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Posted: **Mon Mar 02, 2015 6:18 pm**

Hi Ahmet,

I have a question about the boundary conditions as implemented in Version 2 of the Generation 1 model. From what I can see in the FEB file (tf_joint_FEBio_v2.feb), it appears that the prescribed kinematics are applied over the interval 0 to 1 s, but in version 1 this was done over the interval 1 to 2 s. Also, in Version 2 it appears that neither kinematic nor force constraints are changing between the interval 1 to 2 s.

Here are the relevant sections of the FEB file:

Code: Select all

<rigid_body mat="1">
         <prescribed bc="Rx" lc="2">0.785</prescribed>
</rigid_body>

<loadcurve id="2" type="smooth">
        <point>0,0</point>
        <point>0.1,0.1</point>
        <point>0.9,0.9</point>
        <point>1,1</point>
        <point>1.1,1</point>
        <point>1.9,1</point>
        <point>2,1</point>
</loadcurve>

Since the force constraints all have zero magnitude it appears that everything is constant between 1 and 2 s.

I assume that this means simply that the new version's boundary conditions do not precisely replicate the previous version's?

Please confirm at your convenience.

Cheers,

Todd

Posted: **Mon Mar 02, 2015 7:20 pm**

Hi Todd,

I changed the prescription of boundary conditions and loads in the new version slightly, mostly for convenience. With the newer version, we are applying a passive flexion from 0 to 0.785 radians in 1 second and holding the joint at that angle for the remainder of the simulation, which ends at 2 s. We also defined another load curve, which is set to 0 for t=0-1s and ramps up to 1 in t=1-2s. Using this load curve we apply loads to remainder degrees of freedom of the joint. Right now, these loads are set to 0 but can be changed to any desirable load by the user.

Best,

Ahmet

Posted: **Wed Mar 04, 2015 8:17 pm**

Understood, thanks for clarifying.

Just curious: is that flexed-posture loading meant to relate to a particular in vitro loading experiment or a particular in vivo task?

Posted: **Thu Mar 05, 2015 10:19 am**

That is how we do the in vitro loading in our specimens. Nonetheless you should be able to change load curves and magnitudes to any that you would like.

ahm.

Posted: **Mon Mar 09, 2015 12:56 am**

Great, thanks for that Ahmet.
And thanks again for sharing this fabulous resource with the community!
Todd

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Version 2 boundary conditions

Version 2 boundary conditions

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Re: Version 2 boundary conditions