Effects of extensible modelling on composite riser mechanical responses
Effects of extensible modelling on composite riser mechanical responses
The change from steel risers to composites comes with uncertainties that led to large safety factors. One area of uncertainty is the predicted response and stresses derived from commercial packages that are based on formulations that assume in-extensible riser. However, composite pipes exhibit a lower axial stiffness and therefore the velocity of the axial waves will change with a corresponding change in dynamic response. To determine the effect of this assumption, this paper assesses the effect of extensibility on the time-domain response. It is found that the in-extensible model predicts 3 times the number of high frequency tension cycles in the 20kN tension range. To determine the impact of this change on the stress, the accuracy of available composite pipe models is benchmarked using shell, continuumshell and solid elements. The quadratic and continuum-shell elements provide a maximum percentage difference of 4% compared to solid elements but the continuum-shell is selected as it has a lower computational cost. The response from the extensible and in-extensible models are input into the pipe model, they provide similar Tsai-Wu failure factors, alleviating concerns when modelling the strength. However, the change in dynamics remains a concern for other applications such as machine-learning or digital-twins.
Benchmarking, Cable dynamics, Composite risers, Time domain
Ragheb, Hossam Ali
0cb06fbc-791d-4535-ba2c-1e3f53ba958b
Sobey, Adam
e850606f-aa79-4c99-8682-2cfffda3cd28
15 January 2021
Ragheb, Hossam Ali
0cb06fbc-791d-4535-ba2c-1e3f53ba958b
Sobey, Adam
e850606f-aa79-4c99-8682-2cfffda3cd28
Ragheb, Hossam Ali and Sobey, Adam
(2021)
Effects of extensible modelling on composite riser mechanical responses.
Ocean Engineering, 220, [108426].
(doi:10.1016/j.oceaneng.2020.108426).
Abstract
The change from steel risers to composites comes with uncertainties that led to large safety factors. One area of uncertainty is the predicted response and stresses derived from commercial packages that are based on formulations that assume in-extensible riser. However, composite pipes exhibit a lower axial stiffness and therefore the velocity of the axial waves will change with a corresponding change in dynamic response. To determine the effect of this assumption, this paper assesses the effect of extensibility on the time-domain response. It is found that the in-extensible model predicts 3 times the number of high frequency tension cycles in the 20kN tension range. To determine the impact of this change on the stress, the accuracy of available composite pipe models is benchmarked using shell, continuumshell and solid elements. The quadratic and continuum-shell elements provide a maximum percentage difference of 4% compared to solid elements but the continuum-shell is selected as it has a lower computational cost. The response from the extensible and in-extensible models are input into the pipe model, they provide similar Tsai-Wu failure factors, alleviating concerns when modelling the strength. However, the change in dynamics remains a concern for other applications such as machine-learning or digital-twins.
Text
Effects of extensible modelling on composite riser mechanical responses pre-print
- Accepted Manuscript
More information
Accepted/In Press date: 26 November 2020
e-pub ahead of print date: 22 December 2020
Published date: 15 January 2021
Additional Information:
Funding Information:
This work was supported by EPSRC Centre of Doctoral Training grant no. EP/L015382/1. We thank wood company for providing academic license of their riser analysis software Flexcom which is used to benchmark the results published in this paper. We would also like to thank Lloyd's Register Foundation, grant no. G0095 for supporting this research.
Funding Information:
This work was supported by EPSRC Centre of Doctoral Training grant no. EP/L015382/1. We thank wood company for providing academic license of their riser analysis software Flexcom which is used to benchmark the results published in this paper. We would also like to thank Lloyd's Register Foundation , grant no. G0095 for supporting this research.
Publisher Copyright:
© 2020 Elsevier Ltd
Keywords:
Benchmarking, Cable dynamics, Composite risers, Time domain
Identifiers
Local EPrints ID: 445992
URI: http://eprints.soton.ac.uk/id/eprint/445992
ISSN: 0029-8018
PURE UUID: ff15e3e6-cc51-4a2c-9e6a-2ce8214304ee
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Date deposited: 18 Jan 2021 17:31
Last modified: 17 Mar 2024 06:12
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