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Deformation Plasticity

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leo81

Bioengineer
Dec 6, 2007
43
Hi FEM guys and girls!
First: Sorry for my English! :)
Second: I need heeeeeelpppp!!! :(
Third: I need to know how ----> after my simulation in which I defined the material of my object (density and deformation plasticity), what I have to see to verify the presence of plasticity in my object???
I need to stay in the elastic range but...to verify it?
Is it correct to consider the voice "plastic strain in integration points"????
Help me pleaseeeeeeeee!!!
Thanks!
;)


Leo
 
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Try doing a contour plot of PEEQ in Viewer. This will show the areas where the model is plastic.

Martin Stokes CEng MIMechE
 
and....PE...what is its mean?
 
second:
if I Try doing a contour plot of PEEQ in Viewer for high loads I see the presence of plasticity...but...why my Von Mises values and the Components values are under the yield stress point of my material???????

I understand this fact as a contradiction!?
 
PEEQ is the equivalent plastic strain remaining when you remove the loads. If the material hasn't yielded then these will be zero everywhere. If it has yielded then you'll have this residual plastic strain and corresponding stresses, at or below yield.

corus
 
I have seen that my exponent value in the deformation plasticity model is wrong...but i don't find it for my material (Ti-6Al-4V and its alloys)...So I thought to define my material as:
- Elastic
- Plastic ------> but i haven't a stress-strain curve for my material. I know only the stress yield, the stress ultimate yield, the elasticity module, and the elongation at break. For this reason i entered in the voice plastic the datums:
Yield stress Plastic Strain
Rp0.2 0
Rultimate elongation at break

Doing this I don't see plasticity in my model for upper loads too.
But...this second way to modelize my object is correct????
It brings my simulation to differents results!!!
....I'm hopeless....:(

Leo
 
Try just running it as an elastic model and see if you have any stresses above yield. Check your model using simple hand calculations to see if the results you get are about what you'd excpect to see.

corus
 
So please check the definition of PEEQ associated with your model.
If you specify Intial Plastic strain and your material remain elastic then PEEQ will have value. In Cam Clay, PEEQ is a pressure value representing the position of the cap. If there is confusion, I would judge the plasticity of the material by the Plastic Strain PE magnitude.
 
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