Plate deflection

[John2025]

Hi All,
I'm working on repairing one of our cutting presses. It has an 7" hydraulic cylinder (about 80 KIP max force) that the original manufacturer attached the rod end to a 3/4" thick x 6" square CRS plate that is supported on the outside edges. Over about 20 years it indented about .060" and created cracks radiating from the center hole (2-1/4"D) that we found when replacing the rod end seal. I'm planning on making a shim out of 1" 4150 pre-hard to put between the rod end and the cracked plate. I don't have any real engineering behind this, just figure it'll last at least as long as the original. That got me thinking though. I've seen flat plate formulas, but this is a 6" square with a 2-1/4" hole in the center. Can anyone point me to some appropriate formulas or methods?
Thanks,
John

 

[robyengIT]

May be I misunderstand, but, if You place a plate "as a shim", that will work "as a shim" without modifying the stressed structure but only uniformly spreading the load

 

[Lomarandil]

I'm guessing the idea is that if it's placed between the rod end and cracked plate, you don't have to make up any connections, it will just bear on the old plate and use the old connection.

My gut says that your flat plate checks (probably using a point load?) are conservative. But if you want a more precise answer for your 2.25" hole, look into "Roark's stresses and strains". Great reference with lots of mechanics problems like this tabulated.

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The name is a long story -- just call me Lo.

 

[robyengIT]

and, for me even better, "Formulas for stress, strain, and structural matrices" - Walter Pilkey - 1994 - chapter 18

 

[John2025]

Yes, I'm just redistributing the load through the shim so I don't have to pull the platen and repair it.
I'll check out your references, it's an interesting case with the center hole being large relative to the plate size.
Thanks guys!