Tensile armour buckling in flexible pipes
exible pipelines has been widely used by the oil and gas industry the last
decades and this trend is expected to continue as the operating depths are increased
further. For deep water applications the radial and lateral buckling modes can be
critical. Many studies has been carried out using nite element models to study
these failure modes.
In this thesis a nite element model is created with the aim to recreate results
obtained in a recently published article by Vaz and Rizzo. The model is built up
using pipe, beam, contact and spring elements to represent the complex behaviour
of the cross section. The loading is carried out by rst applying the dry mass, then
the external pressure and nally end compression.
When comparing buckling loads generated in this thesis by the ones in the
article by Vaz and Rizzo the observation made is that the buckling loads from this
thesis are signicantly higher. When comparing only the inclination of the end
shortening versus buckling load curves it was seen that the curves from article had
a only slightly larger inclination than the results from the analyses in this thesis.
This indicates that there is a small dierence in the stiness used. By modifying
the stiness it should be possible to get the same inclination of the curve.
Analyses were also carried out on how the slip distance aects the buckling
loads. By increasing the slip distance by 50% and 100% it was observed that
the buckling loads were reduced drastically. In the article by Vaz and Rizzo no
information is given on the slip distance. By tuning the slip distance and stiness
of the springs it should therefore by possible to obtain the exact same results as in
the article. This clearly illustrates the importance of stating all assumptions and
input parameters when describing models used for analysis.
Place, publisher, year, edition, pages
Institutt for marin teknikk , 2012. , 111 p.
ntnudaim:7612, MTMART Marin teknikk, Marin konstruksjonsteknikk
IdentifiersURN: urn:nbn:no:ntnu:diva-18652Local ID: ntnudaim:7612OAI: oai:DiVA.org:ntnu-18652DiVA: diva2:566158
Sævik, Svein, Professor