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Modeling a thermomechanical bending process

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Posts: 4
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(@antmuse72)
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Joined: 7 years ago

Hi,
Im writing on this forum because Im a bit at a lost with an analysis conducted with ANSYS workbench.

Ive got creep response data and springback data: I used a test bench consisting of a constant weight pulling laterally a polypropylene flat bar (somewhat in the manner of a cantilever beam but pulled honrizontally)
SEE PICTURE in attachment
For the creep test: The heat gun warms the flat bar while the force is pulling on it: the magnitude of the angular deformation is measured as a function of time.
For the springback test: The heat from the heat gun and the force are both removed and the springback is measured as a function of time.
Ive developped a creep equation for the creep test that also figures in the ATTACHMENT.
With matlab, Ive fitted the equation and found the right parameters to fit my data.

I am now trying to model this experiment in ANSYS workbench. Ive read a bunch on the subject but Im having a hard time finding where to start and what should be included in my analysis.
From what I understand, I need to make a static structural analysis with the right temperature profile. That I can do. But so far, my analysis is carried out only in the elastic domain and this wont work since a permanent deformation remains in the flat bar, after the springback.

I know I must include PLASTICITY and VISCOELASTICITY in my material properties (like MISO and prony). But workbench asks for stress VS strain data and shear modulus VS time data. All I have is series of data of angular deformation (in rad) as a function of time (seconds).

How can I use my results in Workbench? Can I include my creep response equation in Workbench?

How should I make an FEA analysis of this experiment using Ansys Workbench? Im a bit familiar with command snippets in mechanical but I know next to nothing of mechanical APDL (Ansys classic)

Please help me, my director knows nothing in ANSYS and nobody at my university either

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Posts: 4
Topic starter
(@antmuse72)
New Member
Joined: 7 years ago

I was thinking last night about my post...
Does the analysis must include both MISO (multilinear isotropic hardening) and viscoelastic shearing? Is viscoelastic shearing sufficient alone? Because if both are needed I could go to my university and make some tensile test to obtain Stress VS strain data
Is it absolutely necessary to include my constitutive law (my creep equation) into the analysis?

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Posts: 4
Topic starter
(@antmuse72)
New Member
Joined: 7 years ago

Anyone please..?

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Posts: 4
Topic starter
(@antmuse72)
New Member
Joined: 7 years ago

Ill post some more pictures so you can figure out what Im trying to do and what I have so far.

The angular deformation at

lim = 4.5 Degrees
t -> &#8734,

[U]Question #1a[/U]:

Ive been advised to use the Extended Drucker-Prager model to model that experiment.

I cant find Extended Drucker-Prager model in any of the tabs in the workbench material toolbox. From what I understand, I must use Extended Drucker-Prager material model via command snippets in mechanical. Considering my experimental results, which form of the EDP model would you advise to use, linear, power law or hyperbolic? And how would you go in coding the command to define the model?

MP,GXY or ALPD ?,MAT,C0?
MP,NUXY,MAT,C0?
TB,EDP,1
TBDATA,1,2.9,32,0 ???

[U]Question #1b[/U]:

I dont know how to compare my experimental curve with the model proposed by ANSYS once it has been defined. How can I see if the model fits my data?

[U]Question #1c[/U]:

Also, would that model be applicable to both parts of the experiment? (before AND after the removal of the force)

[U]Question #2[/U]:

Is Extended Drucker-Prager model considered a creep model?

[U]Question #3[/U]:
Do I have to include another model besides EDP? Such as a standard plasticity model in the Plasticity Tab from the workbench material toolbox? Or a standard viscoelastic model in the Viscoelastic Tab from the workbench material toolbox? Or maybe another model altogether via a command snippet? Im just having a hard time figuring what type of non-linear material property has and doesnt have to be included in this experiment in order to get good numerical approximations.

Thanks in advance

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