In a paper published in Nature Physics, Northeastern University Department of Physics Arts and Sciences Distinguished Professor Alain Karma, in collaboration with his postdoctoral research associate Chih-Hung Chen and Professor Eran Bouchbinder of the Weizmann Institute of Science's Chemical Physics Department, discovered the mechanism that causes cracks to behave strangely when they spread very rapidly in brittle materials.
The results of this study will help researchers better understand how fragile materials, such as glass, ceramic, polymers, and bone break--often catastrophically -- and how to better design materials to avoid failure.
Karma's goal was to understand how things break, since a primary way materials fail is through crack propagation, which has long been an issue in materials science, construction, and product development.
More specifically, the collaborative research team wanted to understand how the mechanical properties of the region of high stress concentration around the edge of a crack affects the crack dynamics.
"While straight cracks can, in principle, race through a material as fast as the speed of sound, they never reach that speed for reasons that have remained elusive," said Karma.
Instability causes the crack tip to wobble from side to side and trace out a wavy path through the material.