Applying moments on a 3D model 1

[uwcomposites]

Hello,

I am not able to apply moments to nodes of a 3D model. I tried using both SOLID 45 and SOLID 185. On a 2D model (using SHELL63) I had no problems applying moments to nodes.

Is there a particular reason why it is not possible to apply moments to nodes of 3D elements? Or am i doing something wrong?

Any help is highly appreciated!

Francesco Deleo
Research Assistant
Dept. of Aero and Astro
University of Washington

 

[jiligeo]

Hi , every node at solid element has 3 Dof (ux, uy, uz) and for this reason you are not able to apply moments on solid elements. In shell elements you have 6 Dof (3 displacements and 3 rotations), therefore you are able to apply moments on shell elements.
You can sub situate your moment with a couple of forces for solid elements.

Regards
Jalil

 

[uwcomposites]

Hello Jalil,

thank you very much for your response. I have to apply moments to thousands of nodes so I can't represent each moment by a couple of forces. Do you know how is it usually done?

Thank you again,

-Francesco

 

[jiligeo]

Hi Francesco, Sorry for the late reply. Unfortunately, I do not have any experience for your case.

 

[Struct71]

You may be able to apply surface loads with a gradient to the element surfaces. Use elementary mechanics to find the slope.

sfgrad,pres,0,,,,
sfa,,1,pres,value

Check the help file for the exact syntax.

 

[cbrn]

Hi,
Uwcomposites, I don't understand, or perhaps we are talking of two different things: in a 3D-solid formulation, you CAN NOT apply moment in whichever form to a NODE. You always have to consider that a solid element finds its equilibrium in terms of nodal DISPLACEMENTS (i.e. forces). If you want to apply an external moment load to an entity, you have to think of it in terms of force distribution, and apply this to the nodes belonging to that entity.
If there is a huge quantity of nodes for which to make this calculation, you can write a small APDL with some *DO loop to do it for you.

Regards