Scientists solve 400-year-old mystery of Prince Rupert's drops

[Binary_Bark]

​

Researchers have finally answered a question that has stumped scientists since the early 1600s: Why are the heads of tadpole-shaped pieces of glass called "Prince Rupert's drops" so strong?
In the 17th century, Prince Rupert from Germany brought some of these glass drops to England's King Charles II, who was intrigued by their unusual properties. While the head of the drop is so strong that it can withstand the impact of a hammer, the tail is so fragile that bending it with your fingers will not only break the tail, but cause the entire droplet to instantly disintegrate into a fine powder.
Prince Rupert's drops are easily made by dropping red hot blobs of molten glass into water. Although researchers have tried to understand what causes the unusual properties of these drops for many years, it was not until recently that modern technology has allowed researchers to thoroughly investigate them.
In 1994, S. Chandrasekar at Purdue University and M. M. Chaudhri at the University of Cambridge used high-speed framing photography to observe the drop-shattering process. From their experiments, they concluded that the surface of each drop experiences highly compressive stresses, while the interior experiences high tension forces. So the drop is in a state of unstable equilibrium, which can be easily disturbed by breaking the tail.
One open question, however, is how the stresses are distributed throughout a Prince Rupert's drop. Understanding the stress distribution would help to more fully explain why the heads of these drops are so strong.
To do this, Chandrasekar and Chaudhri began collaborating with Hillar Aben, a professor at Tallinn University of Technology in Estonia. Aben specializes in determining residual stresses in transparent three-dimensional objects, such as Prince Rupert's drops.

Read more at: https://phys.org/news/2017-05-scientists-year-old-mystery-prince-rupert.html#jCp

 

[azbob]

 

[TribbleZA]

I learnt something new - thank you. One should learn something new every day. Makes life more interesting.

A simplistic question - wouldn't it naturally be stronger on the curve as the molecules would "hold onto" each other more tightly? But on a straight surface they are more relaxed? (bigger gaps)

 

[AfricanTech]

:crylaugh:


@Sugarman - thanks - cool bit of info - I remember reading about this a while back (before they understood why it is so strong)

 

[IzZzy]

Smarter Every Day on YT has two recent videos of him shooting Prince Rupert's Drops with various types of ammo, and prior videos on the drops generally.