Biomedical subjects

Xianxiang Huang

Publications and source records attributed to Xianxiang Huang.

3 recordsLinked to original sources

PubMed2006

Static shear modulus of electrorheological fluids.

We report measurements of the static shear modulus of electrorheological (ER) fluids consisting of water-wetted silica microspheres in silicone oil. A shear-annealing method, using creep-recovery (CR) cycles under an external electric field, is used to enhance ER properties of the fluid. The shear-annealing method enables the silica spheres in the ER fluid to form better aligned and denser column microstructures. A stable state with elastic shear deformation is obtained after a sufficient number of CR cycles, with an optimal combination of stress duration and shear strength. Static shear modulus is obtained by measuring the elastic deformations at different shear stresses for an electric field frequency from 10 to 1000 Hz. A water-bridge model is proposed to explain the enhanced shear modulus.

Journal Article↗

PubMed2005

Structural transition in bidispersed electrorheological fluids.

We present results from finite element calculations on electrorheological fluids consisting of bidispersed dielectric microspheres and nanoparticles suspended in liquid, with one type much smaller than the other. The face-centered-cubic (fcc) structure of the larger microspheres is shown to be the ground state when the volume concentration of the nanoparticles is between 3-5 %. This is in contrast to the usual situation in which the body-centered-tetragonal (bct) structure is the lowest-energy state. As a function of the nanoparticles' concentration, the bct-fcc structural transition occurs when the nanoparticles' dielectric constant exceeds a threshold value, leading to the electrostatic energy curves of the two structures crossing each other.

Journal Article↗

PubMed2003

The giant electrorheological effect in suspensions of nanoparticles.

Electrorheology (ER) denotes the control of a material's flow properties (rheology) through an electric field. We have fabricated electrorheological suspensions of coated nanoparticles that show electrically controllable liquid-solid transitions. The solid state can reach a yield strength of 130 kPa, breaking the theoretical upper bound on conventional ER static yield stress that is derived on the general assumption that the dielectric and conductive responses of the component materials are linear. In this giant electrorheological (GER) effect, the static yield stress displays near-linear dependence on the electric field, in contrast to the quadratic variation usually observed. Our GER suspensions show low current density over a wide temperature range of 10-120 degrees C, with a reversible response time of <10 ms. Finite-element simulations, based on the model of saturation surface polarization in the contact regions of neighbouring particles, yield predictions in excellent agreement with experiment.

Barium Compounds↗