Origin and Composition of Nanoparticles Induced in a Complex Plastic-Brittle Transition Process of Xiaomei Shear Zone, Hainan Island, China

Micro and nano structures of quartz schist, plagioclase granite, and granitic gneiss in the Xiaomei Shear Zone located in southeastern Hainan Island, China are observed using Scanning Electron Microscope (SEM). Ultramicroscopic analyses indicate that three types of nanoparticles were found in the samples, including spherical nanoparticles, agglomerated nanoparticles and nanofibers. These nanoparticles are mainly developed in the fracture zones. The more fractures there are, the more nanoparticles are developed. Energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) are used to ascertain the composition of the nanoparticles. The results suggest that the nanoparticles are mainly composed of silicate, dolomite and calcite, rich in O, Si, Al, Ca. Based on our results, we suggest that nanoparticle formation is a complex, plastic-brittle transition process. Thermal decomposition driven by steady shearing possibly forms well-organized nanoparticles, while fast-moving dislocations by shock-like stress release possibly forms radial nanofibers.

A general fluid–sediment mixture model and constitutive theory validated in many flow regimes

We present a thermodynamically consistent constitutive model for fluid-saturated sediments, spanning dense to dilute regimes, developed from the basic balance laws for two-phase mixtures. The model can represent various limiting cases, such as pure fluid and dry grains. It is formulated to capture a number of key behaviours such as: (i) viscous inertial rheology of submerged wet grains under steady shearing flows, (ii) the critical state behaviour of grains, which causes granular Reynolds dilation/contraction due to shear, (iii) the change in the effective viscosity of the fluid due to the presence of suspended grains and (iv) the Darcy-like drag interaction observed in both dense and dilute mixtures, which gives rise to complex fluid–grain interactions under dilation and flow. The full constitutive model is combined with the basic equations of motion for each mixture phase and implemented in the material point method (MPM) to accurately model the coupled dynamics of the mixed system. Qualitative results show the breadth of problems which this model can address. Quantitative results demonstrate the accuracy of this model as compared with analytical limits and experimental observations of fluid and grain behaviours in inhomogeneous geometries.

Steady shearing flows of deformable, inelastic spheres

We extend models for granular flows based on the kinetic theory beyond the critical volume fraction at which a rate-independent contribution to the stresses develops.

Rheological Properties of Plastisols Based on Low-Toxicity Plasticizers

The rheological properties of plastisols based on low-toxicity plasticizers have been evaluated using a DV-79+ pro coaxial cylinder viscometer by steady shearing. The effect of plasticizer and temperature on the shearing rate dependence of apparent viscosity, non-Newtonian index ( n ) , as well as apparent activation energy ( Ea ) was investigated. The results indicate that all the plastisols prepared in this experiment show shear thinning pseudoplastic behavior before and after aging process. The plastisols prepared by DOTP shows an obvious shear thinning behavior than that of plastisols prepared by ATBC and DINCH. The dependence of viscosity properties on temperature of plastisols accord with Arrhenius formula except DOTP-based system, and the apparent activation energy of plastisols prepared by DINCH is bigger than that of plastisols prepared by ATBC.

Experimental Analysis of the Slip Phenomenon of Sewage Sludge

Wall slip of sweage sludge and affect slip possible factors were studied experimentally by using a rotational rheometer with parallel plate fixtures and by means high speed camera. In the steady shearing flow, the technique involves placing a straight line marker monitoring of wall slip,checking the gap dependence of the stress/ strain data. For sweage sludge of water content 80%, in the shearing flow it was found that, as the strain amplitude increasing, the stress data obtained at different gaps, then, at the certain strain amplitude, started to diverge, indicating that wall slip occurred. But for sweage sludge of water content 90%, these curves are superimpose, indicating no slip occurred. In the dynamic oscillatory shear flow, we analyze the total wave. While strain, stress amplitude decreases with the time, while strain, the stress amplitude remains constant.