the Altair insider

The Altair Insider
Your HyperWorks Newsletter
Altair® HyperWorks® is A Platform for Innovation™
V
76
2008
In this Issue
New Fatigue
Process
Manager
Page two
Upcoming
Training Dates
HYPERWORKS INDUSTRY VERTICAL WEBINAR SERIES
PRESENTED BY ALTAIR AND THE HYPERWORKS ENABLED PARTNER COMMUNITY
INDUSTRIES
Aerospace - Nov 6, 11, 13
Shipbuilding - Nov 18
Medical - Nov 20
Automotive - Dec 9, 11
HYPERWORKS ENABLED PARTNERS
CFD - Dec 1, 5
Fatigue - Dec 2, 4
Electromagnetics - Dec 8
Page SIX
Today’s business and design challenges are expanding in both
Tips and Tricks
Page SEVEN
complexity and scope across all market sectors. Join Altair’s
top industry vertical specialists to explore how HyperWorks, an
enterprise simulation platform, can dramatically improve the
effectiveness and efficiency of your product design process from
the concept stage through manufacturing.
Attend our FREE 40-minute webinars to learn how HyperWorks can:
• Be used early in the design cycle to reduce time to market
• Reduce your CAE cycle time
• Reduce software investments
• Automate CAE processes
• Improve results consistency
• Improve decision making with product performance information
• Provide on-demand access to HyperWorks and partner
Phone: +1 248.614.2400
Fax: +1 248.614.2411
www.altair.com
product technologies
REGISTER TODAY!
HYPERWORKS 9.0:
NEW FATIGUE PROCESS MANAGER
HyperWorks 9.0 provides fatigue analysis based on S-N
approach. A new tool called Fatigue Process Manager
(FPM) has been developed to provide a user-friendly way
to setup fatigue analysis in HM9.0. First, an overview of
the fatigue capability in HyperWorks 9.0 is presented along
with the technical background. Second, an overview study
demonstrating the capabilities of FPM is provided.
Overview of Fatigue Capability in
HyperWorks 9.0 (S-N)
S-N curve
HyperWorks 9.0 provides fatigue analysis based on S-N
approach (stress-life). It is developed for predicting the life
(number of loading cycles) of structures under cyclic loads.
S-N approach is well accepted in engineering for high-cycle
life prediction. It was first developed by Wöhler, which gave
the relationship between nominal stress and cycles to failure
obtained from experiment data as shown in Figure 1.
Analysis1, ASTM E1049-85), which is also the approach
developed in RADIOSS.
Equivalent Nominal stress
Since S-N theory deals with uniaxial stress, the stress
components need to be resolved into one uniaxial or
combined value for looking up damage on S-N curve.
Radioss provides various stress combination types and
the default option is “Absolute maximum principle stress”.
Generally for brittle materials, “Absolute maximum principle
stress” is recommended. For ductile material, “Signed von
Mises stress” is recommended.
Mean stress correction
Generally S-N curves are obtained under standard
experiments with fully reversed cyclic loading. However
the real fatigue loading could not be fully reversed and the
normal mean stresses have significant effect on fatigue
performance of components. Tensile normal mean stresses
are detrimental and compressive normal mean stresses are
beneficial in terms of fatigue strength. In Radioss, two mean
stress corrections are available - Goodman or Gerber.
Overview: Fatigue Process Manager (FPM)
This overview demonstrates how to launch Fatigue Process
Manager, and use FPM to import a model, define fatigue
subcase, including fatigue analysis parameters, fatigue
elements and their fatigue properties, and loading sequences.
It also includes how to use FPM to submit fatigue analysis of
the problem, view results summary and launch HyperView to
do the post-processing about damage and life contours.
Figure 1: S-N curve
Damage model
Palmgren-Miner’s linear damage summation rule is used in
RADIOSS. Failure is predicted when
Where, Ni,f is material fatigue life (number of cycles to failure)
from its S-N curve at a combination of stress amplitude and
mean stress level i, ni is number of applied stress cycles at
load level i, Di is cycle ratio (cumulative damage).
Cycle Counting
Cycle counting is used to extract discrete simple “equivalent”
constant amplitude cycles from a random loading sequence.
Rainflow cycle counting is the most widely used approach
(See Standard Practices for Cycle Counting in Fatigue
The following steps have been demonstrated:
• Launching Fatigue Process Manager
• Importing model
• Creating fatigue subcase
• Defining fatigue analysis parameters
• Defining fatigue elements and SN properties
• Defining load-time history and loading sequence
• Submitting the job
• Viewing results summary and launch HyperView
for post-processing
Overview
The model being used for this case study is that of a
control arm. The HM model of the control arm along with
forces and boundary conditions are shown in Figure 2.
The S-N curve used for the fatigue analysis is shown in
Figure 3. There are two subcases defining the loads and
the load-time histories for those two subcases are shown
in Figures 4 and 5.
page two
Launching Process Manager in HM9.0
Process Manager can be launched from the Applications
menu bar in HM 9.0. This loads the process manager
environment, a programmable task management that guides
through pre-defined standard work processes. A Process
Manager tab is then added to the HM tab area to the left as
shown in Fig 6.
Figure 2: Loads and constraints for total life
prediction of solid control arm
Figure 3: S-N Curve used for total life prediction of control arm
Figure 6: Process manager tab in HM 9.0
Launching Fatigue Process Manager
To load the fatigue process template (process definition file),
a Fatigue_PM.pmt file is to be loaded using the Open Process
Template icon in the process manager panel. Once loaded, a
Create process instance window pops up and a New Instance
of the fatigue process template can be created. This opens up
the fatigue process tree to the HM tab area as shown in Fig 7.
Figure 4: Load-time History used for total life
prediction of control arm (for static subcase 1)
Figure 5: Load-time History used for total life
prediction of control arm (for static subcase 2)
Figure 7: Fatigue process tree after launching FPM
page tHREE
Importing model in FPM
A HM or Radioss/Optistruct model can be imported in FPM.
The FPM then guides the user to the Fatigue Subcase task
of the fatigue process tree.
Creating Fatigue Subcase in FPM
By selecting the Fatigue Subcase task in the fatigue process
tree, a Create new fatigue subcase field is created.
The fatigue subcase can then be defined which will be
used for the following processes: analysis parameters,
fatigue elements and properties, loading sequences, etc.
See Fig 7a below. Once this is done, the FPM guides the
user to the next task Analysis Parameters of the fatigue
process tree.
Figure 7a: Defining Fatigue Subcase in FPM
Defining Fatigue Analysis Parameters
The fatigue analysis parameters to specify analysis type,
stress combination method, mean stress correction method,
FEA stress unit, rainflow type, gate etc can all be defined by
selecting the task Analysis Parameters (Fig 8). For details on
the fatigue parameters, please consult the HyperWorks 9.0
online help.
Once this is done, the FPM guides the user to the next task
Elements and Materials.
Figure 9: Material data definition
As shown in Fig 9, from the Element entity type, the
appropriate Property type should be selected (in this
overview, the shell skin coating the solid control arm
is selected).
For the material data, Yield strength (YS) and/or the
Ultimate tensile strength (MPa) (UTS) should be specified.
The S-N curve can be defined in several ways –
1.directly inputting the S-N curve parameters (if known)
2.using Slope – Interception method
3.using Slope – Transition stress method and
4.Estimating from UTS - the user needs to select the
appropriate material type (ferrous, aluminum etc) and
the FPM will evaluate the parameters from the UTS.
Figure 8. Fatigue analysis parameters definition
Defining Fatigue Elements and Materials
To define the property (PSOLID or PSHELL) whose fatigue
life and damage is to be evaluated, a Material Data
window has been developed under the task Elements
and Materials (Figure 9).
For this overview, the S-N curve parameters have been
obtained by using Estimate from UTS method specified
above, for the aluminum control arm (UTS of 600 MPa).
Once the parameters have been determined, the S-N curve
can be plotted by using Plot SN curve in the Material
Data window. The parameters defining S-N curve corrections
can be defined too (Fig 9). The elements and materials
definition in FPM is shown in Figure 10. Once this is done,
the FPM guides the user to the next task, Load-Time History.
page FOUR
Figure 10: Elements and material definition in FPM
Defining Load-Time History
The load-time histories can be defined by reading in
files or by inputting values directly under the task
Load-Time History. When adding by file, a load-time history
window pops up, allowing the user to read files of CSV or
ASCII formats. The load-time histories can also be plotted in
FPM. Please note: To read in a file of DAC format, it can be
very easily imported in Altair HyperGraph and converted to
CSV format for use by FPM.
For this overview, two load-time histories have been
considered, one for each subcase (Figure 11). The FPM
then guides the user to the next task, Loading Sequences.
Figure 12: Associate load-time history with static subcase
In this overview, two fatigue loading sequences have been
created: one is made up of one fatigue event and the other
is made up of two fatigue events as shown in Fig 12a (linear
super-positioning is required during fatigue analysis).
Figure 12a: Loading sequences in FPM
Submitting fatigue analysis
Figure 11: Load-time history definition
The fatigue analysis can be submitted under the task
Submit Analysis (Fig 13). If the job was successful,
results files can be seen in the same directory where the
Radioss/OptiStruct model file was written. A new ascii output
file called *.fat file which contains fatigue results of each
fatigue subcase for each iteration is also written.
Defining Loading Sequences
Multiple fatigue loading sequences can be created,
sequences which are made up of fatigue event(s) in the
Loading Sequences task of the fatigue process tree.
An Enter Load-Time History window will pop up (Fig 12).
Figure 13: Submit fatigue analysis
page FIVE
Post Processing
When fatigue analysis has finished successfully, it will
automatically go into the task Post Processing of the fatigue
process tree.
Under this task, it is possible to:
1.View the life results summary to check the top 0.1%,
1.0%, 5.0% average life, and Top 1, 2, 3 most damage
elements lives as shown in Figure 14 (and)
TRAINING COURSES
Develop Your Skills
Here are upcoming HyperWorks training courses.
For more details on these courses, to obtain a full schedule
or to inquire about customized onsite training, call your
local Altair office or email [email protected].
Michigan training classes (Troy)
Intro. FEA Modeling & Results Visualization
November 17-19
Intro. to HyperCrash
November 17
Intro. to Radioss
November 18-19
Figure 14: Summary of Life results in FPM
2.Toggle the Results types to view the damage
results summary.
HyperView can also be launched by clicking on Load H3D
Results (HV) to load the h3d results file for more detailed
results. The contour plot of Damage for the control arm is
shown in Figure 15.
Intro. Concept Design & Fine Tuning w/OptiStruct
November 24-25
Intro. DOE, Optimization & Stochastic Studies
November 26
caLIfornia training classes (irvine)
Intro. FEA Modeling & Results Visualization
November 11-13
WASHINGTON TRAINING CLASSES (BOTHELL)
Intro. Concept Design & Fine Tuning w/OptiStruct
November 18-19
Canada training classes (Toronto, Ont.)
Intro. FEA Modeling & Results Visualization
November 4-6
Intro. to Radioss Linear
November 25
Concept Design Optimization for Metallics
and Composites
November 26-27
Figure 15: Damage contour in HyperView
Intro. DOE, Optimization & Stochastic Studies
November 28
Step-by-step tutorial
Please click here to download the assets featured in
this tutorial.
SPECIAL ANNOUNCEMENTS
We have recently added 3 new software updates.
Please visit our website for full release notes and
the ability to download them.
SuperComputing ’08
November 17-20 – Austin, Texas - Booth #933
Join us at SC08, the premier international conference on
high performance computing, networking, storage and
analysis. Click here to learn more.
HWupdate-90-SA1-020-HyperGraph
Release Date: 10/23/2008
HWupdate-90-SA1-005-DataManager
Release Date: 10/1/2008
HWupdate-90-SA1-011-OnlineHelp
Release Date: 10/1/2008
page SIX
ADDITIONAL
HYPERWORKS MACROS
SUPPORT TIPS & TRICKS
coincident_node_link.zip: This HM macro creates zerolength spring elements between coincident nodes. This
macro works for Optistruct and Nastran user profiles. A
detailed description about the macro and installation
instructions is available in the zip file. Download
CatiaSpotWeldReader.zip: This macro can read the spot
weld file (generated from CATIA V5) and create respective
spot weld connectors in HyperMesh. Download
KB #1: 782
Quick definition of deck properties for ANSYS solver in
HyperMesh. Download
KB #2: 783
Fatigue Manager Utility in HyperView allows you to write
a partial FES file fatigue analysis using nCode solver.
Download
ALTAIR IN THE NEWS
Our latest
magazine out now
subscribe
free
Altair Adds Leading Industrial Design Software solidThinking to its
HyperWorks Enabled Community
October 21, 2008
New Online Altair Store Sells PBS Professional Software Licenses and
Support 24/7 to Customers Worldwide
October 8, 2008
Penguin Computing and Altair to Deliver Enhanced Utility to HPC
Cluster Users
September 17, 2008
UPCOMING EVENTS
In the near future, Altair is participating in the following events:
ArchLED
SC08
regonline.com
sc08.supercomputing.org
November 12-14
Chicago, IL
REGISTER TODAY
If you are new to this site or have not
registered as an Insider user, we invite
you to complete a brief sign-up form.
As a registered user, you will have access
to other support resources, including documentation, tutorials, software updates
and macros. You will also have access
to the iExchange message board.
EuroMold 2008
November 15-21
Austin, TX
December 3-6
Frankfurt, Germany
euromold.com
ABAQUS Regional
AeroTest
User’s Meeting 2008 America 2008
November 12 & 13
Plymouth, MI
simulia.com
November 17-20
Fort Worth, TX
aerotestamerica.com
HyperWorks is a division of
Have a support question? Unable to access the web links in this email? We can help.
Please email [email protected] or call +1 248.614.2425 for assistance.
We want to know what you think about the Insider. Please share your opinion at [email protected].
If you no longer wish to receive your HyperWorks newsletter, send an email to [email protected] with “remove” in the subject line.
To learn more about Altair Engineering, visit us at www.altair.com.
page SEVEN