Date : 2016-06-23 12:24:21







b d

0.5 d(bi  bo)

3.14159 d2/4


0.5 (ri  ro)

ri  (d/3)(bi  2 bo)/(bi  bo)

0.5 (ri  ro)




The equations for the stress, sigma, are for pure bending and for a crane hook the bending moment is due to a force acting on one side of the cross section.


 In this case the bending moment is calculated about the centroidal axis, not the neutral axis.


Also additional tensile and / or compressive stresses must be added to the bending stresses, given by the two equations above, to obtain the total stresses acting on the section.

The most highly stressed points in a typical crane hook area E and B, see diagram below: 

sigma = F R ci/ (A e ri) F/A (tension) and 
sigma = - F R co/ (A e ro) F/A

The cross section of many crane hooks can be approximated to that of a trapezium giving rise to only a small error so the data given above can be used.

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