Volume fraction

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

Volume fraction optimization for minimizing thermal stress in Ni–Al2O3 functionally graded materials

Abstract: Functionally graded heat-resisting material, in which the volume fraction of constituents varies continuously and functionally, is investigated for high-temperature engineering applications In this advanced material, the thermomechanical behavior of FGMs is strongly influenced by the spatial distribution of the volume fraction So, the determination of volume fraction distribution becomes a crucial part in the FGM design, for a given specification and loading condition This paper is concerned with the volume fraction optimization for minimizing steady-state thermal stresses in Ni–Al 2 O 3 heat-resisting FGM composites Interior penalty-function method and golden section method are employed as optimization techniques, together with finite difference method for the sensitivity analysis and an appropriate material-property estimate for calculating thermomechanical properties of the graded layer The introduced optimization method, through the numerical experiments, is found to provide optimal volume fraction distributions that minimize thermal stresses significantly, as well as the rapid and stable convergence

Electrical permittivity and conductivity of carbon black-polyvinyl chloride composites

Abstract: Electrical conductivity and permittivity of carbon black‐polyvinyl chloride composites were studied over a wide frequency spectrum (dc, 1.3 GHz). Conductivity of the bulk composites increases with higher volume fraction of carbon black as expected. However, the functional dependence of the increasing conductivity with carbon black loading is different below and above the percolation threshold because of the different mechanisms involved. Bulk electric permittivity increases until the composite percolation is reached and then decreases to zero after fully connected conductive paths have been established. Such highly loaded composites showed a metal‐like electrical behavior. Different electrical percolation threshold of the composites were found for different species of carbon black. Carbon blacks with the lowest packing efficiency reach the percolation threshold with the least volume fraction of carbon black loading. The percolation behavior of spherical carbon blacks showed good agreement with Bruggeman’s effective‐medium theory in terms of both the percolation threshold and frequency dependence of conductivity at percolation.

Processing and mechanical properties of porous 3 16L stainless steel for biomedical applications

Abstract: llighly porous 316L stainless steel parts were produced by using a powder metallurgy proccss, which includes the selective laser sintering(SLS) and traditional sintering. Porous 3 1 hL stainless steel suitable for medical applications was succcssfiilly tiibricatcd in the porosity range of 40%-50% (volume fraction) by controlling the SLS parameters and sintering bchaviour. The porosity ofthe sintered compacts was investigated as a function ofthe SLS parameters and the furnace cyclc. Compressive strcss and elastic modulus of thc 3 16L stainless steel material were determined. The compressive strcngth was found 10 be ranging from 2 1 to 32 Ml'a and corrcsponding elastic modulus ranging from 26 to 43 GPa. The present parts are promising for biomedical applications since tlic optimal porosity of implant materials for ingrowths of new-bone tissues is in the range of 2O'X-59% (volume fraction) and mcchanical properties are matching with human bone.

Self-Assembly of Poly(diethylhexyloxy-p-phenylenevinylene)-b- poly(4-vinylpyridine) Rod−Coil Block Copolymer Systems

Abstract: We describe the synthesis, the morphology, and self-assembly behavior of semiconducting poly(4-vinylpyridine-b-diethylhexyloxy-p-phenylenevinylene) (P4VP-b-PPV) rod−coil block copolymer systems. Three different block copolymers with 55%, 80%, and 88% coil volume fraction were synthesized by convergent anionic polymerization in THF using lithium α-methylstyrene as initiator. The morphology of the block copolymers was studied by transmission electron microscopy, small-angle X-ray scattering, and small-angle neutron scattering as a function of the volume fraction of the rod block as well as different annealing conditions. The microphase-separated morphologies in these block copolymers vary from lamellar, to hexagonal, and spherical, when the volume fraction of the rod is progressively reduced. By combining the lattice parameter measured by scattering techniques with the volume fraction of rod domains obtained by nuclear magnetic resonance, it was shown that the block copolymers in the lamellar structure are ...