<VV> Good Ref re strength of bolts

[Chris & Bill Strickland]

An interesting article by an apparently qualified engineer -- sometimes 
it is a shame that qualified engineers can not see beyond the 
mathematics of their profession -- yes, they have come a long ways since 
"Galloping Gertie", but they still refuse to accept empirical evidence 
that maybe their math on a particular fastener doesn't tell the whole 
story.  There is substantial empirical evidence, mostly from the world 
of aircraft it seems, that some higher strength fasteners do not perform 
as well under repeated cyclical flexing as fasteners of a lower grade.

Maybe they aren't adequately torqued, or the fastened material is too 
soft to maintain that torque during the cycling, and the bolt only has 
it's high strength when under high tension.

Anyway, if you discover that an application is breaking your highest 
strength fasteners, you might consider your own empirical testing with a 
fastener with a lower tensile strength.  If your Grade 8's are working, 
don't fix it!  But remember to periodically inspect critical fasteners 
for wear and corrosion

Godspeed!

Bill Strickland