Issue 50

A. Salmi et alii, Frattura ed Integrità Strutturale, 50 (2019) 231-241; DOI: 10.3221/IGF-ESIS.50.19 236 The results show that the number of cycles increases with the load ratio, that is the higher the load ratio, the greater the cracking resistance at the same maximum stress. We also note that: The paper presents a computational model for determining the lifetime of crack propagation for 2024 T3 aluminum alloy. The fatigue process is divided into crack initiation ( Ni ) and crack propagation ( Np ) periods, which allows the total lifetime to be determined as N Ni Np   (5) I NFLUENCE OF TEMPERATURE hese results present a digital calculation of the plate. Thermal and mechanical results are exposed respectively. Thermal results Fig. 4 shows the temperature changes as a function of the x-position in the thickness. Figure 4: Temperature changes as a function of the x-position in the thickness at different temperatures These results show that the thermal gradient in the thickness continues by conduction and decreases during the inner face of the plate. the temperature field in the plate has been well estimated by our calculations. Mechanical results This section presents the results of the calculation with a model in which the mechanical behaviour of each phase is of the elasto-plastic type with linear cinematic hardening. The axial displacement variations follow the thickness are represented by the Figs. 5 < A (a=5.08mm); B (a=5.50mm); C (a=6.34mm); D (a=7.18mm)> for differing temperatures at crack widths ranging from 5.08 to 7.18. On the one hand in Fig. 5: - we note that for each x-position in thickness, when the temperature increases from + 30°C to +60°C, the changes in the very high axial displacement is more apparent for crack widths greater than 7.18 mm. - On the other hand, for a x-position in thickness and constant temperature, with an increase in crack width from a=5.08mm to 7.18mm, the changes in axial displacement increase. Deformation variations according to thickness are illustrated in Fig. 6 < A (a=5.08mm); B (a=5.50mm); C (a=6.34mm); D (a=7.18mm)> to differentiate temperatures at crack widths ranging from 5.08 to 7.18 mm. These results also indicate that: - The overall deformations of the plate increase significantly, when the thermal and mechanical aspect are coupled. - Overall, compared to the thermo-mechanical growth cases presented above, the overall deformations of the plate are less well simulated in this case. T