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The present article has utilized the WIEN2k computational code to examine the structural, elastic, electronic, magnetic, thermoelectric, and dynamic aspects of the CoCrS Half-Heusler (HH) compound. In this work, calculations have been performed by utilizing the full-potential linearized augmented plane wave method using density functional theory. The electronic bandgap was better interpreted by using the modified Becke–Johnson exchange–correlation functional. We evaluated various electronic properties of the CoCrS HH compound, including band structure plots and density of states. Furthermore, we examined the magnetic characteristics through the computation of magnetic moments and the examination of the spin-polarized electronic state behavior. We also determined the elastic properties of the CoCrS HH compound. These properties, which include stiffness, resilience, and general stability, provide important information about how the material responds to mechanical deformation. Moreover, we explored the electronic structure and found that type 5 of CoCrS exhibits a metallic behavior. In addition, we examined the compound's thermoelectric properties. Finally, the dynamical properties indicate that type 5 of CoCrS is dynamically stable. [ABSTRACT FROM AUTHOR]

We consider in this paper the elastic and viscous properties of Silly Putty and confirm the well known fact that the properties depend on the rate at which the material is deformed. Rapid deformations were studied by dropping masses onto one end of a Silly Putty cylinder, and slow deformations were studied by compressing the cylinder in a materials testing machine. The results were compared with a simple engineering model of viscoelastic materials to estimate the stiffness and the viscosity of the Silly Putty cylinder. It was found that stress induced in Silly Putty relaxes with a time constant of about 0.1 s, Young's modulus for a rapid deformation is about 1.7 x 106N/m², and the viscosity for a slow compression is about 8 x 104pa s. When subject to a short impact, Silly Putty vibrates as a result of compressional wave propagation through the material. [ABSTRACT FROM AUTHOR]

Dielectrostriction is a rheo-dielectric phenomenon that relates the variation of dielectric properties of a material to deformation. For an initially isotropic material, two independent material parameters, called the strain-dielectric coefficients, α1 and α2, are required to describe dielectrostriction in terms of strain. Deformation affects a material's dielectric properties in two ways: (a) by introducing anisotropy in the material, which is characterized by α1, and (b) by changing the volume density of the polarizable species, which is associated with (13α1+α2). Purely viscous fluids remain isotropic during any flow-induced deformation, and therefore the coefficient α1 is always zero. In this paper, the dielectrostriction effect is studied in viscoelastic materials that are formulated to possess different degrees of elasticity. A special planar capacitance sensor rosette was employed to measure the coefficients α1 and α2 for these viscoelastic materials. The relationship between the material's elasticity and the coefficient α1 is discussed, together with some potential applications based on this relationship in the conclusion. [ABSTRACT FROM AUTHOR]

The effect of parametric wave phase conjugation (WPC) in application to ultrasound or acoustic waves in magnetostrictive solids has been addressed numerically by Ben Khelil et al. [J. Acoust. Soc. Am. 109, 75–83 (2001)] using 1-D unsteady formulation. Here the numerical method presented by Voinovich et al. [Shock waves 13(3), 221–230 (2003)] extends the analysis to the 2-D effects. The employed model describes universally elastic solids and liquids. A source term similar to Ben Khelil et al.’s accounts for the coupling between deformation and magnetostriction due to external periodic magnetic field. The compatibility between the isotropic constitutive law of the medium and the model of magnetostriction has been considered. Supplementary to the 1-D simulations, the present model involves longitudinal/transversal mode conversion at the sample boundaries and separate magnetic field coupling with dilatation and shear stress. The influence of those factors in a 2-D geometry on the potential output of a magneto-elastic wave phase conjugator is analyzed in this paper. The process under study includes propagation of a wave burst of a given frequency from a point source in a liquid into the active solid, amplification of the waves due to parametric resonance, and formation of time-reversed waves, their radiation into liquid, and focusing. The considered subject is particularly important for ultrasonic applications in acoustic imaging, nondestructive testing, or medical diagnostics and therapy. [ABSTRACT FROM AUTHOR]

We consider the effects of adding a PIB-PDMS diblock copolymer as a compatibilizer in model blends composed of polyisobutylene (PIB) and polydimethylsiloxane (PDMS). The ratio of PIB to PDMS was varied from 20:80 to 80:20 and, hence, these blends are dubbed “concentrated” blends. Most experiments were conducted on blends containing 0.01 or 0.1 wt. % compatibilizer. All blends had a droplet-matrix morphology, with the minor phase being the drop phase; thus, phase inversion occured when PIB and PDMS were in a 50:50 ratio. Previously, we have studied effects of compatibilizer in “dilute” blends with PIB and PDMS in a 10:90 ratio. Much of the rheological behavior of the concentrated blends studied here is found to be qualitatively similar to that of dilute blends: compatibilizer increases the terminal complex viscosity, the terminal relaxation time, steady shear viscosity, and the ultimate recovery upon cessation of shear. However, there are two noteworthy differences. The first is that in blends in which PIB forms the continuous phase, the compatibilizer can suppress coalescence of the PDMS drops. Therefore, rheological properties that depend on drop size, e.g., relaxation time or ultimate recovery, are correspondingly affected. Second, the compatibilizer increases the viscosity, especially the terminal complex viscosity, of the concentrated blends far more than it does in dilute blends. This can be interpreted in terms of a partial immobilization of drop surfaces by the compatibilizer. Indeed, in blends with PIB as the continuous phase, the viscosity is only slightly lower than of a suspension of rigid spheres, suggesting that the compatibilizer immobilizes the interface almost completely. [ABSTRACT FROM AUTHOR]

Stresses within unsteady simple shear flows of suspensions of non-Brownian spheres constrained to move in the velocity-gradient plane are calculated using Stokesian dynamics simulations. The unsteady flows considered include shear reversal and oscillatory flows of varying strain amplitude. The evolution of the stresses in time are reported along with the corresponding microstructural development for all flow conditions. For shear reversal, the shear stress rapidly decreases to a minimum before gradually returning to the steady state value reached in the previous direction, whereas the normal stress briefly changes sign upon reversal of shear before returning to the steady state value. For oscillatory shear flow, the shear stress increases with total strain before attaining a steady state that depends upon the applied strain amplitude, indicating irreversible behavior even at small strain amplitudes. The shear stresses show a nonmonotonic dependence on the applied strain amplitude that agrees with experimental results [Bricker and Butler, J. Rheol. 50, 711–728 (2006)]. The steady state normal stresses also depend on the strain amplitude and may change signs at low strain amplitudes. [ABSTRACT FROM AUTHOR]