Issue 50

M. Belhamiani et alii, Frattura ed Integrità Strutturale, 50 (2019) 623-637; DOI: 10.3221/IGF-ESIS.50.53 628 Figure 4 : The variation of maximum J integral value in the Crack tip (1,2) with the loading pressure. We outcome in the fig.4 a nonlinear prportionality behavior of the value of maximum of J integral with loading pressure, this latter is due to the elastic plastic behaviore of the API 5L X65 PSL2 pipe and the existence of an important plastic zone in the vicinity of the front of crack. In our case of study the J integral max of the line 1 and slightly higher of the line 2 for the unrepaired pipe and repaired respectively 33% and 50%. This is probably due to the non-symmetry of crack geometry and stress distribution in the crack boundary. Also we can note that the crack propagation in depth is more dangerous than the longitudinal crack. This is for the repaired and unrepaired pipe. b. Crack length From the analysis of Fig.3 and to analyze the effect of the crack length one limits oneself in this study of the value c/t=2. In the Fig 5 some plots are shown which refer to the behaviore of J integral max (a) and the J* (b) vs crack length . It must be appointed that the J integral max increase as the crack length increase . This behaviour increases the risk of pipe rupture. Figure 5 : The variation of the J integral for repaired and unrepaired pipe and J* with the crack length (a/t=0.5). y z