Meshing textile for dry fibre analysis

[anuragdixitiitd]

Hi Louise,
Thanks for the reply.
One Major question which I wanna ask regarding modelling in TexGen is that:
1. While exporting the dry fiber file there are only two options for the element selection i.e. C3D8R & C3D8? What about if I want to use other elements (may be tetrahedral or quadrilateral)? If for that I have to change my script then what is the procedure.Can you please provide some link or example...

2. Similarly for the change in mesh....? Where should I edit or make change in my script.

Best Regards
Anurag

[louisepb]

Hi Anurag,

The only ways that you can produce a mesh of the dry fibres from within TexGen are using the dry fibre export (using hex and wedge elements) or by selecting just the yarn in the voxel mesh export (giving regular hex elements). Obviously if you use the voxel export then you will need to add compression plates yourself if you're simulating compression.

If you want to produce other meshes of just the fibres then you will need to export the surface model and then use some external meshing software to produce your mesh. You will then need to produce your ABAQUS input file yourself from this. Using the File->Export->Surface Mesh option will enable you to export the surface mesh (as you see when you render in x-ray mode) to either .vtu or .stl file format. Alternatively you can export the model in either STEP or IGES formats.

Louise

[anuragdixitiitd]

Hi Louise,
I can understand this, but in dry fiber export option there are only brick elements (c3d8r & c3d8) available there are no hex & wedge elements. The same is the case with voxel export option. I mean to say suppose I want to use 4 node tetrahedral elements (c3d4) should I simply export using surface mesh and then use abaqus or any other meshing software to produce these.
Regards
Anurag

[louisepb]

Hi Anurag,

Although the dry fibre export only specifies brick elements (which are essentially hex elements) it actually exports both hex and wedges. If you look at the mesh produced you can see that it puts wedge elements in the 'corners'.

As I said before, if you want to produce tetrahedral elements of just the fibres then you will need to export the surface and use other meshing software to produce the mesh. The File->Export->Volume Mesh option will produce tetrahedral elements of both the yarn and matrix. I suppose that you could possibly use this and then remove the matrix elements (haven't tried that though - it's just a thought).

Best regards,
Louise

[anuragdixitiitd]

Hi Louise,
I can easily export the 1x1 (.step &.iges file) from Tex Gen, but when I am trying to export the same files for 2x2 twill or satin weave geometry, a message occured "An unhandled exception occured" Press abort to terminate the programme.How should I export?????
Secondly which third party software would you recommend for mesh generation!! I am currently using NETGEN 4.9.13 (open cascaded), but can only import IGES file not STEP & surface mesh files, also facing probs in refinement and generation of meshes.

Thanks & Best Regards
Anurag

[louisepb]

Hi Anurag,

The problem when exporting is probably with the OpenCascade export functions. Which TexGen version are you using? The 64-bit version seems to be more robust when exporting to IGES and STEP. You could try that if you're not using it (if you have a 64-bit machine obviously!). Otherwise you could send me the textile you're trying to export and I can double check whether the problem is in the OpenCascade part of the software or whether it's a TexGen problem.

I think that Hypermesh is probably the software most often used for meshing in our department.

Louise

[anuragdixitiitd]

Hi Louise,
I will double check and reply you.
Best Regards
Anurag

[louisepb]

Message posted on other thread:
Hi Louise,

I'm interested to know detail on dry fibre options. In your other thread, you did mentioned about creating geometry without matrix, where there are 2 options; a) exporting them using Dry fiber or b) voxel mesh without matrix. However, in Dry fiber options, I need to state the compression percentage that I would like to achieve. Let say, I created a design in voxel mesh options, how could I get the same design as in voxel with dry fiber options? I mean in terms of the loading condition. I intend to put in the friction info in my geometry in which I did created a geometry with voxel mesh options previously. Since you mentioned the only way to modify the friction is with Dry fibre option so I'm aware about the implementation of load in both cases.

Yanie

[louisepb]

Hi Yanie,

I'm not absolutely clear as to what you're asking here. You can create a textile and then either mesh it with the voxel mesh or dry fibre option. If you leave the scales as 1.0 and don't apply compression plates in the dry fibre export then you will have the same model as produced by the voxel export but meshed differently. You will need to specify loads etc yourself to suit your requirements.

Louise

[dyeyanie]

HI Louise,

Sorry for many questions. If I checked the compression plates and leave the scales as 1 how could I specify the load?I'm not really clear about that. If I compared to voxel meshing options, loads are automatically reloaded. Could I just gained this load values into dry fibre meshing?

Yanie

[louisepb]

Hi Yanie,

I think that my last answer was slightly misleading. The dry fibre export applies the load differently to the voxel export. Essentially a displacement is applied which is specified by the scale. If you apply a scale then the Step section will apply a displacement to the node closest to the centre of each yarn in each of the x, y and z directions as appropriate. You can see this in the section which starts with the comment "*** Constrain the nodes closest to the geometrical center of each yarns".

If you want to specify different loading yourself then you can leave the scales as 1.0 and edit the .inp file to add your own loads as required.

Louise

[dyeyanie]

Hi Louise,

thanks for your fast response. So, from what I understand here, the loading condition in dry fibre export is correlated to the compression, bending and tension analysis where by identifying the X, Y and Z load differently, we managed to impose the load as in tension, compression or bending condition. Is this true? I went through a paper of you entitled "Automated geometric modelling of textile structures" which highlighted these conditions. May you share here how you implemented them in Dry fibre export?

Yanie

[anuragdixitiitd]

Hi Louise,
Hope you must be fine.
Suppose I wanna achieve 50% compression along with the compression plate in abaqus dry fiber export file, should i enter 0.50 in all X,Y,Z scale or only in Z scale keeping X and y scale as 0. Can I change these values in .inp file if yes I couldn't find it where!! or every time i have to export again and again with different values of X,Y,Z scale.
Secondly, how can I maintain a initial distance between two platen before compression starts? Lastly how can I play with loading conditions directly in .inp file as no option or text of loading occurs in the .inp file.
Sorry for too many questions.
Regards
Anurag

[louisepb]

Hi Anurag,
If you want to apply a compression in the z direction you should specify the z scale and use the compression plate. The compression plates are necessary as there are no boundary conditions specified in the z direction. As described earlier in this thread the displacements are applied to the centre points of each yarn. These are calculated by TexGen so if you want these calculated for you then you will need to reexport for different levels of compression.

The initial spacing of the compression plates is specified as being the top and bottom of the domain. You will need to look at the Abaqus manual if you want to change this.

If you want to apply different loadings then you can edit the .inp file yourself, adding required sections for loads etc. Again you need to refer to the Abaqus User Manual to find what you want to do.

Best regards,

Louise

[anuragdixitiitd]

Thanks Louise!!