Effects of cell wall property on compressive performance of aluminum foams

The effects of cell wall property on the compressive performance of high porosity, closed-cell aluminum foams prepared by gas injection method were investigated. The research was conducted both experimentally and numerically. Foam specimens prepared from conditioned melt were tested under uniaxial compressive loading condition. The cell wall microstructure and fracture were observed through optical microscope（OM） and scanning electron microscope（SEM）, which indicates that the cell wall property is impaired by the defects in cell walls and oxide films on the cell wall surface. Subsequently, finite element（FE） models based on three-dimensional thin shell Kelvin tetrakaidecahedron were developed based on the mechanical properties of the raw material and solid material that are determined by using experimental measurements. The simulation results show that the plateau stress of the nominal stress-strain curve exhibits a linear relationship with the yield strength of the cell wall material. The simulation plateau stress is higher than the experimental data, partly owing to the substitution of solid material for cell wall material in the process of the establishment of FE models.

Variable viscosity in peristalsis of Sisko fluid

This paper aims to examine variable viscosity effects on peristalsis of Sisko fluids in a curved channel with compliant characteristics. Viscous dissipation in a heat transfer is studied. The resulting problems are solved using perturbation and numerical schemes to show qualitatively similar responses for velocity and temperature. A streamline phenomenon is also considered.

Microstructure and Properties of Cement Foams Prepared by Magnesium Oxychloride Cement

Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams（MOCF） with various MgO powders and water mixture ratios were studied. Their infl uences on compressive strength, water absorption and resistance of MOCF were also discussed in detail. The experimental results indicated that moderate and slight excess MgO powders（MgO/MgCl2 molar ratios from 5.1 to 7） were beneficial to the formation of excellent microstructure of MOCF, but increasing water contents（H2O/MgO mass ratios from 0.9 to 1.29） might result in opposite conclusions. The microstructure of MOCF produced with moderate and slight excess MgO powders could enhance the compressive strength, while serious excess MgO powders addition（MgO/MgCl2 molar ratios = 9） would destroy the cell wall structures, and therefore decrease the strength of the system. Although MOCF produced with excess MgO powders could decrease the water absorption, its softening coefficient was lower than that of the material produced with moderate MgO powders. This might be due to the instability of phase 5, the volume expansion and cracking of cell walls as immersed the sample into water.

Nano Fluid Flow Analysis in the Presence of Slip Effects and Wall Properties by Means of Contraction and Expansion

The present article is a study of mixed convective peristaltic flow of Cu-blood nanofluid confined in a non-uniform tube along with the velocity slip conditions and wall properties.Endoscopic or catheterized special effects are also taken into description.Upon utilization of the large wavelength and small reynolds number approximation,the non-dimensional governing differential equation took a more simplified form,which is then solved for the exact solutions.Afterwards,these outcomes are offered graphically and are debated in detail.Velocity profile for pure blood as well as Cu-blood and no-slip and slip effects are also discussed separately.Streamlines pattern is also discussed for different physical parameters.

Biofluidics Study in Digestive System with Thermal Conductivity of Shape Nanosize H2O＋Cu Nanoparticles

In the present article, peristaltic transport of copper nano fluid in a curved channel with complaint walls is studied. Shape effects of nanosize particles are discussed. The mathematical formulation encompasses momentum and heat conservation equations with appropriate boundary conditions for compliant wails. Sophisticated correlations are employed for thermal conductivity of the nanoparticles. The nonlinear boundary value problem is normalized with appropriate variables and closed-form solutions are derived for stream function, pressure gradient and temperature profile. A detailed study is performed for the influence of various nanoparticle geometries （bricks, cylinders and platelets）. With greater curvature value, pressure gradient is enhanced for various nanoparticle geometries. Temperature is dramatically modified with nanoparticle geometry and greater thermal conductivity is achieved with brick shaped nanoparticles in the fluid.