External surface cracked offshore steel pipes reinforced with composite repair system subjected to cyclic bending
An experimental investigation
Zongchen Li (TU Delft - Mechanical Engineering)
Xiaoli Jiang (TU Delft - Mechanical Engineering)
Hans Hopman (TU Delft - Mechanical Engineering)
Ling Zhu (Wuhan University of Technology)
Zhiping Liu (Ministry of Education Hangzhou)
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Abstract
In this paper, we experimentally studied the external surface crack growth in steel pipes reinforced with Composite System Repaired (CRS). CRS reinforced surface cracked API 5L X65 pipes were tested, containing three initial notch sizes and four reinforcement schemes. During the tests, the crack growth results, as well as the strain on the external mid-bottom composite laminate around the cracked area, and the vertical deflection of the specimens were recorded. The results showed that within the surface crack growth stage, the composite laminates were adequately bonded on the steel substrate, which significantly decreased the crack growth rate and prolonged the residual fatigue life. In addition, CRS reinforcement has increased the stiffness of the surface cracked pipes. Through the analysis on applying different reinforcement schemes, we indicated that increasing the amount of composite layers evidently facilitated the reinforcement effectiveness, while increasing the bond length did not; and the inversely diagonal wrapping pattern performance less effective.
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