Technical question about steel

[Idaho]

Someone on this site has to know the answer to this question.

I make my jack adapter frames out of 14 gauge 1 inch square steel tube. That is very heavy steel, very stiff and in no way will it bend under the weight of the Nomad. There are four points where the bike frame rests on the adapter and due to the short distances between these points it would take an amazing amount of pressure to get the tube to bend.

My question is "how much pressure would it take?" I've been trying to do some research online but can't find any figures on the tensile strength or the bending strength of these tubes and I would like to know.

Anyone have an answer based on real technical data? Or, know where I can find it?

Thanks, Bud

[Cajunrider]

Bud, I worked with steel for many years but can't answer that question. If there is a local metalurgy lab in your area you could find out there. They could test a piece and tell you the yield and tensile strength. I can tell you it's much more than the weight of the Nomad.

[paul]

Is it schedule 40, typical, hard or mild?

[ringadingh]

I don't have the answer either, but the steel supplier should be able to get those answers either from his catalogs or from the supplier that supplies him. At my old job I had a chart that gave the the tensile strength of the different tube sizes. We manufactured tow truck wreckers and sometimes had to make custom parts for certain applications.

[Idaho]

It is A36 mild carbon steel. I called the supplier and they had no idea. At least the gal that I talked to did not. She sent me a Material Test Report that only turned out to give the chemical make up of the steel. Nothing about tensile strength or compression resisitance. I found a report online from ASTM but it is $39 for 8 pages and the only way for me to see if what I'm looking for is in there is to pay for it.

Still looking.

[Cajunrider]

That's probably going to be difficult to find online Bud.

[oldbikers]

Bud I have several books on that stuff because I am a little slow and can't remember anyway I will try to find my books tomorrow and see if I can help you I was a welder for 25 years.

[Cajunrider]

I too have several specification books with tube and pipe wall thickness, weight per foot, etc. None of them give tensile or yield strength though Jim. Hope you have something.

[ringadingh]

I imagine that mechanical engineering manuals may have that spec. Engineers need to know that so they can determine how to design whatever it is they are making.

[usranger74]

Ask an Engineer

http://engineering.mit.edu/ask/

http://www.engineering.com/Ask/tabid/3449/Default.aspx

http://www.aboutcivil.com/answers/steel-structures

These sites may help.

[wrongway]

A36 structural steel shapes : Mechanical Properties
tensile strength (Ksi min) 58-80 :
Yield Point (Ksi min) 36 :
Elongation in 2 in. % min 23

ASTM A36 covers carbon steel shapes, plates and bars of structural quality for use in riveted, bolted or welded construction of bridges and buildings and for general structural purposes. strength requirements are 58-80 ksi tensile and 36 ksi min. yield strength

I hope this helps.......

[Idaho]

Kelly, what is ksi????

I found an online calculator to tell me how much this tube will bend. If I use a 12 inch beam with fixed ends and apply 1000 lbs it only deforms 7/1000 of an inch. That is way overkill for several reasons. One is the bike does not weigh 1000 lubs. Second is that the weight would have to be divided among the lift points. there are four points of contact to the frame and four more to the jack. That divides down to about 100 lubs per point of contact. using 100 pounds and a six inch beam it comes up 28/10,000 of an inch of deflection. that is nothing.

[ve3hzz]

ASTM A36 Mild (low-carbon) steel Yield Strength, psi 36,300 = 12000psi at allowable safety factor of 4x = 82 Mpa = 843kg/cm2

So your on the right track with what you found out. So like has already been stated, the form factor and your run of this far out performs it's purpose used, so your good to go.

Now the only FACTOR that is in question (again I don't think it's a big concern) is the weld joints stresses and if this is under a load that will even come close to the shear force of what the welds can handle. I again doubt there is concern, but that would be the weakest point in your determinations, which again have a lot of factors to find out or do destructive testing of a weld joint to determine this, but not something to worry about in your case Bud.

Still, funny that your steel supplier doesn't have a chart in the sales office to give to you. If it was a receptionist you spoke to maybe she doesn't know, but one of the guys in the shop should or they better if I'd be going there for there products

Scott

[wrongway]

a ksi is a unit of measurement of Stress or Pressure
1000 lb/inch squared = 1 ksi
The ksi ("kilo-pound[-force] per square inch") is 1000 psi

[Idaho]

Scott and Kelly, my thanks to you both. Now I need to figure out a positive way to present all of these facts in my E-Bay listing.

My competitor is poo-poohing the 14 ga steel tube that I use. I need to come up with a way to present those frames with real numbers to prove the strength of the adapters whenever a prospective buyer is comparing between his and mine.

It makes me grin to see him dirt shoot me because I know I'm making him feel the heat. HA But, I'm going to go there with him. I'm going to keep my posting on the positive side.