A new discovery shows that stress cracks can reach near supersonic velocities and defy conventional velocity constraints.
Physicists at the Racah Institute of Physics at the Hebrew University of Jerusalem have uncovered a discovery that questions how the mechanics of refraction have been traditionally understood. Dr. Meng Wang, Dr. Songlin Shi and Prof. The group, led by Jay Fineberg, conducted experiments to demonstrate the existence of "supershear" stress cracks moving at near supersonic speeds and beyond conventional speed limits. Their research has been published in the journal Science.
Brittle materials have historically been seen to break down through rapidly spreading cracks. Stress fractures that release elastic energy in a concentrated region at their ends and have a Rayleigh wave velocity (CR) velocity limit are defined as mobile by classical fracture mechanics. But recent research at the Hebrew University points to a paradigm shift in this perspective.
The team's work with brittle neo-Hookean materials revealed the presence of "supershear" stress cracks that accelerate smoothly above the conventional CR speed limit. Unexpectedly, these cracks were also found to exceed the shear wave velocity (cS). These supershear cracks occasionally approached the velocities of dilation waves, exhibiting hitherto unrecognized phenomena in classical fracture mechanics.
The observation that supershear dynamics are governed by rules different from those governing traditional breaks is one of the most striking findings of the discovery. This non-classical form of stress rupture is activated at critical stress levels that depend on the properties of the material, rather than occurring randomly.
The lead author of the study, Prof. “This finding represents a fundamental shift in our understanding of the fracture process in brittle materials,” said Jay Fineberg. “We have opened up new avenues to study fracture mechanics and its applications,” the authors write. “By demonstrating the existence of supershear stress cracks and their capacity to exceed conventional velocity limits.”
These findings have implications that go beyond physics. Researchers have opened the door to a new understanding of fracture mechanics by showing that stress cracks can move faster than conventional speed limits.
📩 28/07/2023 11:19