Issue 40

K. Kaklis et alii, Frattura ed Integrità Strutturale, 40 (2017) 1-17; DOI: 10.3221/IGF-ESIS.40.01 13 the test, suggesting a limited formation of isolated micro-cracks. High values of RT are observed at the final stage of the rupture (after t=72 s), as in the case of the specimen 2.3, but there is no indication of any macroscopic crack before the final rupture of the specimen. Figure 14: 2D pattern of the location of cumulative events at different selected times, during the CCNBD test of the specimen 2.3 (mode I loading). The positions of the 4 sensors at the front side of the specimen that were used in the location algorithm and the chevron notch are also indicated. The color scale denotes the highest amplitude of the recorded hits in each event and thus is an estimation of the magnitude of the events. Figure 15: Time evolution of acoustic emission parameters during the CCNBD test of the specimen 3.23 (mode II fracture). (a) The distribution of amplitudes of all sensors located to the surface of the specimen, in conjunction with the applied load (b) The mean hit rate of all sensors. (c) The cumulative distribution of hits from sensors 1, 2 and 6 and (d) the rise time of hits recorded in channel 8.