Agosto de 2012
Umbilical Design Using UmbiliCAD and Helica
Fan Joe Zhang Sesam Business Development Manager – DNV Software / Houston
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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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UmbiliCAD
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Power cable/umbilical Steel tube umbilical Control umbilical
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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
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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
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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]
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The Dynamic Umbilical Design Process
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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
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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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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
Value133.235.939.442.421.625.128.13.0210.8677.321.316.727.50.00
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]
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
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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
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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
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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
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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
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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
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Step 1 Create cross-sections and calculate mass properties UmbiliCAD will do both
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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
Value117.023.026.528.712.015.517.72.6151.1476.329.023.743.50.00
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]
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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
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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.
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Long term fatigue histograms
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Case19_layer3_component1_location11_hotspot5
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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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