Small-scale FE modelling for the analysis of flexible risers

Mohammad Rahmati, Giulio Alfano, Hamid Bahai

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

4 Citations (Scopus)


Flexible risers which are used for transporting oil and gas between the seabed and surface in ultra-deep waters have a very complex internal structure. Therefore, accurate modeling of their behaviour is a great challenge for the oil and gas industry. Constitutive laws based on beam models which allow the large-scale dynamics of pipes to be related to the behaviour of its internal components can be used for multi-scale analysis of flexible risers. An integral part of these models is the small-scale FE model chosen and the detailed implementation of the boundary conditions. The small scale FE analyses are typically carried out on models of up to a few meters length. The computational requirements of these methods limit their applications for only multi-scale structural analysis based on a sequential approach. For nested multi-scale approaches (i.e. the so called FE2 method) and for multi-scale multi-physic analyses, e.g. fluid structure interaction modeling of flexible risers, more efficient methods are required. The emphasis of the present work is on a highly efficient small-scale modelling method for flexible risers. By applying periodic boundary conditions, only a small fraction of a flexible pipe is used for detailed analysis. The computational model is firstly described. Then, the capability of the method in capturing the detailed nonlinear effects and the great advantage in terms of significant CPU time saving entailed by this method are demonstrated. For proof of concept the approach is applied on a simplified 3-layer pipe made of inner and outer polymer layers and an intermediate armour layer made of 40 steel tendons.
Original languageEnglish
Title of host publicationProceedings of the ASME 34th International Conference on Ocean, Offshore and Arctic Engineering -2015
Place of PublicationNew York
PublisherAmerican Society of Mechanical Engineers (ASME)
Number of pages6
ISBN (Electronic)9780791856512
Publication statusPublished - 2015
Externally publishedYes
Event34th International Conference on Ocean, Offshore and Arctic Engineering: ASME 2015 - St. John's, Canada
Duration: 31 May 20155 Jun 2015


Conference34th International Conference on Ocean, Offshore and Arctic Engineering
CitySt. John's


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