Deflection of Plastically deformed Cantilever beam

[Joselito]

Picture a steel plate (24" x 4" x 0.25&quot clamped to a table such that the plate is cantilevered out away from the table by 22". Apply a load at the tip of the plate, normal to a surface, large enough to plastically deform the plate and permanently deflect the tip of the plate, say 2 inches.

Now, unclamp the plate and flip it over, and reclamp, such that the downwardly deflected tip now points up. Again, apply a load to the cantilevered tip of the plate, which is sufficient enough for plastic deflection to take place.

Will the plate return to its initial shape (will it straighten)?

 

[sancat]

Theoretically, yes; actually, no.

It will be very hard to avoid flexo-torsional warp of the cantilever, or waves on the lower part of the cantilever. But if they do not happen, most possible is that, the superior part will elongate, and the plate will take a shape close to a parabola, while the lower part will not compress, as theoretically predicted. The elongation will be highest at the top of the plate, 0 at some point very close to the bottom, and some elastic compression will be present at the bottom.
When the plate is turned upside down, and plastically deformed again, waves on the inferior part will be close to unavoidable due to deformation hardening, and the plate will be warped with no practical solution. The superior and inferior part will be longer than the middle part, the plate will take an helical or wavy form.
sancat

 

[Joselito]

SANCAT,

Thanks for your reply. Lots of bent paper clips seem to support your conclusion. I appreciate it.

Jose

 

[nigelt]

If I may be so bold - I'd be grateful if you could take a look at my question in "electromech pkg design".
Thanks in advance!