Mystery of Prince Rupert's Drop at 130,000 fps

Smarter Every Day

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How was this done by so small a force?

Smarter Every Day heads to a glassblowing workshop in Alabama to reveal the unique mechanical properties of the Prince Rupert's drop – a tadpole-shaped glass structure created by dropping molten glass in cold water.

As Destin demonstrates, the very high residual stress within the bulbous end of the drop allows it to withstand a blow from a hammer. However, a slight touch on the drop’s tail will cause the whole structure to explode.

Filming in high-speed with a Phantom v1610 the team capture the explosion at100,000 frames per second to reveal, for the first time, exactly how the Prince Rupert drop explodes.

But why does this happen? With thermal imaging (and some mini-Destins!) we are shown how the cooling process sets up extremely high levels of compressive stress in the outside layers of the drop and extremely high levels of tensile stress on the inside..

As Destin explains:

"If one link in this tension chain is ever cut, it breaks on down the line feeding off of its own stored up energy just like a chemical explosion."

Mechanical strain energy is released in a phenomenon known as a "mechanical failure front". Shooting at 130,000 fps allows the team to measure the velocity of drop’s failure front at over a mile per second! 

Themes

Materials

Details

Type:
Demo
People:
Destin
Location:
Alabama, US
Published:
2013
Filmed:
2013
Credits:

Smarter Every Day

Licence: Standard YouTube License

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