FEA analysis and bolts

[mechamania]

Hi

I have a design that includes metal parts that are hold together using bolts.

When I try to analyse this using FEA, peak stresses occur on the edges of the parts that are bolt together.

In practive these peaks will not be present because the parts can shift a little at these edges.

So how should I analyse this?

The parts should be able to slide at the edges but not at the positions where he bolds hold them together.

Is there a way to analyse this?

Should I analyse this with the bolts included? How do I define that the parts can not slide at the bolt positions, but

that further away from the bolts the parts can actually slide a little.

Any help is welcome!

[JDMather]

Split Face the for the clamping faces for the bolts. (do not include the fasteners in the analysis.

Attach your assembly here if you can't figure it out.

[mechamania]

Do you mean I have to create an area around the bolt (using the split feature)?

And then somehow glue these areas face to face and the remaining area should be free from sliding and moving apart?

If that is what you mean, how can I do that?

If my understanding is correct, the FEA analysis will glue everything together that is less then about 0,1mm apart.

So how can I make the FEA analysis act as if only the areas around the bolts are glued together?

I attached a test project where a profile should be bolted to a plate. I made two 7mm holes. Arround this holes

I made circular areas to be glued together. But when assambled this way, the FEA analysis acts as if the complete

profile is glued to the plate. Not only at the circular areas.

Is this the way to go? And how to glue only the circular areas together?

P.S. I tried to attach the Pack And Go files. But that was to big (even when zipped). So I attached the

project folder. I hope that is good enough.

[JDMather · Accepted solution]

The spit faces should be in the same locations as the actual contact faces of the fasteners.

You should also look at the Contact types (these can be edited fron Bonded), right click to edit.

[mechamania]

But if you do not include the fastener itself, what is the use of these split areas?

And what should the contact type be?

Can I find some example somewhere?

[mechamania]

Do I understand correctly that I should add a manual 'bonded' contact between these split faces (bolt contact areas) that

correspond to one bolt?

And that I should change the contact type that exists between the pieces I bolt together from 'bonded' to something like

'seperating'?

[blair]

The better solution, would be to upgrade to something such as Simulation Mechanical. You can apply a FEA bolt-cage the the hole and surrounding area and apply a clamping force. You could do a crude fix such as JD pointed out and create a circular Split-Face to simulate the bolt face and nut face and apply a force load on each face to duplicate the clamping force.

[mechamania]

Currently Simulation Mechanical is to expensive for me. And the cloud version I do not like because I want to do a lot of very simple and small simulations. Which makes the cloud version even more expensive for me.

So currently I will have to manage it with Inventor Simulation.

What sould I do with the split faces? Defining a clamping force on it?

What contact type is best for the contact between the parts bolted together? Seperating no sliding?

[blair]

I would use the contact bonded. Create your Split-Faces to replicate the contact area the head of the bolt-nut/washer would contact on your faces of the parts. You should be able to find the proper torque loads for your fasteners and apply forces to the Split-Face to match the fasteners loads/forces.

[mechamania]

But bonded is far from realistic. Especially when bonding larger areas. The contact area close to the bolt should never seperate or slide. So bonded probably is best choise there. But further away from the bolt I think the contact should be able to slide and or seperate. So what to use? Can I use different types for area close to the bolt and area far from the bolt?

[blair]

I believe short of going into Dynamic Sim and creating Pinned for the Split-Face and sliding for the other faces (not even sure if it would work there)

Again, I would be doing advanced FEA in Sim-Mech for these reasons.