An image displays material distortions caused by a fast-moving crack spreading from left to right. Image courtesy of Meng Wang, Hebrew University.
A team of scientists at the Racah Institute of Physics in Hebrew University of Jerusalem has introduced results that challenge long-held views in the field of fracture mechanics. Led by Dr. Meng Wang, Dr. Songlin Shi, and Prof. Jay Fineberg, the researchers have empirically detected the existence of “supershear” tensile cracks, which exceed the previously understood classical speed constraints, nearing supersonic velocities.
Picture of a traditional crack moving at half the speed of sound. Courtesy: Meng Wang, Hebrew University.
Historically, the rapid spread of cracks has been the primary failure mode observed in brittle materials. Classical fracture mechanics explains the movement of tensile cracks that dissipate elastic energy in a localized area at their ends, which sets a cap on their speed at the Rayleigh wave speed (CR). The recent discoveries by the Hebrew University team, however, suggest a foundational change in this comprehension.
By using fragile neo-Hookean substances in their investigations, the researchers detected the emergence of “supershear” tensile cracks that effortlessly exceed the traditional speed cap of CR. Astonishingly, these cracks were seen to overtake the shear wave speed (cS) too. In some instances, the velocities of these supershear cracks were found to be close to dilatation wave speeds, revealing phenomena never before seen in conventional fracture mechanics.
Image of the shockwave from the super-sonic crack, akin to a sonic boom. Courtesy: Meng Wang, Hebrew University.
An extraordinary part of this discovery is that the principles controlling supershear dynamics are different from those guiding traditional cracks. This unconventional tensile fracture mode is not an accidental event; instead, it is triggered at specific strain levels, contingent on the material characteristics.
Prof. Jay Fineberg, the research’s corresponding author, stated, “This discovery marks a radical alteration in our comprehension of how brittle materials break. By proving the presence of supershear tensile cracks and their capability to go beyond traditional speed barriers, we have initiated new paths for analyzing fracture mechanics and its practical uses.”
Picture of the experimental setup that produces super-sonic lab-made earthquakes at Hebrew University Laboratory. Credit: Meng Wang, Hebrew University.
This study has ramifications that reach outside the field of physics. By demonstrating that tensile cracks can break through their traditional speed boundaries, the scientists have laid the groundwork for a novel comprehension of fracture mechanics.
Reference: “Tensile cracks can shatter classical speed limits” by Meng Wang, Songlin Shi, and Jay Fineberg, published on 27 July 2023, in Science. DOI: 10.1126/science.adg7693.
Table of Contents
Frequently Asked Questions (FAQs) about fokus keyword: tensile cracks
What are the new discoveries about tensile cracks mentioned in the research?
The research unveils that tensile cracks can approach near-supersonic velocities, challenging traditional beliefs in fracture mechanics. The scientists from the Racah Institute of Physics at the Hebrew University of Jerusalem have experimentally shown “supershear” tensile cracks that surpass classical speed limits. They utilized brittle neo-Hookean materials to observe these cracks accelerating beyond traditional speed limits, even surpassing shear wave speed in some cases. The discovery represents a fundamental shift in understanding fracture processes in brittle materials, opening up new avenues for studying fracture mechanics and its applications.
Who conducted the research on tensile cracks and where was it published?
The research was conducted by scientists from the Racah Institute of Physics at the Hebrew University of Jerusalem, spearheaded by Dr. Meng Wang, Dr. Songlin Shi, and Prof. Jay Fineberg. The study was published in the scientific journal “Science” on 27 July 2023.
What materials were used in the experiments to study the tensile cracks?
The research team utilized brittle neo-Hookean materials in their experiments to study the tensile cracks. These experiments helped them identify the occurrence of “supershear” tensile cracks that could exceed classical speed limits.
What implications does this research have for the field of physics and beyond?
The discovery of tensile cracks surpassing classical speed limits has broad implications that extend beyond the realm of physics. By showing that tensile cracks can reach speeds that were previously unthought of, the researchers have laid the groundwork for a new understanding of fracture mechanics. This could lead to advancements in various applications and technologies that rely on understanding material fractures.
What is the significance of “supershear” tensile cracks in this research?
The term “supershear” refers to tensile cracks that smoothly accelerate beyond classical speed limits, in some cases even surpassing shear wave speed. The observation of supershear cracks was one of the most remarkable aspects of this research, representing phenomena previously unobserved in classical fracture mechanics. The understanding of supershear dynamics could lead to a radical alteration in the comprehension of how brittle materials break and create new paths for analyzing fracture mechanics.
5 comments
Wow, these findings are mindblowing! Never thought that tensile cracks could move so fast, its like science fiction becoming reality.
Anyone else here struggling to understand all the scientific jargon? Still, it’s clear this is something big and probably means a lot for engineers and stuff.
Could this affect everyday materials? Need to kno more but this seems pretty fascinating, maybe even scary in some ways.
This research is a huge leap for fracture mechanics, opens up so many new possibilities. Hats of to the researchers at Hebrew University!
does this mean that buildings can fall apart faster than we thought? im concerned about the safety implications here.