Recurring Meeting of Cleveland Clinic - University of Utah

Date: March 10, 2016

Time: 4:00 PM EST

Means: Conference call

Attendees:

1. Ahmet Erdemir (Cleveland Clinic)
2. Jeff Weiss (University of Utah)
3. Steve Maas (University of Utah)

Agenda:

1. Discuss immediate action items from the last meeting.
2. In situ strain plug in documentation.
3. Decide action items for next meeting.
4. Other.

Immediate Action Items:

• Cleveland Clinic (Ahmet)
  • Re-schedule conference call with Stanford University team.
• University of Utah (Jeff)
  • Recap new shell element formulations for possible implementation in FEBio.
• University of Utah (Steve)
  • Evaluate potential contact formulation changes to accommodate shell elements.
  • Update documentation on the use of in situ strain feature.
  • Provide Ahmet new examples of in situ strain feature.

Notes:

1. Discuss immediate action items from the last meeting.

   • Joy Ku has been occupied with staging of SimTk.org upgrade. Ahmet will schedule a conference call after the release of new SimTk.org.

   • University of Utah group mostly worked on fixing bugs in the in situ strain feature and documenting its use, see the discussion in the next agenda item. Dave provided Ahmet a new version of PostView compatible with in situ strain output. Explorations for shell element formulations remain.

2. In situ strain plug in documentation.
   • Steve has sent Ahmet documentation on the use of in situ strain feature. He updated the code, which made previous examples provided to Ahmet irrelevant. The group went over the documentation. In situ strain feature allows prescription of a "prestrain gradient" or "in-situ stretch" with constraints "prestrain update rule" (favoring original reference geometry) or "in-situ stretch update rule" (favoring prescribed prestrain). Ahmet and Jeff recommended changing the labeling of prescription strategy and constraint related updates to prevent confusion. Jeff also recommended adding examples to the documentation to better guide the users.
   • Steve has fixed a bug related to the update rules to satisfy constraints when prescribing in situ strains. He has been having difficulties to re-run some simulations, particularly those that strongly prescribe a given prestrain gradient. Ahmet and Jeff noted that such problems may be difficult to solve, simply because the prestrain distribution should be consistent with the geometry and material properties. Ahmet raised the possibility to exactly prescribe prestrains along one direction yet let off-axis prestrains free to adjust, a mix of both update rules to enforce constraints. Jeff and Steve will meet to take a look at this.
   • The revised manuscript on in situ strain feature will be submitted after completion of simulations with the updated implementation.
3. Decide action items for next meeting.
   • See Immediate Action Items above.
4. Other.
   • None noted.