Calculating the shear stress at the base of a padeye 1

[tnteng]

Should the shear stress at the base of a lift eye (padeye) be calculated using the average shear stress formula or the transverse shear stress formula (sress=1.5*(V/A)) for a rectangular section? The padeye has transverse loading in the plane of the padeye.

Thanks in advance for any help with this question.

Tony Billeaud
Mechanical Engineer

 

[vonlueke]

tnteng: Use whatever is specified in the design code required in your project. If not specified in the required design code, and if you want to ensure no material yields, then ensure FS*1.5*V/A < 0.577*S, which simplifies to FS*2.60*V/A < S, where FS = factor of safety, and S = tensile yield strength for static loading or tensile fatigue strength for cyclic loading. (In the worst case, for a very large number of stress cycles, the minimum tensile fatigue strength would be the material endurance limit.) The 0.577*S term is the shear strength per von Mises theory for ductile materials.

Note that if the padeye is tapered, the peak shear stress at the base won't be the maximum peak shear stress, but instead the peak shear stress (1.5*V/A) will increase at cross sections as you move away from the base.