High forces with gravity equal 0

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Gabriel Oliveira
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Joined: Thu Apr 20, 2017 3:51 pm

High forces with gravity equal 0

Post by Gabriel Oliveira » Wed Sep 13, 2017 8:41 am

Hi everyone,

I runned a SO in shoulder model in static position and gravity equal 0. So the results expected was that no muscles have forces (because there is no gravity), however some muscles have high force.

What could produce this high forces?

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Dimitar Stanev
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Joined: Fri Jan 31, 2014 5:14 am

Re: High forces with gravity equal 0

Post by Dimitar Stanev » Wed Sep 13, 2017 10:16 am

If there is a motion then you need forces. Moreover, muscles are passive elements and due to bad scaling it is possible that they induce large passive forces.

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Gabriel Oliveira
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Joined: Thu Apr 20, 2017 3:51 pm

Re: High forces with gravity equal 0

Post by Gabriel Oliveira » Thu Sep 14, 2017 2:01 am

Hi Dimitar,

Thank you for the answer and attention. The question is, however, still open for the following reasons:

- In the simulation there is no motion; I simulate a static position (no any change in the DOF in the time). Therefore no inertia forces can arise.

- If I block all the DOF in the model, and run the SO, the muscle forces disappear. Therefore an "overstretch" of the muscles can also be excluded. Furthermore, the muscle are activated, so that the fores are not passive forces but due to activation for unclear reasons.


Do you have any Idea how I can figure out the reason of the "mystery" activation of mules?

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