[Top] [All Lists]

[TowerTalk] 4130 Chrome Molybdenum Mast

To: <>
Subject: [TowerTalk] 4130 Chrome Molybdenum Mast
From: (W7XU Arliss)
Date: Thu, 23 Sep 1999 04:08:44 +0000

I'm not an engineer, but it's my understanding that the yield strength is 
a function of the material/alloy and is independent of the dimensions.  So
4130 has the same yield strength regardless of it's dimensions.

You need to calculate the section modulus, which for round tubing is:
                   Pi*(D^4 - d^4)/32D
where D is the outer diameter and d is the inner diameter.

You then calculate the maximum bending moment, which I think is what you
are really after, by multiplying the section modulus by the yield strength.
This answer is the maximum force, measured in inch-lbs, that the material
can withstand.

A quick check on the calculator shows that for 1 inch OD tubing, the
0.120 wall material (4130) has about 59% of the strength of the 0.25 wall
material.  For 2 inch OD tubing, the 0.120 wall tubing is only 53% as
strong as the 0.25 wall tubing.  So you see that to really answer your
question we have to know the specific diameters involved.

I hope some of the engineers can set me straight if I have this wrong.

73,  Arliss  W7XU


"Mike Nash, ND6A" wrote:
> I have a quick question regarding strenth of this stuff
> In using the Marc program I see that 4130 has a yield strength of 115000
> psi for .250 wall thickness.
> What is the strength for .120 wall thickness?
> Is it exactly half?
> Mike...ND6A
> Please note the new e-mail
> --
> FAQ on WWW:     
> Submissions:    
> Administrative requests:
> Problems:       
> Search:         

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>