insert stress curve/strain

[Nastran994]

Hello everyone, I need another help! !
I should do a non-linear analysis regarding plasticity, to do this I should insert the data of my sigma-epsilon curve. I read on the manual:
"stress/strain curve
defines the nonlinear elastic stress-strain curve. you must select a field from the listbox. it can be strain and/or temperature dependent. tabular definition of the stress-strain curve via the fields application using a material field of strain should follow the specifications as outlined by nastran. the first point of the material field should be the origin and the second point must be at the initial yield point. this material curve is elastic, meaning that in both loading and unloading the material behavior follows the stress-strain curve as defined. it is not recommended that both nonlinear elastic and elastoplastic constitutive models be active or defined for the same material. for work hardening, use the elastoplastic constitutive model. see the nastran quick reference guide for more details."so I looked for these fields in which to insert the curve, I found under utilities->field->field from xy curves that should be just what it does to my case, but I do not understand how I can insert the data of my curve. Can someone give me more advice?? Thank you very much

 

[Onda]

I think you could start with an elastoplasty material. then elastic up to yeld and then plastic with a different elastic module.
set as from image:
in this case it was a plastic material.
then, if it works, you can deepen with a curve and then a table.

 

[Onda]

to do the field, you have to do it for the material, as from below image.
on the one hand, put the strain on the other, the stress that has the material to that strain. (I think, but I should check on the manual, I do not use it frequently).
But initially I would go with the bilinear model. much easier.

 

[Nastran994]

I think you could start with an elastoplasty material. then elastic up to yeld and then plastic with a different elastic module.
set as from image:
in this case it was a plastic material.
then, if it works, you can deepen with a curve and then a table.View attachment 54045

Thank you very much, I had seen this screen but I didn't know how to use it. in practice inserting this command the sigma-epsilon curve would consist of two straights? one for the linear tract to the yielding and another for the plastic tract? then I also wanted to ask you the hardening slope what would it be? the percentage of epsilon when you have the yield? or the inclination of the straight before or after plasticization?? then what does yield point take? the value in mpa of yielding??? Thanks again

 

[Nastran994]

to do the field, you have to do it for the material, as from below image.
on the one hand, put the strain on the other, the stress that has the material to that strain. (I think, but I should check on the manual, I do not use it frequently).
But initially I would go with the bilinear model. much easier.
View attachment 54046

I should be able to use this command, but maybe as I first try the elasto-plastic material. where I can find some info on this command, so maybe I see how it works and all the connected commands

 

[Onda]

Thank you very much, I had seen this screen but I didn't know how to use it. in practice inserting this command the sigma-epsilon curve would consist of two straights? one for the linear tract to the yielding and another for the plastic tract? then I also wanted to ask you the hardening slope what would it be? the percentage of epsilon when you have the yield? or the inclination of the straight before or after plasticization?? then what does yield point take? the value in mpa of yielding??? Thanks again

in this way the sigma-epsilon curve consists of two straights. one for the stretch and one for the plastic tract. is called hardening slope because it is the trait where a metal undergoes hardening.
in practice:
you must define the point where the hardening slope begins and ends the elastic part of the material. (in mpa) if you use [mm, ton, N] as a unit of measurement. or any other pressure that is congruent with your measuring units.
the elastic module of the material during the plastic phase (then straight inclination after plasticization) put it in hardening slope.

 

[Onda]

I should be able to use this command, but maybe as I first try the elasto-plastic material. where I can find some info on this command, so maybe I see how it works and all the connected commands

mah, try to look at the nastran guide for the sol400 nonlinear user guide. explains the materials.
Then look at nastran's qrg and read the bdf so you know what you're pulling out of patran. Good luck...

 

[Onda]

try to see the demonstration manual problems of nastran.
find chapter 15 inside. tube flaring where you analyze the contact between two components, with plasticization of these,. It seems very similar to what you have to do.
nastran guides should have them in the installation directory.

 

[Nastran994]

in this way the sigma-epsilon curve consists of two straights. one for the stretch and one for the plastic tract. is called hardening slope because it is the trait where a metal undergoes hardening.
in practice:
you must define the point where the hardening slope begins and ends the elastic part of the material. (in mpa) if you use [mm, ton, N] as a unit of measurement. or any other pressure that is congruent with your measuring units.
the elastic module of the material during the plastic phase (then straight inclination after plasticization) put it in hardening slope.

So in hardening slope would you like angle degrees or some form of elasticity? ?

 

[Nastran994]

try to see the demonstration manual problems of nastran.
find chapter 15 inside. tube flaring where you analyze the contact between two components, with plasticization of these,. It seems very similar to what you have to do.
nastran guides should have them in the installation directory.

Where can I find this "demonstration problems manual"? I found on help->tecnhical support but I don't know if that's exactly what you tell me

 

[Onda]

Where can I find this "demonstration problems manual"? I found on help->tecnhical support but I don't know if that's exactly what you tell me

together with nastran, you should have also had all manuals and guides.
the fundamental is called qrg "quick reference guide" where you find the explanation of nastran instructions.
then there is a manual for linear analysis, one for non-linear, then there are problems done.
I can't turn your manuals, but they are part of the installation and must be the first source of information.
where I have indicated you find both models performed, similar to what you have to do. both in detail and input data you have to enter.
If you don't understand, try.
flat slab, pull over the ribbing and do the deformation accounts. , you make a clear idea of how the software behaves. with a 10-minute model.

 

[Nastran994]

I found the qrg, the other manuals sincerely not, I try to see if I find something on the net. What name can I look for? ?

 

[Onda]

I don't think you can find them on the net. you must have them together with the installation files of nastran. is the necessary documentation.

 

[Nastran994]

I try to find them then, thank you for the help!
On the other hand I managed to load through excel files (.cvd) the points of the stress/strain curve in the field, assigned to the material as elastoplasty, the fact is that, even once loaded the material as property and assigned to the solid and made mesh, I tried to do the analysis both as sol101 and as sol400 but it does not give me any result and in the f06 tells me "no material properties exist". Can you tell me why? ?

 

[Onda]

I'm sorry. But I can't help.
try to make a bar, meshata with shell. and in case, charge the bdf of this. a simple plan. bound to one end and loaded into traction to the other. with simple measures, so as to check with hand accounts.
At that point, apply pressure on the edge. in order to have a uniform shift. the initially verification as elastic material, then as bilinear material, finally as elastoplasty

 

[Nastran994]

Maybe I try to do this, thank you very much