Hybrid thermography and acoustic emission testing of fatigue crack propagation in Aluminum Samples

In this paper the crack propagation process was monitored by two different experimental techniques. Acoustic emissions sensors were placed on the sample in order to monitor the evolution of the acoustical events during the test; at the same time the change in temperature was monitored by thermography. Test were run on aluminum samples (Al 5068). Specimens were previously cracked, by cutting notches having known sizes and geometry. Successively, X-Ray diffractometry analysis were performed in order to establish the given initial stress state of each sample. Specimen were then subjected to mechanical tests. During these tests the crack propagation was continuously monitored and recorded by both techniques. Data obtained, in terms of number of hits, amplitude signals and maps' temperature, were critically compared in order to assess the capability of each technique in following the evolution of the damage process.