Abaqus note Introduction to Abaqus 6.13

Introduction to Abaqus 6.13 This document introduces features in Abaqus that have been added, enhanced, or updated since the Abaqus 6.12 release. Chapter 1 provides a brief overview of the Abaqus products included in this release. Chapters 2–14 provide short descriptions of new Abaqus 6.13 features in AbaqusStandard, AbaqusExplicit, AbaqusCFD, and AbaqusCAE, categorized by subject: • Chapter 2, “General enhancements”: general changes to the Abaqus interface. • Chapter 3, “Modeling”: features related to creating your model. • Chapter 4, “Analysis procedures”: features related to defining an analysis. • Chapter 5, “Analysis techniques”: features related to analysis techniques in Abaqus. • Chapter 6, “Materials”: new material models or changes to existing material models. • Chapter 7, “Elements”: new elements or changes to existing elements. • Chapter 8, “Prescribed conditions”: loads, boundary conditions, and predefined fields. • Chapter 9, “Constraints”: kinematic constraints. • Chapter 10, “Interactions”: features related to contact and interaction modeling. • Chapter 11, “Meshing”: features related to meshing your model. • Chapter 12, “Execution”: commands and utilities for running any of the Abaqus products. • Chapter 13, “Output and visualization”: obtaining, postprocessing, and visualizing results from Abaqus analyses. • Chapter 14, “User subroutines, utilities, and plugins”: additional user programs that can be run with Abaqus. Each entry in these chapters clearly indicates the Abaqus product or products to which the feature applies and includes crossreferences to more detailed information. Chapter 15, “Summary of changes,” summarizes in tabular format the changes to Abaqus elements, keyword options, user subroutines, and output variable identifiers.

Abaqus 6.13

Release Notes

Release Notes

Legal Notices

CAUTION: This documentation is intended for qualified users who will exercise sound engineering judgment and expertise in the use of the Abaqus Software The Abaqus Software is inherently complex, and the examples and procedures in this documentation are not intended to be exhaustive or to apply

to any particular situation Users are cautioned to satisfy themselves as to the accuracy and results of their analyses.

Dassault Systèmes and its subsidiaries, including Dassault Systèmes Simulia Corp., shall not be responsible for the accuracy or usefulness of any analysis performed using the Abaqus Software or the procedures, examples, or explanations in this documentation Dassault Systèmes and its subsidiaries shall not

be responsible for the consequences of any errors or omissions that may appear in this documentation.

The Abaqus Software is available only under license from Dassault Systèmes or its subsidiary and may be used or reproduced only in accordance with the terms of such license This documentation is subject to the terms and conditions of either the software license agreement signed by the parties, or, absent such an agreement, the then current software license agreement to which the documentation relates.

This documentation and the software described in this documentation are subject to change without prior notice.

No part of this documentation may be reproduced or distributed in any form without prior written permission of Dassault Systèmes or its subsidiary The Abaqus Software is a product of Dassault Systèmes Simulia Corp., Providence, RI, USA.

Viewing boundary conditions in the Visualization module 2.2

3 Modeling

Enhanced control for creation of geometry from orphan elements 3.2

Support for modeling crack propagation using the virtual crack closure technique 3.5

4 Analysis procedures

Efficient subspace iteration algorithm for buckling analysis 4.1The SIM architecture supports coupled structural-acoustic eigenmodes 4.2

5 Analysis techniques

Enhancements to the XFEM-based crack propagation capability 5.2

Substructure generation using the AMS eigensolver 5.4

Co-simulation between electromagnetic and thermal or stress analysis procedures 5.8Global and element-by-element matrix generation in heat transfer analyses 5.9

6 Materials

7 Elements

Enhanced convergence behavior for Abaqus/Standard contact analyses 10.2Contact pressure–dependent constraint enforcement in perturbation steps 10.3

Temperature and field-variable dependence of the friction coefficient 10.5User-defined tracking thickness for user subroutineVUINTER 10.6

11 Meshing

Querying for geometry not associated with a mesh 11.1

12 Execution

Configuration file requirement for co-simulation execution 12.2Improved translation of Abaqus substructure data to MSC.ADAMS 12.3

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Improved coverage and functionality for Nastran translation 12.4

13 Output and visualization

Enhanced diagnostics for nearly incompressible materials and instabilities 13.3Visualizing component surfaces for Abaqus/Explicit general contact 13.4Customizing element orientation for composite output 13.5

14 User subroutines, utilities, and plug-ins

VUEOS: User subroutine to define equation of state material model 14.1

15 Summary of changes

I.1 Product Index

• Chapter 2, “General enhancements”: general changes to the Abaqus interface.

• Chapter 3, “Modeling”: features related to creating your model

• Chapter 4, “Analysis procedures”: features related to defining an analysis

• Chapter 5, “Analysis techniques”: features related to analysis techniques in Abaqus

• Chapter 6, “Materials”: new material models or changes to existing material models

• Chapter 7, “Elements”: new elements or changes to existing elements

• Chapter 8, “Prescribed conditions”: loads, boundary conditions, and predefined fields

• Chapter 9, “Constraints”: kinematic constraints

• Chapter 10, “Interactions”: features related to contact and interaction modeling

• Chapter 11, “Meshing”: features related to meshing your model

• Chapter 12, “Execution”: commands and utilities for running any of the Abaqus products

• Chapter 13, “Output and visualization”: obtaining, postprocessing, and visualizing results from Abaqusanalyses

• Chapter 14, “User subroutines, utilities, and plug-ins”: additional user programs that can be run withAbaqus

Each entry in these chapters clearly indicates the Abaqus product or products to which the feature appliesand includes cross-references to more detailed information Chapter 15, “Summary of changes,” summarizes

in tabular format the changes to Abaqus elements, keyword options, user subroutines, and output variableidentifiers

1.1 Key features of Abaqus 6.13

This section provides a list of the most significant new capabilities and enhancements available in Abaqus 6.13;refer to the table of contents for a complete list of new features

• Performance improvements:

– Subspace iteration algorithm

– Automatic node selection in the AMS eigensolver

– GPGPU support for unsymmetric solver

– EMC3D6 prism element

– Nonlinear magnetic permeability in Abaqus/CAE

– Thermal matrix output

– Uncoupled heat transfer in Abaqus/CFD

• Crack modeling and propagation:

– XFEM enhancements

– Abaqus/CAE support for VCCT in Abaqus/Standard models

• Contact enhancements:

– Contact modeling for beams and shells

– Convergence behavior for Abaqus/Standard

– Contact calculations for thick shells/beams

– Friction coefficient dependencies

– User-defined tracking thickness

• Abaqus/CAE modeling and usability:

– Gravity waves in Abaqus/Aqua

The remaining chapters in this guide provide details on these and other new features of Abaqus 6.13 Inaddition to the enhancements listed here, most of the known bugs in Abaqus 6.12 are corrected

Preprocessing and postprocessing

• Abaqus/CAE: This product is a Complete Abaqus Environment that provides a simple, consistentinterface for creating, submitting, monitoring, and evaluating results from Abaqus simulations.Abaqus/CAE is divided into modules, where each module defines a logical aspect of the modelingprocess; for example, defining the geometry, defining material properties, generating a mesh, submittinganalysis jobs, and interpreting results

• Abaqus/Viewer: This subset of Abaqus/CAE contains only the postprocessing capabilities of theVisualization module It uses the output database (.odb) to obtain results from the analysis products

INTRODUCTION TO Abaqus 6.13

The output database is a neutral binary file Therefore, results from an Abaqus analysis run on anyplatform can be viewed on any other platform supporting Abaqus/Viewer It provides deformedconfiguration, contour, vector, andX–Y plots, as well as animation of results

Add-on analysis

• Abaqus/Aqua: This add-on analysis capability for Abaqus/Standard and Abaqus/Explicit provides acapability for calculating drag and buoyancy loads based on steady current, wave, and wind effects formodeling offshore piping and floating platform structures Abaqus/Aqua is applicable for structures thatcan be idealized using line elements, including beam, pipe, and truss elements

• Abaqus/Design: This add-on analysis capability for Abaqus/Standard allows the user to performdesign sensitivity analysis (DSA) The derivatives of output variables are calculated with respect tospecified design parameters

• Abaqus Topology Optimization Module: This capability is available in Abaqus/CAE to performshape and topology optimization This functionality requires an additional license to submit anoptimization process for analysis

• Abaqus/Foundation: This analysis option offers more efficient access to the linear static and dynamicanalysis functionality in Abaqus/Standard

• CZone for Abaqus: This add-on capability for Abaqus/Explicit provides access to a state-of-the-artmethodology for crush simulation based on CZone technology from Engenuity, Ltd Targeted toward thedesign of composite components and assemblies, CZone for Abaqus provides for inclusion of materialcrush behavior in simulations of composite structures subjected to impact

Optional analysis functionality

• Abaqus/AMS: This add-on analysis capability for Abaqus/Standard allows the user to selectthe automatic multi-level substructuring (AMS) eigensolver when performing a natural frequencyextraction

• Co-simulation with MpCCI: This add-on analysis capability for Abaqus can be used to solvemultiphysics problems by coupling Abaqus with any third-party analysis program that supports theMpCCI interface

Interfaces

• Abaqus Interface for Moldflow: This optional interface translates finite element model informationfrom a Moldflow analysis to an Abaqus input file

Associative interfaces and geometry translators

• SIMULIA Associative Interface for Abaqus/CAE: This add-on capability for Abaqus/CAE creates

a connection between a CATIA V6 session and an Abaqus/CAE session This connection can be used totransfer model information from CATIA V6 to Abaqus/CAE Subsequent modifications to the model in

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Printed on:

CATIA V6 can be propagated to the Abaqus/CAE model while retaining any analysis features (such asloads or boundary conditions) that were defined on the model in Abaqus/CAE The CATIA V6 model in

an assembly file (.eaf) format can also be imported directly into Abaqus/CAE

• CATIA V5 Associative Interface: This add-on capability for Abaqus/CAE creates a connectionbetween a CATIA V5 session and an Abaqus/CAE session This connection can be used to transfermodel information from CATIA V5 to Abaqus/CAE Subsequent modifications to the model inCATIA V5 can be propagated to the Abaqus/CAE model while retaining any analysis features (such

as loads or boundary conditions) that were defined on the model in Abaqus/CAE The geometry ofCATIA V5-format Part (.CATPart) and Product (.CATProduct) files can also be imported directlyinto Abaqus/CAE

• SolidWorks Associative Interface: This add-on capability for Abaqus/CAE creates a connectionbetween a SolidWorks session and an Abaqus/CAE session This connection can be used to transfermodel information from SolidWorks to Abaqus/CAE Subsequent modifications to the model inSolidWorks can be propagated to the Abaqus/CAE model while retaining any analysis features (such asloads or boundary conditions) that were defined on the model in Abaqus/CAE

• Pro/ENGINEER Associative Interface: This add-on capability for Abaqus/CAE creates aconnection between a Pro/ENGINEER session and an Abaqus/CAE session This connection can beused to transfer model information between Pro/ENGINEER and Abaqus/CAE Modifications to themodel in Pro/ENGINEER can be propagated to the Abaqus/CAE model without affecting any analysisfeatures (such as loads or boundary conditions) that were defined on the model in Abaqus/CAE,and certain geometric modifications can be made in Abaqus/CAE and propagated to the model inPro/ENGINEER

• Abaqus/CAE Associative Interface for NX: This add-on capability for Abaqus/CAE creates

a connection between an NX session and an Abaqus/CAE session This connection can be used

to transfer model data and to propagate design changes between NX and Abaqus/CAE TheAbaqus/CAE Associative Interface for NX can be purchased and downloaded from ElysiumInc (www.elysiuminc.com)

• Geometry Translator for CATIA V4: This add-on capability allows the user to import the geometry

of CATIA V4-format parts and CATIA V4 assemblies (.model, catdata, and exp files) directlyinto Abaqus/CAE

• Geometry Translator for Parasolid: This add-on capability allows the user to import the geometry

of Parasolid-format parts and Parasolid assemblies (.x_t, x_b, and xmt files) directly intoAbaqus/CAE

Translator utilities

• Abaqus translators are provided with the release They are invoked through the Abaqus executionprocedure (the “driver”) The translators and the commands to invoke them are described below:abaqus fromansys translates an ANSYS input file to an Abaqus input file

abaqus fromdyna translates an LS-DYNA keyword file to an Abaqus input file

INTRODUCTION TO Abaqus 6.13

abaqus fromnastran translates a Nastran bulk data file to an Abaqus input file

abaqus frompamcrash translates a PAM-CRASH input file to a partial Abaqus input file.abaqus fromradioss translates a RADIOSS input file to a partial Abaqus input file

abaqus adams translates the results in an Abaqus SIM database file into an MSC.ADAMS modalneutral (.mnf) file, the format required by ADAMS/Flex

abaqus tonastran translates an Abaqus input file to Nastran bulk data file format

abaqus toOutput2 translates an Abaqus output database file to the Nastran Output2 file format.abaqus tozaero enables you to exchange aeroelastic data between the Abaqus and ZAERO analysisproducts

Other utilities

• Additional programs are included with the release They are all invoked through the Abaqus executionprocedure (the “driver”) The utilities and the commands to invoke these programs are described below:abaqus append joins separate results files into a single file

abaqus ascfil translates Abaqus results files between ASCII and binary formats, which is useful formoving results files between different computer types

abaqus cosimulation runs a co-simulation using a single command where the analysis job optionsspecify two Abaqus jobs

abaqus cse runs the SIMULIA Co-Simulation Engine (CSE) Director process that governs simulation between Abaqus and third-party solvers Typically, when performing a co-simulationbetween Abaqus solvers only, you are not required to invoke the CSE Director process; it is invokedautomatically when you run the Abaqus co-simulation procedure using abaqus cosimulation.abaqus doc accesses the Abaqus documentation collection using a web browser

co-abaqus dymola runs a co-simulation between an Abaqus/Standard or Abaqus/Explicit model and

a model exported from Dymola

abaqus emloads converts results output from an electromagnetic analysis for use as loads in asubsequent analysis

abaqus encrypt creates an encoded, password-protected version of an Abaqus input file,

while abaqus decrypt converts an encrypted file back into its original, unencoded format.abaqus fetch extracts example input files from the libraries included with the release

abaqus findkeyword provides a list of sample problems that use the specified Abaqus options Thisutility will help users find examples of features they may be using for the first time

abaqus free converts all fixed format data in an input file to free format

abaqus licensing provides management and monitoring tools for FLEXnet and Dassault Systèmes(DS) licensing

abaqus make compiles and links user-written postprocessing programs for Abaqus and createsuser-defined libraries of Abaqus/Standard and Abaqus/Explicit user subroutines

1–6

Abaqus ID:

Printed on:

abaqus mtxasm assembles element matrices contained in a SIM document and, optionally, writesthe assembled matrices to text files.

abaqus networkDBConnector creates a connection to a network ODB server that can be used toaccess a remote output database

abaqus restartjoin appends an output database file produced by a restart analysis of a model to theoutput database produced by the original analysis of that model

abaqus odbcombine combines the results data in two or more Abaqus output database files into asingle output database file

abaqus odbreport creates organized reports of output database information in text, HTML, or CSVfile formats

abaqus python accesses the Python interpreter

abaqus resume resumes an Abaqus analysis job

abaqus script initiates a Python scripting session

abaqus substructurecombine combines the model and results data produced by two of a model’ssubstructures into a single output database file

abaqus suspend suspends an Abaqus analysis job

abaqus terminate terminates an Abaqus analysis job

abaqus upgrade upgrades an input file or output database file from previous versions of Abaqus tothe current version

The following enhancements to Abaqus licensing have been implemented:

• A new utility is available to generate historical reports from license usage data The utility can be runwith the following command:

abaqus licensing reporttool [options]

For more information, see “Using the reporttool utility,” Section 3.10 of the Abaqus Installationand Licensing Guide

• A new environment file parameter lmproject can be used to record information about internal projectnames or numbers for your company The information is recorded on the license server and can

to modal neutral file format for analysis in MSC.ADAMS,” Section 15.1.7 of the Abaqus Example ProblemsGuide.

Changes in the Abaqus Scripting Interface

Abaqus makes every attempt to be backward compatible and can execute most Abaqus Scripting Interfacescripts from previous releases of Abaqus However, backward compatibility is not guaranteed beyond severalreleases of Abaqus, and it is recommended that you upgrade your commands to the most recent release Acomplete list of Abaqus Scripting Interface commands that have changed is included in “Summary of AbaqusScripting Interface changes between Abaqus 6.12 and Abaqus 6.13” in the Abaqus Scripting Reference Guide

1.3 Changes in interpretation of input data

A list of changes to the Abaqus input file interface is provided in Chapter 15, “Summary of changes.”

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2 General enhancements

This chapter describes the following general enhancements that have been made to Abaqus:

• “Persistent color mapping,” Section 2.1

• “Viewing boundary conditions in the Visualization module,” Section 2.2

• “Enhanced viewport linkage,” Section 2.3

2.1 Persistent color mapping

Product: Abaqus/CAE

Benefits:You can now save color mapping definitions to the model database, to an output database, or to anXML file This enhancement provides an easier method for saving and reusing color mappings than in earlierreleases

Description: By default, the color mappings you specify to distinguish between components in your modelpersist only for your current session and only in the viewport in which you define them In earlier releasesyou could save color mappings only by creating a color macro that recorded your color mapping definitions.Abaqus/CAE now includes color mappings among the session objects and options that you can save andreuse using theSave Session Objects & OptionsandLoad Session Objects & Optionsdialog boxes.This enhancement streamlines the process of saving and loading color mappings by including this step withthe maintenance of other settings in your session

When you save color mappings as session options, Abaqus/CAE records the settings currently displayed

in theColor Codedialog box only For example, if the dialog box displays color mappings for part instances,only the mappings you specified for part instances are recorded to the model database, output database, or file

Abaqus/CAE Usage:

All modules:

File→Save Session ObjectsorLoad Session Objects: Color Mapping

References:

Abaqus/CAE User’s Guide

• “Managing session objects and session options,” Section 9.9, in the HTML version of this guide

• “Understanding color coding,” Section 77.1

Figure 2–1 shows an example in which the U2 degree of freedom is displayed for a displacementboundary condition namedContacts The Field Output toolbar is included in the example to show how the

individual values can be selected

Figure 2–1 Visualization of boundary conditions

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Abaqus ID:

Printed on:

Abaqus/CAE Usage:

Visualization module:

Results Tree:Model Databases:model name: select boundary condition from the Field Output toolbar

Reference:

Abaqus/CAE User’s Guide

• “Overview of results selection from the current model database,” Section 42.2

2.3 Enhanced viewport linkage

Product: Abaqus/CAE

Benefits: You can now share additional characteristics among the set of linked viewports in your session.Linked viewports can now share a common center of rotation, viewport annotation options, and view cuts

Description: Linked viewports can now share any of the following characteristics:

• A common center of rotation

• The same display behavior for viewport annotations When this option is selected, any changes you make

to display, hide, or customize viewport annotations in theViewport Annotation Optionsdialog boxfor one linked viewport are reflected across all other linked viewports This enhancement enables you toperform changes such as hiding the legend or changing the triad’s font across all linked viewports

• The same view cut definitions in the Visualization module

Abaqus/CAE Usage:

All modules:

Viewport→Linked viewports: Rotation centers, Viewport annotation options, and View cuts Reference:

Abaqus/CAE User’s Guide

• “Linking viewports for view manipulation,” Section 4.5, in the HTML version of this guide

3 Modeling

This chapter discusses features related to creating your model, such as node and element definition inAbaqus/Standard, Abaqus/Explicit, and Abaqus/CFD; part and assembly definition in Abaqus/CAE; andimporting models to Abaqus/CAE It provides an overview of the following enhancements:

• “Enhanced import of parts in STEP format,” Section 3.1

• “Enhanced control for creation of geometry from orphan elements,” Section 3.2

• “Model instances in Abaqus/CAE,” Section 3.3

• “Displaying material stacking directions,” Section 3.4

• “Support for modeling crack propagation using the virtual crack closure technique,” Section 3.5

• “Assigning sections to element sets,” Section 3.6

3.1 Enhanced import of parts in STEP format

Abaqus/CAE Usage:

Part module:

File→Import→Part: File Filter: *.STP*or*.STEP*: Use part name from file

Reference:

Abaqus/CAE User’s Guide

• “Importing a part from a STEP-format file,” Section 10.7.10, in the HTML version of this guide

3.2 Enhanced control for creation of geometry from orphan elementsProduct: Abaqus/CAE

Benefits: When you use orphan element faces to create geometric faces, you can now specify the stitchtolerance and the tolerance value for surface fitting as you create the geometric faces You can also deferall stitching until after all geometric faces have been created These enhancements streamline the process ofcreating geometry and, in turn, parts from orphan mesh parts

Figure 3–1 RevisedCreate Part from STEP Filedialog box

Description: TheFace from geometrygeometry editing functionality now enables you to control thestitch tolerance and the tolerance for fitting of analytic surfaces as you create geometric faces from orphanelements Figure 3–2 shows the new options as they appear in Abaqus/CAE

Figure 3–2 New geometry editing options

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If you defer stitching, you can still use the geometry editing tools to edit the newly created features and tostitch edges Deferring most or all of the stitching until late in the modeling process can be a more efficientmodeling option because each stitching operation can require a fair amount of processing power to complete.

Abaqus/CAE Usage:

Part module:

Tools→Geometry Edit: Face: From element faces: click Optionsin the prompt area

Reference:

Abaqus/CAE User’s Guide

• “Create face from element faces,” Section 69.7.10, in the HTML version of this guide

3.3 Model instances in Abaqus/CAE

When you create a new model instance, the main assembly of the referenced model is instantiated in theassembly of the current (working) model Model instances produce a subassembly from the contents of theother model Since the referenced model assembly may contain other model instances as children, multiplelevels of complex subassemblies are possible

Model instances can be created from theCreate Instancedialog box, as shown in Figure 3–3.Model instances have the following characteristics:

• A particular model can be instantiated multiple times, and you can instantiate as many different models

as desired

• Model instances are always dependent, not independent

• You can freely mix model instances with part instances

• Model instance subassemblies can contain either geometric parts or orphan mesh parts

• Model instances can be positioned and oriented in the main assembly by using transformations(Translate, Translate To, Rotate) and positioning constraints; linear and radial patterns are not

supported with model instances

• Part instance commands such as Suppress/Resume, Hide/Show, Delete, and Show Parents/Childrencan also be used on model instances (Replace,Switch Context, Exclude from Simulation, and Merge/Cutare not supported with model instances.)

Figure 3–3 Creating model instances

• Sets or surfaces defined in the referenced model are brought into the model instance, maintaining theModel Tree hierarchy of features

• Model instances are supported and selectable in Display Groups and in the Instance tab of the

Assembly Display Options.

Abaqus/CAE Usage:

Assembly module:

Instance→Create: from Models

References:

Abaqus/CAE User’s Guide

• “Working with model instances,” Section 13.4

• “Creating a part or model instance,” Section 13.10.3, in the HTML version of this guide

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3.4 Displaying material stacking directions

Product: Abaqus/CAE

Benefits: You can now view the material stacking directions while assigning material orientations

Description: Material stacking directions for solid and continuum shell elements are now visible while youedit the material orientation in the Property module The material directions are displayed as white arrows onthe elements of the selected regions, as shown in Figure 3–4

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Figure 3–4 Material stacking directions

Note: The selected regions must be meshed for Abaqus/CAE to display a stack direction

Abaqus/CAE Usage:

Property module:

Assign→Material Orientation

Reference:

Abaqus/CAE User’s Guide

• “Assigning a material orientation or rebar reference orientation,” Section 12.15.4, in the HTML version

Description: You can use the virtual crack closure technique (VCCT) to study the initiation and propagation

of a crack along a known crack surface Abaqus/CAE supports modeling crack propagation using VCCTonly for Abaqus/Standard models (three-dimensional solid and shell models and two-dimensional planar andaxisymmetric models)

Abaqus/CAE Usage:

Interaction module:

Special→Crack→Create: Name:crack name,Type: Debond using VCCT, select the step and

the surface-to-surface (Standard) interaction,Debonding force: SteporRamp

References:

Abaqus Analysis User’s Guide

• “Crack propagation analysis,” Section 11.4.3

Abaqus/CAE User’s Guide

• “Using the virtual crack closure technique to model crack propagation,” Section 31.4

3.6 Assigning sections to element sets

Product: Abaqus/CAE

Benefits: You can now assign sections to element sets as well as to geometric sets

Description: In previous releases you could assign sections only to geometric sets in the Property module.Abaqus/CAE now lets you assign sections to sets of meshed elements that you have previously defined, asshown in Figure 3–5

Figure 3–5 Selecting element sets for section assignment

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Abaqus/CAE Usage:

Property module:

Assign→Section; click Sets; select named element set from list

Reference:

Abaqus/CAE User’s Guide

• “Assigning a section,” Section 12.15.1, in the HTML version of this guide

4 Analysis procedures

This chapter discusses features related to defining an analysis It provides an overview of the followingenhancements:

• “Efficient subspace iteration algorithm for buckling analysis,” Section 4.1

• “The SIM architecture supports coupled structural-acoustic eigenmodes,” Section 4.2

• “Automatic node selection in the AMS eigensolver,” Section 4.3

• “Complex eigensolver enhancements,” Section 4.4

• “Solid heat transfer in Abaqus/CFD,” Section 4.5

• “Prescribed motion in eddy current simulations,” Section 4.6

• “Steady-state analysis in Abaqus/CFD,” Section 4.7

• “K–omega turbulence model in Abaqus/CFD,” Section 4.8

• “Hybrid wall functions in Abaqus/CFD,” Section 4.9

4.1 Efficient subspace iteration algorithm for buckling analysis

Product: Abaqus/Standard

Benefits: The new implementation of the subspace iteration method offers two significant improvements.Previously, the number of eigenmodes was restricted by the 2 GB limit imposed on the size of the subspace.The new version of the subspace iteration algorithm removes this limit There is also significant improvement

in the run time performance In the new implementation the orthogonalization of the dynamic modes,which previously dominated the run times, has been sped up significantly by using efficient computationaltechniques

Description: A new implementation of the subspace iteration algorithm delivers significant performanceimprovement and eliminates the restriction on the size of the subspace used In addition, the tolerance foreigenvalue convergence has been reduced from 10–5 to 10–6 for better convergence This may, however,increase the number of iterations

Table 1–1 illustrates the performance improvement in the buckle step, using the new subspace iterationmethod All three models were run on an 8 core, 2.27 GHz Intel Nehalem processor machine with

24 GB RAM

ANALYSIS PROCEDURES

Table 4–1 Performance improvement of the buckle step using the new subspace iteration algorithm

Abaqus 6.12 Abaqus 6.13 Model DOF

(Millions)

Number of Modes Number

of Iterations

Wall Time (Minutes)

Number of Iterations

Wall Time (Minutes)

Speed up

Benefits: The coupled structural-acoustic eigenmodes extracted by the Lanczos eigensolver can be stored

on the SIM architecture In addition, the modal methods can utilize these modes for superposition

Description: If the model includes structural-acoustic coupling, Abaqus/Standard can extract coupledmodes The coupled eigenmodes can now be stored on the SIM architecture, which is much more efficientthan the traditional architecture for large-scale modal analyses, and subsequent modal procedures can usethese modes

The coupled structural-acoustic modes are supported in the following modal procedures that use the SIMarchitecture:

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Abaqus ID:

Printed on:

• Lanczos eigenvalue extraction,

• complex eigenvalue extraction,

• mode-based steady-state dynamic analysis, and

• subspace-based steady-state dynamic analysis

References:

Abaqus Analysis User’s Guide

• “Natural frequency extraction,” Section 6.3.5

Abaqus Keywords Reference Guide

• *COMPLEX FREQUENCY

• *FREQUENCY

• *STEADY STATE DYNAMICS

Abaqus Theory Guide

• “Coupled acoustic-structural medium analysis,” Section 2.9.1

4.3 Automatic node selection in the AMS eigensolver

• nodes at which a concentrated load is applied in the subsequent mode-based procedures,

• nodes at which output is requested in the eigenvalue extraction analysis or in the subsequent mode-basedprocedures,

• nodes at which residual vectors are requested,

• nodes of elements at which a distributed load is applied,

• nodes of elements with frequency-dependent material properties, and

• nodes of elements at which output is requested in the eigenvalue extraction analysis or in the subsequentmode-based procedures

ANALYSIS PROCEDURES

References:

Abaqus Analysis User’s Guide

• “Natural frequency extraction,” Section 6.3.5

Abaqus Keywords Reference Guide

References:

Abaqus Analysis User’s Guide

• “Complex eigenvalue extraction,” Section 6.3.6

Abaqus Keywords Reference Guide

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Abaqus Analysis User’s Guide

• “Uncoupled heat transfer analysis,” Section 6.5.2

Abaqus Keywords Reference Guide

• *ENERGY EQUATION SOLVER

• *HEAT TRANSFER

4.6 Prescribed motion in eddy current simulations

Product: Abaqus/Standard

Benefits:You can prescribe motional velocity in both time-harmonic and transient eddy current simulations

Description: A translational or a rotational velocity of a conductor in a magnetic field results in motionalcontributions to the electromagnetic induction in the conductor Such effects are important in applicationssuch as induction heating where the workpiece is often moved with a constant velocity to result in uniformheating

References:

Abaqus Analysis User’s Guide

• “Eddy current analysis,” Section 6.7.5

Abaqus Keywords Reference Guide

ANALYSIS PROCEDURES

References:

Abaqus Analysis User’s Guide

• “Incompressible fluid dynamic analysis,” Section 6.6.2

Abaqus Keywords Reference Guide

4.8 K–omega turbulence model in Abaqus/CFD

Product: Abaqus/CFD

Benefits: You can now apply the popular SSTk– turbulence model to fluid flow problems

Description:The SSTk– turbulence model is a two-equation model The model can be applied throughoutthe viscous sublayer without further modification, in contrast to the alternativek– model The SST form ofthek– model includes the additional benefits of reduced sensitivity to freestream turbulence values and alimiter to prevent excessive shear stress levels in boundary layers

References:

Abaqus Analysis User’s Guide

• “Incompressible fluid dynamic analysis,” Section 6.6.2

Abaqus Keywords Reference Guide

Abaqus Analysis User’s Guide

• “Incompressible fluid dynamic analysis,” Section 6.6.2

5 Analysis techniques

This chapter discusses features related to analysis techniques in Abaqus It provides an overview of thefollowing enhancements:

• “New approach for mesh smoothing,” Section 5.1

• “Enhancements to the XFEM-based crack propagation capability,” Section 5.2

• “Enhancements for import analysis,” Section 5.3

• “Substructure generation using the AMS eigensolver,” Section 5.4

• “Substructuring enhancements,” Section 5.5

• “Discrete element method,” Section 5.6

• “Parallel enhancement of SPH analysis,” Section 5.7

• “Co-simulation between electromagnetic and thermal or stress analysis procedures,” Section 5.8

• “Global and element-by-element matrix generation in heat transfer analyses,” Section 5.9

• “Matrix input capability enhancements,” Section 5.10

5.1 New approach for mesh smoothing

To avoid extra memory allocation for solving the linear elasticity equations, the matrix-free iteration strategy

is used The implicit approach is very useful in problems where large deformation might occur due to themesh motion

References:

Abaqus Analysis User’s Guide

• “Incompressible fluid dynamic analysis,” Section 6.6.2

• “Commonly used control parameters,” Section 7.2.2

Abaqus Keywords Reference Guide

• *CONTROLS

Description: The extended finite element method allows you to model crack growth without remeshing thecrack surfaces since it does not require the mesh to match the geometry of the crack As a crack initiates andpropagates through the model, a crack surface representing both facets of the cracked elements is generated

on those enriched elements that are intersected by a crack during the analysis Distributed pressure loads cannow be applied to the crack surface

You can specify if the stress/strain values at the element centroid, at the crack tip, or the combination ofboth locations are used to measure the crack propagation criterion

References:

Abaqus Analysis User’s Guide

• “Modeling discontinuities as an enriched feature using the extended finite element method,”Section 10.7.1

Abaqus Keywords Reference Guide

• *DAMAGE INITIATION

• *DSLOAD

• *ENRICHMENT

• *SURFACE

Abaqus Benchmarks Guide

• “Crack propagation of a single-edge notch simulated using XFEM,” Section 1.19.1

• “Crack propagation in a plate with a hole simulated using XFEM,” Section 1.19.2

5.3 Enhancements for import analysis

Products: Abaqus/Standard Abaqus/Explicit

Benefits: You can use the import capability to transfer desired results and model information from anAbaqus/Standard or Abaqus/Explicit analysis to a new Abaqus/Standard or Abaqus/Explicit analysis, whereadditional model definitions can be specified before the analysis is continued Mass and rotary inertia elements

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are now available for model transfer In addition, the model transfer capability is extended to support the use

of any element set

Description: In an import analysis, model transfer is facilitated by the specification of element sets thatdefine the model to be extended You can import any element sets that you defined in the original analysis;previously, only element sets used to define the section properties could be imported Imported element setscan consist of elements of type MASS and ROTARYI in addition to other supported element types Thepresence of overlapping elements in the imported element sets is allowed since duplicate element entries areeliminated

References:

Abaqus Analysis User’s Guide

• “Transferring results between Abaqus analyses: overview,” Section 9.2.1

• “Transferring results between Abaqus/Explicit and Abaqus/Standard,” Section 9.2.2

• “Transferring results from one Abaqus/Standard analysis to another,” Section 9.2.3

• “Transferring results from one Abaqus/Explicit analysis to another,” Section 9.2.4

Abaqus Keywords Reference Guide

• *IMPORT

Abaqus Example Problems Guide

• “Deep drawing of a square box,” Section 1.5.2

Abaqus Verification Guide

• “Transferring mass and rotary inertia elements,” Section 3.14.8

5.4 Substructure generation using the AMS eigensolver

Products: Abaqus/Standard Abaqus/AMS

Benefits: A new innovative algorithm generating a free-interface or mixed-interface substructure usingthe AMS eigensolver significantly improves the performance of a substructure generation procedure Thisnew algorithm allows for partial recovery of eigenmodes at the user-defined node set, which allows you toavoid computationally expensive full eigenmodes recovery and to reduce the overall data storage requirementfor substructure generation In addition, the performance of conventional substructure generation for free-interface or mixed-interface substructures is improved

Description: A new fast substructure generation capability using the AMS eigensolver was first introduced

in Abaqus 6.12 for fixed-interface substructures (Craig-Bampton substructures) In Abaqus 6.13 the new fastsubstructure generation capability also supports the generation of free-interface substructures (Craig-Changsubstructures), general mixed-interface substructures, and substructures with partially retained nodes In

• Model 1 is a 13 million degree-of-freedom powertrain model with no substructure matrix recovery.

• Model 2 is a 4.5 million degree-of-freedom powertrain model with selective substructure matrix recovery

• Model 3 is a 10 million degree-of-freedom automotive vehicle body model with full substructure matrixrecovery

Table 5–1 Performance improvement of free-interface substructure generation procedure due

to a new fast substructure generation capability of the AMS eigensolver

Abaqus 6.12 Elapsed Time (hh:mm)

Abaqus 6.13 Elapsed Time

(hh:mm) Model

Degrees

of Freedom

(Millions)

Number of Retained Degrees of Freedom

Number of Modes Conventional Enhanced

Due to the changes in the order of the system of equations regarding retained nodes, it is possible toobserve slight differences in the number of eigenmodes extracted by AMS in Abaqus 6.12 versus Abaqus 6.13.These differences are expected since AMS eigenmodes close to the user-specified maximum frequency aregenerally less accurate and more sensitive to perturbations (e.g., changes in the order of the system of equations

or parallel execution of the element operator generation procedure) However, the substructure usage-levelresults of the subsequent modal dynamic procedures are very close to the results in Abaqus 6.12 and previousreleases

The new fast substructure generation capability does not support the following features (the conventionalalgorithm is used for these cases):

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