How to Calculate maximum torque a riveted joint can stand

[gowtham]

A plate is riveted with a rivet having small rod like projection over the head and the point as shown in drawing.Considering we fix the plate to a vise,and then giving torque to the Rivet Rod;What will be the Maximum Torque the rivet can withstand without getting loosened and how to calculate the Maximum Torque" it?

 

[lekh2003]

View attachment 216260 A plate is riveted with a rivet having small rod like projection over the head and the point as shown in drawing.Considering we fix the plate to a vise,and then giving torque to the Rivet Rod;What will be the Maximum Torque the rivet can withstand without getting loosened and how to calculate the Maximum Torque" it?

It depends on how hard rivet and plate are attached together. If you know that, then this is a simple torque/force question which you can solve with some basic equations.

 

[gowtham]

You mean riveting load?

 

[russ_watters]

This is unclear to me; where is the torque applied and about which axis? Can you draw it?

 

[JBA]

A better view of the rivet's location an orientation would help,as well.

 

[gowtham]

The torque is applied about the rivet axis!

 

[gowtham]

 

[russ_watters]

The torque is applied about the rivet axis!

Wouldn't that mean the rivet just spins in its hole?

 

[Dr.D]

Wouldn't that mean the rivet just spins in its hole?

I think the question is largely one of friction torque, and that is something that will be very hard to determine without knowing the details of how the rivet was originally installed.

 

[gowtham]

Wouldn't that mean the rivet just spins in its hole?

Of course the rivet spin in its hole,But there might be some force involved, above only which it will start spinning. Assuming that force as frictional force.How do we proceed with it?

 

[gowtham]

Of course the rivet spin in its hole,But there might be some force involved, above only which it will start spinning. Assuming that force as frictional force.How do we proceed with it?

The rivet is actually installed using an air hammer.

 

[Tom.G]

From a non-mechanical guy: It seems the clamping force between rivet and disk will be limited by the plastic deformation limit of either the mating surfaces or the rivet shank. Knowing that, and the contact area between the rivet head(s) and the disc, you can find the maximum clamping force. Then use the coefficient of friction between the two components, the clamping force, and the contact area to find the sliding force.

Note that this will give the maximum, ideal, sliding force. A generous safety factor should be included to cover non-ideal manufacturing and contaminents in the joint.

As an improvement, there could be radial grooves in which ever is the harder material of the joint (or maybe in both). This will add a material shear restraint to the frictional restraint.

That's a starting point anyhow. Since there were no material characterisitcs or assembly procedures given, I doubt much else can be said at this point.

 

[lekh2003]

The simple problem here is that OP has not given any specifications or extra details besides the diagram.

 

[Nidum]

That type of joint is bad in principle for any higher torque or safety critical applications . @Tom.G gives you the hint on how to make it better . Contrive some type of positive keying to carry the drive load and just use the rivet to hold the parts together .

 

[Dr.D]

From a non-mechanical guy: It seems the clamping force between rivet and disk will be limited by the plastic deformation limit of either the mating surfaces or the rivet shank. Knowing that, and the contact area between the rivet head(s) and the disc, you can find the maximum clamping force. Then use the coefficient of friction between the two components, the clamping force, and the contact area to find the sliding force.

It is actually more complicated than this. Knowing the maximum clamping force does little good; what is needed is the detailed distribution of the clamping force over the contact zone. Then the maximum moment capability of that distributed force can be computed. This is all rather theoretical and the actual distribution is virtually unknowable. It probably varies from one rivet installation to the next, because it depends upon the details of the driving event (how hard it is hit, how squarely it is hit, etc).

In short, a single rivet is a lousy way to support a torque!