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Super Jeep: A Re-build

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#121 ·
Weasel said:
Yes I know that. The further apart also means the web is taller, along with the top and bottom pieces getting thicker so does the flange.

Take a piece of flat strap and bend it along the width, then take the same strap and bend it along it's thickness. Which direction resist bending better?
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The flanges being further apart is what drives the increase in strength. The web being taller is a bi-product.

Once the strap is welded to the bottom and top of the frame it effectively becomes a thicker "flange" and has different bending characteristics from when it was just a strap.

It's been a while since I did the calculations but an I-beam gets something like 90% of it's strength from the flange thickness and spacing. Basically all the web is doing is holding the two flanges together. If you look up stress strain diagrams for I-beams it'll shed some light on it.

To go off on a tangent this is similar to why you can gun drill a shaft (to a point) and have a negligible loss in strength.
 
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#122 ·
With a symmetrical beam subjected to bending loads, whether it is I, rectangular solid, or hollow section, the further the material is from the mid plane the more effectively it can carry the load.

Think about it this way:

Remember that with elastic material such as steel, increasing the tensile or compressive load results in greater elongation or compression, just like a spring. From that result realise that the load carried is proportional to the deformation.

Now a bending load on a beam deforms it, ever so slightly, into a curve. At the extreme inside of the curve, the material is compressed (shortens) the most, while at the extreme outside of the curve, the material is tensioned (stretched) the most.

Between those extremes, the deformation will not be as much and at the mid plane there is none at all. The mid pane where there was no change, is called the neutral axis.

The deflection is proportional to the distance it is from the neutral axis. Thus more load is carried out where the deflection is greater.

If more material is added out near the extremities, such as the flanges of an I beam, it is more effective when subjected to bending. Conversely, adding material at the neutral axis will not increase the bending strength.

However the web is essential and plays two important roles:

When one flange is shortening and the other stretching, they create shear forces in the longitudinal direction, and this is greatest at the neutral axis. If the web can't resist the longitudinal shear force, the flanges wont stretch/shorten.

Beam bending loads are often concentrated loads acting perpendicular on the beam. These loads are transverse shear forces and are carried by a small portion of the web under the load. The web has to be thick enough to not buckle (the taller the web the thicker it needs to be), or else it must be stiffened locally.

Beams are often called upon to carry some twisting/torsion loads. Open sections like I beams are not efficient when subjected to torsion. Hollow sections are far superior. A chassis rail is a good example of a member subjected to combined bending and torsion.

Plating the top and bottom flanges of a rectangular hollow section will increase its bending strength. Plating the webs will increase the torsional capacity.
 
#123 ·
Its too bad that this is the 123rd post in this thread and about 100 of them are total nonsense. I am excited about this build and have great respect for the skills and abilities of the OP but I wouldn't blame him for abandoning this thread rather than wallowing through all this shit and addressing the points made by all these armchair quaterbacks.
 
#125 ·
ChiScouter said:
Its too bad that this is the 123rd post in this thread and about 100 of them are total nonsense. I am excited about this build and have great respect for the skills and abilities of the OP but I wouldn't blame him for abandoning this thread rather than wallowing through all this shit and addressing the points made by all these armchair quaterbacks.
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And you just added to it. :flipoff2:

The discussion about beam strength was very informative. As for the rest, this thread started in GCC, so what do you expect?

Lastly, OP has stated that he is busy with some other stuff. When that happens, threads either languish or stay active with sidebar conversations. If they bug you, you have the option of not returning until you see another post from the OP.
 
#127 · (Edited)
Weasel said:
yeah but I don't think it's the flanges where a I beam gets its strength from, it's the middle web. The top and bottom parts of the rail don't have as much load carrying capacity as the side will. In the same way a thin piece of strap won't be as effective as using fish plates.
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actual the top and bottom is exactly where it gets its strength from. The Web just ties it in. So top and bottom take the load by tension and compression and the Web ties it together. It's in shear.
 
#128 · (Edited)
plym49 said:
And you just added to it. :flipoff2:

The discussion about beam strength was very informative. As for the rest, this thread started in GCC, so what do you expect?

Lastly, OP has stated that he is busy with some other stuff. When that happens, threads either languish or stay active with sidebar conversations. If they bug you, you have the option of not returning until you see another post from the OP.
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I agree, the guy is an engineer. His old frame lasted him a long time, he's been doing this a long time... I think he knows what he's doing, can we drop the frame bashing and let some of us enjoy the rebuild...
 
#129 ·
Well, everyone's blabbing on this thread so I guess I will too. Congrats on the win. Wasn't sure who I wanted to root for. The brothers have a bond like me and my bro and they were the underdogs, which is something a like. War wagon was wicked awesome, especially with the boggers. The other 4 runner was blah, looked like it was all just bolt ons from the local 4x4 shop. I don't like rovers. And then super jeep...CHEVY heartbeat, highly modified in every aspect, definitely just by looking at it for 3 seconds could tell it was the most capable and well rounded rig there. Kinda had a feeling you'd win. I'm excited to see what you do next with it. Hope to learn a lot from this build, cuz you definitely know your stuff.
 
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Discussion starter · #130 ·
Super Jeep, How it is.

OK I'm back after KOH, and finally got a chance to put together a vid on How Super Jeep is put together, and all the problems that happened in Alaska, so we can move forward, on fixin it.
 
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Discussion starter · #132 ·
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#136 ·
With a new frame, does that mean it you are also going to re-do the cage, hopefully tying it all together for more strength and rigidity?
 
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Discussion starter · #138 ·
mouse said:
With a new frame, does that mean it you are also going to re-do the cage, hopefully tying it all together for more strength and rigidity?
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yes starting with a front bumper, stinger, tie into the limb lifter rails, correct triangulation situation.
 
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