Issue 43

F. Majid et alii, Frattura ed Integrità Strutturale, 43 (2018) 79-89; DOI: 10.3221/IGF-ESIS.43.05 87 The coefficient α, β and η represent respectively the ratio of the ductile rupture pressures, the life fraction and the non- dimensional ratio of the applied pressure and the rupture one. β Pa is the life fraction corresponding to the pressure before rupture. The representation of the adaptive model is given in Fig. 8: Figure 8 : Approximate theoretical damage, through corrected Faupel, adaptive and experimental damages according to the life fraction. The representation of the continuum damage model is almost the same as the one given by the adaptive damage model as illustrated in Fig. 8. The difference is explained by taking into account the applied experimental pressure (Pa = 11.9 bar) for the continuum damage model independently of the theoretical equations. Figure 9 : Approximate theoretical damage, through corrected Faupel, adaptive, continuum D (β) and experimental damages as a function of the life fraction. . We observe from the damage curves of Figs. 8 and 9 that the theoretical damage is linear as the damage of Miner, while the experimental damage clearly shows three phases of evolution. The first phase is characterized by slow evolution under the theoretical damage up to the life fraction of 17%. In the second phase, we observe a steady increase of the latter up to the 65% of life fraction. In the third phase, a significant acceleration of the damage to reach the unit was registered. Concerning the adaptive damage, we found that the developed model traces perfectly the model of static damage obtained