A new technology of composite wrapped joints emerges as a promising solution for improving the longterm performance of connections between circular hollow sections (CHS). The use of composite materials is shown to improve the fatigue life of structures. However, a major challenge to the implementation of this technology is to ensure the long-term performance of the composite materials subjected to the operational conditions. This work aims to evaluate the effects of temperature changes on the fatigue delamination of a glass fiber reinforced polymer (GFRP) for application in offshore structures. Specimens were manufactured by hand lay-up and series of experiments are performed to access delamination fatigue crack growth behavior in a range of operational temperatures: -10, 21 and 70 °C. Displacement controlled end-notched flexure (ENF) tests were applied to measure the fatigue behavior together with a digital image correlation (DIC) system to monitor the displacements during the tests. Results show that the delamination fatigue performance of the composite material is not significantly affected by the range of tested temperatures. The fracture behavior also remained unchanged. Standard ENF test method has limited range of crack growth to evaluate the fatigue behavior of composite laminates.@en

Debonding is one of the most critical failure modes for bonded joints under fatigue loads. Numerical prediction on the fatigue debonding behaviour of bonded interfaces with complex geometry still remains a problem. This paper proposes a numerical methodology based on fracture mechanics to predict crack growth in a complex bi-material interface and illustrates the prediction procedure by a case study on wrapped composite joints. Interface coupon tests provide the fatigue crack growth properties at the composite-to-steel interface used as inputs for finite element (FE) modelling. The FE model is calibrated against fatigue tests of small scale wrapped composite joints with different steel surface roughness subject to different load levels. A sensitivity analysis is conducted to investigate the influence of key modelling parameters. The calibrated model is validated against fatigue tests on upscaled joints. Good agreements are shown between the test and modelling results in terms of crack growth and stiffness degradation, demonstrating the potential of the proposed numerical methodology for predicting fatigue debonding behaviour of complex bi-material interfaces.

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