Molecular simulation and multiscale homogenization analysis for microinhomogeneous clay materials

Abstract

Materials commonly involve microstructure. Clay is a microinhomogeneous material with nanoscale microstructure. Key issues to understand the behavior of such a finely microinhomogeneous material are as follows: the microstructure is characterized in detail, the local distribution of material properties is identified by experiment or simulation, and the microscale characteristics are related to the macroscale behavior by a seamless manner. For characterizing a microstructure of bentonite, we introduce a conforcal laser scanning microscope (CLSM) together with SEM. By CLSM we can specify a 3D configuration under atmospheric condition. Properties of water‐saturated bentonite are mainly controlled by hydrated montmorillonite, which is the major clay mineral of bentonite. Smectite minerals including montmorillonite are extremely fine and poorly crystallized, so it is difficult to determine the properties by experiment. We inquire into the physicochemical properties by a molecular dynamics simulation method. Then, we develop a multiscale homogenization method to extend the microscopic characteristics to the macroscopic behavior. We show numerical examples of a diffusion problem.

Diffusive fractionation of 3H and 3He in groundwater and its impact on groundwater age estimates

“…By comparison, Solomon et al [1993] assumed aqueous phase diffusion coefficients for 3 He and 3 H of 6.5 × 10 −4 m 2 /d (citing the work by Jähne et al [1987]), and 1.2 × 10 −4 (citing the work by Wang et al [1952]), respectively, for α′ D > 5. Fractionation factors in clays are likely larger than those based on free solution aqueous phase coefficients because the larger molecular size of tritiated water compared to that of 3 He results in increased Knudsen diffusion effects [ Ichikawa et al , 2003]. Here we use two different fractionation factors: α′ D = 3.6 and 1.0.…”

Interface defects in unidirectional composites by multiresolutional finite element analysis

“…They can include spatial averaging techniques, classical asymptotic approaches as well as recently developed multiresolutional homogenisation methods [4,6,12,14] reflecting the wavelet bases constructing the analytical formulas for composite material properties. It would be very interesting to modify the present version of multiresolutional homogenisation to insert into the highest resolution the molecular approach to solids similarly to the models from [3,8]. The second idea is to insert the wavelets into the shape functions of the finite elements responsible for interfaces modelling or structural heterogeneities.…”

“…(11) to describe (a) Young modulus: E 1 = 20E9, E 2 = 210E9, a = 0.025, d = 500, b = 10 5 , c = À5 · 10 8 , (b) mass density: q 1 = 10, q 2 = 100, a = 0.04, d = 500, b = 3 · 10 À5 , c = 0. A periodicity cell is discretised now using from 0th to 5th order multi-scale discretisations adequate to 1,2,4,8,16 and 32 finite elements. Material characteristics at each zoom were calculated as the relevant spatial averages of the multiresolutional functions over the finite elements domains using the system MAPLE.…”

A review on clay‐reinforced ethylene propylene diene terpolymer composites

“…[19,48] Besides, Bt can be used in other applications such as in cement, adhesives, and ceramic bodies as well as binding agent in the manufacturing of taconite pellets. Finely ground Bt is typically used as dry-cleaning substance for F I G U R E 4 Typical structure of bentonite particle [47] purifying transformer oil. Recently, Bt clay was used in pyrotechnics applications to make end plugs and rocket engine nozzles due to their self-stickiness and highpressure ramming or pressing capability.…”

“…The Bt particle is made up of several entities such as the stacks of MMT lamellae, macro‐grains, entrapped air, and pore water. [ 47 ] Bt can be processed to produce sodium and calcium MMT, activated clays, or modified into organoclays. These products of Bt possess different properties and can be exploited into wide range of applications commercially.…”