David-aviator
Well Known Member
In 1941 the Aluminum Company of America published some interesting data regarding driven rivets.
"Inspection of Driven Rivets"
"The standards to which driven rivets should conform are frequently uncertain. In addition to dimensions (thickness,diameter) and perfection of shape, inspection is concerned with whether the driven head is co-axial with the shank (not "clinched") and whether the metal is in a sound condition (not badly cracked). Cracking at the edge of the head frequently results from overdriving or from driving rivets that have under gone too much age hardening. However, it has been determined that even badly cracked heads are strong enough to develop the full shear and tensile strength of the shank."
(photo of 10 rivets heads of various shapes from good to very poor)
(I tried to scan the photo but could not get it done.)
"The series of rivet heads shown above was tested in tension to determine how well formed a head had to be in order to develop full strength. The tensile strengths of all of the rivets in the photograph were within fire percent of the strongest one."
The article goes on to say "The foregoing is presented for the purpose of indicating that superficial cracks in rivet heads and minor deviations from the theoretical desired shape of head are not cause for concern or replacement. The second rivet that is driven in any one hole is likely to be even more defective than the first...."
Just food for thought when you have a bad looking rivet in a hard to get to spot....
Thanks to friend Roger Mell who somehow obtained this 1941 Aluminum in Aircraft technical document.
"Inspection of Driven Rivets"
"The standards to which driven rivets should conform are frequently uncertain. In addition to dimensions (thickness,diameter) and perfection of shape, inspection is concerned with whether the driven head is co-axial with the shank (not "clinched") and whether the metal is in a sound condition (not badly cracked). Cracking at the edge of the head frequently results from overdriving or from driving rivets that have under gone too much age hardening. However, it has been determined that even badly cracked heads are strong enough to develop the full shear and tensile strength of the shank."
(photo of 10 rivets heads of various shapes from good to very poor)
(I tried to scan the photo but could not get it done.)
"The series of rivet heads shown above was tested in tension to determine how well formed a head had to be in order to develop full strength. The tensile strengths of all of the rivets in the photograph were within fire percent of the strongest one."
The article goes on to say "The foregoing is presented for the purpose of indicating that superficial cracks in rivet heads and minor deviations from the theoretical desired shape of head are not cause for concern or replacement. The second rivet that is driven in any one hole is likely to be even more defective than the first...."
Just food for thought when you have a bad looking rivet in a hard to get to spot....
Thanks to friend Roger Mell who somehow obtained this 1941 Aluminum in Aircraft technical document.
