Tensile Strength vs Shear Strength of bolts? 2

[iawia]

Hi,

I have done a search over this forum and the web, but I am coming up short. I am trying to determine the failure of fasteners in shear. I have found on some web searches that we can use .58*tensile_yield_stress to approximate the failure strength in shear, but it is over forums, and nothing really official. Is there some reference or mil spec that anyone knows of that I can look at? Or a discussion perhaps can help me get convinced that this is true.

Please help. Thx!

-t

 

[CoryPad]

The 0.58 ratio between tensile yield and shear yield comes from the yield criterion known variously as von Mises, distortion energy and/or octahedral shear stress. The ratio between ultimate shear and ultimate tensile is close to 0.6 for many materials, but does vary. One reference is VDI 2230 Systematic calculation of high duty bolted joints. Another source is MIL-HDBK-5 METALLIC MATERIALS AND ELEMENTS FOR AEROSPACE VEHICLE STRUCTURES and its successor DOT/FAA/AR-MMPDS-01 Metallic Materials Properties Development and Standardization.

 

[iawia]

thanks cory

 

[racookpe1978]

If your fasteners are threaded check that your shear force is not acting through the small thread root dia. A proper length bolt should have the full diameter as a shear section, but a theraded rod or a all-threaded bolt or screw will not.

If a pop river (hollow) use the correct cross-section area.

 

[Guest262653]

From the von Mises yield criteria entry in Wikipedia:

"at the onset of yielding, the magnitude of the shear yield stress in pure shear is √3 times lower than the tensile yield stress in the case of simple tension"

1/SQRT(3) = 0.58

 

[Tmoose]

page 31 here ? -

http://www.holo-krome.com/pdf/Consolidated_Tech_Manual.pdf