change contact control during analysis
issueid=544 05-26-2012 12:32 PM
Moderator
change contact control during analysis

I'd like to be able to change the control parameters for contact during the course of analysis.

My specific need right now is that I'd like to be able to turn on augmented Lagrangian contstraint enforcement for contact analysis only on the last timestep (or last few timesteps). This would save a significant amount of computational cost for many analyses where one only wants the constraint enforced very accurately at the end of the analysis.

Other uses include changing the penalty scale factor, or changing the type of contact from, e.g., tied to sliding with gaps.

It seems like the logical place to add this feature is in the context of the multistep analysis capabilities.

Thanks,

Jeff
Issue Details
Issue Number 544
Issue Type Feature
Project FEBio
Category Unknown
Status Implemented
Priority 5 - Medium
Suggested Version Unknown
Implemented Version (none)
Votes for this feature 1
Votes against this feature 0
Assigned Users maas
Tags (none)




07-13-2015 11:36 AM
Lead Code Developer
Hi Jeff,

Just going through some old posts. I think you know that this is now possible, but for the record, most contact parameters (including the laugon flag and penalty) can be prescribed via a loadcurve. To turn on augmentations a specific time, you just need to create a loadcurve that is zero when you don't want augmentations and non-zero when you do want to augment. For example to turn on augmentations on at time 1.0, first define the load curve attribute on the laugon parameter.

Code:
<laugon lc="1">1</laugon>
Make sure the value is set to 1 since this multiplies the load curve value. Then, define the load curve as follows.

Code:
<loadcurve id="1" type="step">
  <point>0,0</point>
  <point>0.99,0</point>
  <point>1,1</point>
</loadcurve>
Cheers,

Steve

07-13-2015 11:39 AM
Moderator
Thanks Steve :)

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