FEA Tensile test

[Anonymous]

Hey,

For my master thesis is am performing tensile tests on 3D printed materials such as PLA,ABS,... These are non homogenous materials. I would like to model this behaviour as a homogenous material in FEA. To achieve this i try to simulate tensile tests and compare force vs displacement to the actual tensile tests. In attachement you can see a simulation i made. I fixed the parts of the planes that are between campls on a tensile testing machine on one side. On the other side i applied a shear force. However when i look at the stress i notice a high stress concentration on the side that is fixed. Does anybody have a better idea on how to set my boundary conditions?

Thank you in advance!!

[JDMather]

Attach your *.ipt file here.

[Anonymous]

Here you go.

thank you

[JDMather]

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@Anonymous wrote:

For my master thesis... 

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Has your instructor covered basic sketching?

Issues that I see:

4 failed feature fillets

Origin datum not in logical location

Unnecessarily repeated dimensions

My first sketch would probably look something like this.

How much of the tab on the specimen will be clamped>  The entire 35mm or some portion of that tab?

I idealized my model for analysis (but didn't verify yet).  The layering of 3D printing would result in far different properties.

[Anonymous]

Hey, 

As far as my instructor goes i am sort of on my own due to covid-19 restrictions.

I knew my sketch was not made very good. So i changed it. However i still see a stress concentration on the side where i fix the part.

I think the problem is with this fixed constrained. Any possibilty i could set a force on both sides and work without a fixed plane?

thank you already for your response.

[Anonymous]

Im sorry i forgot to mention. The sample is centered between clamps with disctance 98mm between the tips of the clamps.

[JDMather]

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@Anonymous wrote:

Im sorry i forgot to mention. The sample is centered between clamps with disctance 98mm between the tips of the clamps.

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That doesn't answer the question - how much of the 35mm on each end is clamped?

Can you ask your instructor to join this discussion?

I just spent the last 8 weeks in remote instruction with my students.

[mikejones · Accepted solution]

If you want to run the analysis by 'pulling' in both directions and remove all constraints then you will need to tick the box shown below to stabilize the model during the analysis since it will have no constraints to fix it in place. I get te following results done this way.

Mike

[Anonymous]

This might be what i am looking for. Thank you i will try it and keep you updated if this worked.

[Anonymous]

hey,

Thank you for this video. 

What i actually dit is apply a shear force on both sides of the sample on parts of the surface that are clamped. So if you messure 49mm from the center of the sample to the outside this part is not clamped. (beyond this point the rest of the sample is clamped) (in both directions ofcourse). The reason i had this stress concentration is because i used a fixed constraint on one side and applied a shear force on the other side. Apparently applying a force on both sides is a better solution (this didn't work before because i did not know how to stabilize my part). I now show results with a smaller deformation then my actual experiment. This means i will have to decrease young's modulus to approximate better the 3D printed parts as a homogenous material, wich is the result i expeted to see.

Thank you for your help.

Kind regards

[alecGF6C9]

Hello, I have been working on a material library of 3D-printed materials (including PLA, ABS, PETG, etc.) using data from filament manufacturers and research papers. Many parameters had to be estimated, and it would be wonderful to get some more data or possibly add material properties for different infill levels, temperatures, etc. If you have any interest in looking over these values or contributing your findings to the library, please do not hesitate!

https://github.com/alecGraves/Fusion360PrinterMaterials

Anyone may download the library from GitHub. Please feel free to suggest updates or additions using the issues section there.