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Research Papers: Piper and Riser Technology

Bonded Flexible Pipe Model Using Macroelements

[+] Author and Article Information
Rodrigo Provasi

Department of Structural and
Geotechnical Engineering,
University of São Paulo,
Avenida Professor Almeida Prado,
Trav. 2, No. 83,
São Paulo, SP 05508-900, Brazil
e-mail: provasi@usp.br

Fernando Geremais Toni

Department of Mechanical Engineering,
University of São Paulo,
Avenida Professor Mello Moraes, No. 2231,
São Paulo, SP 05508-900, Brazil
e-mail: fernando.toni@usp.br

Clóvis de Arruda Martins

Department of Mechanical Engineering,
University of São Paulo,
Avenida Professor Mello Moraes, No. 2231,
São Paulo, SP 05508-900, Brazil
e-mail: cmartins@usp.br

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received December 28, 2017; final manuscript received April 3, 2018; published online April 26, 2018. Assoc. Editor: Jonas W. Ringsberg.

J. Offshore Mech. Arct. Eng 140(5), 051702 (Apr 26, 2018) (8 pages) Paper No: OMAE-17-1233; doi: 10.1115/1.4039923 History: Received December 28, 2017; Revised April 03, 2018

Flexible pipes are structures composed by many layers that vary in composition and shapes. The structural behavior of each layer is defined by the role it must play. The construction of flexible pipes is such that the layers are unbounded, with relative movement between them. Even though this characteristic is what enables its high bending compliant behavior, if the displacements involved are small, a bonded analysis is interesting to grasp the general characteristics of the problem. The bonded hypothesis means that there is no movement relative between layers, which is fine for a small displacement analysis. It also creates a lower bound for the movement, since when considering increasingly friction coefficient values, it tends to the bonded situation. The main advantage of such hypothesis is that the system becomes linear, leading to fast solving problems (when compared to full frictional analysis) and giving insights to the pipe behavior. The authors have previously developed a finite element based one called macroelements. This model enables a fast-solving problem with less memory consumption when compared to multipurpose software. The reason behind it is the inclusion of physical characteristics of the problem, enabling the reduction in both number of elements and memory used and, since there are less elements and degrees-of-freedom, faster solved problems. In this paper, the advantages of such model are shown by using examples that are representative of a simplified, although realistic, flexible pipe. Comparisons between the macroelement model and commercial software are made to show its capabilities.

Copyright © 2018 by ASME
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References

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Figures

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Fig. 2

Bridge element (in gray, top view)

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Fig. 3

ANSYS mesh (with beam rendering option on)

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Fig. 4

Convergence test for radial displacement for the internal tendon in MacroFEM (fixed 100 axial divisions)

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Fig. 5

Convergence test for circumferential displacement for the internal tendon in MacroFEM (fixed 100 axial divisions)

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Fig. 6

Convergence test for axial displacement for the internal tendon in MacroFEM (fixed 100 axial divisions)

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Fig. 7

Convergence test for radial displacement for the internal tendon in MacroFEM (fixed Fourier series order in 4)

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Fig. 8

Convergence test for circumferential displacement for the internal tendon in MacroFEM (fixed Fourier series order in 4)

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Fig. 9

Convergence test for axial displacement for the internal tendon in MacroFEM (fixed Fourier series order in 4)

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Fig. 10

Performance of MacroFEM with 50 elements in axial division while varying the number of terms in Fourier series

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Fig. 11

Convergence test for radial displacement for the internal tendon in ANSYS

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Fig. 12

Convergence test for axial displacement for the internal tendon in ANSYS

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Fig. 13

Convergence test for circumferential displacement for the internal tendon in ANSYS

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Fig. 14

Radial displacement of a tendon in the internal armor. Traction case.

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Fig. 15

Radial displacement of a tendon in the external armor. Traction case.

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Fig. 16

Circumferential displacement of a tendon in the internal armor. Traction case.

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Fig. 17

Circumferential displacement of a tendon in the external armor. Traction case.

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Fig. 18

Axial displacement of a tendon in the internal armor. Traction case.

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Fig. 19

Axial displacement of a tendon in the external armor. Traction case.

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Fig. 20

Radial displacement of a tendon in the internal armor. Compression case.

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Fig. 21

Radial displacement of a tendon in the external armor. Compression case.

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Fig. 22

Circumferential displacement of a tendon in the internal armor. Compression case.

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Fig. 23

Circumferential displacement of a tendon in the external armor. Compression case.

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Fig. 24

Axial displacement of a tendon in the internal armor. Compression case.

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Fig. 25

Axial displacement of a tendon in the external armor. Compression case.

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Fig. 26

Radial displacement of a tendon in the internal armor. External pressure case.

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Fig. 27

Radial displacement of a tendon in the external armor. External pressure case.

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Fig. 28

Circumferential displacement of a tendon in the internal armor. External pressure case.

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Fig. 29

Circumferential displacement of a tendon in the external armor. External pressure case.

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Fig. 30

Axial displacement of a tendon in the internal armor. External pressure case.

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Fig. 31

Axial displacement of a tendon in the external armor. External pressure case.

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