Recurring Meeting of Cleveland Clinic - University of Utah

Date: August 27, 2014

Time: 2:00 PM EST

Means: Conference call

Attendees:

1. Ahmet Erdemir (Cleveland Clinic)
2. Craig Bennetts (Cleveland Clinic)
3. Jeff Weiss (University of Utah)
4. Ben Ellis (University of Utah)
5. Steve Maas (University of Utah)

Agenda:

1. Recap on in situ strain test problem.

   • http://wiki.simtk.org/openknee/Febio/InSituStrain

2. Recap on set definitions in FEBio input and output.

   • http://wiki.simtk.org/openknee/Febio/SetDefinitions

3. Update on local coordinate systems and connector elements.

   • http://wiki.simtk.org/openknee/Febio/RigidBodyMotions

4. Upgrade of Open Knee(s) - Generation 1 to FEBio v2.0.
5. Decide action items for next meeting.
6. Other.

Immediate Action Items:

• Cleveland Clinic (Craig)

  • Try PreView to convert Open Knee(s) - Generation 1 to FEBio version 2.0 format.

• Cleveland Clinic (Ahmet)
  • Prepare a test problem to evaluate set functionality.

• University of Utah (Jeff & Steve)

  • Meet to iron out details of in situ strain feature presentation at CMBBE 2014.
• University of Utah (Steve)
  • Explore the possibility to develop a command line tool or a plug in for FEBio model update.

Notes:

1. Recap on in situ strain test problem.
   • Prescription of pre-strain at element level was extended to both coupled and uncoupled formulations. Currently the feature supports transversely hyperelastic materials and the immediate goal is to extend it to any transversely isotropic material. Jeff and Ahmet asked if it would be possible to extend this feature to any elastic material. Steve noted that this would not be a problem as every material has a generalized coordinate system that can be utilized for this purpose.
   • As far as test problems go, the single ligament model was solved. Jeff wondered if it is time to test the feature in Open Knee(s). Ahmet noted that the Open Knee(s) - Generation 1 should be converted to FEBio version 2.0. In following, it will serve as a good case study. Steve also utilized the artery model in the CMBBE 2014 abstract. He is working on more relevant examples to compare our approach to what was done in the past.
   • Steve will need some time to focus on CMBBE 2014 presentation related to this feature. His particular concern is related to incompressibility of the material, which requires appropriate handling of prescribed in situ strains. Steve and Jeff will discuss these before CMBBE 2014.
2. Recap on set definitions in FEBio input and output.

   • Cleveland Clinic team has to implement a test problem to evaluate this feature in PreView, FEBio, and PostView.

3. Update on local coordinate systems and connector elements.
   • Ahmet will meet with Gerard and Steve during CMBBE 2014 to discuss rigid body formulations in FEBio. This may be a good opportunity to design the implementation of local coordinate systems and connector elements.
4. Upgrade of Open Knee(s) - Generation 1 to FEBio v2.0.
   • Ahmet wondered if there is a utility software (e.g. a stand-alone command line script) to update/convert FEBio models of older versions to the newer versions. This can allow batch conversion of multiple FEBio files. Jeff noted that this will be a useful tool, particularly to update verification test suite. Currently, such a tool does not exist. FEBio solver can accommodate files which are in past formats (albeit only recent versions are supported). The general consensus is that model conversion should be separated from analysis. Steve will likely work on this.

   • Utah team noted that one can open an FEBio file with an older format in PreView and save it in the most recent format. Some bugs exist and based on Ben's experience not all models are converted fully. Cleveland Clinic group will try this approach with Open Knee(s) - Generation 1.

5. Decide action items for next meeting.
   • See Immediate Action Items above.
6. Other.

   • Ben noted the possibility of saving session in PostView. This feature allows visualization of simulation results from different analysis in a similar manner. View settings can be saved and complex movies can be generated. Ahmet asked if it was possible to open multiple results file in PostView and display them side by side in a linked manner in child windows within PostView. This may help comparative visualization. Steve noted that this is not possible. Yet, it will likely be a useful feature.