Why Does Shear Increase with Distance in Torque-Shear Calculations?

[apointyrodent]

For some reason I am having a hard time visualizing the torque-shear equation, specifically when it comes to finding shear in rivet patterns with a non-symmetric load. We have been using the Tr/J formula to find the shear in the individual bolts. However, with this equation with increasing distance from the CG the shear also goes up. This seems counter-intuitive.

For example.. think about torquing a bolt. The farther you are from the center of rotation the less force is required to produce a given torque... so why is the reverse not true? I.e. "Given a constant torque, the farther you are from torque center the less force required to resist it, therefore less stress is induced?"

I've never had a problem with this before but it's been bugging me today for some reason. Thanks.

 

[nvn]

Your second paragraph is an analogy for comparing two bolt (rivet) patterns, whereas your first paragraph is a question regarding one given bolt pattern. Within a given bolt pattern, the highest shear stress (and therefore shear force) occurs on the bolt having the largest distance from the center of rotation, which is shown by the relation T*r/J.