Issue 49

D. E. Belhadri et alii, Frattura ed Integrità Strutturale, 49 (2019) 599-613; DOI: 10.3221/IGF-ESIS.49.55 605 The K II variation on the crack front for a repaired and unrepaired pipe is shown in Fig. 7(A). It is visible that the composite repair also reduces the K II for a rate of only 17% for the median position of the elliptical crack. Conversely, at * K I , the * K II repair efficiency increases towards the extreme edge of the elliptical crack to reach 55%. Fig. 7(B) For K III Fig. 8 shows the variation of the K III along the crack front for a cracked pipe and a repaired pipe, it can be clearly seen that there is no effect of the repair at the bottom of the crack for the K III on the other hand is approaching the end of the crack the effect of the repair is more marked with a reduced rate of 81%. -10 0 10 20 30 40 50 60 70 80 90 100 110 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 K III ( MPa.mm 0,5 ) Normalized distance repaired pipe unrepaired pipe Figure 8: Variation of the K III along the front of the elliptical crack pipe (c = 60mm, a = 5mm). B) Effect of the crack dimensions: The durability of composite patch repairs of damaged structures depends on the nature and size of the defects. The application of this technique will not be reliable if the size of the defect repaired exceeds a critical value. In this part, the effect of the crack size is represented by the crack progression in the thickness for the evaluation of the variation of the SIF. Figure 9: Variation of the K I along the front of the elliptical crack pipe for different crack depth (c = 60mm). Position 1 Position 2 Position 3 0 10 20 30 40 50 60 70 80 90 100 -20 -15 -10 -5 0 5 10 15 20 25 K I (MPamm 0,5 ) Normalized distance a/t=0,39 a/t=0,55 a/t=0,71 a/t=0,79 a/t=0,87