Stacked (non-laminated) Plates

[sam21black]

Hello,
I apologize if this has been asked before.

I have a series of small tabs made from thin plate that are bolted together on one end and loose on the other end. The tabs are supported on one end, and a loading force is applied to the opposite end. (Please see image. The dimensions are in inches, besides the threaded rod.) My question is, how do you calculate the shear and bending force in this situation? How is the section modulus accounted for? Any help is greatly appreciated.

Thank you,
Sam

 

[JStephen]

Physical testing comes to mind.
I can visualize how a lot of those tabs might just rotate to the side when enough force is applied; failure mechanism might not be as obvious as it seems.

 

[sam21black]

Thanks JStephen for the quick reply! However, these are currently used and have been used for the past 20 years in my company's products. They are placed into a slot that inhibits any detrimental rotation. We are starting a new product line, and now need to "prove" through engineering the validity of these tabs. Thank you again.

 

[JStephen]

With stacked plates, you'd normally assume the deflection is the same in each, that lets you calculate the percentage of load carried by each, then work back to the stress. But in your case, I think it's rather doubtful that a uniform deflection is actually carried all the way from top to bottom. Using that approach might give you some feel-good numbers to put on paper, but I don't know how closely they'd match up to reality. You might also be limited by shear at the very top, if you looked at a sloping plane in the top one or two pieces.

 

[BridgeSmith]

To me, it seems friction between the plates is the key variable, and it's highly variable. If you assume zero or some conservative value for friction, you'll get an answer that's massively conservative. I think the only way to really know is to test it and see how it performs, perhaps at the extreme tolerances for lubrication of the plates clamping force from the threaded rod, etc., to get an envelope of the performance range. You could try to do some fancy theoretical analysis, that would ultimately be a WAG, but why would you waste your time on that, when you can test the real thing and get actual performance data?

 

[sam21black]

Thank you all for the responses. My main concern is, is there a risk of shearing the top tab, and then have it shear the next and the next, etc? I don't know how much strength the additional tabs provide...

 

[Compositepro]

What is the purpose of this assembly? I cannot figure that out. Knowing that would probably help provide more useful answers.

You do not show all the loads or else this object will rotate.

You show point loading. The way the load is applied seems to be an important factor to your question. Contact area and geometry is also a major factor. If there is any possibility of shearing the tabs I cannot see what the assembly would be useful for.