seminar nov 2010 - ansys · pdf fileseminar –nov 2010 ... –fully integrated...

© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary

Steve Varnam

Richard Mitchell

ANSYS UK

Seminar – Nov 2010

Engineering Simulation

Software for the Offshore,

Marine and Wave/Tidal

Renewable Energy Industries

Structural Mechanics

© 2010 ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary

Agenda

• ANSYS Heritage in Offshore Structural Analysis

– ANSYS ASAS

• Analysis of Offshore Structures in our

mainstream software

– ANSYS Mechanical

• Addressing the next generation of structural

analysis requirement

– ANSYS Workbench

• Fatigue

• Composites

• Optimisation


ANSYS Offshore Solutions

- proven for Oil & Gas applications

• ANSYS® ASASTM

– Offshore Structural FE Analysis

– Coupled wave/current/wind-structure interaction with

nonlinear structural response

– Fatigue assessment with irregular waves and using

deterministic and spectral methods

• ANSYS® AQWATM

– Fully Integrated Multi-body Hydrodynamic and Motion Analysis

– Mooring, stability, vessel motions in regular and irregular waves

• within time and frequency domain

• with coupled cable dynamics

• with forward speed

• Since 1971, AQWA & ASAS have been developed for analyzing a large

variety of oil & gas offshore structures

– WS Atkins Century Dynamics ANSYS

cargo lowered onto vesselshielding


AQWA & ASAS Overview

- Main Application Areas

• Offshore Structures– Fixed

• Steel Jackets

• Concrete

– Compliant

• Jack-ups

– Floating• FPSOs

• SPARS

• Semi-Submersibles

• Tension Leg Platforms

– Risers

– Offshore Wind Turbines

• Harbours

• Ships– Design

– Offloading

Images courtesy of Arup, Moss Maritime AS, Technip Offshore Finland and REpower Systems AG


ASAS

- Typical Applications

• Some example applications

Courtesy of REpower Systems AG

Courtesy of Fraunhofer CWMT

Offshore Wind Turbines

Jacket Structures

Transportation of Spar Truss on Heavy Lift VesselCourtesy of Technip Offshore Finland

Tidal Turbine Structure


ANSYS ASAS

- Relevance for Offshore Renewables

• For more than 30 years, (ANSYS) ASAS has been successfully used

for analyzing a large variety of offshore structures subjected to

wave, current and wind loading

– More than half of all North Sea jacket structures have been designed with the

aid of ASAS

• CAE requirements for Offshore Renewables are very similar:

– Variety of foundations ranging from concrete gravity-based to steel jackets

– Combined wave, current and wind loading – incl. spectral fatigue

– Variety of local joint flexibility for tubular joints

– Seismic loading

– Soil-pile-structure and soil-pile interaction

– Range from shallow to deep water conditions

– Member and Joint Code Checking (e.g., API RP2a-WSD 21st Ed.)


ANSYS ASAS

- in a nutshell

• Offshore/Marine Structural Finite Element Analysis

• Coupled wave/current/wind-structure interaction with nonlinear structural response

• Linear and non-linear analysis

– Comprehensive modeling capabilities for frame structures

– Extensive library of Finite Elements

– Multi-level superelement capability

– Frequency domain or time history dynamic analysis

• Fatigue assessment with irregular waves and using deterministic and spectral methods

• Seismic loading using response spectrum technique

• Comprehensive Code Checking for Framed structures - AISC and API (working stress and LRFD), NORSOK, BS5950 and DS449.


ANSYS ASAS

- Coupled Wave-Structures

• Coupled hydro-elastic analysis for tubular framed structures

– Fully coupled hydrodynamic loading with non-linear analysis capability

– Automatic computation of hydrodynamic damping

– Regular and irregular waves

– Ability to take RAO results as time history loading

– Tube-in-tube contact

• Wave loading for application of Morison

forces (coupled for non-linear analyses)

• Calculation of added mass due to

marine growth

• Hydrodynamic mass calculations

• Buoyancy calculations, including

free flooding


ANSYS ASAS

- Wind, Wave & Current Loading

• Coupled wave/current/wind-structure interaction with nonlinear

structural response

– Capability to handle compliant structures with regular & irregular waves

– Wave theories include:

• Conventional waves such as linear wave (Airy), solitary wave (Cnoidal 1st), Stokes

5th order, Stream function but also Shell New Wave (dispersive wave)

• Irregular waves such as JONSWAP, Pierson-Moskovitz, user-defined

• API Wave recipe

– Current theories include:

• API WSD 20th Ed. and LRFD 1st Ed. codes of practice!


ANSYS ASAS

- Soil-Pile-Structure Interactions

• Capabilities– Single pile or pile group analysis

– Soil-pile-structure interaction with single piles or pile groups

– No limit to number of piles or soil layers

– Piles may have non-constant cross sections

– Automatic sub-division of piles taking into account changes in cross section, soil layers, etc.

– Automatic calculation of Mindlin coefficients for group pile analysis

– Automatic generation of lateral forces (P-Y) and skin friction (T-Z) curves

– Efficient nonlinear solution for soil-pile-structure interactions via superelement (sub-structuring) approach

– Non-tubular cross sections


ANSYS ASAS

- Code Checks

• Joint Code & Member Code checks including:

– AISC 10th edition working stress and 2nd edition LRFD

– API RP2a-WSD 21st edition working stress

– RP2A-LRFD 1st edition

– BS5950 part 1 1992

– NORSOK 2000

– NORSOK NS3472 1984

– NPD 1992

– DS449 1984 (with 1994 amendments)

– DS412 1984 (with 1994 amendments)

– ISO 19902 implementation started

• Easy-to-use code check facilities including:

– Code checks on time histories

– Code checks on combined load cases

– Visualization of code checks

– Ability to use them in combination with ANSYS calculations


ANSYS ASAS

- Fatigue Assessments

• FATJACK module offers both deterministic and spectral fatigue

capabilities

– for tubular frame structures subjected to waves and current or wind including

wind gusts

– can be used in frequency and time domain

– sea states: JONSWAP, Pierson-Moskovitz, Occhi-Hubble, Scot-Weigel and

Shell New Wave, or user-defined wave spectra

• FATJACK includes explicit SCF definitions

– SCFJ – if crown & saddle SCF is known e.g. from empirical formulae

– SCFA – if SCF is known at specific locations e.g. from FE

– SCFB – if SCF is constant across a section

– SCFP – if SCF values vary with location

• Automatic (empirically derived) SCF definitions based on

– Efthymiou, Wordsworth, Kuang or DS449


ANSYS ASAS


– It is possible to use results from up to 1000 different transient dynamic analyses and loading (i.e., multi-directional wave spectra)

– Uses Rainflow counting method to produce stress range histogram

• Rainflow counting fatigue

– Reduces spectrum of varying stress into simple stress reversals

– Allows the application of Miner’s rule to assess fatigue life of structure

subject to complex loading

– Based on ASTM E1049-85 (2005) Standard Practices for Cycle

Counting in Fatigue Analysis


ANSYS ASAS


– Within the fatigue (FATJACK) module these results can be combined using a probabilistic based Rainflow Counting approach

– Output includes: • fatigue life (based on Miner´s rule)

• usage factors

• damage per wave (history)

• stress histograms

– Results are stored for further processing (e.g. ASAS Visualizer)

• Rainflow counting fatigue


ANSYS ASAS

- Wind/Wave/Current & Rotor Blade Loading

Interface to FLEX5

• FLEX5 is one of a number of highly specialized

wind loading programs

– thoroughly validated for wind turbines

– however, limited to simple substructures

• This limitation can be overcome by combining FLEX 5 with ANSYS ASAS– Simplified substructure (in FLEX 5) can be replaced by a

realistic structural model (in ANSYS ASAS) that can accurately model the structural behavior and wave loading

• This capability was initiated, sponsored and verified by REpowerSystems AG


ANSYS ASAS


• Allows complex substructure

modelling for offshore wind turbines

• Fatigue and extreme condition design

• Analysis process:

– ASAS(NL) generates FLEX 5

substructure input model data.

– FLEX 5 performs WT analysis

– ASAS(NL) reads the FLEX 5 results and

adds wave load to extract member

forces.

– ASAS performs fatigue analysis via

rain-flow counting.

• It has been successfully applied for

the certification of the Beatrice wind

farm demonstrator project, and others

(e.g., 150MW Ormonde wind farm).Photo courtesy of REpower Systems AG

Interface to FLEX5


Impact of substructure on tower bottom fatigue loads

With Waves

90%

95%

100%

105%

110%

115%

120%

125%

130%

135%

140%

Shear long. Shear lat. Vertical

force

Bending

lat.

Bending

long.

Torsion

OJQ

CCT

FFT

With Wave Loading

Why is this (integrated) Loading Combination Important?

ANSYS ASAS


Global

Natural

Frequencies

OWEC

Jacket

Quattropod

Centre

Colum

Tripod

Flat Face

Tripod

f0 [Hz] 0.33 0.26 0.3

f1 [Hz] 1.64 1.35 0.86

Court

esy o

f R

Epow

er

Syste

ms A

G

Influence of Substructure on Tower Bottom Fatigue Load

Without Wave Loading

Increase of Fatigue Loads up to 35%!


Why is this (integrated) Loading Combination Important?

ANSYS ASAS


Court

esy o

f R

Epow

er

Syste

ms A

G

• For local problems it is even more important.

– Local eigenfrequency is blade mode (flap wise direction)

– Bracings in one of the lower bays are also part of this local mode shape

• The highest loading on bracings is the out-of-plane bending moment due to waves.


ANSYS Mechanical FEA Suite

• Founded in 1970, ANSYS have been

developing generic Mechanical FEA software

for 40 years

• Originally developed for the nuclear industry,

quality was paramount in its design, now

in accordance with ISO quality controls

• ANSYS FEA has the broadest range of

capabilities in the market-place, with

technologies for:

– Linear & Nonlinear (geometric/material)

analyses

– Static, frequency-domain & time-domain

– 0-D to 3-D elements

– Isotropic, anistropic, layered materials

– ....


ANSYS Mechanical Applications

• Offshore Structures

• Pipelines and Risers

• Tubulars, connectors

• BOPs

• Pressure vessels

• Seals

• Hulls

• Etc….

Courtesy of Delta Marine Engineering Company


ANSYS Mechanical Solutions

ANSYS Mechanical solutions articulates the best in class CAE

products and technology for structural, thermal, acoustics

and coupled physics analysis that offers a unique class of

integrated simulation solution for the entire product

development process …


Product Offering/Target Users

• Built upon robust technology offers a range of products with a clear upgrade path from designers to

analyst.

ANSYS

Professional

PlanDrafting

CAD

Concept

Simulation

Virtual

Prototyping

Advanced

AnalysisEvaluate Production

ANSYS

DesignSpace

ANSYS

Structural

ANSYS

Mechanical

ANSYS

DesignSpace

Mid-RangeFront End High-End

ANSYS

Professional

ANSYS

Structural

ANSYS

Mechanical

ANSYS

Multiphysics

Functi

onality

/Pri

ce


Product/Technology Description

ANSYS

DesignSpace

ANSYS

Structural

ANSYS

Professional NLT

ANSYS

Mechanical

Linear Structural

Steady State Thermal

Linear Structural


Transient Thermal

Linear Dynamics

Linear Structural

Non-Linear Structural

Linear Dynamics

Nonlinear Dynamics

Linear Structural

Non-Linear Structural

Linear Dynamics

Nonlinear Dynamics


Transient Thermal

Acoustics

Direct Coupled

Solver Technology

ANSYS

Professional NLS

Linear Structural


Nonlinear Structural

Linear Dynamics


Analysis Methods & Solvers

Technology Components

• Elements & Materials

• Contact Analysis

• Nonlinear Analysis

• Solver Technology



Elements Technology

Solid Elements

2D Quad/Tri

3D – Hexa/Tetra/Wedge/Pyramid

Layered Solids

Solid Shell

Beam Elements

Multi material beam analysis

Beam Cross Section Definition

Shell Elements

Lower/Higher Order

Layered Shells

Special Elements

Rebars/Reinforcements

Links/Pipes/Springs

Cohesive Zone

User Elements

Gaskets



Materials Modeling

Material Models

Isotropic/Orthotropic Elasticity

Hyperelasticity

Plasticity

Viscoelasticity

Viscoplasticity

Creep

Other Models

Cast Iron Plasticity

Drucker-Prager

Shape Memory Alloy

USERMAT

Gasket Material

Concrete

Gurson DamageGasket Material

Hyperelastic Material



Contact Analysis

• Node-Node; Node-Surface; Surface-Surface; Line-Line; Line-Surface

• Small and Large Sliding

• Lower and Higher order elements

• Pure Penalty; Augmented Lagrange; Pure Lagrange; MPC contact

• Semi-Automatic Contact Stiffness Update

• Multiphysics Contact; Rigid Contact

• Friction Sliding (Small/Large Deformation)

• Shell/Beam Thickness Effects

• Contact Manager Wizard

• Automatic Assembly Contact


Umbillical Analysis

• Geometry built in DesignModeler:

– Core tubing

– 6 helical tubes wrapped around core

– External insulation

• Loads:

– Bent to 36’ radius

– Hydrostatic loads

– End tension

– Gravity


Threaded Connector

• 2D Axisymmetric

model created from

parasolid model

– 9.3e-3” interference

• Loads:

– 10 ksi internal

pressure

– 10,000 lb axial load


Barge Analysis

• Partial deck model

• Maximum load-spreading reaction applied to patches

• Deflections are less than 0.192” in (5 mm) at any point


Explicit - Impact


Explicit – Explosion


Explicit - Explosion


Model all aspects of the design

• From the topsides.....

.. ....to the drill bit

Courtesy of Pluere

Courtesy of AKERE Energy, CA


ANSYS Workbench

• Being part of the ANSYS Workbench

infrastructure opens up several

enhancements in overall process for the

structural mechanics users

– Geometry

– Meshing

– Post-processing

– Reporting

– Process scripting & chaining

– Automatic Project updates


ANSYS Workbench


ANSYS Structural Mechanics

• Geometry

– Direct CAD Links

• Connect to real CAD models

and create true parametric

analysis

– Create analysis geometry

• Geometry clean-up

• Simplification

• Create Shell & Beam

geometry

– Work with imported files



• Preprocessing

• Materials

• Linear-Elastic

• Plastic

• Hyper-elastic

• Creep

• Soils, Concrete

• Damage models

• Meshing

• From fully automatic to highly controlled

• Loads

• Imported data fields

• Time dependant

• Complex systems

• Contact

• Model real assemblies

• Bonded, Frictionless & Frictional contact



• Solving

• ANSYS solver technology

evolving to keep pace

with PC developments

• Multi-core

• 32 & 64 bit

• Clusters

• GPU



• Postprocessing

• Stress, Strain, Creep,

Contact, Reactions

• Linearisation

• Images

• Tabular data Excel

• Movie files

• Automated report

generation



• ANSYS Structural analysis


DesignXplorer

• Start with a workbench defined process

– Use parameters in:

• CAD

• DesignModeler

• SpaceClaim

• Engineering data

• Preprocessor

• Postprocessor

• Derived parameters

– Define design envelope• Parameter limits

• Descrete/continuous

– Define goal• Near target

• Min/Max

• Trade offs


DesignXplorer

• DOE

– Select DOE type

– Custom + Sampling (OSF)

• Candidate designs

• Response surface

• Six Sigma analysis

– Manufacturing best/worst case


ANSYS Composite Prep/Post

• Composite materials

– Light

– Strong

– Good corrosion resistance

• Complex manufacturing

– Multiple materials

– Multiple directions

Composite examples

Simple geometry's easy to handle



• Take loaded FE model from

ANSYS Mechanical

• Build model as manufactured

– Ply by ply manufacture

– Draping

– Section cuts

• Use proven ANSYS FEA solver

• Post process using composite

criteria



• Composite specific

post processing

– Layer by layer

– User selected failure

mechanisms

– User defined failure

criteria


ANSYS nCode DesignLife

• Premier fatigue analysis tool

• Analyze implications of repeated,

fluctuating, and rapidly applied loads,

which can result in failure or damage• Stress-Life (single, multi-curve, Haigh diagrams)

• Strain-Life (automated multi-axial corrections)

• Multi-axial safety factor (Dang Van)

• Seam welds and spot welds

• High temperature fatigue

• Vibration fatigue (shaker simulation)

• Multiple runs in a single analysis

• Complete duty cycles

• Multi-processor enabled for fast results

• Use Python for proprietary or custom methods


Offshore Structures – ANSYS

Product Roadmap

• Transfer of ASAS unique solver technology to ANSYS

Structural Mechanics products

– Single FE product suite

– Recognition of ASAS key features

• Creation of a Design Assessment system to handle

post-processing of analysis results

– Delivered as part of Structural Mechanics products

– For offshore related use, this covers load case

combinations and code checking

• Additional Products

– Separate Code Checking and Fatigue Products


ANSYS Workbench

• The vehicle for integration of ASAS

capabilities into our mainstream FEA product

is the ANSYS framework called Workbench

• Workbench acts as a common environment

for all of our mainstream products –

structures, fluids, thermal, electronics

electromagnetics .....

• It enables us to interface software modules

directly without going through intermediate

files and manual processes


ASAS to Mechanical

- Beams and Wave Theories

• Beam Post-Processing

enhancements

– Shear Force and Bending

Moment diagrams

• Beam End-Releases

• Wave Theories Added

(Mechanical already has 4

wave theories implemented)

• Irregular waves

• Shell New Wave

• Constrained Wave


ASAS to Mechanical

- Soil-Pile-Structure Interaction

• Soil/Pile Interaction Solver (SPLINTER) enhanced to

work with Mechanical (via command snippets &

Matrix27 elements)

– PILEGEN and PILECALC macros included with the

ASAS installation (capability only available via ASAS

Offshore license)


Design Assessment

- New System in Workbench

• Design Assessment System

– Available with Professional NLS and above

– Post-analysis assessments of FEA results

– Load Case Combinations

• Static Structural

• Flexible Dynamics (at a specific time)


Design Assessment

- Customization

• Design Assessment System

– Advanced post-processing of FEA results

• Targeted at user wanting to do design code

assessment based on FEA models and results

– Predefined scripts supplied for ANSYS

supplied code checking tools

– Enables the customer to define additional data

that is associated with their model and then

perform custom post processing

• Custom definition of input data

• Custom result definitions

• Custom Solve & Post scripts (Python based)


Design Assessment

- Assessment Types

• ANSYS or User Defined

– ANSYS Supplied Tools

• FATJACK

– Beam joint fatigue of

framed structures

• BEAMCHECK

– Member checks on

frame structures

• Solution Combination only

– User Defined

• User can build/integrate own

load case combination and

code checking tool


Design Assessment

- Additional Code Checking Products

• ANSYS FATJACK

– Beam joint fatigue assessment

– New separate product

(also remains part of ASAS

Offshore)

– Python scripts provided

• ANSYS BEAMCHECK

– Was available initially at 12.0

– Python scripts provided

Joint Unitary

Check for

BEAMCHECK

FATJACK

Fatigue Result


Mechanical

- Example Jacket Structural Analysis

Project Page showing various

“Mechanical” Systems

Detailed jacket model in

DesignModeler

Jacket model in Mechanical

Bending moment plot

SF/BM plots

along member


Mechanical

- Example with Design Assessment (1)

Project Page showing various

“Mechanical” Systems

Simple riser in DesignModeler – each of 5

members with different diameter/thickness

Mechanical model – APDL macros for

wave loading and pile-substructure

Stress plot result using

Beam Tool


Mechanical

- Example with Design Assessment (2)

Simple load combination (load factor) with first

Design Assessment system

Factored deformation

Second Design Assessment system

applies API code check

Code check parameters

entered in details panes

Unity check result

showing Yield

utilization


Summary

• ANSYS continues to offer and invest in significant

capabilities for offshore applications

– Significant progress in implementing key features of

ASAS in ANSYS Structural Mechanics products

– New Design Assessment tool enabling advanced

customized post-processing, including application of

ANSYS developed code checking tools and user

custom capabilities (not limited to Offshore)

– Separate code checking products

seminar nov 2010 - ansys · pdf fileseminar –nov 2010 ... –fully integrated...

Documents