×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Pull-Through of Fasteners in Thin Sheet

Pull-Through of Fasteners in Thin Sheet

Pull-Through of Fasteners in Thin Sheet

(OP)
I've gotten what seemed a simple request;
What load is required to pull X size fastener through Y thick aluminum cladding?

I went to ever faithful Roark and no direct cook book.  The issue is 'thin' sheet, the membrane stresses are substantial so anything I can analytically calculate ignores them, and as such calculates a force much too high.

Does anyone have a reference or direct formula to help me out?

I have a fastener (0.312dia shoulder / 0.187dia shank) through a 0.12 thick 5083-H32 aluminum sheet (S=36.3 ksi).  Using Roark I get 905 lb.  

If it took that much force to pull 1 nail through aluminum cladding Florida would never have to worry about hurricanes. ;P  Please help.

Today is gone. Today was fun.
Tomorrow is another one.
Every day, from here to there,
funny things are everywhere. ~'Dr.' Theodor Geisel

RE: Pull-Through of Fasteners in Thin Sheet

What were you using in roark?

You could take the circumference of the bolt head if it round (or inscribed if hex etc). Then you know the material shear allowable. So you have the P/A fastener shear out formula. The bolt head could pop-off if thats the way the joint was designed.

If your bolt head is 0.312" dia, then your shear-out circumference = pi x .312 = 0.98"
the thickness is 0.120" so the area = 0.118in^2
material Fsu = 36300psi so the pull-out force =
36300 x 0.118 = 4283lb

RE: Pull-Through of Fasteners in Thin Sheet

(OP)
40818,
Failure wouldn't be by shear, do you believe it would take ~2 ton of force to pull an 3/16 screw head through a 1/8 thick aluminum sheet?

Failure would occur when bending stress of the hole is large enough to 'fail the hole' (ie open to slip the head through.

Like I said though, since its a thin sheet, you can't assume the midplane is stress-free, you get membrane stress that I can't figure to account for.  My gut says you should be able to pull this thing with about 500 lb, I just can't prove it.

Even experiment data would help if anybody has any.  Maybe I could correlate the data, etc.  My whole assessment is based on the fact of proving that this will fail at a relatively low load. (~700 LB)

Today is gone. Today was fun.
Tomorrow is another one.
Every day, from here to there,
funny things are everywhere. ~'Dr.' Theodor Geisel

RE: Pull-Through of Fasteners in Thin Sheet

I vote for an experimental determination of the pull-out strength. I can picture running the screws into a piece of the sheet and then inverting the sheet/screw over a hole in a set-up block (screw head down) and determining "push-out" strength on an air-powered arbor press. If you have an air pressure gauge on the regulator you should get a fairly good idea of the forces.

RE: Pull-Through of Fasteners in Thin Sheet

for self drilling screws have a look in the back of the hilti catalogue.

RE: Pull-Through of Fasteners in Thin Sheet

(OP)
MJ,
Thanks but no I don't think this applies.  Its an empirical formula to bend the metal and overcome the holding force to draw.  What it did though is re-enforce for me that this may be an FEA solution, as crazy as it may sound.

Is there maybe a correction fudge factor of membrane stress based on material thickness that people know about.  

Just to clarify;
The fastener is a solid rivet.  I think I may cross-reference this in the aeronautics forum.

Today is gone. Today was fun.
Tomorrow is another one.
Every day, from here to there,
funny things are everywhere. ~'Dr.' Theodor Geisel

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources