×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

# Aluminum bolt calculation request3

## Aluminum bolt calculation request

(OP)
I am designing an aluminum (356-T6) coupling with an M14 thread (male). Will the M14 aluminum male thread be able to withstand 2000N of force (tensile)? Bolt is 25mm long.
Will the aluminum thread strip? How should this be calculated?
Any help is appreciated.

Thanks,
John

### RE: Aluminum bolt calculation request

2
The quick answer is yes, the M14 fastener should withstand 2000 N.  The method is:

stress = force / area

so,

force = stress * area
force = 180 MPa * 115 mm^2
force = 20.7 kN

The stress I used is a typical yield stress for 356 T6 material.  The area I used is the fastener stress area.  I recommend reviewing the contents of this website to get more information.  Try these:

### RE: Aluminum bolt calculation request

Your answer (based on the external thread tensile stress area) appears to assume that the length of thread engagement is sufficient to fail the bolt thread in tension (that is, that the length and strength of the external and internal threads is sufficient that they will not "strip" or "shear" prior to bolt tensile failure, but will support the full tensile capability of the bolt).  There doesn't appear (to me) to be enough information in the original post to support that assumption.

I think additional information is needed:

We are told the "bolt length" is 25mm.  But is this the length of the engaged internal and external threads?  If not, what is the length of engaged threads?

Are both the external and internal threads the same material/strength (A356-T6)?

Is the pitch 2mm, as you apparently assumed based on your tensile stress area (needed for thread shear area calculations)?

While the externally threaded meter of the coupling has been described as a “bolt”,  on the off chance does this “bolt” have a hole through the middle of it?  The use of  “coupling” in the post makes me wonder if this is a “fluid” coupling – which might be hollow...

What is the thread class/fit (this can have and effect of thread stripping/shear calculations)?

CoryPad, don’t take this personally, I am (and remain) a fan...

### RE: Aluminum bolt calculation request

Kenneth,

I didn't take anything you said as negative criticism.  You are correct that I assumed a 2 mm pitch, and axial and diametral thread engagements that would cause tensile failure.  Considering the large margin between typical force (2000 N) and calculated break (20,000 N), I would wager that any small differences (like pitch, thread class, etc.) will not materially affect the results.

My philosophy on this forum is to try and move people in the right direction, not necessarily do the complete analysis that may be required.  That is why I did a simple calculation, and encouraged JohnF_Al to seek the detailed information available at this and other sites.

### RE: Aluminum bolt calculation request

(OP)
Thanks to both of you for the info. The Fed std H28/2B document was very helpful.

John.

#### 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.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!