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Yeild Strength Charts


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Ok now this is gonna seem a little weird and it is for the purposes of discussion and not to be any sort of definitive guide for anything, but I have created some charts based on the MINIMUM yield strengths from the material data of a few common steel stocks and the different cross sectional areas of different sized bars.

Now, the type of steel, it's size and shape and length are the major factors for the difficulty of a bend. So consider these comparisons are all round stock and all cut to equal length.

Bend Radius I think is also another huge factor but I will get to that later.

Firstly here are the stocks I choose and thier minimum yield strengths.

Minimum Yield Strength Chart

Here are the Cross Sectional areas that I used.

Cross Sectional Area Chart

Now here is the controversial stuff, I multiplied the cross section (square inches) by the yield strength (pounds per square inch)

This is the yield force in pounds of the different bars at the point of deformation. These numbers are huge because this is with no leverage, you would divide these numbers by however much leverage you have with the length of the bar to get real force numbers. That part is very tricky and where the bend radius comes into play but I will discuss that later.

Here are the charts. I was generous with the cutoff on these btw. :blink

Unbraced Length Chart

Braced Length Chart

Like I said the numbers on the left side are pounds. Let me know what you think of some of the crossover points and comparisons. I think there is a bunch of interesting stuff going on here that needs explaining. I have a few ideas but I will wait and see what you guys think about it first.

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I like the idea. Using elementary material properties to estimate the force required for bending. And Eric's calibration results serve as experimental validation data points.

As you mention, finding the formula to correctly estimate the actual forces required at the end of the bar will be tricky. I think some simple model will probably work with small angles. But when going close to full bends effects of bending radius etc. will make it harder.

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Well then, the yield strength for a 5/16 G8 is greater than the yield strength for 3/8 G5, 7/16 303 Stainless and 9/16 HRS. All "feel" aside, you would just have to have the kink strength to start a piece that thick and, so long as it's the weakest piece of it's particular batch, all the above are possible unbraced ALREADY. But again, "feel" complicates things and the pain factor is another HUGE complication.

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It always amazes me how different types of steel can vary so much in strength.

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I don't have anything to add yet but please keep this one going - I find the technical info on steel very interesting.

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Well, this really shows that no one is going to bend 1/2" x 7" CRS any time soon ;)

For the rest, great idea!!!!

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that's just too much thinking for me i just like to bend the metal and see the metal bent when you pay so much attention to all this stuff it makes it seem impossible kind of (at least it does to me) i just want to hit something when i'm feeling strong :)

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