Numerical Study of Effective Factors Caused by Composite Patch on Increasing the Performance of Semi-Elliptical Cracked Cylinder

In this paper, the effect of composite patch on reinforcement of cylindrical tube containing a surface crack under internal pressure is investigated using a three dimensional finite element method. The cylindrical tube contains an external circumferential semielliptical crack and the aspect ratio of the cracks is between 0.2 and 1 and its relative depths are 0.2 and 0.8. In order to ensure the accuracy of modelling, first, a cylinder containing a surface crack is simulated under uniform tension loading and the results are compared with the available data. The stress intensity factor at the crack tip is determined using the J-integral. Then, the cracked cylinder under internal pressure is repaired using topical composite patch. In this regard, in order to select the appropriate patch, the effect of different parameters such as length, width, thickness, material and angle of composite multi-layer fibers on the stress intensity factors are examined. The results indicate that the stress intensity factors can decrease about 23% by using the appropriate patches which caused the increase of fatigue life due to the decrease of fatigue crack growth rate.