Failure Prediction in Multiphase Deep-Water Buoyancy Systems
The objective of this thesis is to explore how a new type of buoyancy material for
oshore applications will perform under operating conditions. This includes buoy-
ancy loads and extreme hydrostatic pressure. The new material system, Compbuoy,
consists of porous, low cost pellets in a polymer matrix. Conventional buoyancy
elements today are lled with syntactic foam, a much more expensive material. As
the promising material Compbuoy has been developed, critical failure mechanisms
must be investigated to ensure the sustainability of the solution.
Shear stress was identied as the most critical stress component and shear strength
testing was performed both experimental and numerical. A new punch tool test
method was developed to measure the load required to break the sample in shear,
and calculate the shear strength by analyzing the results. A test rig was constructed
and test samples were produced and tested. Finite element analysis was performed
to verify the validity of dierent test parameters. The numerical results were found
to coincide well with the general mechanical behavior of the experimental shear test.
FEA was also used to estimate the shear strength and failure strain of the sample,
but some large deviations were discovered. Further testing of material properties
was performed to explain the reason for these deviations.
The shear test results were compared with the design requirements for service at
2500m water depth. Improvements are suggested to improve the compressive and
Place, publisher, year, edition, pages
Institutt for produktutvikling og materialer , 2013. , 115 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-22198Local ID: ntnudaim:10082OAI: oai:DiVA.org:ntnu-22198DiVA: diva2:648653
Echtermeyer, Andreas, Professor