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T
thaise1-Visitor
1-Visitor
July 18, 2019
Question

setting non linear material

  • July 18, 2019
  • 1 reply
  • 5834 views

Hello, so I'm doing a simulation analysis in CREO 3.0, and I end up with some doubts:
As shown in the Figure 1, the material properties I need is for the curve at 23°C.
So, when I enter the curve into the material definition box, it's like in Figure 2.
Can anyone confirm that the information I put is correct? Because the curve that I set is not like the real one.

And if I try to make it more real, like Figure 3, the program doesn't allow for me to continue, because the Tensile Yield Stress is zero.

1 reply

skunks
skunks19-Tanzanite
19-Tanzanite
July 18, 2019

my example:

 

PA66-GF15_BASF.JPG

T
thaise1-VisitorAuthor
1-Visitor
July 18, 2019

Thank you for you response, but I already tried that, and when it goes to simulate, he never reached the convergence, and there is a message that says: " The stress is much higher than the yield strength of one of the elastoplastic materials in your analysis. Check the properties and/or units of your material."

 

It also continue to apply a "load factor", at first 0.5, and then it didn't converge again, so it applied "load factor" of 1, and it was almost 3 hours of simulation, so I stopped it. 

 

 

S
SweetPeasHub17-Peridot
17-Peridot
July 18, 2019

First, There is no one answer for modelling materials.  If you are expecting to strain beyond 4% you should do something like these images below.  The first (elastic) part will have to be approximated with a straight line.  If you are staying below 4%, I have done as you have, but watch out when larger strain than the curve definition.  You might look at modelling as a hyperelastic material.

 

Second you have a separate, but linked, issue with slow convergence at higher load, that may have other remedies.  If for example your load can never be reached, the model will stretch and stretch until usually you have very distorted elements.  Try smaller elements.  Also break up your output steps into more steps and have a measure to watch the maximum strain and manually stop when it becomes large.  You can still pull up all the results for steps up to the point you manually stopped it.  Look at the last successful step and see where the high strain is occurring.  Sometimes the model can be changed slightly to help convergence.  (load on too small of a surface, or lack of a fillet - singularity etc.).  Finally elasto-plastic analysis can take a long time, and is somewhat unpredictable.

 

 

Model for larger strainsModel for larger strains

 

Datasheet propertiesDatasheet properties

 

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