topic Re: FEA multiple load points in Inventor Forum

FEA multiple load points

btaylor — Mon, 18 Dec 2017 14:45:49 GMT

I am trying to run a stress analysis on a storage rack. I am running the test on only half the rack to see the forces involved. In the end this will be a boxed frame.

The rack will hold up containers with four small feet. Every scenario I try ends up putting the entire load in the center of the beam, which is not accurate. I created small pucks to simulate the container feet, and applied the load to their faces. The edges of the pucks are my highest stress points which bring my safety factor down to .1's while the frame remains unstressed.

I have attached a photo of where my actual load points will be. Is there a way I can apply these loads directly to the beam? Or a way to eliminate my puck edges from the simulation?

Thank you.

Re: FEA multiple load points

JDMather — Mon, 18 Dec 2017 15:31:31 GMT

@Anonymous wrote:

... a way to eliminate my puck edges from the simulation?

The usual technique is Split Face.

Re: FEA multiple load points

btaylor — Mon, 18 Dec 2017 18:39:42 GMT

Thank you for the response. Can you elaborate on how the split face technique would help here?

If I was unclear, the load points are separate parts which are placed on top of the box tube. As the box tube deforms it sort of pinches the edges of the puck (see photo below). I'm worried making the points too small would concentrate the forces too much.

In short, what is the best method to put multiple load points at specific locations across a face?

Re: FEA multiple load points

JDMather — Mon, 18 Dec 2017 19:06:44 GMT

@Anonymous wrote:

.... Can you elaborate on how the split face technique would help here?

If I was unclear,

Yes, attach your assembly here and I will demonstrate with your assembly.

Re: FEA multiple load points

btaylor — Mon, 18 Dec 2017 20:17:57 GMT

I have attached a .zip with a pack and go file.

Thank you for taking the time to show me.

Re: FEA multiple load points

blair — Mon, 18 Dec 2017 21:18:13 GMT

You need to edit the beam, create a sketch that matches your "Load Puck" contact surface and use the Split-Face command. This will allow you to place a load within the designated circle. You would then need to do this process for each load circle on the upper beam.

Your beam is in a library, which be default makes it a Read Only item.

Re: FEA multiple load points

btaylor — Mon, 18 Dec 2017 21:21:27 GMT

Sorry about that. I'm not terribly familiar with pack n go. I have attached my second attempt.

Re: FEA multiple load points

btaylor — Mon, 18 Dec 2017 21:31:15 GMT

Thank you Blair. I was able to figure that out.

The beam is a library part as you pointed out, but that will be easy to work around.

Re: FEA multiple load points

blair — Mon, 18 Dec 2017 22:26:15 GMT

Within Inventor, the Library Folders are misleading. By default Inventor makes all folders designated a Library within the Project File scope as Read-Only. We use this for all parts that come from suppliers that are the supplies own items. This makes the modification of these items rather difficult when working on our own designs.

If we are working on a custom unit, then our standard parts folder and our suppliers parts are then shown as Library Folders. This way we can't modify any of our own stock items. We would need to copy the stock item into the customer work folder and make any special modifications there.