Umbilicals Design with UmbiliCAD and Helica

Umbilical Design Using UmbiliCAD and Helica

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

Agosto de 2012

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

© Det Norske Veritas Ltda. Todos os direitos reservados. 2

UmbiliCAD
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

Capacity Curve
1200
100% Utilisation
1100 80% Utilisation
1000
900
800

Tension [kN]
700
600
500
400
300
200
100
0.0
0.0 0.04 0.08 0.12 0.16 0.2 0.24 0.28
Curvature [1/m]


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.


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


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

Moment

Curvature


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.


Demo Case
Umbilical Component and
Cross-section Design


Cross-section

Parameter Valu e Un it
Ou ter Diameter 1 4 3 .1 [mm]
Mass Emp ty 3 0 .8 [k g /m]
Mass Filled 3 2 .6 [k g /m]
Mass Filled An d Flo o d ed 3 5 .2 [k g /m]
Su b merg ed Weig h t Emp ty 1 4 .3 [k g f/m]
Su b merg ed Weig h t Filled 1 6 .1 [k g f/m]
Su b merg ed Weig h t Filled An d Flo o d ed 1 8 .7 [k g f/m]
Sp ecific Weig h t Ratio 2 .1 [-]
Su b m. Weig h t. Dia. Ratio 1 3 0 .8 [k g f/m^2 ]
Ax ial Stiffn ess 4 3 1 .5 [MN]
Ben d in g Stiffn ess 2 4 .9 [k Nm^2 ]
Ben d in g Stiffn ess (frictio n free) 1 5 .0 [k Nm^2 ]
To rsio n Stiffn ess 1 4 8 .6 [k Nm^2 ]
Ten sio n /To rsio n Facto r -0 .0 2 [d eg /m/k N]


The Dynamic Umbilical Design
Process


CLIENT
Function.list

Functional Requirements Cross-section
Component Design
Standards and Codes drawing
(UmbiliCAD)
(ISO 13628-5)

Mechanical
Cross-section Design Properties
(UmbiliCAD & Helica)
Capacity Curves

Local Analysis
(Helica)

Global Design and
Analysis
(DeepC Riflex)

Global Analysis Global Extreme Analysis Global Fatigue Analysis Global Fatigue
Report (e.g. 100 year hurricane (Full scatter diagram Analysis Report
DeepC Riflex) DeepC Riflex)

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


Component and Cross-section Design
 Using UmbiliCAD and Helica


Local Analysis
 Using Helica
- Compute cross sectional properties

To rsio n Stiffn ess 2 7 .5 [k Nm^2 ]
Ten sio n /To rsio n Facto r 0 .0 0 [d eg /m/k N]

Capacity Curve
Helix position : 270.0000 500
100% Utilisation
600 450 80% Utilisation

400
500
350
Total helix stress

400
Tension [kN]

300

250
300
200
200 150
100
100
50
0 0.0
-0.0004 -0.0003 -0.0002 -0.0001 0 0.0001 0.0002 0.0003 0.0004 0.0 0.04 0.08 0.12 0.16 0.2 0.24 0.28 0.32
Curvature Curvature [1/m]


Global Design and Analysis
 Using DeepC Riflex
- Coupled or de-coupled analysis

Wave loading Forced floater motions

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
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


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: σ (t ) - Fatigue stress time series

Fatigue stress
- Stick/slip friction due to
bending
Time

Stress range

- Bending about local axis
- Stresses due to tension
(from axisymmetrical analysis)
 Rainflow cycle counting
 Fatigue damage calculation


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


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
y
analysis yl
xl
Computation time – standard single core lap-top
Model Total Per case
φ
Tube, no friction 0.38 hours 5 seconds x
Helix, no friction 3.8 hours 50 seconds
Helix with friction 5.8 hours 77 seconds

Global TD analyses not included in computation time


Example
Local Fatigue Analysis


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

Lay-out of the riser

27 Environment conditions


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

To rsio n Stiffn ess 4 3 .5 [k Nm^2 ]
Ten sio n /To rsio n Facto r 0 .0 0 [d eg /m/k N]


Step 2 Calculate stiffness using Helica


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.

Inpmod.inp
run-riflex.bat
Stamod.inp executing…
Dymod.inp

Trafile.tra


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


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)


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.

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


Long term fatigue histograms

Case19_layer3_compone
nt1_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


Safeguarding life, property
and the environment

www.dnv.com


Umbilicals Design with UmbiliCAD and Helica

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