fe-safe 2017 - massachusetts institute of technology · fe-safe, abaqus, isight, tosca, the 3ds...

fe-safe EXTENSION FOR ANSYS®WORKBENCH fe-safe 2017

Contents

FE-SAFE® EXTENSION FOR ANSYS® WORKBENCH ......................................................... 1

1 INTRODUCTION TO THE FE-SAFE EXTENSION FOR ANSYS WORKBENCH ..................... 3

1.1 ABOUT FE-SAFE ........................................................................................................ 3

1.2 ABOUT ANSYS WORKBENCH ................................................................................... 3

1.3 ABOUT THE FE-SAFE EXTENSION ............................................................................... 3

1.4 HOW TO USE THIS MANUAL ...................................................................................... 4

2 USING THE FE-SAFE EXTENSION FOR ANSYS WORKBENCH ...................................... 5

2.1 INSTALLATION INSTRUCTIONS .................................................................................... 5

2.2 UNDERSTANDING THE EXTENSION ............................................................................. 7

2.3 HOW TO USE THE FE-SAFE EXTENSION ....................................................................... 9

2.3.1 Specify the model .................................................................................................. 9

2.3.2 Configure the project ............................................................................................ 10

2.3.3 Parameterisation .................................................................................................. 13

2.3.4 File Management ................................................................................................. 14

2.3.5 Resetting the cell ................................................................................................. 15

2.3.6 Limitations ............................................................................................................ 15

3 INTERFACE REFERENCE....................................................................................... 17

3.1 FE-SAFE CLIENT APPLICATION GUI VS COMPONENT GUI ........................................... 17

3.2 FE-SAFE MODEL READING PROPERTIES ................................................................... 17

3.3 FE-SAFE PROJECT SETUP PROPERTIES .................................................................... 18

3.3.1 Material Properties ............................................................................................... 18

3.3.2 Fatigue Analysis Scope ....................................................................................... 20

3.3.3 Loading Block ...................................................................................................... 21

3.3.4 Surface Properties ............................................................................................... 22

3.3.5 FOS Properties .................................................................................................... 23

4 PREPARING FE MODELS FOR USE WITH THE EXTENSION ......................................... 25

4.1 SUPPORTED ANSYS FILE FORMATS ........................................................................ 25

4.2 MODEL CONSIDERATION ......................................................................................... 25

4.3 UNITS .................................................................................................................... 25

4.4 GENERAL ADVICE ................................................................................................... 25

4.5 TROUBLESHOOTING ................................................................................................ 25

5 TUTORIAL: STANDARD FATIGUE ANALYSIS ............................................................. 27

5.1 INTRODUCTION ....................................................................................................... 27

5.2 SETTING UP THE ANALYSIS IN WORKBENCH ............................................................. 28

Trademarks

fe-safe, Abaqus, Isight, Tosca, the 3DS logo, and SIMULIA are commercial trademarks or registered

trademarks of Dassault Systèmes or its subsidiaries in the United States and/or other countries. Use of any

Dassault Systèmes or its subsidiaries trademarks is subject to their express written approval. Other

company, product, and service names may be trademarks or service marks of their respective owners.

Legal Notices

fe-safe and this documentation may be used or reproduced only in accordance with the terms of the software

license agreement signed by the customer, 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.

Dassault Systèmes and its subsidiaries shall not be responsible for the consequences of any errors or

omissions that may appear in this documentation.

© Dassault Systèmes Simulia Corp, 2016.

Third-Party Copyright Notices

Certain portions of fe-safe contain elements subject to copyright owned by the entities listed below.

© Battelle

© Endurica LLC

© Amec Foster Wheeler Nuclear UK Limited

fe-safe Licensed Programs may include open source software components. Source code for these

components is available if required by the license.

The open source software components are grouped under the applicable licensing terms. Where required,

links to common license terms are included below.

IP Asset Name IP Asset

Version

Copyright Notice

Under BSD 2-Clause

UnZip (from

Info-ZIP)

2.4 Copyright (c) 1990-2009 Info-ZIP. All rights

reserved.

Under BSD 3-Clause

Qt Solutions 2.6 Copyright (c) 2014 Digia Plc and/or its

subsidiary(-ies)

All rights reserved.

http://opensource.org/licenses/BSD-2-Clause

http://opensource.org/licenses/BSD-3-Clause

Copyright © 2016 Dassault Systemes Simulia Corp. fe-safe® extension for ANSYS® Workbench 3

Issue: 4.0 Date: 31/08/2016

1 Introduction to the fe-safe extension for ANSYS Workbench

1.1 About fe-safe

fe-safe is a powerful, comprehensive and easy-to-use suite of fatigue analysis software for Finite Element

models. It is used alongside commercial FEA software to calculate:

where fatigue cracks will occur;

when fatigue cracks will initiate;

the factors of safety on working stresses (for rapid optimisation);

the probability of survival at different service lives (the ‘warranty claim’ curve).

Results are presented as contour plots which can be plotted using standard FE viewers.

fe-safe has direct interfaces to the leading FEA suites.

1.2 About ANSYS Workbench

ANSYS Workbench provides powerful methods for interacting with the ANSYS family of solvers. This

environment provides a unique integration with CAD systems, and the user’s design process.

ANSYS Workbench Applications are a development framework upon which ANSYS applications are built.

Applications are available in the areas of structural mechanics, geometry, CFD, rigid dynamics,

electromagnetics, optimization and more.

1.3 About the fe-safe extension

The fe-safe extension for ANSYS Workbench is an added capability which allows for fe-safe to be inserted

into an existing project schematic in Workbench with fatigue analyses being configured and conducted from

within Workbench.

The fe-safe extension has been completely redesigned for the fe-safe 2016 release. It is only compatible with

ANSYS versions 15 and 16, and incompatible with versions of fe-safe prior to fe-safe 2016.

Users of the fe-safe extension for ANSYS Workbench are assumed to have a working knowledge of fe-safe,

including such techniques as configuring a fatigue analysis and setting properties for different parts of the

model, defining the fatigue loading, running an analysis and exporting fatigue results. The use and application

of fe-safe is described in the fe-safe user guide, which should be referred to alongside ANSYS Workbench

Help from ANSYS.

Features of the fe-safe extension for ANSYS Workbench include:

Support for Finite Element solutions from ANSYS RST files

Simplify the configuration of the project for basic workflows

For more complex fatigue analysis configurations, the fe-safe component mode can still be accessed

Verity in fe-safe can be used with automatic weld detection or legacy weld definition files

4 fe-safe® extension for ANSYS® Workbench Copyright © 2016 Dassault Systemes Simulia Corp.

Issue: 4.0 Date: 31/08/2016

Methods for post-processing fe-safe results files in the ANSYS Mechanical application

1.4 How to Use This Manual

Chapter 2 provides installation instructions and an overview of the actions required in order to perform an fe-

safe analysis as part of a project schematic in ANSYS Workbench. It also contains details on installing the fe-

safe extension and briefly explains how the extension works. Chapter 0 (Interface Reference) offers further

details of the available options. The prerequisites for ANSYS Workbench schematics are explained in Chapter

4 (Preparing FE Models for use with the extension). Worked examples of the process are provided in a

tutorial.

Users new to fe-safe

Because this manual assumes some familiarity with fe-safe, it will be necessary to learn a little about the main

program first. Work through some of the tutorials in the fe-safe user guide, including at least one

demonstrating the use of data from ANSYS, then return here.

fe-safe users new to ANSYS Workbench

Some understanding of the ANSYS Workbench environment and ANSYS Mechanical application is required

to make the best use of the software. The ANSYS Customer Portal available from www.ansys.com provides

learning material for those unfamiliar with the software.

Experienced users of ANSYS Workbench new to the fe-safe extension for ANSYS Workbench

Read Chapter 4, Chapter 2, then work through the tutorial to familiarise yourself with the fe-safe extension for

ANSYS Workbench. Once you have done this, follow the procedure described in Chapter 2 with your own

data, referring to Chapter 0 as necessary.


Issue: 4.0 Date: 31/08/2016

2 Using the fe-safe extension for ANSYS Workbench

2.1 Installation Instructions

For convenience, the following path contractions are used in the instructions:

Shorthand Typical Location

<fe-safe-installation-dir> C:/SIMULIA/fe-safe /2016

<fe-safe-data-dir> C:/SIMULIA/fe-safe /2016/data

<ANSYS-installation-dir> C:/Program Files/ANSYS Inc/v150 (ANSYS 15.0 64-bit)

C:/Program Files/ANSYS Inc/v160 (ANSYS 16.0 64-bit)

Go to the Tools menu in ANSYS Workbench, and click Options. From the options on the left, select

Extensions. In the text box Additional Extension Folders, enter the path:

<fe-safe -installation-dir>\components\Workbench

Figure 2-1The Workbench Options Dialog

Make sure that the Save Binary Extensions with Project option remains as “Never”. Ticking the Debug Mode

is not required for normal use, only troubleshooting.


Issue: 4.0 Date: 31/08/2016

Now the fe-safe extension is available for use in any Workbench project. To add the fe-safe to extension to

any Project Schematic select ExtensionsManage Extensions (see below) and check the box next to fe-safe.

Figure 2-2 The Workbench Extensions Manager

Ticking the checkbox next to fe-safe will make it available in the current Workbench project, and it will appear

within the Toolbox, ready to be deployed in a Workbench project.

Figure 2-3 Analysis Systems

Note: It is important not to use the Install Extension menu item to link the fe-safe extension to Workbench.

This copies the extension files elsewhere on the file system and breaks the link with the fe-safe solver and data resources.

A failure will be observed when opening the project in ANSYS Mechanical if this has occurred. To resolve this, the

extension must be uninstalled via the Extensions Manager and the steps above followed to correctly install the extension.


Issue: 4.0 Date: 31/08/2016

Figure 2-4 Uninstalling an extension

Unlike most Workbench extensions, the fe-safe extension is not copied when the project is copied, because it

is dependent on resources from an fe-safe installation which may not be present on another user’s machine.

The advantage of the current installation method is that it’s straightforward to change the options in

Workbench to use the newest installation of fe-safe.

The fe-safe data directory <fe-safe-data-dir> contains Workbench folders for each supported version.

Find the archive used in Tutorial: Standard Fatigue Analysis in this directory.

2.2 Understanding the extension

The fe-safe extension is dependent on solution data from upstream systems. This means that the fe-safe

system should be placed downstream of Static Structural system or Steady-State Thermal system as shown

below in Figure 2-5 Connected Systems.

Figure 2-5 Connected Systems

Drag-and-drop the fe-safe system onto the Model cell of an existing Static Structural (or Steady-State Thermal

system) to read results from an existing ANSYS analysis.

The system’s task is to define and run an fe-safe job. For this it needs an fe-safe project to be configured

based on an ANSYS RST file or RTH file, which comes from the upstream system. An fe-safe project must be

defined for the fe-safe system to update correctly. The location of this project directory is determined

automatically by Workbench.

Right-click or double-click on the Setup cell of the fe-safe system to open it in ANSYS Mechanical. The outline

will contain a selection of common settings to simplify the configuration of the project for basic workflows.


Issue: 4.0 Date: 31/08/2016

Figure 2-6 fe-safe Project Basic Setup

The groups of elements to be analysed in fe-safe (i.e. which subsets of the model are to be analysed by fe-

safe) is controlled from the settings in ANSYS Mechanical; bodies or named selections can be used to define

the fatigue analysis scope.

The material information can be passed from Engineering Data (dependent on your local material databases),

or configured within the normal fe-safe GUI. Basic one-block loading definitions and surface finish properties

can be defined within ANSYS Mechanical.

For more complex fatigue analysis configurations and workflows, the Advanced Setup option is provided. This

opens the standard fe-safe GUI in “component mode” and gives access to the majority of fe-safe controls

(including all the export contours). Any setup performed whilst in Advanced Setup mode will override the

settings in ANSYS Mechanical.

The output of the fe-safe extension is a potable result for each of the fe-safe contours that were chosen for

export.


Issue: 4.0 Date: 31/08/2016

Figure 2-7 fe-safe Result Contours

2.3 How to use the fe-safe extension

2.3.1 Specify the model

The first step in setting up an fe-safe system is to specify an FEA solution file to base its analysis upon.

Connect the fe-safe system downstream of a Model cell in another system. This will mean you will need to

make sure that the Solution cell is updated before performing the connection (since the FEA solution file will

not exist until the cell is up-to-date.)

Pre-scanning of the FEA solution is not supported when using Workbench (see Limitations in section 0

below). However, many settings regarding which FEA solution variables and other data are read can be made

in the Analysis Settings item in the ANSYS Mechanical project tree. See section 0. Datasets are loaded for all

extension workflows using full read settings configured in the Details of “Analysis Settings” panel (see more

about selecting datasets to read in section 3.2).

Note: On subsequent executions of the schematic, upstream systems will likely update the FEA solution file. If an fe-safe

system is connected to one of those upstream systems, it will refresh its datasets from the most recent FEA solution file

that was passed from upstream. It does not matter if the filename or location is different, the system will respect whatever

solution file was most recently supplied. The caveat to this is that users must be sure that upstream systems will not

change the solution file in a way that will invalidate the fe-safe project you set up. (For example, if the number of steps or

material assignments are changed , or if a geometry selection is invalidated). If you think that an fe-safe project setup may


Issue: 4.0 Date: 31/08/2016

have been “invalidated” by upstream changes, you should right-click the Project cell and select Reset to clear the project

configuration.

2.3.2 Configure the project

This is a description of a basic workflow for the fe-safe extension.

Right-click the Setup cell and select Edit to start setting up an fe-safe project. The Mechanical window will

appear with the fe-safe system in the outline. The properties can be set up in any order.

Project Setup

Figure 2-8 fe-safe Basic Project Setup

The settings in the ANSYS Mechanical Details of “Project Setup” panel are provided to accelerate

configuration of basic workflows that use simple load cases, and to tell fe-safe which regions of the model to

analyse. More details on each property can be found in section 3.3below.

The only required property (highlighted in yellow) is the Fatigue Analysis Scope (for details, see section 3.3).

All other properties are set to appropriate defaults.

The default fatigue loading will create a single elastic-block (1 repeat) with a sequence of FEA solutions

(dataset sequence) formed from all of the steps in the upstream system.

Anything configured within this panel can be overridden in the Advanced Setup mode. If these properties do

not give enough fine-grained control over a particular fatigue configuration, then Advanced Setup mode

should be selected by right-clicking on Project Setup in the outline.


Issue: 4.0 Date: 31/08/2016

Advanced Setup

Figure 2-9 fe-safe Advanced Project Setup

This mode is for any workflows that are not covered by the simplified controls in ANSYS Mechanical. When

Advanced Setup is first used, fe-safe will respect any settings that were configured in ANSYS Mechanical to

setup the fe-safe project. Subsequent changes whilst in component mode will take precedence when the

analysis is run.

Selecting the Advanced Setup menu item opens the fe-safe GUI in a “component mode” and starts to open

the solution (e.g. file.rst) in fe-safe component mode. This is a special mode used for controlling the input

and output of files for fe-safe, from an external software component. The controls for Source and Results

files/paths, and project directory that users expect to be able to set in a standalone version of fe-safe are not

accessible from the component, but instead are set by the configurations made in Workbench.

Whilst in component mode, the workflow is mostly identical to the workflow in the standalone fe-safe product.

Any kind of loading can be configured, the analysis groups can be configured individually, and any extra

output contours that are enabled will be available to plot in ANSYS Mechanical.

When the configuration is finished, close the fe-safe component mode GUI and return to ANSYS Mechanical.

Notice that the properties are now read-only:

Figure 2-10 Disabled Properties


Issue: 4.0 Date: 31/08/2016

This is to indicate that Advanced Setup now has control over the settings, However, these controls can be

unlocked via the Unlock Properties menu item:

Figure 2-11 Unlocking Properties

Be aware that any further changes within these properties can potentially reset configuration in the Advanced

Setup. It is not a problem to change the scope of the analysis within ANSYS Mechanical from one named

selection to another; the effect will be that the now-redundant analysis group will be moved to the list of

Unused Groups in fe-safe.

Execution

To run the fe-safe analysis, simply solve the schematic or the individual fe-safe system as shown in Figure

2-12 (if in the Workbench GUI). From the ANSYS Mechanical window, use the Solve ( ) action on the

outline for the fe-safe Solution cell.

Figure 2-12 Update the Project

After execution, the results contours will be available to plot under the Solution item in the fe-safe system in

ANSYS Mechanical. If results are missing, right-click on Solution to select the Worksheet: Result Summary

option:


Issue: 4.0 Date: 31/08/2016

Figure 2-13 Results Summary

All of the result contours that were found in the fe-safe results file (*.FER) file should be listed under List

Available Solution Quantities.

Figure 2-14 ANSYS Solution Quantities

To plot any of these results, right-click and choose Create User Defined Result.

Figure 2-15 Creating a viewable result

These results should now appear under the Solution item and can be evaluated like any other ANSYS

Mechanical result.

2.3.3 Parameterisation

Parameterisation is not supported in the current release of the fe-safe extension.


Issue: 4.0 Date: 31/08/2016

2.3.4 File Management

The fe-safe project directory can be set manually when starting a regular instance of fe-safe. When using the

fe-safe extension for the Workbench environment, this directory resides in the project directory for the same

Workbench project, alongside the other systems. These fe-safe working files in the project directory will be

saved when the Workbench project is saved or archived (and reloaded when the schematic is loaded). The

directory structure logic is identical to other ANSYS Workbench systems with respect to design points. The

naming convention for fe-safe files within the working directory is for an “SYS” prefix, possibly followed by “-1”,

“-2” etc depending on how many instances of the fe-safe system were dropped into the schematic.

Identifying the fe-safe working files and their location (if required) in the Workbench project directory can be

accomplished by selecting the View Files menu selection from the Workbench interface as shown below in

Figure 2-16.

Figure 2-16 Files Table


Issue: 4.0 Date: 31/08/2016

2.3.5 Resetting the cell

If required, you can reset the fe-safe project to its initial state using the Reset Project menu item. This deletes

the underlying fe-safe project directory, forcing fe-safe to create a new project and re-read the FEA solution

from scratch.

Figure 2-17 Resetting the project

2.3.6 Limitations

Pre-scanning of the FEA solution is not supported when using Workbench, as fe-safe has no way at present

to replay the pre-scan choices when the solution is refreshed by subsequent runs. The steps in the FEA

solution are loaded in full every time it is updated by Workbench.

PSD-based loading from Harmonic Analyses are not possible at the current release.

Nodal groups are not supported and fe-safe only reads the element-nodal (corner) data from the FEA

solution.

Plug-in modules (fe-safe/Rubber, or user-defined plugin algorithms defined using Custom Module Framework

or CMF for fe-safe_ cannot be used at this release.

The Engineering Data cell provides its material data as a MatML file (an XML extension designed to support

standardised material data). Presently fe-safe has no interpreter for MatML so cannot receive its material data

from this cell, although in this release there is an option for matching material names with a fe-safe material

database file.

At this release, fe-safe does not support concurrent execution. Measures have been put in place to stop fe-

safe being invoked concurrently within a Workbench schematic; however you should take care not to design a

schematic where this could occur.


Issue: 4.0 Date: 31/08/2016


Issue: 4.0 Date: 31/08/2016

3 Interface Reference

Note that only those interface elements of particular importance for using fe-safe with Workbench are

described here.

3.1 fe-safe client application GUI vs component GUI

When Advanced Setup is selected, fe-safe opens up in component mode. The look of this is essentially

identical to standalone fe-safe, with some minor differences. These are shown in Figure 3-1.

Figure 3-1fe-safe stand-alone GUI (left) and Workbench component GUI (right)

The differences are mostly located in the Fatigue from FEA window. In component mode, the buttons for

choosing the source file and output file have been removed (they have been moved to the Workbench project

schematic). Also, the Analyse! button has been removed, since the purpose of the Workbench extension is to

run fe-safe from inside the Workbench project environment.

3.2 fe-safe Model Reading properties

As noted in 2.3.1 above, pre-scanning is not available in the component mode, and the default full read

settings for Ansys RST files in fe-safe can be configured using the Details of “Analysis Settings” panel

accessible from of the fe-safe Analysis Settings in Mechanical. These settings are used to control what model

data and FEA solutions from the RST/RTH file are read by fe-safe as shown below:

Figure 3-2 RST full read options


Issue: 4.0 Date: 31/08/2016

Checkboxes corresponding to Read Geometry and Detect Surface are enabled by default to complete surface

detection in fe-safe as described in the fe-safe user guide. If you are using a 3D shell model, this is not

necessary but not detrimental either.

FEA solutions of elemental-nodal strain, force, and temperature can be added to the Dataset Read Options by

engaging checkboxes for those options, and subsequently used in the fe-safe extension. Stress is read by

default since most FEA Fatigue analysis are based on elastic material with plasticity correction during the

analysis process in fe-safe.

Note that it is the responsibility of the engineer to read strains only when elastic-plastic material properties

have been applied to the body selected for FEA Fatigue analysis in fe-safe. Similarly, forces are only required

in the case of welded joint fatigue using Verity in fe-safe (loading them is not detrimental to analysis).

Temperatures will only have an impact if a material with temperature variability is selected for FEA Fatigue

analysis (loading them is not detrimental to analysis). As with all FEA interfacing, loading unnecessary

datasets may take more time.

3.3 fe-safe Project Setup properties

The properties below are configured as part of the Details of “Analysis Settings” panel in the Mechanical

window.

3.3.1 Material Properties

At the present release, the materials supplied by default with ANSYS Engineering Data do not have all the

material properties that fe-safe requires for a fatigue analysis. Conversely the material databases that are

supplied with fe-safe are not compatible with ANSYS. Accordingly, for fe-safe to find the material data it

needs, a material database file (*.dbase) must be the source of the data. There are two methods available

with the fe-safe extension for specifying the material data:

Figure 3-3 Comparison of Material Properties defined with Advanced Setup (above)

versus Match with Engineering data (below)


Issue: 4.0 Date: 31/08/2016

Define within fe-safe Advanced Setup

This is the default option. It requires that the Advanced Setup mode be used to open up the fe-safe GUI and

assign materials to analysis groups, as in a normal fe-safe workflow. Any .dbase file that is opened in fe-safe

can be used; if this step is omitted then fe-safe will report an error to the Workbench log when the system is

solved.

Match with Engineering Data

With this option, fe-safe will attempt to match the materials from Engineering Data to a given fe-safe materials

database, based on the material name.

The fe-safe material *.dbase file must be specified in the Material Database Location field (this is a file

browser field).

fe-safe will look at each body in the model to discover which material has been assigned:

Figure 3-4 Determining the material for a given body


Issue: 4.0 Date: 31/08/2016

In this case, “Structural Steel” is associated with the body “Solid 1”. Then when the analysis groups are

created, fe-safe will expect to find a “Structural Steel” material in the database (the name match is case-

sensitive and punctuation-sensitive), and it will assign fatigue properties with the same name to the group in

fe-safe created for that body. If the fatigue analysis is based on named selections, fe-safe will create an

analysis group for each named selection and apply the material associated with that named selections. If a

named selection spans several materials, analysis groups will be created for each.

To use this approach effectively, a *.dbase file must be maintained with materials that match those available

in Engineering Data. It is only recommended for organisations with a standardised library of materials.

3.3.2 Fatigue Analysis Scope

This is where the scope of the analysis can be restricted to regions of the model. Under Scoping Method there

are three options:

Geometry Selection

Figure 3-5 Scoping a fatigue analysis to Geometry

With this mode, either bodies or faces can be selected. fe-safe will create an analysis group for the chosen

entity. Click on the yellow field, use the body/element pickers in ANSYS Mechanical to choose the entity, then

click Apply.

Named Selection

Figure 3-6 Scoping a fatigue analysis to a Named Selection

With this mode, either bodies or faces can be selected. fe-safe will create an analysis group for the chosen

named selection. The drop-down box displays any pre-created named selections, or a named selection can

be picked from the viewer.

All Named Selections

Figure 3-7 Scoping a fatigue analysis to all Named Selections


Issue: 4.0 Date: 31/08/2016

fe-safe will create an analysis group for all named selections that are currently defined. This is recommended

for users with a complex fatigue case who may want to assign different group properties across the model.

Using Advanced Setup to open up the fe-safe component mode GUI will allow greater control over each

analysis group (including moving some groups to the Unused Groups list).

3.3.3 Loading Block

This panel is a means to specify fatigue loading comprised of a single elastic block in fe-safe containing a

dataset sequence. For scale-and-combine and elastic-plastic loadings, the Advanced Setup must be used. An

appropriate LDF file for the project will automatically be generated from these settings (and this can be viewed

through the Advanced Setup).

Figure 3-8 Loading Block Properties

System

This defines which system in the schematic (and in turn which RST/RTH file) fe-safe should read the stress

datasets from.

Step Sequence

This tells fe-safe which steps to include in the loading, and in turn which stress datasets to use. The numbers

used refer to the ascending numerical index of the step. It is a text field which allows the following syntax

forms:

Lists

These can be combined with ranges:

1,2,3

1,4,66,99

3,1,4,2

3,1,44-67

Ranges

These can be combined with lists:

1-3

1-3,4,5,6


Issue: 4.0 Date: 31/08/2016

Hints

These special keywords can only be used on their own and not in combination with lists or ranges. Valid

values are:

All, First, Last (case-insensitive)

For example, in a 6-step solution:

All results in a dataset sequence of 1,2,3,4,5,6

Last results in a dataset sequence of 6

First results in a dataset sequence of 1

Increment Sequence

This is only appropriate to solutions that contain steps with multiple increments (or timesteps) to be used in

FEA Fatigue analysis. Otherwise this property is ignored. It tells fe-safe which increments under each step to

include in the loading. The syntax is identical to that outlined for the Step Sequence.

Scale

This specifies the scale applied to the block.

Repeats

This specifies the number of repeats on the block.

3.3.4 Surface Properties

Figure 3-9 Surface Finish Properties

These are equivalent to the surface finish properties in the fe-safe standalone product; all the options that are

available in fe-safe are available by dropping down the Define Surface By box.

The surface properties that are setup here are applied to every analysis group in fe-safe. For analyses that

require different surface properties on each analysis group, use the Advanced Setup. If the surface properties

are defined in Advanced Setup, they will override whatever is configured in this panel.


Issue: 4.0 Date: 31/08/2016

3.3.5 FOS Properties

In this panel, a Factor of Strength (FOS) analysis can be configured, with a choice between infinite life and a

target life or design life (in repeats). An additional contour will automatically be generated to define the scale

factor on elastic stress to apply to each element node in order to meet the target life. By default, FOS

calculations are disabled.

Figure 3-10 FOS Properties

This is the equivalent of the Factor of Strength Calculations dialog in fe-safe:

Figure 3-11 Factor of Strength Calculations Dialog

Note: FOS is an iterative procedure and it can take much more time to run fe-safe analyses when it is turned

on than when it is off, so use caution when running fe-safe for the first time with a particular model.

When FOS is run in fe-safe, the Apply Corrections to Safety Factors field can be used to activate a critical

distance correction factor calculation using the Theory of Critical Distances (TCD). To use this, choose

between Line Method and Point Method (by default this is disabled). For more details refer to the main fe-safe

user guide. This will produce additional contours to describe the factor of strength for the critical length (TCD

FOS).

Note: TCD is a crack growth procedure and uses different fatigue damage parameters than the finite life

algorithms specified by default for most of the materials in fe-safe. Do not be alarmed if there is not direct

relationship between the FOS and the TCD FOS.


Issue: 4.0 Date: 31/08/2016


Issue: 4.0 Date: 31/08/2016

4 Preparing FE Models for use with the extension

4.1 Supported ANSYS file formats

Currently the ANSYS RST files supported by the fe-safe extension for ANSYS Workbench are the same as

are supported in the fe-safe stand-alone application; this means Ansys 5.5 and higher. Refer to Appendix G of

the fe-safe User Guide for additional information about supported versions.

4.2 Model Consideration

No special model requirements need to be met to be able to use the fe-safe extension. Any analysis you have

performed in the fe-safe stand-alone application can be used with the fe-safe extension for ANSYS

Workbench.

4.3 Units

Ansys Workbench contains two types of FEA model units, those which are solved (as shown in the solve.out

file) and those used to display results in the Mechanical Viewer (available from the Units menu). These Units

in Mechanical allow users to change the stress units on the fly for display purposes only. The file.rst file

solved in the solution cell of the static structural or thermal system always has an internal set of solved units

as shown in the solve.out file. These are the units needed for fe-safe, and the Workbench extension will set

the unit system in fe-safe accordingly.

4.4 General Advice

Ensure the system is solved (green check mark next to the Results cell) before connecting an fe-safe

system to it.

There isn’t an Analyse button in the GUI view of the fe-safe extension. To analyse, close fe-safe

component mode and return to ANSYS Mechanical or ANSYS Workbench, where the standard Solve

command can be used to perform the fatigue analysis.

4.5 Troubleshooting

If the LOGLife-Repeats contour does not appear after Advanced Setup is completed, return to the

component mode using Advanced Setup to ensure that the loading and material properties are

assigned.

If after solving, a red lightning bolt appears next to the solution cell, select Solution Information to look

for errors and warnings. These warnings indicate a need to revisit the Advanced Setup:

o Error: An analysis algorithm needs defining for at least one group

o Error: Material is invalid.

o Error: Unable to decode default analysis 'Undefined' from material

'Undefined' for group 'Solid 1' (index 1)


Issue: 4.0 Date: 31/08/2016

If the LOGLife-Repeats shown is 7 this means infinite life, e.g.: Log(7)=1e7 repeats. One common

reason for this is units. Look at the Solution Information on the fe-safe system and find the FEA Units,

does the order of magnitude of the Tensor Datasets in the same solution information file reasonable?

Close fe-safe component mode and go back to Mechanical to set the Units to reflect the Internal units

of Workbench (see the Solution Information of the upstream system).


Issue: 4.0 Date: 31/08/2016

5 Tutorial: Standard Fatigue Analysis

(Using an ANSYS RST file from a Workbench Project)

5.1 Introduction

This tutorial outlines how to perform a standard fe-safe fatigue analysis from within Workbench. It is assumed

that the user has experience using fe-safe, thus detailed information on how to set up an fe-safe analysis is

not included in this tutorial. A certain comfort level of working with Workbench is also assumed, so that the

focus of the tutorial is on the flow rather than the minute technicalities. For a detailed reference of using

ANSYS Mechanical, please refer to ANSYS Workbench Help.

This analysis is based upon a model created for training purposes in 2011. Figure 5-1 shows the geometry

and first step; the plot was created using ANSYS Mechanical application.

Figure 5-1: Tapered cantilever beam subject to eccentric loading

The model presented is a tapered cantilever steel beam subjected to a remote load of 1 N in the negative Y

direction as depicted by the red arrow. The indicated load is applied in first step and then a 1 N-mm torsional

load is applied in a second step at the end of the beam in the X-direction. For tutorial A, the first load step (i.e.

dataset in fe-safe) is to be used for the fatigue analysis in combination with a data file.

ANSYS Mechanical has also been used to mesh the model as shown in Figure 5-2.


Issue: 4.0 Date: 31/08/2016

Figure 5-2 Meshed FE model in Mechanical application

5.2 Setting up the Analysis in Workbench

To create the schematic, start Workbench and make sure you have configured Tools Options to the add

the folder for the fe-safe extension as detailed in Chapter 2, Section 2.1. Now, follow the steps outlined below

to complete the fe-safe analysis:

1) Use the File Menu in Workbench to open the example archive file included in the provided

cantilever.wbpz file (see section 2.1for details). Select File Restore Archive and browse to your

example archive file cantilever.wbpz. Follow the directions to save the workbench project that is

created, and the schematic will appear:

Figure 5-3The static structural system in the Workbench schematic

2) Drag and drop the fe-safe system onto the Model cell to connect the systems as shown in Figure 5-4 Add

the fe-safe system to the project schematic. (If fe-safe is not shown in the Toolbox, select Extensions

Manage Extensions to load the fe-safe extension)


Issue: 4.0 Date: 31/08/2016

Figure 5-4 Add the fe-safe system to the project schematic


Issue: 4.0 Date: 31/08/2016

3) From the fe-safe system (C), right-click on the Setup cell (C4) and select Edit…

Figure 5-5 Set up the fe-safe analysis

The ANSYS Mechanical application will open and the fe-safe system will appear in the project tree.

Figure 5-6 Results are automatically opened in the fe-safe extension


Issue: 4.0 Date: 31/08/2016

4) Select on the Project Setup item under “fe-safe (C4)”.

5) Click on the yellow field next to Geometry, select the whole cantilever body (select the icon from the

main toolbar, then click the cantilever within the viewer). Click Apply and the field should change to say “1

Body”, and there should be a green tick next to Project Setup:

Figure 5-7 The loaded FEA model

6) Leave all other settings at their defaults.

7) Right-click the Project Setup item in the tree and choose the Advanced Setup menu item. The fe-safe GUI

should now open in component mode and go on to load the RST file.

Figure 5-8 The loaded FEA model

Notice the stress units set to MPa in the Current FE Models units. If this is not done, close fe-safe and go

back to step 4.

Notice that fe-safe has created a single analysis group to represent the single body that was picked for

analysis:


Issue: 4.0 Date: 31/08/2016

Figure 5-9 Analysis Group Properties

8) Set the material for this group to the SAE_950C-Manten material in the “local.dbase”.

9) Using fe-safe open the data file Cantilever-scalers.amc which is provided in the cantilever_files project

directory that Workbench extracted.

10) Delete the default dataset sequence loading and define the loading so that it includes a scale-and

combine using Add Load * dataset. The Loading Settings should be as shown:

Figure 5-10 Completed load definition in fe-safe (component mode)

11) Exit fe-safe (component mode) – you will now be returned to ANSYS Mechanical. Notice that the

LOGLife-Repeats contour has appeared automatically under the Solution (C5) item, with a lightning bolt

icon to indicate that the solution needs updating.

Figure 5-11 System ready to solve

12) Run the analysis by right-clicking on the “fe-safe (C4)” cell and selecting Solve as shown below in Figure

5-12.


Issue: 4.0 Date: 31/08/2016

Figure 5-12 Update the system

When the FEA Fatigue analysis has completed there should be green check marks next to all items.

13) View the results in ANSYS Mechanical by clicking the LOGLife-Repeats item. Right-click on the contour

legend and select Color Scheme to change the contour “Reverse Rainbow” and show the lowest lives in

red. Select Solution Information to view the results log. Use the Minimum tag or the 123 tag to probe

values.

Figure 5-13 The Log-Life result

LOGLife or Life contours shown with Averaged display may not match the lowest life reported by fe-safe.

This is because the logarithmic life values should not be averaged on a linear basis.


Issue: 4.0 Date: 31/08/2016

14) Review the Solution Information of the fe-safe system to find the line containing Worst Life-Repeats: (In

this case it is 13637.602). In log base 10 this is equal to 4.1347, but the averaged contour shows a higher

Minimum. Use the Display Option of the LOGLife-Repeats contour to select Unaveraged. Right-Click on

the LOGLife-Repeats and select Evaluate All Results. The Legend will now show a minimum of 4.1347.

fe-safe 2017 - massachusetts institute of technology · fe-safe, abaqus, isight, tosca, the 3ds...

Documents