14 research outputs found
Depinning transition for a screw dislocation in a model solid solution
On the basis of the classical dislocation theory, the Solid Solution
Hardening (SSH) is commonly ascribed to the pinning of the edge dislocations.
At the atomic level, the theoretical study of the dislocation cores contrasts
with such a prediction. Using the static molecular simulations with some
interatomic effective potentials, we demonstrate numerically that the critical
resolved shear stress associated to a screw dislocation in a random Ni(Al)
single crystal has same order as the edge one. Such a result is imposed by the
details of the dislocation stacking fault and the core dissociation into
Shockley partials. The SSH statistical theory is employed to tentatively
predict analytically the data acquired through our atomistic simulations at
different Al concentration
Predicting plasticity in disordered solids from structural indicators
Amorphous solids lack long-range order. Therefore identifying structural
defects -- akin to dislocations in crystalline solids -- that carry plastic
flow in these systems remains a daunting challenge. By comparing many different
structural indicators in computational models of glasses, under a variety of
conditions we carefully assess which of these indicators are able to robustly
identify the structural defects responsible for plastic flow in amorphous
solids. We further demonstrate that the density of defects changes as a
function of material preparation and strain in a manner that is highly
correlated with the macroscopic material response. Our work represents an
important step towards predicting how and when an amorphous solid will fail
from its microscopic structure
Faraday wave lattice as an elastic metamaterial
Metamaterials enable the emergence of novel physical properties due to the existence of an underlying subwavelength structure. Here, we use the Faraday instability to shape the fluid-air interface with a regular pattern. This pattern undergoes an oscillating secondary instability and exhibits spontaneous vibrations that are analogous to transverse elastic waves. By locally forcing these waves, we fully characterize their dispersion relation and show that a Faraday pattern presents an effective shear elasticity. We propose a physical mechanism combining surface tension with the Faraday structured interface that quantitatively predicts the elastic wave phase speed, revealing that the liquid interface behaves as an elastic metamaterial
Entwicklung eines solaren Aufwindtrockners
TIB: ZO 7282(1990,11) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman