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Hanging from a beam?

Posted 24 giu 2014, 02:57 GMT-4 Structural Mechanics Version 4.4 3 Replies

krc
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Hi all, sorry in advance for a possibly very easy question.

I want to hang a block from a fixed point with a strong wire, and I think that a beam is the right object to use for the wire. I've been trying to follow the advice on this thread (I think what I need is essentially the same as a pendulum:

www.comsol.com/community/forums/general/thread/23709/

When I read the documentation for beams, though, it looks like I can only attach them to the edge of an object. But I want the beam to stretch from a point up above the object down to the face of the object. Is this possible? Or do I need to use some other type of object to do this?

(If it helps to see what I am referring to, I've attached the file; the beams would stretch from the isolated points straight to the object in the y-direction.)

Thanks!

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3 Replies Last Post 26 giu 2014, 03:46 GMT-4
krc
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Posted: 1 decade ago 25 giu 2014, 22:03 GMT-4
I have tried following the channel beam example by setting up a couple of lines for it to follow, but I'm still running into trouble getting the beam to work. I cannot put a material on the beam, and I am not confident about my method in general. I have attached an updated version, which should be clearer, if it'd be possible to take a look at. Thanks again for the help!
I have tried following the channel beam example by setting up a couple of lines for it to follow, but I'm still running into trouble getting the beam to work. I cannot put a material on the beam, and I am not confident about my method in general. I have attached an updated version, which should be clearer, if it'd be possible to take a look at. Thanks again for the help!

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Henrik Sönnerlind COMSOL Employee

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Posted: 1 decade ago 26 giu 2014, 02:40 GMT-4
Hi,

A Truss is probably better than a Beam for a thin wire, but I do not really think that it matters in your case.

You need to add one more material for the beams. A material can only be assigned to one geometric level (Domain, Boundary, Edge) so when you mix for example solids, shells, or beams you need to add one material for each.

Regards,
Henrik
Hi, A Truss is probably better than a Beam for a thin wire, but I do not really think that it matters in your case. You need to add one more material for the beams. A material can only be assigned to one geometric level (Domain, Boundary, Edge) so when you mix for example solids, shells, or beams you need to add one material for each. Regards, Henrik
krc
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Posted: 1 decade ago 26 giu 2014, 03:46 GMT-4
Thanks for the response! This is great; I have materials now.

I have also added a gravitational edge load to the wire like in the channel beam example, but in the channel beam example, they use a point load on the end. I am wondering if, instead of adding an assigned point load, I can just make the end of this wire attach to the surface below it and use this as the load.

I believe that right now, the two are not attached, because I am getting degrees of freedom errors. I've attached the new file if anyone has any thoughts on this issue. Thanks very much!
Thanks for the response! This is great; I have materials now. I have also added a gravitational edge load to the wire like in the channel beam example, but in the channel beam example, they use a point load on the end. I am wondering if, instead of adding an assigned point load, I can just make the end of this wire attach to the surface below it and use this as the load. I believe that right now, the two are not attached, because I am getting degrees of freedom errors. I've attached the new file if anyone has any thoughts on this issue. Thanks very much!

Attachments:

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