Calculating Minimum Diameter for Steel Pin w/ Partial Uniform Load

[roldy]

I'm a bit rusty on partial uniform loading on a pin. I want to find the minimum diameter a cold rolled steel pin has to be using a factor of safety of 2 with a loading of 25000 lbs. The pin in the picture is welded between two plates (the right plate bends in and is welded to the left plate below the pin) . These plates are welded to a box (another pin is located on the opposite side of the box). A hook grabs onto this pin. I've tried finding equations regarding partial uniform loading. The equations I've turned up show the center piece the same width as the gap.

 

[Mech_Engineer]

I think this paper may provide some insight for you, it is an analysis of a pin in double shear: http://www.ewp.rpi.edu/hartford/~kw...es/Edward Kwon - Preliminary Final Report.pdf

 

[roldy]

Thanks for the paper. However, this does not show how the stress changes if the clevis has two different thicknesses. I guess I could take the worst case scenario and use the lesser of the two thicknesses for my t₁.

 

[Mech_Engineer]

Based on the posts so far I'm guessing that running an FEA model for your specific geometry is not an option?

 

[roldy]

You are correct. I was hoping that I could come up with an equation for this type of scenario.

 

[Mech_Engineer]

Your scenario is challenging to find an analytical solution for because there is a gap between the inner and outer clevis which will cause a bending load on the pin, and the outer clevis's plates are asymmetric in thickness.

Have you considered making some assumptions to simplify your modeling task? I think you could consider a beam bending model of just the pin with a simply-supported beam. This would be a "worst-case" analysis because the pin would not be stiffened by the clevis in this case. Otherwise, FEA really may be your best option.

 

[roldy]

Yes I've considered beam analysis and I am currently working on this.

 

[Mech_Engineer]

Make sure to calculate the Von Mises stress to combine shear and tensile/compressive stresses for your analysis.

 

[Divya Shyam Singh]

Do you have a 3D model of the same? Its hard to properly understand the system...
A hand drawn 3D view would also suffice.

 

[roldy]

A lifting hook goes around the pin.

 

[Mech_Engineer]

Looks like a questionable strength design to me. How are you evaluating the strength of the bracket holding the pin?

 

[greentlc]

I would agree with Mech_Engineer, I think you'll find that the 1/4" plate will be a limiting factor in this design.

Maybe you haven't got there yet, but I think you should check tear out shear on that plate section.