Kai-wen Tong , Fei Yu , Zhang-jun Dai , Hao Wang , Kang Huang , Shan-xiong Chen , Jian-hua Guo
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引用次数: 0
Abstract
Microscale experimental techniques are challenging in terms of test time, sample preparation, and resolution. It is also difficult for molecular dynamics (MD) to overcome spatial and temporal limitations. Wyoming sodium montmorillonite was used in this study. Based on the Gay-Berne potential (GB), the unloading properties of clay aggregates under different environmental conditions were simulated using coarse-grained molecular dynamics (CGMD) method. The results showed that for each case, the deformation was closely related to the distribution of the stacks. In particular, the relationship between the total number of stacks and void ratio followed the Boltzmann distribution. At the same time, it was found that the stress states in different cases during unloading depend on the particle orientation. For one-dimensional unloading, the particle arrangements exhibited significant anisotropy, leading to a smaller vertical rebound. Owing to the isotropic compression at 1 atm and lateral confinement, the lateral pressure coefficient (k) is >1 in the atmospheric environment. In contrast, limited lateral expansion caused k to be smaller than 1 in a vacuum. With decreasing confining pressure, a linear increase in the void ratio was observed. During this process, the number of small-sized stacks gradually decreased, accompanied by an increase in the number of large-sized stacks. From 100 MPa to 1 MPa, the longer the unloading path, the smaller the rebound. In the range of 0.1–0.7 MPa, the clay configurations reached equilibrium and the unloading paths had no obvious effects on the distribution of stacks. This work demonstrates the validity of the GB potential model, which provides a basis for bottom-up mechanical prediction of the hierarchical structure of Na-montmorillonite particles.
期刊介绍:
Powder Technology is an International Journal on the Science and Technology of Wet and Dry Particulate Systems. Powder Technology publishes papers on all aspects of the formation of particles and their characterisation and on the study of systems containing particulate solids. No limitation is imposed on the size of the particles, which may range from nanometre scale, as in pigments or aerosols, to that of mined or quarried materials. The following list of topics is not intended to be comprehensive, but rather to indicate typical subjects which fall within the scope of the journal's interests:
Formation and synthesis of particles by precipitation and other methods.
Modification of particles by agglomeration, coating, comminution and attrition.
Characterisation of the size, shape, surface area, pore structure and strength of particles and agglomerates (including the origins and effects of inter particle forces).
Packing, failure, flow and permeability of assemblies of particles.
Particle-particle interactions and suspension rheology.
Handling and processing operations such as slurry flow, fluidization, pneumatic conveying.
Interactions between particles and their environment, including delivery of particulate products to the body.
Applications of particle technology in production of pharmaceuticals, chemicals, foods, pigments, structural, and functional materials and in environmental and energy related matters.
For materials-oriented contributions we are looking for articles revealing the effect of particle/powder characteristics (size, morphology and composition, in that order) on material performance or functionality and, ideally, comparison to any industrial standard.