ansys offshore products 14-0 update - schofield (1)

7/24/2019 ANSYS Offshore Products 14-0 Update - Schofield (1)

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2011 ANSYS, Inc. September 8, 20111

ANSYS Offshore Products

14.0 Update

Paul Schofield

[email protected]

+1 281-676-7001
mailto:[email protected]:[email protected]


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Introduction

What are the ANSYS Products for Offshore?

Historical Perspective

On-going Development Themes

14.0 Specifics

Case Studies

Conclusions

ANSYS Products for Offshore - 14.0Update


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Reliable and Safe Product and Processes -

Drilling and Production

Deep-waters, high pressures

Temperature variation

Hurricane, waves, Dense areas, combustible and

hazardous products

Drilling through complex geology, long

distances

Many production and processing

equipment : Topside, subsea

Key Market Problems


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Cost of Failure

Human life

Environmental concerns

Delays and fines

Loss of capital, time and equipment

Key Market Problems


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Structural Integrity Huge established inventory of fixed

steel platforms

Requirement for on-going structural

integrity and re-assessment

Assessment carried out at the global(system) level

Additional need for component level

detailed design

Assessment of Fixed Offshore Structures


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Transportation

Installation

Wave loading

Pile/soil modelling

Beam joint fatigue assessment

Member and joint code checking

Decommissioning

Fixed Structures - Design Solutions

Joint Check

Member Check

Jacket Launch


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Remaining new Oil & Gas fields

largely offshore, and in everdeeper water

One off designs

High capital investment

Failure consequences high

Extreme environmentalconditions

Ultra deep water

Hurricanes

Difficult to physically prototype

given the design requirements

Assessment of Floaters



Stability

Integrity of mooring/tether systems

Dynamic positioning (station keeping)

Fatigue of moorings/risers

Wave slamming

VIM/VIV

Structural integrity

Human factors

Assessment of Floaters



General Products

DesignModeler/SCDM

ANSYS Mechanical

Explicit

CFX/FLUENT

ANSOFT

EKM

Vertical Applications

AQWA

ASAS?

What are the ANSYS Offshore Products?

EKM



ANSYS Mechanical has been traditionally used for component

analysis.

We will look at capabilities specific to global analysis.

Will discuss what are the plans for ASAS.

ANSYS AQWA will be looked at in more detail here as largelyoffshore/marine related product.

ANSYS Offshore Update Scope


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For almost 40 years, ANSYS ASAS has been

successfully used for analyzing a large variety of

offshore structures subjected to wave, current

and wind loading

Many North Sea jacket structures have been

designed with the aid of ASAS

But Utilization outside of Europe limited

Much duplication with mainstreamMechanical/MAPDL model

Resulting in transfer of ANSYS ASAS unique solver

technology to ANSYS Structural Mechanics

products

Never any long term scope fordeveloping/supporting multiple FE products

Recognition of ANSYS ASAS key features

Historical PerspectiveANSYS ASAS


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CAE requirements for Fixed Offshore

structures:

Variety of foundations ranging fromconcrete gravity-based to steel

jackets

Combined wave, current and windloading

Variety of local joint flexibility fortubular joints

Seismic loading

Soil-pile-structure and soil-pileinteraction

Range from shallow to deep waterconditions

Member and Joint Code Checking(e.g., API RP2A, AISC, ISO 19902.)

Deterministic, spectral and timehistory fatigue

ANSYS ASAS Migration


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Software development is structured to reflect solutions to

market problems

Some solutions are common to all markets

Others reflect specific application areas to a given market

The major themes covering the development strategy for thispresentation are:

Safety of offshore structures.

Alternative energy devices (specifically here offshore wind

and wave energy systems).

Workbench migration of existing technologies (specifically

here ANSYS AQWA).

Migration of global analysis capabilities to ANSYSMechanical and MAPDL.

Physics coupling.

On-going Development Themes


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Global Offshore Structures

AQWA Workbench Integration

AQWA Enhanced Environmental Conditions

AQWA Frequency Domain Drag Linearization

Extended Wave Loading in Mechanical

Coupling of Mechanical with Third Party Aeroelastic Tools

Design Assessment

14.0 Specifics


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Hydrodynamic Time Response systemenhancements include

Fenders (similar to contact)

Allows connections between 2 structures

or between a structure and a fixed point

Articulations (similar to joints)

Connection points on structures now defined

in AQWA, not in original geometry

Enhanced Productivity with ContinuingAQWA Integration in Workbench

Offloading arm

represented with series

of typical articulations


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AQWA Enhanced Environmental Conditions

Introduction of multi-directional wave spectra

allows more realistic modelling of real wave

conditions, and is important for the accurate

simulation of moored vessels and offshore

platforms Almost any combination of wave spectra to

be modelled in the solver modules LIBRIUM,

DRIFT and the Hydrodynamic Time Response

system in Workbench

Gaussian formulated wave spectrum nowavailable in the core solver and the

Hydrodynamic Time Response system


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Inclusion of linearized drag on

Morison elements inDiffraction/Radiation analysis

Determined using a user specified

wave spectrum.

Computation of modified RAOsusing the additional drag.

SF/BM plots can now be made on

models including Morison elements

(and not just ship shaped).

Used in design wave calculations formixed models e.g. truss spar.

AQWA Frequency Domain DragLinearization

Courtesy of Technip Offshore Finland


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Diffracted wave loading

Provides simplified pressure loading fromHydrodynamics Diffraction systems (AQWA)

onto MAPDL system

Harmonic Wave Loading Regular wave loading now available for harmonic

response analyses

ANSYS FATJACK (for beam joint fatigue of framed

structures) automatically reads the RST file data

for harmonic load cases

Extended Wave Loading in Mechanical

Vessel Loading Transfer fromAQWA to Mechanical

Courtesy of Vuyk Engineering Rotterdam


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Aeroelastic coupling (for wind turbine support

structures)

Sequential Allowing structural (ANSYS) and aeroelastic (3rd

party) analyses to be run independently

Just use a provided MAPDL macro to write outinput data for the aeroelastic analysis

Fully coupled Co-simulation of structural and aeroelastic tools

Custom build of MAPDL required, with a macro to

manage the data availability from and to MAPDL

Coupling Mechanical with 3rdPartyAeroelastic Tools for Offshore Wind

Turbine Modeling

Images Courtesy of REpower Systems AG


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Sequential Solution Example

MAPDLSubstructure analysis to generate

matrices and load history for aeroelastic code

Aeroelastic softwareWave-Wind Analysis

MAPDLAnalysis of foundation structure

FATJACKFatigue calculations

BeamcheckStrength calculations

Mass matrixDamping matrix

Stiffness matrix

External force time series

Top node force

or displacementtime series


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Fully Coupled Solution

Aeroelastic interface to MAPDL using the USER300 element. This elementallows user defined stiffness, damping and mass data. This utilizes ashared memory dynamic link library, so requires modification to the

aeroelastic code to facilitate the interface.


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Design Assessment

Design Assessment is a framework forpost-processing of Mechanical results

Provides out-of-the-box

Load combinations

Regulatory compliance for frame

structures

Joint fatigue

User defined functionality allows access to

external processing similar to MAPDL

customizable

ANSYS BEAMCHECK (for member checks

on framed structures) and ANSYS FATJACKnow delivered with Mechanical

installation (licensed separately)


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Updates to Design Assessment

Extended upstream

capabilities permitswider application range

Modal

Harmonic Response

Random Vibration

Response Spectrum

Explicit Dynamics


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Expanded Result Access

Filteringof potentially invalid combinations can be suppressed to

enable greater user control. This allows the user to access results

not typically available in the base analysis.

Modal=No Beam Results

DA + Allow all

Available Results

allows beam results


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Design Assessment for Advanced User DefinedResults

Design Assessment enables

users to extend user definedresults capabilities with:

Expressions, including

mathematical operators

Coordinate systems, Units

Systems

Nodal, Element-Nodal &

Elemental result types

Units support for input

parameters

Results may be presented as

contours, vectors or stress

tensor form


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Previous slides have shown some of the developments

undertaken to couple wave loading with structuralapplications

Following are example case studies that show how ANSYS

technology can be coupled to good effect to solve complex

problemssystem level solutions. Storage Vessel Design, combining CFD, Hydrodynamics and

Structural aspects in one application.

Riser Design, showing how various aspects of the riser

problem can be solved using the ANSYS toolset.

Case Studies


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Case Study

Storage Vessel Design


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Storage Vessel DesignEffects of FPSO Movement

Liquid-gas interface unstable

Need to reduce sloshing to maintain separation efficiency

What stresses are seen by components?

Can we still use standard baffle configurations?

Bolts and welds

Fatigue loading Not something thats easy to do experimentally!

Potentially dangerous

Significant cost of rig & instrumentation


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Objectives

Design study for a 12m long storage tank on board an FPSO

Design considerations:

Internal baffle arrangement to reduce sloshing

Operational load characteristics

Sloshing loading

Fatigue Welds and bolts


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Vessel Motion

xy

z

Non-accelerating motion

Ship moving at fixed speed

No waves or swell

No acceleration force

No sloshing!

Free motion

Bow of the ship in a storm

3 Rotations

Roll, Pitch & Yaw

3 Linear Accelerations

Surge, Sway & Heave

Sloshing expected!

x

y

z


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Hydrodynamic analysis with a given sea state provides motion profile

for CFD and FEA

Velocity motion profiles applied using Six Degree Of Freedom model

in CFD solve

accelerations could be applied directly to momentum

equations Volume of Fluid model used to model gas-liquid interface

in CFD solver

Transient one-way FSI, surface pressures mapped from CFD

analysis to FEA model

Displacement profiles from Hydrodynamic solver applied

to FEA model to account for inertia of solid structure

Methodology


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Simulation Process

Step Solver Design Consideration Output Data

1 HydrodynamicAsses ship hydrodynamic

response to different sea states

Motion Profiles:

Velocities for CFD

Displacements for FEA

2Computational

Fluid Dynamics

Analyse baffle design to assess

sloshing

Surface Pressure Profiles

3Structural Finite

Element

Analyse stresses to look at

welds and bolt arrangements

and fatigue loading

Velocity

Profiles

Pressures &

DisplacementsHydrodynamics CFD FEA


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ANSYS Workbench Project


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Hydrodynamic Analysis

Motion Profile Output for all six motions, used for CFD and

Structural FE models

Displacements, Velocities and Accelerations


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Computational Fluid Dynamics Analysis

Surface Pressure

Profile used for

Structural model


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Structural FEA

Pressure Loading ONLY Fluid inertia considered

Fixed constraints to feet

Inertia of solid structureignored


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Structural FEA with CFD Free Surface


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Case Study

Risers


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Riser Systems

Risers are the physical connectors between anoil and gas wellhead and the drilling or

production platform (fixed or floating)

Many different types

Drilling, production

Rigid, flexible, steel catenary, etc

Attached, top tensioned, riser towers, etc

Failure costs are high, both financially and

environmentally


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Riser Systems

Floating systems are operating in deeper waters.

Mooring and riser systems are a bigger

proportion of the total system

Vessel, mooring system and risers act as an

integrated dynamic system

Vessel motions coupled with slender structural

members motions (mooring and riser)

For physical model test very deep tank required


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Riser Issues

The analysis of risers represents a majortechnical challenge

Extremely long

Highly flexible

Multi-physics requirements

Mechanical (connections and welds) External hydrodynamic loads

Internal flow assurance

Usually in groups and subject to

interaction effects

Risers are subject to vortex- induced-vibrations (VIV) among one of the the

most complex of fluid-structure

interaction problems


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How We Can Solve Riser Problems

The ANSYS product range provides the toolkit for solving riser designrequirements

Mechanical model for looking at connections (detailed), riser string behavior

(global), tensioning systems, etc.

Hydrodynamic model for investigating effects of riser bundles on floating vessel

response.

Fluids model for flow assurance, VIV, interference effects.

But, at the moment they do not all act in an integrated manner for this type

of application. Further work is necessary to enable best in class capabilities in

this important area.


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Umbilical, Risers & Flexible Piping

Geometry built inDesignModeler:

Core tubing

6 helical tubes wrapped

around core

External insulation

Loads:

Bent to 36 radius

Hydrostatic loads

End tension

Gravity


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Release 14.0 represents the continuing development of

capabilities and technologies to solve problems commonlyencountered in the Offshore Oil & Gas sector.

The range of physical models enables differing levels of

simulation, offering analyses from the macro to the system

level. Improved productivity through continuing integration of

AQWA technology into Workbench

Greater exposure of offshore specific structural applications

through the integration of ANSYS ASAS technology into

ANSYS Mechanical and MAPDL

Conclusions

ansys offshore products 14-0 update - schofield (1)

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