Table Of ContentWelcome to Adams/Durability 1
Welcome to Adams/Durability
2 Adams/Durability
Introduction to Adams/Durability
Introduction to Adams/Durability
Adams/Durability, part of the MSC Adams 2011® suite of software, extends the traditional test-based
durability design process into the virtual world. With Adams/Durability, you can simulate a durability
duty cycle and write out component load histories in or formats and drive a durability test rig using
output data in RPC III Format or DAC Format. You can visualize stress or detect hot spots in flexible or
rigid components, and you can improve component design by interfacing with fatigue life prediction
programs.
Some of the features of Adams/Durability are available as a demand-loaded library (DLL), while the rest
are available as a plugin to the various Adams interface or vertical products, such as Adams/View,
Adams/PostProcessor, and Adams/Car.
How You Benefit from Using Adams/Durability
Adams/Durability enables you to work faster and smarter, letting you easily interface with durability test
machines using the RPC III Format, and with fatigue life calculation programs using DAC Format, or with
an FEA program for stress recovery.
You benefit from using Adams/Durability in the following ways:
• Shortens your development cycle, reducing costly durability testing.
• Reduces disk space requirements and improves performance by providing direct file input and
output in RPC III and DAC formats. For example, when you perform a 25-second Adams
simulation with 300 channels of data, sampled at a rate of 409.6 points per second, to capture a
durability event, the Adams Request files are approximately 48 MB, whereas the RPC III file is
only 6 MB.
• Provides access to the system-level simulation capabilities of Adams/View, or vertical products,
such as Adams/Car.
• Provides access to dynamic stress recovery methods using NASTRAN or ANSYS.
• Performs modal stress recovery of flexible bodies.
• Provides access to component life prediction using MSC.Fatigue or FE-Fatigue.
Using Adams/Durability On Demand
The Adams/Durability installation includes a library that is compatible with most of the Adams products,
including Adams/View, Adams/PostProcessor, Adams/Solver, and the vertical product solvers such as
Adams/Car Solver. This library provides the DAC and RPC III file capabilities of Adams/Durability. It
is demand-loaded automatically by the various products when you use a feature of Adams/Durability that
requires this library; therefore, you do not need to know how to access this library.
With the Adams/Durability demand-loaded library, you can simulate a durability duty cycle in Adams
and write out component load histories in RPC III and DAC formats. For example, you can simulate a
virtual test rig where actuator inputs like spindle loads are taken from field measurements and stored in
Welcome to Adams/Durability 3
Introduction to Adams/Durability
the RPC III format. Then, you can write out component load histories in DAC format for subsequent
component durability testing or fatigue life prediction.
You can perform the following with DAC or RPC III files:
• Browse the files for header information, such as number of time steps, sample rate, number of
channels, channel names, channel maximums, and channel minimums.
• Plot the time history data.
• Filter, integrate, or transform the sampled data.
• Drive or excite Adams models with the data.
• Interpolate the channel data by cubic splines.
Loading the Adams/Durability Plugin
The Adams/Durability plugin gives you access to the various stress recovery techniques in Adams, and
interfaces to NASTRAN, ANSYS, FE-Fatigue, and MSC.Fatigue. This plugin is available in most of the
Adams interface or vertical products, such as Adams/View, Adams/PostProcessor, Adams/Car, and
Adams/Driveline.
To load the Adams/Durability plugin:
1. Start one of the Adams interface or vertical products.
2. From the Tools menu, select Plugin Manager.
3. Select the Load checkbox next to Adams/Durability.
4. Select OK.
This creates the Durability menu, adds various stress and strain Plot Type menu options for the
Contours tab in Adams/PostProcessor, and adds several functions to the Misc. Functions category
in the Adams/View Function Builder, such as LIFE, MAX_STRESS, HOT_SPOTS, and
TOP_SPOTS.
To unload the Adams/Durability plugin:
1. From the Tools menu, select Plugin Manager.
2. Clear the Load checkbox next to Adams/Durability.
3. Select OK.
4 Adams/Durability
Introduction to Adams/Durability
Performing Stress Recovery 1
Performing Stress Recovery
2 Adams/Durability
Stress Recovery in Adams/Durability
Stress Recovery in Adams/Durability
With Adams/Durability you can recover stresses on flexible or rigid bodies. Recovering stresses on
flexible bodies is called Modal Stress Recovery (MSR). You can perform MSR inside Adams or, in the
case of NASTRAN, outside of Adams.
Recovering stresses on rigid bodies is based on the loading time history of the component and its
geometry and mass. If a finite-element mesh is available for the rigid component, the forces from an
Adams simulation can be exported and applied to the component’s mesh. A finite element program like
NASTRAN can then be employed to recover the static stress resulting from the foce application at each
Adams output step. This method of stress recovery is sometimes referred to as quasi-static stress
recovery.
Note that user functions are available for modal stress recovery to determine hot spot regions and
maximum stress. Learn more about User Functions.
Performing Stress Recovery 3
Modal Stress Recovery
Modal Stress Recovery
The benefit of this process is being able to recover any type of output that is available in MSC.Nastran
(also MD Nastran) such as element stresses or strains, nodal forces, and so on. Due to limitations of the
MNF, only grid point stresses or strains can be post-processed in Adams. Also, MSC.Nastran does not
allow grid point stress or strain on composite shell elements or beams, so it is not possible to post-process
strain or stress for these type of elements in Adams. In addition, plates or shells have more than one layer,
but the MNF allows only one layer of stress or strain to be stored in the file. These limitations are avoided
by exporting data for MSC.Nastran.
MSC.Nastran has the function to recover stresses and strains in the version 2006 (MDR1) and later, and
a special DMAP is not required. For modal stress recovery, a restart run is used thus MSC.Nastran
database (.MASTER and .DBALL) have to be kept in the primary run to build the flexible body for
Adams, and to do that the command option "scratch=no" should be applied. Modal transient response
analysis (SOL 112) and modal frequency response analysis (SOL 111) should be applied for time
dependent data and frequency dependent data respectively with ADMPOST parameter.
Learn Exporting Data for NASTRAN.
Note: AUTOQSET cannot be used for the primary run due to the limitation of MSC.Nastran
restart capability
Restarting NASTRAN
A restart MSC.Nastran for modal stress recovery needs to be specified at the top of the MSC.Nastran
input deck in the file management section:
ASSIGN <logical name>='<database name>'
RESTART LOGICAL=<logical name>
where <logical name> is the logical name of the database to be assigned and <database name>
is MASTER file name of the primary run. Note that the logical name is arbitrary characters within 8
letters and first one should be alphabet.
Reading Modal Deformations File (MDF)
Modal deformations to be read have to be in binary (OUTPUT2) format, and the following statement
needs to be specified near the top of the MSC.Nastran input deck in the file management section:
ASSIGN INPUTT2='<MDFilename>' UNIT=<load ID> [FORM=<binary
format>]
where <MDFilename> is the name of the modal deformations file from Adams. For directions on how
to create this file, see the FEMDATA or OUTPUT Adams/Solver statement. And <load ID> indicates
an ID number of DLOAD statements in the case control section. The option FORM may be requested
when the binary format of MDF is not applicable to the platform of MSC.Nastran (see the MSC.Nastran
quick reference guide for more information).
4 Adams/Durability
Modal Stress Recovery
Results Postprocessing
Dynamic stress/strain output can be either in F06, PUNCH OUT, XDB or OUTPUT2 according to
standard MSC.Nastran functionality, and the output files can be postprocessed in Patran or SimXpert
Structures.
If displacements, stresses, and/or strains are to be available for postprocessing, one or more of the
following statements must appear in the case control section of the MSC.Nastran input file:
DLOAD = <load id>
DISP(PLOT) = <set id>
STRAIN(FIBER,PLOT) = <set id>
STRESS(PLOT) = <set id>
where <load id> is a ID number indicated by ASSIGN statement in the executive control section, and
<set id> is a ID number defined in SET statement.
PARAM, ADMPOST
Request modal stress recovery (see the MSC.Nastran quick reference guide for more information):
• 0: Modal stress recovery is not activated (default)
• 1: Request modal stress recovery without rigid body motion
• 2: Request modal stress recovery with rigid body motion
This parameter is used to activate modal stress recovery and control the addition of rigid body motion
with modal deformations. Rigid body motions from an Adams simulation are included in the modal
deformations file (MDF), but they are not applied unless this parameter is set to 2. Including rigid body
motion affects the display or animation of the flexible component, but it has no effect on dynamic
stresses.
PARAM, POST
Request stress/strain/displacement output for postprocessing (see the MSC.Nastran quick reference
guide for more information):
• <= 0: Yes
• > 0: No
Example of Input File
An example MSC.Nastran input file for modal stress recovery run compared to a typical input file for
building flex body is shown below. These examples are located in the following installation files:
• <Adams installation directory>/durability/NASTRAN/plate.dat
• <Adams installation directory>/durability/NASTRAN/plate_msr.dat
• <Adams installation directory>/durability/NASTRAN/plate.cmd
Performing Stress Recovery 5
Modal Stress Recovery
Note that "plate.cmd" is the command file to create the example model with the flex body (MNF) by
"plate.dat" and run the dynamic simulation.
For building flex body (plate.dat) For modal stress recovery (plate_msr.dat)
ASSIGN PRIMARY='plate.MASTER'
Restart setting
RESTART LOGICAL=PRIMARY
ASSIGN INPUTT2='plate.mdf' UNIT= 31 → Read MDF
SOL 103 SOL 112 → Modal transient analysis
CEND CEND
$ GLOBAL CASE $ GLOBAL CASE
METHOD = 1 METHOD = 1
ADAMSMNF FLEXBODY=YES
DLOAD = 31
DISP(PLOT) = ALL Output data setting
STRESS(PLOT) = ALL
BEGIN BULK BEGIN BULK
PARAM, ADMPOST, 2
Parameter setting
PARAM, POST, -1
DTI, UNITS, 1, KG, N, M, S
ASET1, 123, 1, 11, 78, 88
SPOINT, 10001, THRU, 10030
QSET1, 0, 10001, THRU, 10030
Geometry data is not needed
EIGRL, 1, , , 30
$
GRID, 1, , 0.0, 0.75, 0.0
GRID, 1, , 0.1, 0.75, 0.0
…
ENDDATA ENDDATA
6 Adams/Durability
Stress on Flexible Bodies
Stress on Flexible Bodies
Recovering Stresses on Flexible Bodies
In order for Adams/Durability to compute stresses on a flexible body, the flexible body in your model
must contain FEA stress mode information in its modal neutral file (MNF). For more information on
including stress mode shapes during MNF generation, see the Adams/Flex online help.
You can also compute strains on a flexible body if its MNF contains strain mode information from FEA.
Computing Stresses or Strains
You can use Adams/Durability to calculate nodal stress or strain values. These values can be used to
generate x-y plot displays. When you compute nodal plots, the directions x, y, and z are with respect to
the flexible bodies' local-body-reference-frame (the FEA package's global coordinate system).
To compute stresses or strains:
1. From the Durability menu, select Nodal Plots.
The Compute Nodal Plot dialog box appears.
2. In the Analysis text box, enter the name of a previously run analysis. Tips on Entering Object
Names in Text Boxes.
3. In the Flexible Body text box, enter the name of the flexible body.
4. In the Node to Add to List text box, enter one or more nodes on which to calculate stresses.
You can right-click in the text box, and select Pick Flexbody Node. Then, select a node by
clicking on a position in the model. As you pick the nodes individually, the Selected Nodes List
text box accumulates a list of all selected nodes.
5. Select stress or strain.
6. Select the values desired, as necessary.
7. Select OK.
8. Adams/Durability stores the stress or strain components in a flexible body result set for the
specified analysis. It adds the following field to the Adams/View database for the flexible body
being analyzed:
FBname_STRESS.NodeID_Value (for stress components)
FBname_STRAIN.NodeID_Value (for strain components)
where:
FBname is the name of your flexible body
NodeID is the node whose stress or strain you are calculating
_Value is the value of stress or strain you're calculating
You can also print these values to a text file.
Description:are available as a plugin to the various Adams interface or vertical products, such as Adams/View,. Adams/PostProcessor, and Adams/Car. How You Benefit
