Hi Marloes,

You should check the Outputs section of you febio file, to make sure you are requesting the "fiber stretch" output. It is not automatically added. See the febio users manual for details on requesting outputs.

Best,
Ariel

Hi Marloes, I personally do not have experience using febio studio, however I strongly recommend you open the .feb file in an xml compatible text reader (ex: SciTE). This is the file that is actually read by FeBio when it is running the model, so the issues you have with "disappearing" properties wi...

Hi Yidan, I apologize my wording was confusing in the sentence you highlighted. What I mean is that the prestrain constraint is defined in the step. Therefore prestrain is being applied the whole time from time 0 to time 2. But using the load curves (take MCL as an example), we defined the initial s...

Hi Yidan, I am not sure I understand your questions. It may be helpful for you to share your model file. When you refer to "Steps" it sounds like you are applying prestrain and loading in separate FEBio step. If you look back at the beginning of our correspondence I showed how prestrain and loading ...

Hi Yidan, If you look through the prestrain manual, you can see that depending on the way you have prestrain defined, it may not solve so that the prestrain in every element is exactly what was defined. Depending on the problem you are trying to solve, you may want to define it one way or the other....

Hi Yidan, I don't think it matters how you fix the femur during prestrain, as long as you are able to successfully apply the prestrain, and then load your model as you like. With regards to the problematic rotation you are seeing - if you were previously able to apply the valgus loading without pres...

Hi Yidan, If the prestrain step converged, and you were able to apply a compressive load following prestrain, it sounds like you got over the challenge of prestrain application followed by loading. You can check the postview file and look at prestrain stretch at the end of the prestrain step to see ...

Hi Yidan, I had another thought about something that may help you. In some of our prestrain models, we have had convergence success by turning off augmentations in the prestrain constraint. This can be done by setting the following: <constraint type="prestrain"> <update>1</update> <tolerance>0.03</t...

Hi Yidan, A model not converging is a very difficult problem to troubleshoot, especially without having full knowledge of all details of the model. We have some suggestions on this page of where to start, and some common issues. https://simtk.org/plugins/moinmoin/openknee/Specifications/ModelTrouble...

Hi Yidan, Sorry for the delayed response. In our case, it is applied throughout the entire simulation. The ligament prestrain values are simply held fixed during the remainder of the simulation, defined via the load curves. I do not have experience personally using prestrain in a separate step. Best...