Gait analysis spine forces debug

Dear Moonki,

I am attaching my model as requested. I hope that my problem can be solved. As I have said before, my problems are that I have some penetration problems upon running the inverse dynamic analysis, and that when exporting for FE analysis, I have some stress concentrations which should not be there.

Thank you in advance for your kind help.


Dear Carl,

Yes I could see some penetration issues of muscle via points into the related wrapping surfaces.

I would like to ask of you several questions.

  1. Which bone are you interested in for exporting the forces for FE analysis?

  2. And what kind of strange pattern of stress concentration did you notice?
    And what’s your reference which tells that the stress concentration result should not be like that?

If you can give us more information then it will be helpful for us.

Best regards,

Dear Moonki,

Apparently, the stress concentrations were occurring due to a mistake in the material model. This is not an issue now because I have changed the model to a more realistic one. With regards to the penetration errors, what can I do to solve these please? (I am examining the L3 vertebra right now, however I have intensions to expand the study to the L4 and L5 eventually.)

Best regards,

Hi Carl,

When I run your model, I could see the following warning message:
deltoideus_scapular_part_4.SPLine : Penetration of surface : art_tub_minus_tub_majusSurf : Via-point ‘Main.Studies.HumanModel.BodyModel.Right.ShoulderArm.Seg.Scapula.O_deltoideus_scapular_part_4’ on ‘Main.Studies.HumanModel.BodyModel.Right.ShoulderArm.Mus.deltoideus_scapular_part_4.SPLine’ is located below the wrapping surface 'Main.Studies.HumanModel.BodyModel.Right.ShoulderArm.Seg.Humerus.art_tub_minus_tub_majus.art_tub_minus_tub_majusSurf

In this kind of case, I would try the following things:

  1. Hide all the other muscles except the above one which may cause the warnings so that you can see the location of that muscle easily.
  2. Activate (or create ) a drawing object of the wrapping surfaces for that muscle.
  3. Try to change the ‘InitWrapPosVectors’ property of the muscle. This will change the initial kinematic conditions of the muscle.
  4. Try to change the size of the wrapping surfaces. It may help.

I would say that this kind of muscle wrapping may occur at specific cases of the human.

Best regards,