Shear Strength
Shear Strength
(OP)
Does anyone recall the criteria for specifying shear strength? I have found in Machinery Hndbk where the shear strength for steel is 0.75*Su. I also have peers who swear by the criteria of 0.6*St. My old texts lean towards the 0.6*St for failure analysis, but I cannot get an additional reference that proves this. There is a big variation between using the ultimate strength as opposed to tensile strength. In particular I am looking for a reference I can quote as the authority.





RE: Shear Strength
There was some discussion about this a bit back, here is the thread, hopefully it will help a little.
Thread404-37622
RE: Shear Strength
Maui
RE: Shear Strength
RE: Shear Strength
The maximum-shear-stress theory predicts Ssy = Sy/2.
The distortion-energy theory says Ssy = Sy/(3^-1).
Some design codes use Ssy = 0.60Sy.
BTW, if there is a combination of bending (SIGMAx) and torsion (TAUxy), here is an equation for Von Mises stress (SIGMA'):
SIGMA' = (SIGMAx^2 + 3*TAUxy^2)^(1/2)
source: Shigley-Mischke pp 246-251, 1989
RE: Shear Strength
Maximum shear stress and distortion energy theories relate to yield behavior. Shear strength is the term used for the shear stress at fracture. There is no fundamental equation for this value; for many alloys, it is ~ 0.6 times the ultimate tensile strength.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Shear Strength
Circular bars will have higher allowables, but the above is conservative in (almost?) all cases. In reality ult shear will rarely be less than 0.6 * ft.
RP.
RE: Shear Strength
You were originally looking for an authority to refer to when backing up your calculation of shear strength. I also suggest "Engineering Materials" by Joseph Marin, Prentice-Hall, Englewood Cliffs, N.J., 1952.
That sure would beat a bunch of guys on the internet telling you "oh, it's about ~.6*Sut."
Best regards!