ADAMS/Durability Release Notes

Report stresses/strains in other coordinate systems

You can now choose the coordinate system in which to report stresses and strains. In prior releases, you were limited to using the local part reference frame.

Now, you can specify a reference marker from the Compute Nodal Plot dialog box (in ADAMS/Durability), or specify the marker on the FEMDATA statement.

This example (ADAMS/Solver dataset):

FEMDATA/1, STRAIN, FLEX_BODY=11, RM=99, NODE = 101
OUTPUT/STRAIN=DAC

will rotate the six components of strain (Exx, Eyy, Ezz, Exy, Eyz, Ezx) for node 101 on flexible body 11, with respect to the instantaneous coordinate reference defined by marker 99. The complete time history of the transformed strain components will be output to DAC files. Note that marker 99 can be located anywhere in the model and does not have to belong to flexible body 11.

Higher Order Spline Interpolation (C++ Solver and experimental feature only)

In addition to the linear and cubic interpolation methods offered in the FORTRAN solver, in 2005 you now have access to higher-order interpolations for DAC or RPC III file data when using the C++ Solver. To access this feature, you must set the environment variable MDI_SOLVER_DUR_EXPERIMENTAL before running the simulation. For example:

On UNIX: setenv MDI_SOLVER_DUR_EXPERIMENTAL 1
On Windows: export MDI_SOLVER_DUR_EXPERIMENTAL 1

This environment variable can also be set with a special string in the ADAMS dataset as follows:

STRING/9876789,string=MDI_SOLVER_DUR_EXPERIMENTAL

In the INTERP function, you specify the degree of interpolation, which is 1 less than the order (order=degree+1). The cubic method used in the prior release is now equivalent to a degree of 3 (which means it is 4th order).

In this example, 5th-degree interpolation is used for the DAC-based spline/101.

Example (ADAMS/Solver dataset):

SPLINE/101
, UNITS = "length"
, LINEAR_EXTRAPOLATE
, FILE = ./random.dac

VARIABLE/2, IC = 0, FUNCTION = INTERP(TIME+1, 5, 101, 0)

For an example, see Knowledge Base Article 1-KB12411.

Note: This feature is known to give incorrect results for some models after Integration restarts when the integrator has to back up in time. A warning message is issued during the simulation.

Documentation Enhancements

ADAMS/Durability Documentation Improvements

Improved documentation as follows:

• Added information on coordinate reference transformation.
• Updated the online help and the guide, Getting Started Using ADAMS/Durability to reflect other changes made to the product.

Overall Documentation Improvements

For MSC.ADAMS 2005, we've made improvements to the MSC.ADAMS help:

• Added global search so you can search across the entire set of MSC.ADAMS help. To access the global search, do one of the following:

  • At the top of the help, select Switch Products, and then select the Search tab.

  • In any product, select the Search tab, and then in the window that appears, select Global Search.

  Note that the global search does not include any .pdfs (including getting started guides and ADAMS/Driver).

• Removed any hardcoding of font sizes so you can scale the text of the help to any size. Please note that many of the equations do not scale because they are images, and the help looks the best when viewed with medium (or 100%). In addition, your browser will print the text the same size as it is displayed.

• Documented many of the environment variables for the products to help customize your session. The environment variables are for ADAMS/Controls, ADAMS/Durability, ADAMS/Flex, ADAMS/Solver, ADAMS/View, and the template-based products (ADAMS/Aircraft, ADAMS/Car, ADAMS/Driveline, ADAMS/Rail). For more information, see the Running and Configuring help.

ADAMS/Durability licensing simplified

We have simplified the licensing of ADAMS/Durability so that the reading and writing of DAC and RPC III files will no longer require the ADAMS_DURABILITY_IO feature. Now, the other MSC.ADAMS products may freely take advantage of these file formats, allowing you to readily incorporate the usage of those files in your virtual product development processes.

The ADAMS_MSR_FATIGUE feature is now required for any recovery of modal stress (strain or life). The STRESS and STRAIN options on the OUTPUT statement are licensed. Therefore, the value of ADAMS/Durability is clearly focused on its modal stress recovery solution, post-processing, GUI support, and its interface with fatigue tools (for example, MSC.Fatigue).

Note that if you simply want to export load/nodal/modal information for subsequent modal stress recovery elsewhere (such as in MSC.Nastran), then no ADAMS/Durability license is required.

Intermediate output binary file (38543, 40630)

While durability simulations using FEMDATA are running, an intermediate binary file is now written to guard against problems accessing an ADAMS/Durability license, or other problems, such as exceeding disk space, application crashes, and so on. Now, you can postprocess the binary file by running the 'res2dur' utility in the stand-alone durability toolkit. Refer to the ADAMS/Durability online help for information on res2dur.

FEMDATA map and DAC/RPC naming convention (38544)

If environment variable MDI_DUR_LOADMAP is set, then an ASCII file is generated. This is a spreadsheet that maps the loads from MBD to FE for DAC output only. The name of this file is <job_name>.map, where <job_name> is the name given on the FILE argument of the first FEMDATA statement. If no FILE argument is given on any FEMDATA statement, then the simulation run name is used.

Because it was unclear whether or not users would need a header included at the time of implementation, another variable called MDI_DUR_LOADHEADER is checked, and if set, prints the header information to the file.

With MDI_DUR_LOADMAP set, DAC files of all requested FEMDATA loads are sequential and mapped according to the load map file. If an offset other than 0 is desired in the sequential naming of the DAC channel numbers, then the environment variable MDI_DUR_LOADOFFSET can be used to define the offset. For example, without an offset set, DAC files start with the name:

job_name_001.dac
job_name_002.dac
...

If MDI_DUR_LOADOFFSET is set to 300, DAC file names start with:

job_name_301.dac
job_name_302.dac
...

Memory control for hotspots calculations (41305)

For certain large models, the Durability modal stress recovery (MSR) was taking too much memory to process the results (in one instance, more than what was available, so the machine was spending most of its time swapping).

By default, ADAMS/Durability will now take up to a maximum of 400 MB of swap space when performing MSR. An environment variable, DUR_MSR_MB_LIMIT, has been introduced to override this default.

For example, to limit ADAMS/Durability to 800 MB of swap, on most UNIX platforms, set the environment variable as follows before starting ADAMS:

setenv DUR_MSR_MB_LIMIT 800

In general, the more swap space that is available for ADAMS/Durability, the faster MSR will perform. The following formula can be used to determine how much memory ADAMS/Durability will allocate for MSR:

MB = 24e-06 * N * M

where N and M are the number of nodes and modes, respectively, of the flexible body. Typically, you should allow only half of the machine's available RAM to MSR, leaving the other half to the MSC.ADAMS process. Therefore, if the above computation for MB exceeds more than half of the amount of available RAM, consider setting the DUR_MSR_MB_LIMIT environment variable.

45717

DAC file support now works on Linux. Note that DAC file formats are equivalent on Windows and Linux (on Intel).

Results file size and FEMDATA use (46979)

In an effort to minimize the size of ADAMS/Solver output files when using FEMDATA, extra measures have been taken to maximize data compaction. However, these are only in effect if you have not enabled the saving of the results file (.res). Therefore, we recommend that you do not save the results file when using FEMDATA for durability simulations that generate lots of output.

If you must save the results file when using FEMDATA, we recommend that you limit the amount of data that gets written. The following example uses FEMDATA to output loads in DAC file format, saving the results file (which is not normally recommended):

FEMDATA/1,LOADS,FLEX_BODY=2, NOINERTIA
OUTPUT/LOADS=DAC

RESULTS/XRF,DECIMALPLACES=8
,NOVEL,NOACC,NODATA,NOFLOAT
,NOLIN,NOREQ,NOSYS,NOTIR

This RESULTS statement will significantly reduce the size of the temporary .res file that is generated for FEMDATA calculations. The default for DECIMALPLACES is 17 (full double precision), but because DAC stores data in single precision, you can safely use 8 digits after the decimal point. The second and third lines suppress the output of everything except applied and reaction forces. Obviously, when outputting data other than loads to DAC, such as requests or stress, you would need to modify this line accordingly.