Risers are important components of offshore oil extraction facilities as they connect the surface structure to a pipeline or well-head on the seabed to transport hydrocarbons between the two. Damage incidents in risers may lead to catastrophic economic, environmental and human safety consequences. To avoid the disastrous outcomes of such incidents, early detection of damage in risers is of paramount importance and vibration-based structural health monitoring (SHM) is a promising means of achieving this. Although vibration-based SHM has been extensively studied for several types of structures and systems such as rotating machinery, aerospace structures, bridges and wind turbines, its application to risers has hardly been explored to date. In this paper, application of vibration-based SHM to a top tensioned riser is investigated. To that end, an analytical distributed parameter model is formulated using the Galerkin method and dynamic response of the riser to ambient surface wave excitations is obtained at the healthy and damaged states. Corrosion damage is considered here as it is the predominant cause of damage incidents in risers and it is modelled as cross-sectional area loss at the damaged portion of the riser. To represent the wave excitations realistically, energy density distribution of the sea states is obtained from the JONSWAP wave spectrum. Finally, from the dynamic response of the riser, auto-regressive coefficients and riser natural frequencies are identified and their damage sensitivities are compared for a series of damage extents.
|Publication status||Published - Jul 2018|
|Event||9th European Workshop on Structural Health Monitoring, EWSHM 2018 - Manchester, United Kingdom|
Duration: 10 Jul 2018 → 13 Jul 2018
|Conference||9th European Workshop on Structural Health Monitoring, EWSHM 2018|
|Period||10/07/18 → 13/07/18|
- offshore structures
- vibration analysis and testing