## CalculiX generate the substructure stiffness matrix

## CalculiX generate the substructure stiffness matrix

(OP)

Hello everyone

recently I'm trying to use Calculix to generate the substructure stiffness matrix. But I don't know how to control the output directory of the mtx file.

Then I read the source code file ccx_2.10.c and notice there is a parameter about the output file. just post the code as follow

for(i=1;i<argc;i++){

if(strcmp1(argv[i],"-o")==0) {

strcpy(output,argv[i+1]);break;}

}

but when I try to use the -o parameter with ccx.exe, it doesn't show any different with or without using output parameter.

Another problem I encountered is about element stiffness matrix output problem, since there isn't an example for users.

Thanks for any help!

recently I'm trying to use Calculix to generate the substructure stiffness matrix. But I don't know how to control the output directory of the mtx file.

Then I read the source code file ccx_2.10.c and notice there is a parameter about the output file. just post the code as follow

for(i=1;i<argc;i++){

if(strcmp1(argv[i],"-o")==0) {

strcpy(output,argv[i+1]);break;}

}

but when I try to use the -o parameter with ccx.exe, it doesn't show any different with or without using output parameter.

Another problem I encountered is about element stiffness matrix output problem, since there isn't an example for users.

Thanks for any help!

## RE: CalculiX generate the substructure stiffness matrix

You'll probably have more luck asking on the CalculiX forum where the programmer sometimes answers questions: https://groups.yahoo.com/neo/groups/CALCULIX/conve...

## RE: CalculiX generate the substructure stiffness matrix

I already tried, it works. And I also write a bat file to cd to the inp directory, and the output file would be created in the same path.

Another problem is, why the stiffness matrix generated by CalculiX is different from the one generated by Abaqus with the same inp file?

Can anyone help me to figure out which one is correct.

Thanks!

## RE: CalculiX generate the substructure stiffness matrix

To test if it's correct, it's probably easiest to solve it and see if you get the correct displacements - not forgetting to check for mesh convergence.

## RE: CalculiX generate the substructure stiffness matrix

I recover these two output mtx files. The data structure are different.

Calculix result

Abaqus result

I choose to believe abaqus result, and there may be some software bugs in ccx, or I used ccx with a wrong way.

The stiffness matrix is attached as below.

## RE: CalculiX generate the substructure stiffness matrix

## RE: CalculiX generate the substructure stiffness matrix

There have been bugs with beams and shells in CCX related to the way it converts them to solids internally. If anything was going to work right, it would be solid elements.

## RE: CalculiX generate the substructure stiffness matrix

What I need, is the original shell element and exporting the stiffness matrix for the another application to use.

So if there isn't a recovering progress, the directly exported stiffness matrix would not suitable for my using case.

Does anyone has a solution for my trouble, or substitute scheme?

Thanks!

## RE: CalculiX generate the substructure stiffness matrix

## RE: CalculiX generate the substructure stiffness matrix