Learning Forum

[Majeed]

Dear all;

 

I want to apply a tensile test on randomly oriented nanofibers but I faced problems with boundary conditions. If I fix the node in the bottom and apply displacement on the top while the lateral nodes left without conditions the solver gives wrong.

 

I hope you could help me with this issue.

 

 

[peteroznewman]

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[Aniket]

Can you please post an image of the entire geometry so the BCs and the entire model is visible?

If all the nanofibers that you are modeling are originating at the bottom or ending at the top, you should be able to get a solution. (Meaning there are no fibers which have the none of the boundary conditions). Simple way to check that is select all the entities in the boundary condition and hide bodies. There should not be any fibers without any BCs. Ideally, that would not be the case for randomly oriented fibers.

Generally, these kinds of scenarios can be modeled as a cube of material which has frictionless support on 3 faces on 3 mutually perpendicular planes and one or more of the remaining 3 faces given displacement. 

[Majeed]

 

[Aniket]

is there any matrix and is it modelled or just the fibers?

[Majeed]

Hello Aniket;

 

No, only fibers

Thank you for your reply

[Aniket]

Majeed, I don't believe this is the right way to model this, you will need a beam to beam contacts, without matrix. Also, the lateral nodes need to be fixed otherwise you are bound to see the solver errors.

[Majeed]

Aniket, thank you for your reply;

 

there is no method to make contact between beams after running the simulation of tensile test if there any ?

 

on other words if any beam touch the any other beam during the test there is any way to predict it?

[Aniket]

Please check the following discussion for beam to beam contacts:

https://forum.ansys.com/forums/topic/problems-with-the-contact-between-beams-line-by-line-contact/

It is not impossible but wouldn't be feasible given # of contacts generated in your model will be very large.

[Majeed]

Aniket,if I provide matrix material with almost 0 strength,it will help in boundary conditions.

 

but I feel the interaction stress between fibers and matrix will cause problem isn't it?

[Aniket]

Majeed, I believe then using, 3d beam to beam contacts would be a better option as compared to modelling matrix, as the matrix mesh would go out of bounds for a student version most probably. Kindly check following discussion.

https://forum.ansys.com/forums/topic/create-3d-line-to-line-contact-between-beams-in-workbench/

[Aniket]

Also have a look at Material designer, which might be better suited in your case.