Error exporting step file for NCFs

[himani]

Hi,

I am very new to TexGen. I am trying to export a step file from TexGem , in order to further model the tow-tow interaction, tow-stitch interaction using friction laws in ABAQUS. Everytime I try to export the unit cell model, TexGen seems to crash. Could you please provide me further guidance.

Thank you

[louisepb]

Hi,

Please could you provide me with details of which version of TexGen you are using and exactly what procedure you follow (and a file with your model if appropriate) so that I can try to replicate the error.

Best regards,
Louise

[himani]

Hi Louise,


I am using the version v3.8.2. Currently I am using the .tg3 file for NCFs posted by you in the previous posts. In order to export the step file to ABAQUS, I am just using file-export-step file.

Thank you

Himani

[louisepb]

Hi Himani,
I think that TexGen is crashing in the OpenCASCADE export library. I will look into this but, in the meantime, if you choose the 'Faceted' option and deselect 'Join Yarn Sections' then it creates the step file ok. I'm afraid that the OpenCASCADE isn't always terribly robust for complex geometries.

If you want to export just the yarns you could use the File->Export->ABAQUS File->ABAQUS Dry Fibre File option.

Hope that helps,
Louise

[himani]

Hi Louise,

Thank you for your reply. I have managed to import the model in ABAQUS using your suggestions. I am now trying to model stitch-stitch interaction and stitch-tow using element set contacts. Is this something which you have researched into before?

Thank you

Himani

[louisepb]

Hi Himani,
For textiles which have been generated using one of the wizards TexGen outputs contact sets. If you generate, for example, a simple plain weave and then use the dry fibre export you will be able to see what is generated in the .inp file.

It's one of those things that I've intended to generalise but haven't got around to yet..

I'd be interested to hear how you get on.

Best regards,
Louise

[himani]

Hi Louise,

I will surely keep you updated about my progress.

Currently, I seem to be getting confused in understanding the periodic boundary conditions and load cases. If I am trying to simulate the shear behavior of NCFs in ABAQUS in order to replicate the bias extension tests, how do I go about changing the BCs? Could you suggest a suitable reference to start with?

Thank you

Himani

[louisepb]

Hi Himani,

If you look here http://texgen.sourceforge.net/index.php ... and_Abaqus you will find a description of the boundary conditions used with the voxel mesh export and the reference for one of Shuguang Li's papers on boundary conditions. If you use the ABAQUS Voxel Mesh export option in TexGen and take a look at the .inp file produced you will be able to see the ABAQUS implementation of the boundary conditions described in the paper. These will be different to those you require but will hopefully give an example of how they are implemented.

Also there is a paper on the use of TexGen to model fabric shear attached.

Hope that helps,
Louise

[himani]

Hi Louise,

I am simply trying to extract the elastic properties of NCFs. I have assigned the contacts and added it to the input file as you suggested in earlier discussions. I am finidng it difficult to understand how the boundary conditions deal with load cases .i.e. do I have to apply a load or is it accounted for in the periodic boundary conditions?

Thank you

Regards,

Himani

[louisepb]

Hi Himani,

If you look at the .inp file from a voxel mesh export you will see that the loads are applied as described in Li's paper. The elastic properties can then be extracted using the script as described in the link in the previous message. The script applies the equations specified in the paper using the results of the simulation. Hopefully that will enable you to understand the method. If you are using a dry fabric and applying contacts you will probably need to adapt the method to suit.

I hope that helps,
Louise

[himani]

Hi Louise,

Thanks for your reply. I am using dry fiber export which does not have any loads applied. So I guess I can apply the loads as needed. But do I have to make any changes to periodic boundary conditions or they remain as given in the .inp file.

Thank you

Himani

[himani]

Hi Louise,

I have tried running my simulation after applying a uniaxial load in the x direction but I keep getting the following error,



Error in job NC: A BOUNDARY CONDITION HAS BEEN SPECIFIED ON NODE SET ASSEMBLY_DUMMY0 BUT THIS NODE SET IS NOT ACTIVE IN THE MODEL
Error in job NC: A BOUNDARY CONDITION HAS BEEN SPECIFIED ON NODE SET ASSEMBLY_DUMMY0 BUT THIS NODE SET IS NOT ACTIVE IN THE MODEL
Error in job NC: A BOUNDARY CONDITION HAS BEEN SPECIFIED ON NODE SET ASSEMBLY_DUMMY0 BUT THIS NODE SET IS NOT ACTIVE IN THE MODEL
Error in job NC: A BOUNDARY CONDITION HAS BEEN SPECIFIED ON NODE SET ASSEMBLY_DUMMY1 BUT THIS NODE SET IS NOT ACTIVE IN THE MODEL
Error in job NC: A BOUNDARY CONDITION HAS BEEN SPECIFIED ON NODE SET ASSEMBLY_DUMMY1 BUT THIS NODE SET IS NOT ACTIVE IN THE MODEL
Error in job NC: A BOUNDARY CONDITION HAS BEEN SPECIFIED ON NODE SET ASSEMBLY_DUMMY1 BUT THIS NODE SET IS NOT ACTIVE IN THE MODEL
Error in job NC: NODE SET ASSEMBLY_DUMMY0 HAS NOT BEEN DEFINED
Error in job NC: NODE SET ASSEMBLY_DUMMY0 HAS NOT BEEN DEFINED
Error in job NC: NODE SET ASSEMBLY_DUMMY0 HAS NOT BEEN DEFINED
Error in job NC: NODE SET ASSEMBLY_DUMMY1 HAS NOT BEEN DEFINED
Error in job NC: NODE SET ASSEMBLY_DUMMY1 HAS NOT BEEN DEFINED
Error in job NC: NODE SET ASSEMBLY_DUMMY1 HAS NOT BEEN DEFINED

Would you know why this happens?

Thank you

Himani

[louisepb]

Hi Himani,
The error messages seem to suggest that it's trying to use node sets ASSEMBLY_DUMMY0 and 1 but that they haven't been specified. Have you checked your .inp to check if this is the case?

Best regards,
Louise

[himani]

Hi Louise,

I have managed to solve this error. But now there is an issue when running the file. I get the following errors when I apply a uniaxial load in x direction,



***ERROR: An Equation has been used to constrain the rotation of Node 1 which
does not have rotational degrees of freedom active.


***ERROR: An Equation has been used to constrain the rotation of Node 60363
which does not have rotational degrees of freedom active.


***ERROR: An Equation has been used to constrain the rotation of Node 6 which
does not have rotational degrees of freedom active.


***ERROR: An Equation has been used to constrain the rotation of Node 12 which
does not have rotational degrees of freedom active.


***ERROR: An Equation has been used to constrain the rotation of Node 17 which
does not have rotational degrees of freedom active.

I have no idea why this is the case?

Himani

[louisepb]

Hi Himani,
Solid elements do not have rotational degrees of freedom so presumably the equations that you have specified conflict with this in some way. However, I'm afraid that I'm not an Abaqus expert so am not really the best person to advise on this. Is there anyone in your institution who could help?

Sorry not to be more help,
Louise