Learning Forum

[agopalkr]

Hello,

I am trying to simulate the tensile deformation of fibers embedded in a polymer substrate. One end of the substrate is fixed and the other end is subjected to a displacement of about 50-100% of the overall length of the substrate.

I use Body interaction-frictionless and Body Interaction-Reinforcement to bind the fiber to the polymer. It works fine for a single fiber (first image) but for multiple randomly oriented fibers there seems to be no effect on the fibers at all, even though the polymer deforms(Image 2).

In both case the fiber diameter and polymer thickness are the same (0.34 microns and 0.5 microns respectively.

I have seen a bunch of questions in the forum regarding reinforcement of steel fibers in concrete. However, in all the cases I found, it looked to be compression not tension. Does anyone have an experience with my situation or any ideas on how to fix it.

Thanks so much for your time.

[Ram Gopisetti]

Hi @agopalkr, the options you have used seems fine and i have did an small case to see if i can replicate it and i the outcome is i have seen the fiber deformation as the matrix deformed as follows.
solution definition

an 3 beams are modeled to demo the issues and the elongation of 15 mm was applied towards the tensile side.
my line bodies are scoped as reinforcement as follows
after the tensile load was applied the beams and matric deforms as follows

Moreover, my material definition has some form of plasticity. comment down how it worked for you.
Cheers, Ram

[agopalkr]

Thanks so much for your response. I am still not getting any deformation in my model. A couple of points/questions:
Did you make your model in spaceclaim or design modeller? I made mine in Design modeller, I imported the fibers as a DXF (chose frozen and selected line bodies) and then assigned them a cross section. I then drew a rectangle surrounding the fibers and then extruded (symmertically -0.25 microns both side). I did not union any of the bodies, I am not sure if this needs to be done. I modelled the single fiber(which works) without unioning in design modeler and it seemed to work fine.
I notice you have 2 coordinate systems, global and coordinate system ( I think for the beams). I have only one global. My beams are cylindrical so I don't think a coordinate system for then is required, not sure if this is an issue.
My elastomer is hyperelastic and my beams are multilinear isotropic.
I went back to ANSYS version 19.2 and got the same result. So, it doesn't seem to be version related.
Did you merge nodes in your model? from the literature body interactions-> reinforcement does not need nodes merged.
I also substituted my beam materials with the ANSYS default structural steel and got the same result. Which leads me to believe it is not my material.
So, perhaps it is something I am doing in design modeller? I am just importing all the beams a line elements from the DXF and assigned each of them a cross section. I do not union or merge the beams or the substrate.
I know ANSYS employees cannot download model files or archive file. I have my archive file, is there some way I can send it to you to look at it?
Thanks so much for your time, it is greatly appreciated. I have been working on this model for more than a month, I feel i am close but am missing something small.

[Ram Gopisetti]

1) I did my model in Spaceclaim, the tool will not show any significant changes in the simulation.
2) the second coordinate system was wrt my displacement BC where i apply an 15mm extension over 1e-4 sec.
3)Is your hyperelastic has a model like Ogden or yeoh etc? plain old experimental data is not enough to make sense to solver.
4) you don't need to use any other versions of ansys as it an simple and plain case.
5)No merging or share topology was used.
6) In general case of Explicit analysis Plasticity terms are needed and recommended.
7) there could be problem there, alternately you can use Material Modeller to create an microstructure model and and continue your analysis check the image below for RDF; units are in micrometer.
8) There is a no way we can access the file .however, you can post your file here so that any other active member can look at it and may help you.
cheers, Ram

[agopalkr]

Thanks so much for your response again.
My hyperelastic polymer is using Ogden 2nd order coefficients from a paper. The polymer deforms as expected.
My beams are actually use plasticity multilinear isotropic , sorry I should have clarified this better. I expect them to plastically deform. They deform in the single fiber case when the displacement is coincident to the axis of the beam, however when applying the exact same boundary conditions and same materials to the oriented fibers, I see no displacement.
If you don't mind could you show a snapshot of your boundary constraints? Perhaps I am missing something there.
I am also attaching my archive file, in case anyone in the forum would like to look.
Thanks so much for your time, it is much appreciated.

[agopalkr]

If possible could you attach your archive file? If not could you post a screenshot of your boundary conditions and material properties. That would help me a lot to troubleshoot.
Thanks so much for your time.

[agopalkr]

Sorry to bother you again, if you have time could you please send a screenshot of your boundary conditions , materials and analysis settings. I replaced all my materials with ansys non linear polymer and stainless steel from the ANSYS library and am getting the same result.
Which would mean there is something wrong with my boundary conditions or analysis settings. I just need to find out what it is.
Thanks so much for your time again.

[agopalkr]

You seem very knowledgeable on this forum. If you have some free time, would you mind taking a look at my model and see if your notice anything. My model works for a single fiber but for multiple fibers , they seem unaffected.
I have been stuck on this for a month and am looking for some inspiration if possible..

[Missy Ji]

It seems like you do not have shared nodes in the beams, this can be seen from the second picture posted. Please created shared nodes in the beam matrices, so they would be connected.

[agopalkr]

[agopalkr]

Per the ANSYS help guide and even the reinforced concrete example in the ANSYS learning hub, Body Interactions -> reinforcement in explicit did not need shared or merged nodes. Even earlier in the thread said that merged nodes were not required when using body interactions-> reinforcement in ANSYS explicit. Is this not the case?