Volume fraction

About: Volume fraction is a research topic. Over the lifetime, 16312 publications have been published within this topic receiving 374181 citations.

Growth of a semiconductor nanoparticle ring during the drying of a suspension droplet

Abstract: The first study on the growth process of an array comprising colloidal semiconductor nanoparticles (quantum dots) is presented. Two types of particles, CdS and CdSe/CdS (core/shell), suspended in pyridine and water, respectively, have been used. A liquid drop containing the particles is placed on a solid substrate, and the solvent is allowed to evaporate in a nitrogen atmosphere. As the result, a ring-shaped multilayer forms at the drop periphery, with the ring width depending on the particle volume fraction. The kinetics of ring growth is described by a theoretical model which accounts for the effect of experimental parameters. The reported study can serve as background for the preparation of more sophisticated and ordered arrays of semiconductor nanoparticles whose optical properties can be utilized in light-emitting and -converting devices.

Homogenization-based constitutive models for magnetorheological elastomers at finite strain

Abstract: This paper proposes a new homogenization framework for magnetoelastic composites accounting for the effect of magnetic dipole interactions, as well as finite strains. In addition, it provides an application for magnetorheological elastomers via a “partial decoupling” approximation splitting the magnetoelastic energy into a purely mechanical component, together with a magnetostatic component evaluated in the deformed configuration of the composite, as estimated by means of the purely mechanical solution of the problem. It is argued that the resulting constitutive model for the material, which can account for the initial volume fraction, average shape, orientation and distribution of the magnetically anisotropic, non-spherical particles, should be quite accurate at least for perfectly aligned magnetic and mechanical loadings. The theory predicts the existence of certain “extra” stresses—arising in the composite beyond the purely mechanical and magnetic (Maxwell) stresses—which can be directly linked to deformation-induced changes in the microstructure. For the special case of isotropic distributions of magnetically isotropic, spherical particles, the extra stresses are due to changes in the particle two-point distribution function with the deformation, and are of order volume fraction squared, while the corresponding extra stresses for the case of aligned, ellipsoidal particles can be of order volume fraction, when changes are induced by the deformation in the orientation of the particles. The theory is capable of handling the strongly nonlinear effects associated with finite strains and magnetic saturation of the particles at sufficiently high deformations and magnetic fields, respectively.

Finite-element analysis of 1-3 composite transducers

Abstract: The vibrational and electromechanical characteristics of a wide range of 1-3 composite structures, comprising ceramic pillars aligned within a polymer phase, are considered using finite-element analysis. The influence of pillar geometry, ceramic volume fraction, and pillar orientation is described in terms of overall transduction efficiency. It is shown that the finite-element method provides a versatile means of analysis and the results obtained permit a set of useful design guidelines to be developed. In general, a small pillar aspect ratio and a relatively high volume fraction provides the most satisfactory performance, in terms of electromechanical efficiency and uniformity of thickness dilation. >