaxial sinusoidal load, was studied by using an Acoustic Emission (AE) detection system. A couple of detectors was placed on the sample in order to allow localization of the acoustic source. Slots were preliminary cut into the specimens in order to introduce a region of stress concentration. During the whole test all data characterizing the AE were collected, i.e. number of hits, amplitude of the recorded waveform, longitudinal coordinate of the acoustic source etc. Data were analyzed also applying different kinds of post-processing filters in order to isolate, for example, only events occurring in the higher stress region or having amplitude beyond a given selected levels. The system proved itself to have a good capability to localize the crack while, properly filtered cumulative graph of hits, display features strictly connected with the nucleation, and propagation of the cracks. Finally amplitude analysis of the recorded signal shows that two main bands of amplitude were recorded during the test.