Simple-Simple Support for Bending Simulation

[akarmaker]

Hi,

How to constrain a rod at both ends that would represent simple-simple supports, when performing 3-point bend test simulation. If I check all (Tx, Ty, Rx, Ry, Rz), but leave Tz unchecked, then I get the results for a fixed-simple support condition.  The rod length is along the z-axis.

Any suggestion?

Thank you.

AJ

[delaroca]

Hi, @akarmaker 

For the case of the 3-point bend test, it would be a good idea to model the supports as separate parts instead of directly applying a constraint. As there's a slight 'sliding' effect happening in real conditions.

This tutorial follows a great example of this test: 

https://help.autodesk.com/view/NINCAD/2019/ENU/?guid=GUID-931D261B-26D0-4D19-AA59-CD02C48A2F8A

If I were to simplify this case, maybe a good way would be to split the geometries so to represent the support's edges, like this:

And then constrain them as fixed and rotate free on the direction of the edges. So to produce this effect:

 

 

[akarmaker]

Thank you, Delaroca. I will try.

[akarmaker]

Hello Delaroca,

I followed the example in the link you forwarded. That works.

I like your simplified idea, but not sure how to make "split geometries to represent the support's edges " . Do you please have an example? Thank you.

[delaroca · Accepted solution]

Hi, @akarmaker 

To split the geometry, you need to use the plane tool and the split tool (you could also draw a sketch, but I think this way is simpler). Like the image below:

 

You first create the plane in the position you want (using the plane tool), then you split the surface by selecting the plane and the surface you want to split (using the split tool).

By the way, this is a great trick to produce better meshes on Nastran, as the mesh generator always follows the edges of the part. I often use it to make the meshes more symmetrical or to apply forces on specific locations.

Then in Nastran you just need to constrain that edge:

In the simulation I posted, I created two edges on the bottom of the rod, to represent the supports, and one at the middle of the upper surface, to represent the press and apply the force.

Hope that helps 🙂

[akarmaker]

Thank you very much for your help.