 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
eldo(at)unb.ca
Guest
|
 Posted: Wed Mar 08, 2006 8:20 am Post subject: Grades of Nuts & Bolts |
 |
|
I've not being paying close attention to this lengthy exchange; however I couldn't let
Larry's comment go without digging out my notes for Mechanics of Materials and one of
many texts on my shelf (sorry my Aircraft Mechanics Handbook is at home).
I've no idea what the grades you mention are intended to mean but if the strengths are
correct, I wouldn't let them near an aircraft. A high strength AN6 bolt has a yield
strength (start to fail) in shear of 10,500 lb (that translates to about
95,000lb/sq.in.). Ordinary structural steel (A36) that is often cast into concrete has
a yield in tension (starts to fail) of 36,000lb/sq.in (thus the code A36) and ultimate
strength (when it breaks) of 60,000lb/sq.in. Typical yield in shear (the way bolts are
normally meant to be used) is about half that of the tensile strength.... the typical
garden variety steel is therefore at best about 18,000 psi versus 95,000 psi for AN
hardware.
There are other issues of quality control of shoulder radius at the head, size
tolerances etc. that mean AN bolts are are the ticket unless you know the expected
stresses and the allowable strengths for the application and the hardware you wish to
use.
Bottom line... if the designer says this is where an AN bolt goes, I wouldn't want to
chance anything less even if the hardware cost is a couple hundred more and I have to
wait an extra day for FedEx!
Quoting Larry <lrm01(at)centurytel.net>:
| Quote: |
Granted, grade 8s are not legal for certified, but we are not doing
certified aircraft.
I have seen several comments about grade 8 bolts being brittle. Well they
are not, potato chips are brittle. Grade 8s have a strength of 2800 psi, AN
,2600 psi, grade 5, 2500 psi. That relates to the grade 8 being only
around 7% harder than an AN bolt. Yesterday I took a 3/8" X 5" grade eight
bolt, put it in a vise, took a larger hammer, bent it over to 45 degree
angle, bent it back somewhat straight, bent it over again and back. No
visible cracks, didn't break. Brittle is definitely not the right word.
If I could go to any store around here and but AN bolts, I would. They are
just not available unless you order them.
Anyway, I think this horse has been beat to death.
Larry, N1345L, www.skyhawg.com
|
Eldo Hildebrand, PhD., P.Eng.
Assistant Dean of Engineering
University of New Brunswick
P.O. Box 4400 Fredericton NB E3B 5A3
Phone 506 453 5112
Fax 506 453 3568
| | - The Matronics Zenith-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith-List |
|
|
|
| Back to top |
|
 |
Jari Kaija
Joined: 23 Feb 2006
Posts: 69
|
| Posted: Wed Mar 08, 2006 10:20 am Post subject: Grades of Nuts & Bolts |
|
|
| Quote: | I've no idea what the grades you mention are intended to mean but if the
strengths are
|
| Quote: | correct, I wouldn't let them near an aircraft. A high strength AN6 bolt
has a yield
|
Ok, it's time to end this "I think" thread...
http://www.boltdepot.com/fastener-information/Default.aspx#material
| | - The Matronics Zenith-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
