On the extraordinary strength of Prince Rupert's drops

Prince Rupert's drops (PRDs), also known as Batavian tears, have been in existence since the early 17th century. They are made of a silicate glass of a high thermal expansion coefficient and have the shape of a tadpole. Typically, the diameter of the head of a PRD is in the range of 5 –15 mm and that of the tail is 0.5 to 3.0 mm. PRDs have exceptional strength properties: the head of a PRD can withstand impact with a small hammer, or compression betweentungstencarbide platens to high loads of ∼15 000 N, but the tail can be broken with just finger pressure leading to catastrophic disintegration of the PRD. We show here that the high strength of a PRD comes from largesurface compressive stresses in the range of 400 –700 MPa, determined using techniques of integratedphotoelasticity. Thesurface compressive stresses can suppress Hertzian conecracking during impact with a small hammer or compression between platens. Finally, it is argued that when the compressive force on a PRD is very high, plasticity in the PRD occurs, which leads to its eventual destruction with increasing load.

Source: Applied Physics Letters - December 5, 2016 Category: Physics Authors: H. Aben, J. Anton, M. Õis, K. Viswanathan, S. Chandrasekar and M. M. Chaudhri Source Type: research