Force required to bend steel rod?

[Dennis6086]

How can I calculate a concentrated force needed to bend/deform a mild steel rod (3/8&quot? I am familiar with behaviour of materials in the linear region, but not with deformation mechanics.

Thanks in advance.

Dennis

 

[plasgears]

Permanent deformation is related to operation beyond the proportional limit. If you visualize the situation at the P.L., there is a force proportional to the stress at the outer fiber (s=Mc/I). Now, beyond the P.L., 50% of the fibers will be at yield at twice the bending load. 67% of the fibers will be at yield at three times the load, etc. So, you can visualize that about 3 times the load at the P.L. will give you nearly full yield and permanent bend.

 

[plasgears]

Correction -
Rule of thumb would be near full plastic bending at about three times the strain at PL for ductile materials. The load will be about approx 2 times the load at PL.