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Shrinaath

roll bending

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hi 

i am doing simulation on 3 point roll bending in radioss solver 

first step i applied displacement to the top roller in z direction then i applied peripheral velocity to 3 rolls then i stopped the velocity again applied top roller displacement  and given velocity of the roll in different direction.

i am not getting the plastic strain value while the stress i am getting larger than then the yield value material.JPG.d11820e26574acf760d314ed7e691b0f.JPGstress.JPG.5c662edd926962782acfe7510f1760d0.JPGstrain.JPG.a8a826f63510a7de83ecd10c7bfc053d.JPG

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Hi,

 

the issue is with the stress-strain curve: the first point of yield stress functions (plastic strain vs stress) should have a plastic strain value of zero at yield stress. In your case, the first s-s set should be 0 plastic strain at 152 stress (the second 0.002481 plastic strain at 228 stress and so on), while the linear elastic part is described by E parameter= 190000 (Young's modulus).

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Hi ivan

Thanks for your reply i have made the changes for the stress strain curve that 0 strain is at the yield point of the material and the curve progresses as mentioned below. even though i am not getting plastic strain value.  

material.JPG.f4946d1fbde6543a0c73d0bce8f1a2d7.JPGstress.thumb.JPG.dba45577fd174689f0d25bf090f90efb.JPGstrain.thumb.JPG.ab0344aa3ae42bd4abcd2c9fcfa40611.JPG

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You should subtract the elastic strain (0.000799994) to get only plastic strains. So the table should be:

0 @ 152

0.002481 @ 228

and so on

 

It is odd the plastic strain is not visible- can you share the model?

 

Attached is an example of law 36 with plastic strain.

plate_example.hm

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The issue was with solid property parameter Isolid=12, which is an obsolete standard 8-node solid, full integration (no hourglass). Use Isolid =17 (H8C) or 24 (HEPH) instead.

Roll_bending_edit.hm

 

I have edited stress-strain curve and set up advanced mass scaling to speed up computation. 

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thank you so much ivan

in 3 roll bending simulation can we do the simulation in stage wise  (i.e) first step the top roller is moved down that boundary condition is specified for this stage and second stage rotation of rolls now boundary condition is differ from first stage  

 

 

what is multi stage process in hyperform is that helpful for my case?????

i need to consider the spring back also 

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It is possible to carry out simulation in stages. There are various possibilities:

-most boundary conditions can be switched on/off through Tstart/Tstop parameter

-contacts can also be switched on/off (Tstart/Tstop parameter)

-rigid bodies can be activated or deactivated with a sensor or with the options /RBODY/ON and /RBODY/OFF in the Engine files

-multiple engine files can be defined with different simulation controls

 

I am not (yet) familiar multi-stage process in Hyperform so I can't comment on that. But given HF uses Radioss solver it should be possible to set up a similar simulation.

Check Example 24 – Spring-back:

http://altairuniversity.com/wp-content/uploads/2012/08/Example_25.pdf

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