Fracture mechanics, a field that has long been studied and understood, has recently been turned on its head by researchers at the Racah Institute of Physics, Hebrew University of Jerusalem. Led by Dr. Meng Wang, Dr. Songlin Shi, and Prof. Jay Fineberg, this team has made a groundbreaking discovery that challenges the conventional understanding of fracture mechanics. Their research, published in the journal Science, showcases the existence of “supershear” tensile cracks that defy classical speed limits and transition to near-supersonic velocities.
Breaking the Speed Barrier
Traditionally, brittle materials have been observed to fail through the rapid propagation of cracks. According to classical fracture mechanics, the motion of tensile cracks releases elastic energy within a localized zone at their tips, thereby limiting their speed to the Rayleigh wave speed (CR). However, the experiments conducted by the Hebrew University researchers using brittle neo-Hookean materials have revealed a completely new phenomenon.
In their experiments, the researchers identified the occurrence of “supershear” tensile cracks, which smoothly accelerate beyond the classical speed limit of CR. To their surprise, these cracks not only surpassed the shear wave speed (cS) but, in certain cases, approached dilatation wave speeds as well. This discovery presents phenomena that were previously unobserved in classical fracture mechanics.
A Paradigm Shift in Understanding
Perhaps one of the most remarkable aspects of this discovery is the realization that supershear dynamics are guided by principles completely different from those governing classical cracks. This non-classical mode of tensile fracture is not a random occurrence but rather a phenomenon that is excited at critical strain levels determined by the material properties.
Commenting on this groundbreaking finding, Prof. Jay Fineberg, the corresponding author of the research, stated, “This finding represents a fundamental shift in our understanding of the fracture process in brittle materials. By demonstrating the existence of supershear tensile cracks and their ability to exceed classical speed limits, we have opened up new avenues for studying fracture mechanics and its applications.”
Implications Across Disciplines
The implications of this research extend far beyond the realm of physics. This newfound ability of tensile cracks to surpass their classical speed limits opens up exciting possibilities for a new understanding of fracture mechanics. With the previous limitations shattered, researchers can now explore new directions and applications in the field.
The discovery of supershear tensile cracks marks a significant turning point in the understanding of fracture mechanics. The conventional understanding, rooted in classical fracture mechanics, has been revolutionized by the experiments conducted at the Racah Institute of Physics. This groundbreaking research demonstrates that the motion of tensile cracks can far exceed classical speed limits and opens up a new frontier in the study of fracture mechanics. As we delve deeper into this newfound paradigm, we can expect exciting advancements and applications in various fields that rely on an understanding of fracture mechanics.
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