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Old 08-23-2017, 02:21 PM
tomtom00 tomtom00 is offline
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Default Problems about Anybody2Abaqus

hi,everyone!
I run "Anybody MoCap model" to calculate muscle and joint forces as boundary conditions of femoral FE model under walking loading conditions. I read tutorials which says "inertia relief loads will automatically be added to the model in order to provide a full set of boundary conditions".
Hip joint node would be fully constrained using the default method of inertia relief loads in FE models.
I want to know why choose hip joint reference point as fully constrained point in FE model ?
Thanks a lot for your reply.
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Old 08-24-2017, 10:13 AM
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pgalibarov pgalibarov is offline
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Hi,

The hip node was chosen just as an example, there was no logic behind it.
What it will effectively do is fix the bone around hip joint centre, with deformations happening mostly in the distal region. This is equivalent to fixing the femur around knee joint and seeing some sort of bending in the neck region.

Kind regards,
Pavel
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Old 08-26-2017, 08:12 AM
tomtom00 tomtom00 is offline
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Quote:
Originally Posted by pgalibarov View Post
Hi,

The hip node was chosen just as an example, there was no logic behind it.
What it will effectively do is fix the bone around hip joint centre, with deformations happening mostly in the distal region. This is equivalent to fixing the femur around knee joint and seeing some sort of bending in the neck region.

Kind regards,
Pavel
Dear Pavel,
Thank you for your timely reply.
I am performing a FEA of distal femoral fracture-fixation plate using this method. By fully constraining the hip joint reference node, I presume it would introduce a significant force and moment opposing these accelerations. All the proximal muscle forces would be resisted by this constraint and they would have little effect at the fracture site (at distal femur).
Would it not have been better to fully constrain a node on the plate itself? if not or same, please give me some reasons.
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Old 08-30-2017, 01:47 PM
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pgalibarov pgalibarov is offline
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Tom,

I have just noticed it is an Abaqus conversion. Do you actually need this constraints? I remember Abaqus working well without it, just by having inertia relief option on.

In ANSYS it is a different situation, the inertia relief removes associated acceleration, but it still requires a constraint, I believe to deal with residual accelerations, which should be very small. Please have a look here:
https://www.simutechgroup.com/tips-a...inertia-relief

Pavel

P.S. Please add a better version of affiliation.

Last edited by pgalibarov; 08-30-2017 at 02:13 PM.
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