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Creo Simulate - stress and displacement dont fit together?

Forum|Forum|10 years ago
May 15, 2016
3 replies
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Hey there,

I just simulated the displacement in Creo and the results don't fit together. So here is the data:

Part geometry: 40mm x 10mm x 2mm

F=5N on every longitudinal side

E=5 kPa

displ.strain.jpg

How can I have a strain(Dehnung; in the middle) of around 20% and a displacement(Verschiebung;left site) of around 1 metre?

I hope someone can explain,

Best, Kathrin

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Best answer by 346gnu

that looks like 'simulate lite'

your options are very very limited starting with maximum of 200 surfaces and absolutely no good for non-linear of any kind.

you would probably need the advanced license.

J

JonathanHodgson

13-Aquamarine

Are you sure that you don't have a strain of ~20 (2000%)?

As usual, check that your material Young's Modulus isn't off by a factor of 1000 - for some reason it seems too easy to end up with (say) 206 MPa instead of 206 GPa...

K

knispel

Author

1-Visitor

I'm positive that I have a strain of 0.2, so 20%. I doublechecked that with the dynamic analysis. 😕

3

346gnu

13-Aquamarine

I agree, units seem a reasonable candidate.

20% strain = 0.2, you're getting 1000 times this

Check you E value. 5kPa might be right but to me it seems exceptionally small.

Plastics such as polycarbonates are in the order of 3GPa

K

knispel

Author

1-Visitor

I see your point but as said, Im positive that is right.

The small Young's Modulus is because I am simulating tissue, which is actually hyperelastic. Is it a possibility that the mistake comes from doing a linear simulation with a hyperelastic material? I somehow didnt find the properties for a hyperelatic simulation.

3

346gnu

13-Aquamarine

My we look at the model?

Can you upload it?

S

sdensberger

2-Explorer

Kathrin,

How is your model constrained? Did you use 'inertial relief' for your analysis? If so, this could easily be the culprit.

-Shaun

K

knispel

Author

1-Visitor

Sorry for the late response.

I didn't really use it on purpose but since I am simulating a biaxial tension test the body is nowhere really fixed in space. I just selected 'Simulate' in the taskbar and then it asks me for material, constraints, loads, you have to click analyse then and it gives you the results. There is no more options like 'analysis definition form'...