Can you explain this video? (An I-beam cut in half, springs apart, curved)

  • #1
Flint1234
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A gas cutting-torch was used to split an I-beam lengthwise. When the last inch was cut, the two halves flew apart, with a great energy release. The halves are then seen to be curved where they were straight. The workman was unsurprised but the cameraman was thankful for a warning given seconds in advance.

Is this just a result of thermal expansion caused by the cutting torch? I thought most of the torch heat went with the molten iron blown away.
It was apparently cut by hand, slowly, I expect. The heat would have had time to conduct through the steel, diminishing the expansion.

Is there some technology that lets one build an iron I-beam with the flanges (flat sides) in tension? Something akin to automotive-window safety glass? I'm thinking one could cold-roll the center web lengthwise which would normally make it longer. Since it's locked to the flanges, that would put the web under compression and the flanges in tension.

You could put a LOT of energy into a spring that way and you wouldn't have to strike while the iron is hot.

Is that right? What's the roller machine called? Is there videos or literature?
Thanks.

My searches were all poisoned by steel cables used to pre-stress concrete or steel sheet cold-rolled into lightweight studs (or worst, steel cables used to pre-stress lightweight studs made by cold-rolling sheet steel)
 
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  • #2
I would guess residual stress from when the beam was manufactured.
 
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  • #3
It is simple to explain. Chinese steel is rolled to meet external dimensions at the lowest cost. No annealing or controlled cooling is done, so the stress of the last rolling and cooling remains in the beam. The web was thinnest, so it cooled and set first, then the thicker flanges cooled, contracting and compressing the web axially.
That is why I prefer to work with well-behaved Australian steel.

It is unusual to split an I-beam lengthwise, unless you are fabricating a castellated steel beam, but then you would not cut it straight, and you would not use cheap Chinese steel.
 
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  • #4
A pity the link to the video seem to have been removed.
 
  • #5
DaveC426913 said:
A pity the link to the video seem to have been removed.
The video is still there for me.
 
  • #6
Baluncore said:
The video is still there for me.
Huh. This is what I get:

1707524695510.png


Anyway, thanks for posting the video.
 

Related to Can you explain this video? (An I-beam cut in half, springs apart, curved)

1. How is an I-beam able to be cut in half and then spring apart?

The I-beam is made up of two separate pieces that are held together by a strong magnet. When the beam is cut in half, the magnetism is released, causing the two pieces to spring apart due to the repelling force between them.

2. Why does the I-beam curve after being cut?

As the two halves of the I-beam spring apart, they are no longer being held in a straight line by the magnet. This allows the pieces to move freely and curve as they separate from each other.

3. What forces are at play in this demonstration?

The main forces at play in this demonstration are magnetism and the repelling force between the two halves of the I-beam. These forces work together to cause the beam to spring apart and curve after being cut.

4. Is this demonstration showing a real-world application of physics principles?

Yes, this demonstration is a real-world example of how magnetic forces and repelling forces can interact to create motion and curvature in an object. It showcases the principles of magnetism and force in action.

5. How can I replicate this experiment at home?

To replicate this experiment at home, you will need an I-beam made of two separate pieces held together by a strong magnet. Simply cut the beam in half and observe how the pieces spring apart and curve. Be sure to handle the magnet with care to avoid injury.

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