Implementing UMAT using shared library

1

Hi

I am trying to use a UMAT (attached) in calculix as a shared library.
I followed the procedure given in calculix documentation but the solution doesn’t proceed (please check bottom of terminal screenshot).

Here’s what I did:

  1. Assigned UMAT as the name of the subroutine inside the file UJ2PLASEMP.f
  2. Compiled UJ2PLASEMP.f using: abaqus make library=UJ2PLASEMP.f
  3. This resulted in 2 files: UJ2PLASEMP-std.o and libstandardU.so
  4. I renamed the latter file to libUJ2PLASEMP.so
  5. In the input file, I set the material name to: @UJ2PLASEMP_UMAT
  6. Submitted the job on the terminal

Can you please help me with this?
All files are uploaded to this folder

Thanks
Bhanu

Terminal screenshot:

image
image929×1043 101 KB

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2

It would be best if you compiled everything using the same compilers. I’m not sure if Abaqus does something different internally to create the libs. I haven’t tried it this way, to be honest, but it appears to be problematic just by thinking about it.

3

Thank you for your reply.
I just checked the compiler in the environment file of ABAQUS. It is “gfortran”.
And while compiling CalculiX, in the Makefile, the FC variable (Fortran compiler) was also set to “gfortran”.

I have uploaded two new files to the same folder:
File from abaqus directory mentioning Fortran compiler: lin86_64.env
CalculiX Makefile: Makefile

Based on these, can you please tell me if I need to modify the ABAQUS env file?

But otherwise, is the sequence of steps I have taken alright?
I mean could it be a syntax issue because of inconsistent names for the function, library, and material, which prevents CalculiX from reading the UMAT.

Thanks
Bhanu

4

Why don’t you use the umat thru the Abaqus umats and recompile ccx? It is a much cleaner approach and you will know exactly what is the problem because it won’t compile

5

In your Makefile I don’t see the compiler option
-DCALCULIX_EXTERNAL_BEHAVIOURS_SUPPORT
which seems to be needed to link UMAT related dynamic linked libraries to ccx. Try to compile the entire code with this option. Thank you!

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6

It would be also a good idea to also add the option
-DCALCULIX_EXTERNAL_BEHAVIOUR_DEBUG. That gives extra information about what is going on.
See the source code file external.c in the ccx source distribution.

7

Neither the Makefile nor the lnx86_64.env are usable as-is.

The Makefile is for building CalculiX itself.
The Python script lnx86_64.env defines some useful commands but doesn’t execute them.

You should be able to build a shared library from a single file like this:

gfortran -shared -O2 -fPIC -o libUJ2PLASEMP.so UJ2PLASEMP.f

Note that this currently fails because a needed include file is not in your folder:

> gfortran -shared -O2 UJ2PLASEMP.f -o libUJ2PLASEMP.so -fPIC
UJ2PLASEMP.f:18:0:

   18 |       INCLUDE 'ABA_PARAM.INC'
      | 
Fatal Error: Cannot open included file 'ABA_PARAM.INC'
compilation terminated.

Note: The file aba_param.inc can be found here; don’t forget to rename to uppercase.

With ABA_PARAM.INC available, the compilation works, and the shared library contains the external symbol for umat (checked on a FreeBSD UNIX machine):

nm ./libUJ2PLASEMP.so | grep ' T '
0000000000001884 T _fini
00000000000006d0 T _init
0000000000000860 T umat_

If I understand the CalculiX manual correctly, the material name for the user material should indeed be @UJ2PLASEMP_UMAT.

Note that you should rebuild CalculiX with the option to load shared libraries, as @johanngil explained.

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