toughness

Understanding the fracture toughness of glasses is of prime importance for

science and technology. We study it here using extensive atomistic simulations in

which the interaction potential, glass transition cooling rate, and loading geometry

are systematically varied, mimicking a broad range of experimentally accessible

properties. Glasses’ non-equilibrium mechanical disorder is quantified through

Ag, the dimensionless prefactor of the universal spectrum of non-phononic

http://www.pnas.org/content/early/2015/07/01/1502870112.full.pdf?with-ds...

H. Zhu*, S. Zhu*, Z. Jia*, S. Parvinian, Y. Li, O. Vaaland, L. Hu, T. Li, Proceedings of the National Academy of Sciences of the United States of America, Early Edition, 2015 (DOI:10.1073/pnas.1502870112)

To: Engineers, Fracture Analysts, Mechanicians, Physicists...

In science and engineering, we have an excellent tradition: naming a physical unit using the name of a prominent personality from the concerned field. For example, in SI system, we measure force in newton, work in joule, power in watt...

But the unit of fracture toughness, i.e. KIC, is too lengthy to pronounce: (mega) pascal-underoot-meter. Further, it has also been in use for something like half a century by now, perhaps more. So, how do you like the idea of giving a name to this unit?

http://en.wikipedia.org/wiki/Project_Habakkuk

I was surprised several years ago when delving into the literature to not find any references about addition of nanoparticles to ice, to study their impact on the mechanics of ice.  In short, to make nanocomposites where the matrix is ice.  So, with 2 high school students from IMSA, the Illinois Math and Science Academy, we set about (with their limited time for a bit of research) to try adding some nanoparticles to water and to freeze it.  The students simply used their home freezers to do this, and their mechanics measurements were with a hammer and chisel...

When I was a graduate student, I spent several months to measure interfacial toughness between metalic (Cu and Au) films and thick substrates(Si and Polycarbonate). My methods were bulge test (blistering test) and 4-point bending test. I had many problems such as making an initial crack(pre-cracking), changing load phase angle applied to specimens, preparing/patterning thin films, constructing my own test apparatus, etc. The biggest problem was to measure the interfacial toughness over a wide range of loading phase angle. For a bimaterial with a non-zero oscillatory index(epsilon), we don't know the phase angle for a minimum interfacial toughness beforehand. Therefore, we need to measure the interfacial toughness over a wide range of phage angle. For engineering purpose, we need a minimum interfacial toughness value for reliability design because this value will lead to a conservative design of systems.