The aim of the study was to understand the impact of coupling on water diffusion and mechanical stress on marine installations. Moreover, we identified the key phenomena involved during this type of exposure. When we look to these type of applications we can distinguish two type of materials used: one for the structure and another for mooring facilities. The best performing structural materials appear to be composites, while the most effective mooring devices are made with synthetic ropes.
Therefore, we decided to investigate both materials with the same method: first the properties uncoupled, second, as semi-coupled behaviours and finally as one coupled phenomenon. The present work highlights the divergences between uncoupled, semi-coupled and coupled behaviours for the two main types of material used for marine and offshore applications. The need to perform coupled tests to dimension the offshore systems is fully justified.
Moreover, this study proposes an important number of hypotheses to explain these differences when we test the materials coupled. For these reasons, additional work should be performed on the subject for other types or composites and fibre materials in order to increase the data base on coupled behaviour.
Stakeholders or Phd/Writer name
- Corentin HUMEAU
Scientific and technical limitations
The other key issue in marine application is the durability of offshore structures. Initially metallic materials were used to build marine vessels, offshore plants or submarine units. As in the case of ropes, metallic structures appear to have quite limiting properties when used in offshore applications. Most of them are highly subject to corrosion and result in high weight structures. Corrosion is critical in offshore applications due to the high conductivity of salt water, and can generate the ruin of the structure by reducing the thickness of healthy material. Indeed, this phenomenon lowers the ultimate strength of the material and can even create leaks (critical for surface vessels and submarines). On the other hand the strength over weight ratio is not optimum in the case of metals, therefore metallic structures subjected to high mechanical stresses are necessarily heavy and hard to handle.