In this paper, the coupled extensional–torsional behavior of a 4 in. flexible pipe is studied. The pipe is subjected to pure tension and two different boundary conditions are considered: ends free and prevented from axially rotating. The response of the pipe is predicted with a three-dimensional nonlinear finite element (FE) model. Some aspects of the obtained results are discussed, such as the effect of restraining the axial rotation at the extreme sections of the model; the effect of friction or adhesion between the layers of the pipe on the induced axial rotation (or torque) and elongation; and the reduction to simple plane behavior usually assumed by analytical models. The numerical results are compared to the ones measured in experimental tests. Reasonable agreement is observed between all results pointing out that the analyzed pipe is torque balanced and that friction mainly affects the axial twist induced by the applied tension. Moreover, the cross sections of the pipe remain straight with the imposed load, but different axial rotations are found in each layer.

References

References
1.
Ferét
,
J. J.
, and
Bournazel
,
C. L.
,
1987
, “
Calculation of Stresses and Slip in Structural Layers of Unbonded Flexible Pipes
,”
ASME J. Offshore Mech. Arct. Eng.
,
109
(
3
), pp.
263
269
.
2.
Witz
,
J. A.
, and
Tan
,
Z.
,
1992
, “
On the Axial-Torsional Behaviour of Flexible Pipes, Umbilicals and Marine Cables
,”
Mar. Struct.
,
5
(2–3), pp.
205
227
.
3.
Custódio
,
A. B.
, and
Vaz
,
M. A.
,
2002
, “
A Nonlinear Formulation for the Axisymmetric Response of Umbilical Cables and Flexible Pipes
,”
Appl. Ocean Res.
,
24
(
1
), pp.
21
29
.
4.
Ribeiro
,
E. J. B.
,
Sousa
,
J. R. M.
,
Ellwanger
,
G. B.
, and
Lima
,
E. C. P.
,
2003
, “
On the Tension-Compression Behaviour of Flexible Risers
,”
13th International Offshore and Polar Engineering Conference
,
Honolulu, Hawaii
, pp.
105
112
.
5.
Cruz
,
F. T. L.
,
1996
, “
Structural Analysis of Flexible Pipes Through the Finite Element Method
,” M.Sc. dissertation, EPUSP, São Paulo, Brazil (in Portuguese).
6.
de Sousa
,
J. R. M.
,
1999
, “
Numerical Analysis of Flexible Risers
,” M.Sc. dissertation, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil (in Portuguese).
7.
Bahtui
,
A.
,
Bahai
,
H.
, and
Alfano
,
G.
,
2008
, “
A Finite Element Analysis of Unbonded Flexible Risers Under Axial Tension
,”
ASME
Paper No. OMAE2008-57627.
8.
Bahtui
,
A.
,
Bahai
,
H.
, and
Alfano
,
G.
,
2008
, “
A Finite Element Analysis of Unbonded Flexible Risers Under Torsion
,”
ASME J. Offshore Mech. Arct. Eng.
,
130
(
4
), p.
041301
.
9.
Edmans
,
B.
,
Alfano
,
G.
, and
Bahai
,
H.
,
2012
, “
Local Stress Assessment of Flexible Unbonded Pipes Using FEA
,”
ASME
Paper No. OMAE2012-84248.
10.
Saevik
,
S.
, and
Bruaseth
,
S.
,
2005
, “
Theoretical and Experimental Studies of the Axisymmetric Behaviour of Complex Umbilical Cross-Sections
,”
Appl. Ocean Res.
,
27
(
2
), pp.
97
106
.
11.
Saevik
,
S.
,
2011
, “
Theoretical and Experimental Studies of Stresses in Flexible Pipes
,”
Comput. Struct.
,
89
(23–24), pp.
2273
2291
.
12.
Witz
,
J. A.
,
1996
, “
A Case Study in the Cross-Section Analysis of Flexible Risers
,”
Mar. Struct.
,
9
(
9
), pp.
885
904
.
13.
Ramos
,
R.
, Jr.
,
Martins
,
C. A.
,
Pesce
,
C. P.
, and
Roveri
,
F. E.
,
2014
, “
Some Further Studies on the Axial-Torsional Behavior of Flexible Risers
,”
ASME J. Offshore Mech. Arct. Eng.
,
136
(
1
), p.
011701
.
14.
Ramos
,
R.
, Jr.
, and
Pesce
,
C. P.
,
2004
, “
A Consistent Analytical Model to Predict the Structural Behavior of Flexible Risers Subjected to Combined Loads
,”
ASME J. Offshore Mech. Arct. Eng.
,
126
(
2
), pp.
141
146
.
15.
Merino
,
H. E. M.
,
de Sousa
,
J. R. M.
,
Magluta
,
C.
, and
Roitman
,
N.
,
2009
, “
On the Coupled Extensional-Torsional Response of Flexible Pipes
,”
ASME
Paper No. OMAE2009-79468.
16.
Hobbs
,
R. E.
, and
Raoof
,
M.
,
1982
, “
Interwire Slippage and Fatigue Prediction in Stranded Cables for TLP Tether
,”
Behaviour of Offshore Structures (BOSS)
, Vol.
2
, pp.
77
99
.
17.
Raoof
,
M.
, and
Hobbs
,
R. E.
,
1988
, “
Analysis of Multilayered Structural Strands
,”
ASCE J. Eng. Mech. Div.
,
114
(
7
), pp.
1166
1182
.
18.
Kraincanic
,
I.
,
1995
, “
Analysis of the Coupled Axial/Torsional Behaviour of Spiral Strands, Wire Ropes, and Locked Coil Cables
,” B.Sc. dissertation, School of Architecture and Civil Engineering, South Bank University, London.
19.
Timoshenko
,
S. P.
, and
Woinowsky-Krieger
,
S.
,
1959
,
Theory of Plates and Shells
,
2nd ed.
,
McGraw-Hill Kogakusha
,
Tokyo
.
20.
de Sousa
,
J. R. M.
,
2005
, “
Local Analysis of Flexible Risers Using the Finite Element Method
,” DSc. thesis, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil (in Portuguese, available in www.coc.ufrj.br).
21.
de Sousa
,
J. R. M.
,
Magluta
,
C.
,
Roitman
,
N.
,
Ellwanger
,
G. B.
,
Lima
,
E. C. P.
, and
Papaleo
,
A.
,
2009
, “
On the Response of Flexible Risers to Loads Imposed by Hydraulic Collars
,”
Appl. Ocean Res.
,
31
(
3
), pp.
157
170
.
22.
Souza
,
A. P. F.
,
2002
, “
Flexible Pipe's Collapse Under External Pressure
,” D.Sc. thesis, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil (in Portuguese).
23.
Cook
,
R. D.
, and
Young
,
W. C.
,
1985
,
Advanced Mechanics of Material
,
Prentice Hall
,
Upper Saddle River, NJ
.
24.
de Sousa
,
J. R. M.
,
Viero
,
P. F.
,
Magluta
,
C.
, and
Roitman
,
N.
,
2012
, “
An Experimental and Numerical Study on the Axial Compression Response of Flexible Pipes
,”
ASME J. Offshore Mech. Arct. Eng.
,
134
(
3
), p.
031703
.
25.
Belytschko
,
T.
, and
Neal
,
M. O.
,
1991
, “
Contact-Impact by the Pinball Algorithm With Penalty and Lagrangian Methods
,”
Int. J. Numer. Methods Eng.
,
31
(
3
), pp.
547
572
.
26.
Belytschko
,
T.
,
Liu
,
W. K.
, and
Moran
,
B.
,
2000
,
Nonlinear Finite Elements for Continua and Structures
,
Wiley
,
Chichester, West Sussex, UK
.
27.
Benson
,
D. J.
, and
Hallquist
,
J. O.
,
1990
, “
A Single Contact Algorithm for the Postbuckling Analysis of Shell Structures
,”
Comput. Methods Appl. Mech. Eng.
,
78
(
2
), pp.
141
163
.
28.
Besseling
,
J. F.
,
1958
, “
A Theory of Elastic, Plastic and Creep Deformations of an Initially Isotropic Material Showing Anisotropic Strain-Hardening Creep Recovery and Secondary Creep
,”
ASME J. Appl. Mech.
,
25
, pp.
529
536
.
29.
Berge
,
S.
,
Engseth
,
A.
,
Fylling
,
I.
,
Larsen
,
C. M.
,
Leira
,
B. J.
,
Nygaard
,
I.
, and
Olufsen
,
A.
, and
SINTEF
,
1992
, “
Handbook on Design and Operation of Flexible Pipes
,” NTNF Research Program, FPS2000/Flexible Risers and Pipes, SINTEF Structural Engineering, Trondheim, Technical Report No. STF70 A92006.
You do not currently have access to this content.