• RecurringMeetings
• 2017-04-12

Recurring Meeting of Cleveland Clinic - University of Utah

Date: April 12, 2017

Time: 2:00 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. Ongoing and planned activities at Cleveland Clinic.
2. Ongoing and planned activities at University of Utah.
3. Other.

Immediate Action Items:

• Cleveland Clinic (Ahmet)
  • Revisit the wrapping spring problem in Abaqus.
  • Provide link to data management and querying system for University of Utah to test.
• University of Utah (Steve)
  • Work on new formulation of wrapping springs to fine tune the algorithm.

Notes:

1. Ongoing and planned activities at Cleveland Clinic.
   • Ahmet attempted to reproduce the sample wrapping spring model provided by Steve in Abaqus. He did not have a chance to get it convergence. He will likely try a few alternative strategies to see if they work any better. He thought that Steve's algorithm was utilizing additional out-of-plane stiffness to stabilize the model. Steve reminded him that it was the previous strategy. Current strategy is rule based, i.e. distribution of nodes across the length when there is no contact. Steve thinks that he can approximate a stiffness matrix to push to iteration in the correct direction.
2. Ongoing and planned activities at University of Utah.
   • Steve has been working on multiple sample models for wrapping springs in order to understand convergence issues. He can get solutions but convergence is not ideal. He has been trying to modify the algorithm, i.e. to allow it utilize a stiffness matrix during contact iterations. Jeff asked whether he looked at other algorithms. Steve did not. Ahmet recommended literature in civil engineering where contact between truss and membrane structures, as in inflatable architecture, may be useful.
3. Other.
   • Jeff and Ahmet discussed program project grant from University of Utah and iterated various paths for future development of FEBio and how Open Knee(s) may fit.
   • Jeff noted a new paper from his group on collagen molecular damage has been accepted for publication.
   • Ahmet mentioned a data management and querying system that was developed in collaboration with Stanford University. He will send the link for Utah folks to test it out.
   • The participants discussed potential continuation of meetings. Ahmet noted that scheduled meetings may not be necessary as the project folds into no cost extension. Steve noted that our last meeting will be on May 10, 2017 and he will likely have an update on wrapping springs.