Non Linear Material

About the development of the FEM module/workbench.

Moderator: bernd

Klemmkeil
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Joined: Sun Apr 04, 2021 11:12 am

Re: Non Linear Material

Post by Klemmkeil »

here with cleared mesh.
My part is to big for uploading, so i have to delete it.
in the last file i deleted by mistake the nonlinear material.
i will try the nonlinear example now.
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bernd
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Re: Non Linear Material

Post by bernd »

Klemmkeil wrote: Thu Jul 22, 2021 9:40 am Hi Bernd,
i used a non linear material an edited it in the input-file, like shown in the picture above.
Was that the rigth way?
I can not see anything wrong. If you need more than 2 yielding points than yes you need to edit the input file.


But before editing the input file add add dozens of yield points I would make sure it works with the twe yield points you can edit in the gui. If yout get som PEEQ with two yield points I would start to add them by editing the input file.

cheers bernd
Klemmkeil
Posts: 24
Joined: Sun Apr 04, 2021 11:12 am

Re: Non Linear Material

Post by Klemmkeil »

I tried two points and it works.
Now a simulaton with more points is running.
Maybe it's because of the decrease of the curve, under nonlinear material FreeCAD says "simple hardening".
I will slowly increase the number of points.
The picture shows the curve of plasticstrain i would like to use.
i will give later an update
Thanks for your help
Greetings Nic
Attachments
stress-strain-plastic.PNG
stress-strain-plastic.PNG (5.87 KiB) Viewed 1490 times
Klemmkeil
Posts: 24
Joined: Sun Apr 04, 2021 11:12 am

Re: Non Linear Material

Post by Klemmkeil »

Here my Example with :

*MATERIAL, NAME=MaterialSolid
*ELASTIC
2380, 0.360
*PLASTIC
19.10, 0.0
20.8, 0.00175
25.7, 0.00498
30.36123, 0.00747
34.3069, 0.0184


The investigated material is PLA btw.
Attachments
vmis.PNG
vmis.PNG (250.8 KiB) Viewed 1480 times
PEEQ.PNG
PEEQ.PNG (135.54 KiB) Viewed 1480 times
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bernd
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Re: Non Linear Material

Post by bernd »

looks great :)

You may read the Calculix manual in detail ... http://www.dhondt.de/ccx_2.17.pdf section 6.8 Materials from page 246 to 266. On page 251 it says ...
Deformation plasticity is characterized by a one-to-one (bijective) relationshipbetween the strain and the stress. This relationship is a three-dimensionalgeneralization of the one-dimensional Ramberg-Osgood law frequently used formetallic materials (e.g. in the simple tension test) yielding a monotonic increasing function of the stress as a function of the strain. Therefore, deformationplasticity is very well suited to model the relation between the Cauchy (true)stress and the strain.
This would proof your assumption. But I am not 100 % if this text really is for the Calculix keyword "*Plasticity"
Klemmkeil
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Joined: Sun Apr 04, 2021 11:12 am

Re: Non Linear Material

Post by Klemmkeil »

Thank you for the good help.
Nanayaw
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Joined: Thu Feb 14, 2019 3:04 pm

Re: Non Linear Material

Post by Nanayaw »

Hello Klemmkeil

here some information's for non linear plastic material datas

https://forum.freecadweb.org/viewtopic. ... 40#p444477

Greetings

Nanayaw
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M4x
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Re: Non Linear Material

Post by M4x »

The link doesn't work :|
Nanayaw
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Joined: Thu Feb 14, 2019 3:04 pm

Re: Non Linear Material

Post by Nanayaw »

Sorry

if you search at aFEM forum for
FEM Plastic Materialdata Stress and Strain
then you will get

greetings

Nanayaw
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