Freeze Plug and O/S Fastener
Freeze Plug and O/S Fastener
(OP)
Suppose you have a damaged fastener joint. You repair by opening up the hole, putting a freeze plug (dia. D) then installing nominal fastener (dia. d) through the freeze plug.
My question is how to treat this repair when analyzing bearing capability.
Which should I use to compute edge margin, D or d?
My question is how to treat this repair when analyzing bearing capability.
Which should I use to compute edge margin, D or d?





RE: Freeze Plug and O/S Fastener
Depending on the material of the plug and parent material, the fastener may be critical in bearing against the plug, or the plug against the parent material. If the OD of the plug gives you a problem with the edge distance, treat it like a lug, and analyze whatever failure methods could apply.
If this fastener is part of a long row, then the effect of the plug may not be too different from oversizing it, but I suppose you would have oversized it in the first place, if it was a continuous row.
Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout
RE: Freeze Plug and O/S Fastener
Shear Tear-Out
Allowable Load=2(EM-S)(Fsu)(t)
S=DCos40/2
EM=Edge Margin, Fsu=shear allowable for part,
t=part thickness at hole loaction
This formula is from the course notes for the Boeing Repair Design course.
I hope this helps
Alex Connell
RE: Freeze Plug and O/S Fastener
If it is to get a joint shear capability you are actually asking for,then all said before is applicable. Minimum joint is dependant on all components of the repair.
What is it you are repairing anyway?