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This research reports the computation of the fracture parameters, namely T-stress and stress intensity factors of a stepwise functionally graded material (FGM) by using the digital image correlation technique. A five-layer epoxy/glass FGM with layers varying from pure epoxy to 60 % glass/40 % epoxy was investigated. The effects of the crack-tip positions and crack length on the nonsingular terms were analyzed. In addition, the numerical simulation of the layered FGM was investigated to further evaluate the fracture parameters. The numerical and experimental model results were compared, and good agreement was obtained between the experimental and numerical tests. Accordingly, the numerical models developed with the corresponding material properties can be used for the evaluation of fracture parameters of the developed FGM.

Repair of cracked pipeline under internal pressure has been investigated in the present study. To this aim, an experimental test has been done on the cracked pipeline to find failure pressure. A longitudinal crack that cut 65% thickness of pipe has been applied on the external surface. Carbon fiber reinforced polymer has been used to repair the system. Additionally, a finite element model has been developed to estimate failure pressure of the unrepaired pipes. The results show that the failure pressure in unrepaired pipes is identical to the failure pressure predicted by the standards for corroded pipes, however, the failure pressure of repaired system is lower than the predicted results of standard for corroded pipelines.

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