Umbilicals Design with UmbiliCAD and Helica

Agosto de 2012

Umbilical Design Using UmbiliCAD and Helica

Fan Joe Zhang Sesam Business Development Manager – DNV Software / Houston

© Det Norske Veritas Ltda. Todos os direitos reservados.

Introduction to UmbiliCAD UmbiliCAD® by UltraDeep

- A cross-section design, drawing and modeling tool - Drawing contains all material properties - Calculates mass, weights, axial, bending and torsion stiffness - Stress capacity calculation - Analythical methodolgy for stiffness and stress capacity calculation - Tube sizing according to DNV-OS-F101 and ISO 13628-5 - Module for reel capacity calculation - Module for bill of material - DXF export to other CAD tools - Module for Helica calculations - Plugin capability

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http://www.ultradeep.com/index.php


UmbiliCAD

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Power cable/umbilical Steel tube umbilical Control umbilical


Why UmbiliCAD? No need to be an advanced draftsman

Early cross section analysis – first results within hours in stead of days - Linear analysis with no stick/slip

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Capacity Curve

0.0100200300400500600700800900

100011001200

0.0 0.04 0.08 0.12 0.16 0.2 0.24 0.28Curvature [1/m]

Tens

ion

[kN

]

100% Utilisation80% Utilisation


Introduction to Helica Helica™ by DNV

- A cross-section stress analysis tool - Short-term fatigue analysis - Long-term fatigue analysis - a tailor-made software for cross-sectional analysis of flexible pipes and umbilicals - Load-sharing between elements considering axis-symmetric analysis - Calculation of cross-sectional stiffness properties (axial, torsion and bending

stiffness) - Helix element bending performance analysis to describe stresses in helix elements

during bending considering stick/slip behaviour due to interlayer frictional forces.

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Helica Cross-sectional load sharing analysis

- Load-sharing between elements considering axis-symmetric analysis - Calculation of cross-sectional stiffness properties (axial, torsional and bending

stiffness) - Helix element bending performance analysis to describe stresses in helix elements

during bending considering stick/slip behaviour due to interlayer frictional forces

Short-term fatigue analysis - To assess the fatigue damage in a stationary short-term environmental condition

considering fatigue loading in terms of time-series of simultaneous bi-axial curvature and effective tension produced by global dynamic response analysis

- Helica uses results from DeepC as the response database for time domain global dynamic analysis as loading

Long-term fatigue analysis - To assess the long-term fatigue damage by accumulation of all short-term

conditions

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Helica Cross-sectional bending characteristics

- Relative motion between layers/components - Friction, stick/slip behaviour (Tension dependent) - Moment/curvature hysteresis - Non-linear amplitude dependent - Above effects automatically accounted for

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Curvature

Mom

ent


UmbiliCAD and Helica Bundle UmbiliCAD and Helica is a bundeled software UmbiliCAD exports cross

section geometry and material properties to Helica, set up load cases, and build the model for analysis.

Helica can be run from UmbiliCAD and results and plots can be presented in UmbiliCAD

The Helica model can also be exported and run manually in Helica for batch processing.

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Demo Case

Umbilical Component and Cross-section Design

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Cross-section

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ParameterOuter DiameterMass EmptyMass FilledMass Filled And FloodedSubmerged Weight EmptySubmerged Weight FilledSubmerged Weight Filled And FloodedSpecific Weight RatioSubm. Weight. Dia. RatioAxial StiffnessBending StiffnessBending Stiffness (friction free)Torsion StiffnessTension/Torsion Factor

Value143.130.832.635.214.316.118.72.1130.8431.524.915.0148.6-0.02

Unit[mm][kg/m][kg/m][kg/m][kgf/m][kgf/m][kgf/m][-][kgf/m^2][MN][kNm^2][kNm^2][kNm^2][deg/m/kN]


The Dynamic Umbilical Design Process

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© Det Norske Veritas Ltda. Todos os direitos reservados. 12

Component Design (UmbiliCAD)

Cross-section Design (UmbiliCAD & Helica)

Global Design and Analysis

(DeepC Riflex)

Global Extreme Analysis (e.g. 100 year hurricane

DeepC Riflex)

Cross-section drawing

Mechanical Properties

Capacity Curves

Global Analysis Report

Functional Requirements Standards and Codes

(ISO 13628-5)

CLIENT Function.list

Local Analysis (Helica)

Global Fatigue Analysis (Full scatter diagram

DeepC Riflex)

Local Fatigue Analysis (e.g. in BS, sag, hog etc.

Helica)

Global Fatigue Analysis Report

Local Fatigue Analysis Report


Component and Cross-section Design Using UmbiliCAD and Helica

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Local Analysis Using Helica

- Compute cross sectional properties

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Value133.235.939.442.421.625.128.13.0210.8677.321.316.727.50.00


Capacity Curve

0.0

50

100

150

200

250

300

350

400

450

500

0.0 0.04 0.08 0.12 0.16 0.2 0.24 0.28 0.32Curvature [1/m]

Tens

ion

[kN

]

100% Utilisation80% Utilisation

0

100

200

300

400

500

600

-0.0004 -0.0003 -0.0002 -0.0001 0 0.0001 0.0002 0.0003 0.0004

Tot

al h

elix

stre

ss

Curvature

Helix position : 270.0000


Global Design and Analysis Using DeepC Riflex

- Coupled or de-coupled analysis

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Forced floater motions Wave loading

Non-linear load model

Non-linear structure


Global Analysis Using Helica to get capacity curve

- The capacity curve presents all load combinations that result in the specified maximum allowable equivalent stress due to: - Tension - Pressure - Bending - Torsion

- All cross-section members are considered

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Bend stiffener region


Local Fatigue Analysis Using Helica

Load sharing analysis - Axi-symmetrical analysis to establish

tension in each element - Bending analysis including the

hysteretic, friction induced stick/slip behavior of the helix elements

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Local Fatigue Analysis – Short-term Fatigue Analysis

Purpose of the analysis is assessment of fatigue damage in a stationary short-term environmental condition

Specification of: - Helix element - Longitudinal locations - Helix positions/hot-spots - SN-curve

Helix stresses calculated: - Stick/slip friction due to

bending - Bending about local axis - Stresses due to tension

(from axisymmetrical analysis)

Rainflow cycle counting

Fatigue damage calculation

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Fat

igue

str

ess

Time

( ) series timestress Fatigue - tσ

Stress range


Local Fatigue Analysis – Long-term Fatigue Analysis

Purpose of the analysis is to assess the long-term fatigue damage by accumulation of all short-term conditions

Required input: - Fatigue results for all short-term

conditions - Probability of each short-term condition

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Size of problem – numerical performance 270 TD simulations with 1 hour duration (20.000 time steps)

Rectangular tensile armours, 4 hot-spots

12 helix locations

Fatigue damage calculated at 76 locations along riser (including bend stiffener area)

Total of 985.000 1 hour stress time series generated by cross-sectional analysis

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φ

y

xφ

y

x

xl

yl

Computation time – standard single core lap-top

Global TD analyses not included in computation time

Model Total Per case

Tube, no friction 0.38 hours 5 seconds

Helix, no friction 3.8 hours 50 seconds

Helix with friction 5.8 hours 77 seconds

Presenter

Presentation Notes

System and excitation dependant non-linearities - Geometric stiffness - Hydrodynamic loading - Material nonlinearities Solution strategies - Time domain FE dynamic analysis - Full non-linear TD formulation - Linearized TD formulation Basis for subsequent capacity checks - Cross-sectional analysis to determine load sharing between individual elements - Extreme/Fatigue load effect analysis - Combined loading in terms of global response time histories


Example

Local Fatigue Analysis

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Analysis process Calculate cross section parameters

- Mass/weight in UmbiliCAD - Axial, bending and torsion stiffness from Helica

Global analysis using DeepC - Riflex - Inpmod

- Riser definition – Cross section parameters from first step - Environment definition – wave heights, current etc. with corresponding direction

- Riflex – Stamod - Static analysis

- Riflex – Dynmod - Dynamic analysis

Short-term fatigue analysis using Helica

Long-term fatigue analysis using Helica

Design of umbilicals is also based on ULS – this is part of UmiliCAD/Helica analysis, but not covered in this presentation

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Lay-out of the riser

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27 Environment conditions


Step 1 Create cross-sections and calculate mass properties UmbiliCAD will do both

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Value117.023.026.528.712.015.517.72.6151.1476.329.023.743.50.00



Step 2 Calculate stiffness using Helica

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Step 3 Run global response analysis using Riflex For a fatigue analysis, responses under multiple environment conditions (wave scatter) may be

analyzed. Batch executions are normally used. (run-riflex.bat)

Motion RAOs of the vessel will also be used. (trafile.tra)

In this example, the analysis setup contains 27 weather directions.

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Inpmod.inp Stamod.inp Dymod.inp

run-riflex.bat executing…

Trafile.tra


Capacity curve vs. time-domain time series Responses should be within the 80% or 100% capacity curves

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Step 4 Run fatigue analysis using Helica Calculate short term fatigue for critical area

for each of the bins. - In this example the critical areas are the BS area

of SDTube2 and SDTube4 (inner layer of cross-section).

When all bins are completed, fatigue is accumulated and long term fatigue is calculated by Helica.

Following input files are normally needed: - Helica Fatigue analysis input file (BS-

SDTube2_fat_ana.inp) - Helica Cross Section (helica.inp, could be

generated by Helica) - Fatigue setup, (where to calculate fatigue etc

(BS-SDTube2_fat_geo.inp) - Fatigue probabilities (fat_conditions.inp) - SN curves (SN-lib.inp)

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Helica fatigue analysis input file Defining the parameters used in

Helica fatigue analysis, e.g. - Analysis time window - Helix element positions - If friction will be considered - Etc.

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Here ‘2’ means friction will be considered using updated contact force.


Long term fatigue histograms

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Case19_layer3_component1_location11_hotspot5


Summary – Why UmbiliCAD and Helica? To facilitate the deepwater challenge 1) :

- “Increased importance of higher order cross-sectional effects” - Tension/radial displacement coupling - Internal friction

- “These effects may considerably affect dynamic umbilical performance in deep waters”

Main benefits - No need for specialist competence in a CAD system – drawings, cross sectional

properties and early design capacity curves made in hours instead of days - Outstanding numerical performance gives answer in days instead of weeks

- Extreme design – capacity curves for entire cross-section in compliance with applicable design codes

- Fatigue stress analysis of helix elements considering stick-slip behaviour in bending - Calculation of consistent fatigue stresses by direct application of global response time

series from DeepC as external loading - Short-term fatigue life calculation capabilities including Rain-flow cycle counting - Long-term fatigue life calculation capabilities including assessment of long-term stress

cycle distribution

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Presenter

Presentation Notes

1) Ref.: OTC 17986:2006:�“Predicting, Measuring and Implementing Friction- and Bending Stresses in Dynamic Umbilical Design”, � Ekeberg et.al.)

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Umbilicals Design with UmbiliCAD and Helica

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