×
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

Tensile and Shear Strength
3

Tensile and Shear Strength

Tensile and Shear Strength

(OP)
This is probably a dumb question, but no one i work with seems to know the answer.

I am looking for a book/chart that has the tensile and shear strengths of several different Socket Head Cap Screws.  I have been told to call a supplier, but i want to have a hard copy format to keep at the office for anyone that needs it.  Does anyone know where i can find this?

RE: Tensile and Shear Strength

If you need a rough figure (like if you're going to add a safety factor anyway), you can simply calculate the strengths based on the annealed material and a diameter equal to the minor diameter of the threads.  This gives you a worst-case figure (neglecting notch-sensitivity, etc.).

Don
Kansas City

RE: Tensile and Shear Strength

If you know the ultimate tensile strength of the material, you can estimate the shear strength using the equation below for carbon and low alloy steel;

shear strength = 0.6* UTS

RE: Tensile and Shear Strength

(OP)
Here is the situation.

I am designing a lifting fixture to pick up and object that weighs roughly 35,000 lbs.  I need to know how many bolts to put into the object, as well as the fixture itself, so that I know that the Cap screws wont fail ad drop the 35,000 object to the floor.  I am looking at using 1"-8 and 1.25"-7 cap screws.  I just need to know how much 1 of each can old in tension and in shear so I can optimize my design.

RE: Tensile and Shear Strength

Can you weld a lifting lug on the object instead of attempting to design a bolt-on lifting lug?

RE: Tensile and Shear Strength

Depending on the design of the lifting mechanism,  any percentage may be applied at any lifting point.  Thus, a four point harness may have 25%, 50% or 100% of the entire load acting on one lifting point, (depending on tipping and swing of spreader assembly).   

RE: Tensile and Shear Strength

The link prohammy gave you is a decent starting point.  The actual values for mechanical properties are shown in consensus standards like ASTM A 354 Specification for Quenched and Tempered Alloy Steel Bolts, Studs, and Other Externally Threaded Fasteners and ASTM A 574 Specification for Alloy Steel Socket-Head Cap Screws.

Shear properties are listed because you aren't supposed to put threaded fasteners in shear.  Of course they are placed in shear, so general equations like metengr's are used.  Try to have a full body shank (not the threaded section) through the joint's shear plane.

Regards,

Cory

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Tensile and Shear Strength

(OP)
It has to be bolt on so it can be easily removed.

RE: Tensile and Shear Strength

"... so I can optimize my design." ... nice idea but is it worth it ? safety, and a quick analysis, is more important (IMHO).

demonstrate that your structure can handle the loads ... worry about where the cg of the load could be, what SF do you need to lifting a load ? (i'd use at least 3) ... maybe consider one bolt in a group to be ineffective (ie need 5, use 6) ... worry about the shear/tension interaction (i'd use Rt^2+Rs^2 = 1, Rt, Rs = applied load/allowable; 'cause it's slightly conservative and much easier to use)

RE: Tensile and Shear Strength

(OP)
rd1957

You are right.  I am after making sure I have enough bolts in the fixture so it does not fall.  Onc I know that I will add more bolts so i know that the FOS is at least 3.

RE: Tensile and Shear Strength

2
In an ideal world:

You do not use bolts carry loads in tension.

You do not use bolts as shear pins.

Bolts are designed to be used to draw the two parts together. The load is then reacted in shear between the two parts, by friction alone.

Cheers

Greg Locock

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Tensile and Shear Strength

How about the use of bolts for gasket design? this bolt connection , ussually, is under tension in this case.

Kinsrow.

RE: Tensile and Shear Strength

RB1957 is correct, but if i may put my opion forward, i would have a factor of 8 for a lifting apparatus, cant remember where it came from, but its the number that is rattling around the back of my mind. I might be tempeted to use a different shear/tension interaction depedning upon the material of the bolts you decide upon though.

And though greglock is correct, but in the real world bolts are used to carry tension loads, especially in aircraft structures, thats why you can get a variety of bolts for shear or tension applications.

RE: Tensile and Shear Strength

I think 40818 may be correct, I seem to remember that number (8) too.

RE: Tensile and Shear Strength

http://www.spstech.com/aero/prod_lit/socket_brochure.pdf

page 8 - double shear only (as it should be)

Last 2 years I did some work with a big defense contractor for a division of the US Navy.  We ended up having to provide calculations proving between 3X and 5X factor of safety (for lifting), and slings etc rated for a 4 point lift failing to become a 2 point lift, even though the item being lifted would not physically handle being lifted at 2 points, and would have been hopelessly unstable (picture yo-yo) with most combination of 2 point lift.

FEA usually delights in pointing out that several of the bolts in my brackets, etc are completely superfluous.  The solution is Thick flanges and keeping bolts as close as close to gussets (or is it gussets close to bolts?) as wrench clearance permits.

RE: Tensile and Shear Strength

Mark's Handbook of Mechanical engineering. Chapter 8.2 machine elements

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