Finding Reactions moment

[proff_king]

I need to find a reaction moments in a fixed constrained node. i can find and see a reaction force, but there is 0 reaction moment. i tryied some different models, like cube of metal, that constrained at one corner, and aplly force at another corner. in that case i see a rection force, but moment still equals zero. however, model has some displacement, so it turning, that should cause some moment. i`m totally stupid or what?

Simulation 2012 trial

[S.LI]

I think ASIM only outputs reaction moments for these nodes that own rotational DOFs, such as nodes of beam or shell elements.

There are only reaction force, no reaction moments, obtained on translational DOFs.

[proff_king]

thnx for reply! But how i find rotational moment of rection force using simulation?

[John_Holtz]

Hi,

The easiest method of getting the moment reaction about a point would be

1. Delete the constraints currently on a face. (Call it "Surface X")
2. Draw lines from each node on Surface X to the point where you want the moment about.
3. Define the lines as beam elements and make them relatively stiff.
4. Constrain the one point where the beam elements come together.
5. Run the simulation.
6. Look at the reactions. The reaction forces should match your current model.
7. Be sure to look at the displacement and rotation of these beam elements to confirm that they are rigid enough to satisfy your needs.

An easy way to create the lines is to use the "Draw > Design > Centroid Creator". This will draw the lines to the center of gravity of the cross section.

The other way to get the moments is by using the classic definition of a moment: sum of R cross F, where the position vector R and force vector F are 3D vectors.