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khimani_mohiki15-Moonstone
15-Moonstone
December 18, 2018
Question

Creo 5 simulate queries

  • December 18, 2018
  • 1 reply
  • 1435 views

Hopefully someone here can help me, I am not a Simulate users, nor am I an FEA specialist, I am co-ordinating our update from Creo 3 M130 to Creo 5 and I have some specific queries from our Simulate key users:

 

Contact Penetration; Can somebody explain what the contact penetration % means, what is it a percentage of?

Convergence Accuracy; in Creo 5 we now have Low, Medium & High settings, what does these mean and what was the equivalent setting in Creo 3?

 

Thanks in advance

 

Khimani

 

1 reply

S
SweetPeasHub17-Peridot
17-Peridot
December 18, 2018

I will try to answer some of this.  None of these settings are really new.  They were based on config file options for Creo 3.

 

Config file settings for Creo 3...Creo 5.

sim_contact_tolerance_factor  "modifies the convergence tolerance for contact.  The specified factor will be multiplied by the default tolerance"

sim_contact_penetration  "Specify the value of contact penetration depth in percentage (greater than 0.0 up to 100.0 with default as 5.0)"

 

In Creo 5, the convergence tolerance can be modified by the LOW, MEDIUM, HIGH which represent variations on the convergence for the contact residual.  The residual is seen in the "checkpoints" view of the run monitor.  I don't know the exact values targeted and I believe they are dependent on the configuration setting but something like this will demonstrate the function.  LOW = 1E-8  MEDIUM = 1E-11   HIGH = 1E-13  The model has to be converged to below this value before it completes or moves on to the next step.

 

The contact penetration is taken as 5% by default, then the config file setting overrides this, if present, for both Creo3 and Creo 5.  In Creo 5 was introduce the ability to override this value on an interface by interface case.  Contact penetration is converted to a dimension based on the element size, so a 2mm element at 5% contact penetration would control contacts to 0.1mm.  By control we mean that the stiffness of the contact model is adjusted up to avoid exceeding this % of penetration between the contacting surfaces as well it is adjusted down to improve convergence if needed.  The less % depth the harder it tends to be to converge the contacts.  For example I tend to use smaller elements with 15% penetration as my default.

 

Anyway, that is my understanding.  Hopefully someone else can clarify where I am uncertain and/or correct me where I misunderstand.

 

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