MYSTRAN Forum - ComLab and NASTRAN-95

Converting MSC Nastran Input Deck to NASTRAN-95

Sun, 18 Dec 2022 01:11:52 +0000

Hi All,

Does anyone have experience converting an MSC or NX Nastran input deck to a format NASTRAN-95 can read?

Here are some of the things I've done and I think it has got me most of the way there:
-insert lines from "INCLUDE"-ed files
-added an "ID" card at the top
-changed SOL 101 to SOL 1
-replaced CBEAM and PBEAM cards with CBAR and PBAR cards (luckily my model doesn't use advanced CBEAM functionality)
-replaced CBUSH and PBUSH with a set of CELAS1 and PELAS elements
-made sure my coordsys ID numbers on the CQUAD4 and CTRIA3 elements are < 1,000,000 (NASTRAN-95 manual specifies this)
-converted all my line continuations to labeled line continuations with a unique label for each one
-changed the names of my RBE2 and RBE3 elements to CRBE2 and CRBE3

Now the CRBE3 elements seem to be giving me trouble. I am getting singular columns in the stiffness matrix, and for of my RBE3 reference gridpoints, it says "EXTERNAL GRID PT. .... NOT CONNECTED".

The only way these grid points are intended to be connected to the model is through the RBE3 elements. They are used to distribute a point-force (applied at the RBE3 reference grid point) to other nodes. Does NASTRAN-95 not allow this?

Thanks,
Josh

ComLab Enhancments

Tue, 16 Mar 2021 14:49:37 +0000

Here is a list of enhancements that ComLab has:

https://www.mystran.com/comlab/ComLab_Enhancements.pdf

ComLab (an improved NASTRAN-95) has been released to the public

Wed, 10 Feb 2021 07:47:05 +0000

Harry Schaeffer has created an improved version of NASTRAN-95 called ComLab. It was previously a commercial program, but he has now released it to the public and we are hosting it here. We are looking into adding the source code at a later date as well.

Full Package is on hold.
https://www.mystran.com/comlab/CML.pdf - User Manual (part of the full package)
https://www.mystran.com/comlab/INSTALL.pdf - Installation Guide (part of the full package)
https://www.mystran.com/comlab/COMLAB_EULA.pdf - License Agreement (note that Harry has released ComLab to the public now so this may not be a current document, but is provided for reference)

Harry wrote one of the first books about NASTRAN and it was published in 1979. He also helped release one of the first complied versions of NASTRAN-95
https://www.amazon.com/Nastran-Primer-St...B000O15X8Y

hfcNASTRAN95 - Pre/Post processing for NASTRAN95

Sun, 26 Jul 2020 22:44:39 +0000

Hi,

The project is at https://github.com/ceanwang/hfcNastran95

Some case photos could be seen from this post:

https://forum.freecadweb.org/viewtopic.php?f=18&t=39234

and demo case:

https://forum.freecadweb.org/viewtopic.php?f=18&t=48982

Regards,

Cean

CodeBlocks Notes - CalculiX

Sat, 23 May 2020 22:25:29 +0000

Here are some notes from Harry Schaeffer about using C::B to build CalculiX. There is also some history about NASTRAN and some notes about NASTRAN-95. Some of the information here may be useful for building NASTRAN-95 and MYSTRAN.

https://www.mystran.com/misc/Calculix_an...Blocks.pdf

More Notes from Harry Schaeffer

Wed, 13 May 2020 18:49:39 +0000

Notes from Harry Schaeffer:

1. The IFP should be thrown away. I suggest marrying pynastan code and sqlite. Steve has done a lot of work in writing code for parsing and validating bulk data. These data can then be written to sglite tables.

2. Write interface routines to replace the geom1, 2, etc files. The code that implements the bulk data items still expects to find the internal bulk data codes.

3. The MPL should be replaced so that it is easier add new modules.

4.The checkpoint/restart must be replaced with a database restart.

5. Several helper fortran modules such as a scratch file manager would be useful.

6. Rethink the startup code.

7. Remove and replace the eigen and solve routines.

Compling NASTRAN-95

Mon, 27 Jan 2020 03:22:52 +0000

Here is the original source code from NASA:
https://github.com/nasa/NASTRAN-95

Based on this, Thomas Hermann (along with Harry Schaeffer), created this version:
https://github.com/OdonataResearchLLC/NASTRAN-95

Later, it seems (but not exactly sure of the timeline), that Luca created this version for Linux, which was was later distributed with Ubuntu:
https://github.com/ldallolio/NASTRAN-95
I think this is a more user friendly version that is easier to set up on the host computer, but not sure. TBD item.

Note from Vittorio:
I also compiled successfully NASTRAN-95, both under linux (Ubuntu 16.04) and Cygwin/windows. Under ubuntu the simplest way is to use the debian version already available.

Documents

Mon, 27 Jan 2020 03:13:27 +0000

Bill pointed us to the full user manual (1382 pages). The important of this manual (unlike the one on GitHub), is that is has the "Quick Reference Guide", which is what most end users are used to (as opposed to the programming related aspects).

https://ntrs.nasa.gov/search.jsp?R=19720022271

Thomas Hermann has a large collection of documents here:

https://www.odonata-research.com/referen...talog.html

https://www.odonata-research.com/referen...talog.html

A theoretical manual is here:
https://ntrs.nasa.gov/search.jsp?R=19790019360

A list of elements is shown here:
A list of elements is shown here ( https://github.com/SteveDoyle2/pyNastran/issues/583 )

Some Notes about NASTRAN

Wed, 15 Jan 2020 20:09:46 +0000

These are some notes about NASTRAN, which may help to shed light about the state of NASTRAN-95:
-------------------------------

The FTC settlement with MSC resulted in the sale of UAI NASTRAN to a competitor. It wasn't made public. As I recall SDRC was the purchaser. They eventually were taken over by Siemens and UAI Nastran is part of their engineering software offering. The original NASA NASTRAN is still available but I don't know the details about that.

The original Nastran was written in a subset of FORTRAN IV that would compile on IBM, CDC and Univac machines. Starting around 1979 led a project to put NASA Nastran on the Digital Equipment VAX computers running VMS. MSC complained about our doing what they had shown little interest in doing. MSC then did an updated version themselves that ran on VAX and other brands with FORTRAN 77 compilers.

Meanwhile UAI also migrated their version to the VAX and other platforms including PCs running Windows. I provided the VAX computer UAI used for a lot of their debugging. You may recall that we had a rather rocky start with UAI Nastran but I helped them in various ways to use our VAX via a phone dial up connection (1200 baud!). Given the three hour difference in California time, the arrangement worked fairly well as they used our VAX after we went home. Eventually UAI's version worked as well as MSC's did. As you know, UAI had better sub structuring. Eventually MSC took over UAI and then CSA for good measure. Somebody (not us) sicced the FTC on them and that eventually led to the anti-trust trial that almost happened. The day before the trial, MSC folded and negotiated the settlement that led ultimately to the Siemens version.

NASTRAN-95 vs MYSTRAN

Sat, 11 Jan 2020 00:01:03 +0000

It is relevant to compare MYSTRAN to NASTRAN-95 and also discuss the state of NASTRAN-95.

-----------------------------------------------------

NASTRAN-95 (Advantages):
- More developed and includes aero and fluid elements.
- More history of use (more well known)
- The buckling solutions are more developed (MYSTRAN only supports beam elements for Eigen solutions).
- DMAP capability

NASTRAN-95 (Disadvantages):
- The user manual may need updates.
- Some of the element formulations are old (i.e. shells may exhibit shear locking).
- The code may be difficult to develop, but there may be a few developers who can work with it.
- The solver that is used may be outdated by today's standards (considering the solver is at least 25 years old).
- No PSHELL or PCOMP?

NASTRAN-95 (Unknowns):
- There appears to be some nonlinear analysis capability, but the extent is not known. Need to investigate the MATS1.

-----------------------------------------------------

MYSTRAN (Usability)
- A compiled version for Windows exists.
- Complete processes for compiling in Windows using open source tools.

MYSTRAN (Advantages)
- Perhaps the biggest advantage of MYSTRAN is developers should find it more user friendly.
- Created with more modern software and hardware in mind.
- User manual is complete and updated.
- Newer solvers can be incorporated with relative ease.

MYSTRAN (Disadvantages)
- Not as developed (less features) or well known as NASTRAN