Pull out strength of studs threaded into aluminum 1

[AbelGus]

I am looking for tables or formulas for pull out strength of bolts or studs threaded into aluminum. In particular, I am threading an M12 X 1.75 forged stainless steel (alloy 316) eyebolt into 6061-T6511 aluminum or 7075-T651. The thread depth is 20.5mm.
The eyebolt in question is a shoulder eyebolt with a working load of 3.4 kN. I am concerned about straight pull only. I want to ensure that the thread bearing capacity matches the permissible working load when threaded into aluminum.

Abelgus

 

[rb1957]

From AR-MMPDS-01 (you'd be able to find the same info. in MIL-HDBK-5) table 8.1.5(b1), a 1/2" diameter thread in 55 ksi (ftu) has a strength of 8310 lbs. 6061T6 has an Ftu of about 40ksi (that sucks), as allow a stregth of 4155 lbs (1/2 the 55 ksi value) = 18kN ... quite a bit more than your requirement

 

[boo1]

Consider using a threaded insert. This will help you match the strength and reduce the galvanic potential.

 

[IFRs]

Can't go through the aluminum, I guess. Is this temporary, permenant, holding up something that people will be under, subject to getting wet, have vibration loading, carrying other loads?

 

[AbelGus]

These are M12 eyebolts with shoulder threaded into each end of a 1" x 3" x 48" long aluminum bar which supports woven wire fabric under an arcade. There are three splayed cables the attach to each eye. Static calculations have been performed (900 pages worth)for a 30 psf. windload that show the maximum load on any one iontermediate cable in the system is 178 lbs. (The end cables are more highly loaded and use different connectors and bars). There is never a case where all three cable carry the 178 lb. load but assumining they did the outside max.load on the eyebolt would be 534 lbs axial to the bolt. The bolt part of the eyebolt is 20.5mm long, m12 X 1.75. The aluminum is post anodized after machining. This is in a dry location.

 

[AbelGus]

Aerospace,

Is threr a way to access this table via the internet?

 

[AbelGus]

RB1957 (aerospace)

Is there any way to access this table via the internet.

Thanks

ABELGUS

 

[Lutfi]

Listen to boo1. He is so right. I would use KEENSERTS or any similar product. There are many advantages to using them. to add to the advantages than boo1 listed, I would point out that you can replace the inserts and keep the parent aluminum metal threads undamaged.

Here is a link to KEENSERTS links to web sites:

1. Advantages of using the inserts:

http://www.barnhillbolt.com/pdf/keensert.pdf#search='keenserts by tridair'

2. KEENSERTS web site

http://www.keensert.com/

Good luck


Regards,
Lutfi

 

[AbelGus]

Lutfi & boo1

The threaded inserts are a good idea for a number of reasons. The step up in diameter increases strength (tho I am OK there). The other good thing is that the insert can be backed in and out slightly to allow the shoulder eyebolt to be in the correct orientation - this is easier than trying to start the tap in the exact orientation, or shaving material of the end of the bar until the eyebolt sits right. After it is correctly positioned the bar will be cross drilled for set screws.

The dissimilar metals is not really that mush of an issue between aluminum and stainless steel - particularly when Loctite is being used. Also the anodizing helps.

Thanks

 

[MikeHalloran]

The load I'd be concerned about is that developed when the eyebolt shoulder bottoms out and the assembly gorilla sticks a cheater bar through the eye and hangs from it, just to make sure it's 'tight enough'.

By eyeball, the thread engagement seems a little short for that loading condition.





Mike Halloran
Pembroke Pines, FL, USA

 

[rb1957]

5J is out of date, but the data is still good ...

http://www.reliasoft.org/mil_std/mil_hdbk_5j.pdf

check the transverse loads on the lug; the loads don't look like trouble, but it's nice to see a calc (to show things that were considered).

good luck