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## [TowerTalk] 4130 Chrome Molybdenum Mast

 To: [TowerTalk] 4130 Chrome Molybdenum Mast w7xu@dtgnet.com (W7XU Arliss) Thu, 23 Sep 1999 04:08:44 +0000
 ```Hi, 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 Hopefully "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 address...nd6a@arrl.net > > -- > FAQ on WWW: http://www.contesting.com/towertalkfaq.html > Submissions: towertalk@contesting.com > Administrative requests: towertalk-REQUEST@contesting.com > Problems: owner-towertalk@contesting.com > Search: http://www.contesting.com/km9p/search.htm -- FAQ on WWW: http://www.contesting.com/towertalkfaq.html Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com Search: http://www.contesting.com/km9p/search.htm ```
 Current Thread [TowerTalk] 4130 Chrome Molybdenum Mast, Mike Nash, ND6A [TowerTalk] 4130 Chrome Molybdenum Mast, W7XU Arliss <= [TowerTalk] 4130 Chrome Molybdenum Mast, Mike Nash, ND6A [TowerTalk] 4130 Chrome Molybdenum Mast, W4nf@aol.com [TowerTalk] 4130 Chrome Molybdenum Mast, Mark L.