Issue 49

D. E. Belhadri et alii, Frattura ed Integrità Strutturale, 49 (2019) 599-613; DOI: 10.3221/IGF-ESIS.49.55 610 Figure 18: Distribution of the K II along the front for different thickness of the composite (A) variation of the K II as a function of the thickness of the composite (B) - repaired pipe (2c = 45mm, a = 7mm). Figure 19: Distribution of the K III along the front for different thickness of the composite (A) variation of the K II as a function of the thickness of the composite (B) - repaired pipe (2c = 45mm, a = 7mm). Fig. 19 (A) shows the distribution of K III along the front as a function of the thickness of the composite. From this figure, it is noted that the mode III is not sensitive to the thickness of the composite at the bottom of the crack whereas it varies significantly with the thickness of the composite on the outer side of the crack or it is in direct contact with the patch, however it increases with the thickness of the composite up to a maximum value of 85MPa.mm 0.5 for a value of 8mm, beyond this value the K III decreases and the patch resumes its role of absorption of constraints at the edge of the crack. E) Effect of the composite length: Fig. 20 describes the variation of the SIF as a function of the length of the composite patch along the crack front. It is observed that increasing the length of the patch does not reduce much the SIF. Except for the K III , or it can be said that it is sensitive to increasing the length of the composite, the SIF in external position is reduced by 20%. This result confirms that the choice of a long patch does not necessarily increase the effectiveness of the repair of the blow reduces the cost of the maintenance operation.