ANSYS Offshore Products 14.0 Update 1 Paul Schofield paul.schofield@ansys.com +1 281-676-7001
ANSYS Products for Offshore - 14.0 Update Introduction What are the ANSYS Products for Offshore? Historical Perspective On-going Development Themes 14.0 Specifics Case Studies Conclusions 2
Key Market Problems 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 3
Key Market Problems Cost of Failure Human life Environmental concerns Delays and fines Loss of capital, time and equipment 4
Assessment of Fixed Offshore Structures 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 5
Fixed Structures - Design Solutions Joint Check Transportation Installation Wave loading Pile/soil modelling Beam joint fatigue assessment Member and joint code checking Decommissioning Member Check Jacket Launch 6
Assessment of Floaters Remaining new Oil & Gas fields largely offshore, and in ever deeper water One off designs High capital investment Failure consequences high Extreme environmental conditions Ultra deep water Hurricanes Difficult to physically prototype given the design requirements 7
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 8
What are the ANSYS Offshore Products? General Products DesignModeler/SCDM ANSYS Mechanical Explicit CFX/FLUENT ANSOFT EKM Vertical Applications AQWA EKM ASAS? 9
ANSYS Offshore Update Scope 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 largely offshore/marine related product. 10
Historical Perspective ANSYS ASAS 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 mainstream Mechanical/MAPDL model Resulting in transfer of ANSYS ASAS unique solver technology to ANSYS Structural Mechanics products Never any long term scope for developing/supporting multiple FE products Recognition of ANSYS ASAS key features 11
ANSYS ASAS Migration CAE requirements for Fixed Offshore structures: Variety of foundations ranging from concrete gravity-based to steel jackets Combined wave, current and wind loading 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, AISC, ISO 19902.) Deterministic, spectral and time history fatigue 12
On-going Development Themes 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 this presentation 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 ANSYS Mechanical and MAPDL. Physics coupling. 13
14.0 Specifics 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
Enhanced Productivity with Continuing AQWA Integration in Workbench Hydrodynamic Time Response system enhancements 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 Offloading arm represented with series of typical articulations 15
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 now available in the core solver and the Hydrodynamic Time Response system 16
AQWA Frequency Domain Drag Linearization Courtesy of Technip Offshore Finland Inclusion of linearized drag on Morison elements in Diffraction/Radiation analysis Determined using a user specified wave spectrum. Computation of modified RAOs using 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 for mixed models e.g. truss spar. 17
Extended Wave Loading in Mechanical Diffracted wave loading Provides simplified pressure loading from Hydrodynamics 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 Vessel Loading Transfer from AQWA to Mechanical Courtesy of Vuyk Engineering Rotterdam 18
Coupling Mechanical with 3 rd Party Aeroelastic Tools for Offshore Wind Turbine Modeling 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 out input 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 19 Images Courtesy of REpower Systems AG
Sequential Solution Example MAPDL Substructure analysis to generate matrices and load history for aeroelastic code Mass matrix Damping matrix Stiffness matrix External force time series Top node force or displacement time series Aeroelastic software Wave-Wind Analysis MAPDL Analysis of foundation structure Beamcheck Strength calculations FATJACK Fatigue calculations 20
Fully Coupled Solution Aeroelastic interface to MAPDL using the USER300 element. This element allows user defined stiffness, damping and mass data. This utilizes a shared memory dynamic link library, so requires modification to the aeroelastic code to facilitate the interface. 21
Design Assessment Design Assessment is a framework for post-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 FATJACK now delivered with Mechanical installation (licensed separately) 22
Updates to Design Assessment Extended upstream capabilities permits wider application range Modal Harmonic Response Random Vibration Response Spectrum Explicit Dynamics 23
Expanded Result Access Modal=No Beam Results DA + Allow all Available Results allows beam results Filtering of 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. 24
Design Assessment for Advanced User Defined Results Design Assessment enables users to extend user defined results 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 25
Case Studies Previous slides have shown some of the developments undertaken to couple wave loading with structural applications Following are example case studies that show how ANSYS technology can be coupled to good effect to solve complex problems system 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. 26
Case Study Storage Vessel Design 27
Storage Vessel Design Effects 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 that s easy to do experimentally! Potentially dangerous Significant cost of rig & instrumentation 28
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 29
Vessel Motion y Non-accelerating motion Ship moving at fixed speed No waves or swell No acceleration force No sloshing! z x Free motion Bow of the ship in a storm 3 Rotations Roll, Pitch & Yaw 3 Linear Accelerations Surge, Sway & Heave Sloshing expected! y x z 30
Methodology 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 31
Simulation Process Step Solver Design Consideration Output Data 1 Hydrodynamic 2 3 Computational Fluid Dynamics Structural Finite Element Asses ship hydrodynamic response to different sea states Analyse baffle design to assess sloshing Analyse stresses to look at welds and bolt arrangements and fatigue loading Motion Profiles: Velocities for CFD Displacements for FEA Surface Pressure Profiles 32 Velocity Pressures & Hydrodynamics Profiles CFD FEA Displacements
ANSYS Workbench Project 33
Hydrodynamic Analysis Motion Profile Output for all six motions, used for CFD and Structural FE models Displacements, Velocities and Accelerations 34
Surface Pressure Profile used for Structural model Computational Fluid Dynamics Analysis 35
Structural FEA Pressure Loading ONLY Fluid inertia considered Fixed constraints to feet Inertia of solid structure ignored 36
Structural FEA with CFD Free Surface 37
Case Study Risers 38
Riser Systems Risers are the physical connectors between an oil 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 39
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 40
Riser Issues The analysis of risers represents a major technical 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- inducedvibrations (VIV) among one of the the most complex of fluid-structure interaction problems 41
How We Can Solve Riser Problems The ANSYS product range provides the toolkit for solving riser design requirements 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. 42
Umbilical, Risers & Flexible Piping Geometry built in DesignModeler: Core tubing 6 helical tubes wrapped around core External insulation Loads: Bent to 36 radius Hydrostatic loads End tension Gravity 43
Conclusions Release 14.0 represents the continuing development of capabilities and technologies to solve problems commonly encountered 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 44