Channel Iron Mechanical Properties

[npalen]

Working on a project where I'm needing the "I" value (Moment of Inertia) of bar size channel iron 2"x1"x3/16". All of the tables I find are for structural channel sizes which only go down to 3". I'm specifically wanting to compare the strength of the 2" channel iron (in both directions) to 2"x2"x3/16" angle iron.

 

[zzvyb6]

From here :

Calculator for Engineers - Moment of Inertia of Channel section

I get Angle: .2724 in^4 and .2724 in^4

and channel: Ixx= .0668 in^4

Iyy= .0463 in^4

 

[npalen]

For the channel shape, I'm coming up with Ixx=0.575 and Iyy=.063 using 1.00" for the flange width and 0.1875" for the flange depth. (Web thickness would be 0.1875 and web height is 2.000") These numbers would indicate the channel being about twice as strong in the Ixx direction as the angle.
Thanks for the link to the calculator. I may be inputting some incorrect numbers. The calculator doesn't take into account the tapered thickness of the flanges which would make a little difference.

 

[LD1]

Bar channel is 0.376 xx and 0.06 yy for the bar channel. pretty weak in that YY direction.

Angle is only a little weaker (.272) in the xx direction, but a whole lot stronger in the yy direction.

what are you building?

 

[CNC Dan]

There is an App. for that.
It's called "epic FEM"
But it won't give you the I value, but it will show deflection,stress,and sheer values for a given set of loads/supports/lengths.

 

[jmc]

Do those moment of inertia references also calculate the location of the neutral axis? On asymmetrical cross sections, the neutral axis is offset from the "center" of the section, and you need it if you are calculating maximum bending stress. Sorry if you knew that.

 

[npalen]

I'm building a tongue to convert a 3PH box scraper to pull type with hydraulic lift on the backside. The box scraper will be convertible between 3PH and pull type using the upper and lower 3PH connections to mount the tongue. The tongue will be "A-frame design with the 2x2x3/16 angle or 2"x1"x3/16" channel iron making up the two lower members. I have these materials in stock so trying to make use of them.

 

[bcp]

From:
http://www.tractorbynet.com/forums/build-yourself/271386-building-pull-type-scraper-bb.html

Looks like mostly tension and compression forces.

Bruce

 

[zzvyb6]

Make a tubular tongue by welding the channel irons together face to face. The box section will be much stronger than either of the separate types of steel. You could do this with the angle, too, but the channel is easier to clamp into place.

 

[npalen]

Some folks say that having the wheels farther back from the blade makes for better leveling. I feel that just the opposite is true because having the wheels close behind the blade will minimize any changes in blade height due to tractor vertical movement. I suspect it may be a matter of specific surface conditions such as how far apart are the hills and valleys and can they be leveled in one pass etc.