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Developer Items to Consider
#1
This is a list of items for developers to consider. Developers are free take on any project they like. These are just some basic ideas:

MOST STRAIGHTFORWARD:

TBD

INTERMEDIATE:

1. For small DOF problems, the banded solver (LAPACK) can be used and is the current default. However, for larger DOF programs, a sparse solver is more effective. We previously looked at BCSLIB-EXT, but the cost is relatively high and it appears there may be other solvers that are just as good (if not better). The SPOOLES solver is an option, but it seems to be relatively slow compared to other options. PARDSIO with Intel MKL is an option, but requires an Intel compiler and the user must also download the Intel MKL. PARDISO 6 is more improved than PARDISO MKL, but requires the user download a free license every year. PaStiX may be the best option since it is modern and free. We can take a page from CalculiX and see how their investigation is going since they looking at other solvers. CalculiX has historically used SPOOLES, but recently added an option for the PARDISO MKL. EDIT: CalculiX has now implemented PaStiX and I think that will be the best option for MYSTRAN as well.

2. For the Eigen solution, beam elements have a differential stiffness matrix implemented in MYSTRAN. However, the shell and solid elements do not have the differential stiffness martrix coded. This would need to occur for them to be available for the Eigen solution.

3. Add a CBEAM element.

LONG TERM - PRE/POST

1a. pyNastran is capable of reading a BDF input file: ( https://pynastran-git.readthedocs.io/en/latest/ ). However, it can not read MYSTRAN ouptut files. It is capable of reading MSC Nastran OP2 files, but MYSTRAN would have to be coded to create an OP2 file to view the results in pyNastran. Steve Doyle (of pyNastran) is looking into adding OP2 output.

1b. CalculiX GraphiX is a pre/post that works with open source CalculiX solver ( http://www.dhondt.de/ ). It has basic functionality and is a lightweight program. This makes it rather convenient and I have used it with some routines to generate deflection/contour plots and pass them to Excel in real time ( https://www.espcomposites.com/software/advanced.html ). It does not support MYSTRAN, but it may be possible for MYSTRAN to create output files that are compatible with CGX (CalculiX GraphiX). One challenge is that CalculiX only uses solid elements (it expands beams and shells into 3D solids), so this could pose an issue that requires time to modify either the CGX or MYSTRAN programs.

LONG TERM - NONLINEAR

1. A nonlinear solver could be implemented. For starters, a bisection method solution may be acceptable. Using the bisection method, I think geometric nonlinearity would be the easiest to develop and implement. Material nonlinearity could possibly be addressed after that. This would be similar to the MSC Nastran SOL 106, which has some basic nonlinear capabilities. A full nonlinear implementation (with contact, etc.) would probably be beyond the scope in the near term.

LONG TERM - HIGHER ORDER ELEMENTS

1. An 8-node quad and 6-node tri could be developed in MYSTRAN.

--

Brian Esp
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#2
Very interesting! 

May I suggest the implementation of sensitivity output as another long-term development item? I am interested in displacement sensitivity wrt. material stiffness properties for example. 

Also, you suggest 'Developers are free take on any project they like'.  
Is this development managed through git-hub and is it open for community contribution?
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#3
(06-02-2020, 06:55 PM)O_Stodieck Wrote: Also, you suggest 'Developers are free take on any project they like'.  
Is this development managed through git-hub and is it open for community contribution?

Yes, any help is greatly appreciated. As of 7/1/2020, the project is on GitHub for further development.
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