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knutankv / beef

BEam Elements Framework for Python
https://knutankv.github.io/beef/
MIT License
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stiffness in constraint #5

Open dubois34 opened 11 months ago

dubois34 commented 11 months ago

Hello, Thanks for this nice tool.
I was wondering if you had any advice concerning the way to add stiffness to a constraint.
I would like to model a wooden frame with usual junction (tenon and mortise for example).
Kind regards.
frederic.dubois@umontpellier.fr

knutankv commented 11 months ago

Frederic,

Thanks for using beef and thanks for reaching out!

There is no way to add stiffness to a constraint in beef currently - the constraints are assumed fully fixed in the degrees of freedom that are specified. However, this can likely be solved using Springs (Feature).

I have added an example to describe how this can be done in the Examples folder (and also elaborating a bit on the usage of constraints and features): Applying constraints and features.ipynb

The downside is that it is limited to global CSYS (that goes for both constraints and features). Custom transformation matrices for both features and constraints are on the list of features that I will add if there's time at some point! However, currently, it should be able to model stiffness wrt. local axes using the CustomMatrix feature. Then you can carry out the relevant transformation outside beef and input relevant stiffness contributions specified in global CSYS.

I hope that this helps.

Best, Knut Andreas

dubois34 commented 11 months ago

Hi Knut, Thanks for your quick answer. I need some time to play with your proposal. I let you know. Kind regards

De: "Knut Andreas Kvåle" @.> À: "knutankv/beef" @.> Cc: "Frederic Dubois" @.>, "Author" @.> Envoyé: Mercredi 13 Décembre 2023 11:23:56 Objet: Re: [knutankv/beef] stiffness in constraint (Issue #5)

Frederic,

Thanks for using beef and thanks for reaching out!

There is no way to add stiffness to a constraint in beef currently - the constraints are assumed fully fixed in the degrees of freedom that are specified. However, this can likely be solved using Springs (Feature).

I have added an example to describe how this can be done in the Examples folder (and also elaborating a bit on the usage of constraints and features): ( [ https://github.com/knutankv/beef/blob/master/examples/Applying%20constraints%20and%20features.ipynb | Applying constraints and features.ipynb ]

The downside is that it is limited to global CSYS (that goes for both constraints and features). Custom transformation matrices for both features and constraints are on the list of features that I will add if there's time at some point! However, currently, it should be able to model stiffness wrt. local axes using the CustomMatrix feature. Then you can carry out the relevant transformation outside beef and input relevant stiffness contributions specified in global CSYS.

I hope that this helps.

Best, Knut Andreas

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