Issue 51

A. A. Lakhdari et alii, Frattura ed Integrità Strutturale, 51 (2020) 236-253; DOI: 10.3221/IGF-ESIS.51.19 242 6. Incremental time step. 7. Repeat steps 3-6 until the destruction of the structural element . Fig. 2 shows the deformation diagram, constructed taking into account the effects of low temperature hydrogen. Step 4: Results analysis. Figure 2 : Initial deformation diagram (COL2) and modified by the influence of hydrogen (COL1). C ALCULATION AND ANALYSIS OF THE RESULTS alculations were made for a hollow cylinder with the parameters: inner radius of 0.3 m; outer radius of 0.5 m; cylinder length of 3.5 m. The characteristics of the material: modulus of elasticity E=3.0e10; transverse deformation coefficient Nu=0.2; thermal conductivity coefficient Alpha=1.4e-5 ; density of the material Dens=7659 ; coefficients of the function of approximation of the deformation diagram: A 0 =3.0e10, B 0 =2.0e11. The modulus of elasticity, the parameters of the strain diagram and all the constraints on the figures are measured in Pa (Pascal), the time is measured in hours. Tab. 2 shows the different loading cases of the hollow cylinder. № Loading in , MPа P out , МPа P 3 in ,1/ m C 3 out ,1/ m C 1. 0 20 3.2E-4 3.2E-4 2. 0 20 7.2E-4 1.5E-4 3. 0 30 7.2E-4 1.5E-4 4. 20 11 0.5 4 0.00005 E t    3.2E-4 Table 2 : Loading cases and effects of hydrogen Loading №1 . The hollow cylinder is under external pressure P out ; the concentration field of the hydrogen is homogeneous. The concentration field has the form shown in Fig. 3, and it does not change over time. The intensity of the constraints is shown in Fig. 4. The radial, tangential and axial stresses at time t =10 are shown in Figs 5, 6, 7. Fig. 8 shows the stress intensity curves S INT , axial stresses S Z , radial and tangential S X and S Y according to the thickness of the wall of the cylinder. C