Issue 51

M. S. Bennouna et alii, Frattura ed Integrità Strutturale, 51 (2020) 254-266; DOI: 10.3221/IGF-ESIS.51.20 259 Case of a path of the upper face The equivalent strain on the upper surface increases progressively with the number of cycles, the maximum value goes from 1.25 in the first cycle to 4.5 in the third cycle (Fig. 8). Case of a path of the middle face As for the upper surface, the value of the equivalent plastic strain induced by the median path increases with the number of cycles applied but with less values than those induced by the upper surface. Indeed, the maximum value of the equivalent plastic strain does not exceed 0.81 in the third cycle (Fig. 9). Figure 9 : Influence of the number of cycles on the evolution of the plastic strain at the level of the median surface of the sample. Case of a path of the lower face The equivalent plastic strain at the bottom surface of the sample increases gradually with the number of cycles. Indeed, the maximum value goes from 0.9 for the first cycle to 3.45 for the third cycle (Fig. 10). Figure 10 : Influence of the number of cycles on the evolution of the plastic strain at the level of the upper surface. Fig. 11 presents a comparison between the evolutions of the equivalent plastic strain introduced by the number of CGP cycles at the different paths selected in the sample. It is clear that the equivalent plastic strain increases progressively with the number of cycles for the three types of selected paths. We can also see that the equivalent plastic strain in the middle of the sample is very small compared to the other two surfaces for the case of the three cycles and that the lower surface keep the same value of equivalent plastic strain during the second and the third cycles.