No abstract

The stress pulse attenuation of the 62 vol/vol. % dense silica particle-ethylene glycol suspension was investigated by using a modified spilt Hopkinson pressure bar. In comparison to the neat ethylene glycol solution, the transmission pulse of the shear thickening is much weaker under the same impact condition. No energy loss is progressed for the neat ethylene glycol solution, thus it can be concluded that the energy dissipation behavior was happened in the silica particle based shear thickening fluid. In this work, the energy dissipation of the shear thickening fluid was reversible. V

An impedance spectroscopy (IS) method is employed to investigate the magneto-induced microstructure mechanism of magnetorheological plastomers (MRP). The IS of MRP with two typical particle distributions (isotropic and anisotropic) are compared and an equivalent circuit model is proposed to analyze the different impedance responses. It is found that the IS of anisotropic MRP is quite sensitive to the magnetic field and the electron diffusion effect will be restricted in the presence of a magnetic field.Furthermore, the conduction behavior of MRP in the presence of a magnetic field reveals the existence of elasticity in the polymer matrix. The influence of particle chain direction on the conductivity of anisotropic MRP with different particle contents is also investigated. Based on the experimental results, an equivalent method is developed to quantitatively characterize the anisotropy of MRP. With this method, the microstructure-dependent conduction mechanism of MRP can be presented more clearly.

No abstract

An abrupt drop phenomenon of magneto-induced normal stress of magnetorheological plastomer is reported and a microstructure dependent slipping hypothesis is proposed to interpret this interesting behavior. For polyurethane based magnetorheological plastomer sample with 70 wt.% carbonyl iron powder, the magneto-induced normal stress can reach to as high as 60.2 kPa when a 930 mT magnetic field is suddenly applied. Meanwhile, the normal stress shows unpredicted abrupt drop. Particle dynamics is used to investigate the physical generating mechanism of normal stress. The simulation result agrees well with the experimental result, indicating that the interior microstructure of iron particle aggregation plays a crucial role to the normal stress.