Physics/Engineering/Math Problem

[MechEng83]

Originally Posted by Ether

Let me guess: you want to use the cylinder rod as a side-loaded latching mechanism for your kicker/catapult.

If this is actually why you're asking, our team did this on a mechanism in a previous year. I recommend not using the shaft as the locking mechanism, but thread an extension on made out of grade 8 material, then support it as closely as possible on both ends.

"break" is a loosely defined term. Typically it would mean fracture, but in the case of a rod extension from a piston, any permanent deformation (yielding) from bending, or something biting into the shaft would be detrimental to the future operation of the shaft.

If you know the bending moment on the shaft, you could use the formula sigma=M*c/I where c is the radius, and I is the second moment of area. I=pi/2*r^4. Then compare the stress value (sigma) against the yield limit of the steel in the rod extension.