TY - JOUR TI - Multi-physics modeling and simulations of thermally-assisted compaction of granular materials DO - https://doi.org/doi:10.7282/T3BK1F2Q PY - 2015 AB - Having characteristics that differ from those associated with solids, liquids, and gases, granu- lar materials require miscellaneous multi-physics approaches that integrate theories at different scales. The abstract behavior of granular material provides limitless arrangements in terms of microscopic and macroscopic properties, specifically concerning the thermally-assisted com- paction process. However the uniqueness of particulate systems reduces significantly the effec- tiveness of conventional compaction models based on continuum mechanics description. Thus the current study engages with the problem at both discrete and continuum levels, and bridges the gap between particle-mechanics and macro-scale theories. A mathematical formulation that integrates the thermal and mechanical behavior of discrete system of particles is presented. It is worth noting that thermal expansion experienced by the compacted particles increases the nonlinearity in the thermo-elastic contact problem, which results in various interesting aspects unique to granular matter. Numerical analysis reveals the role of thermal expansion, the role applied thermal and mechanical loads during thermally- assisted compaction of spherical, perfectly conforming particles. Modeling consolidated granular media by using continuum mechanics requires an addi- tional concentration on defining the effective transport properties of the material. Taking advantage of the effective medium approximation, an equivalent continuum model for the state of small-strain deformation under the applied thermal gradient is investigated. The discrepancy between discrete and continuum analysis underlines the importance of describing an effective thermal expansion parameter. Starting from the fundamental understanding of particle interac- tions, an effective thermal expansion coefficient is derived for the current problem statement. Unlike the continuum media, granular materials host inhomogeneous distribution of con- tact networks, which results in uneven distribution of loads in the dense particulate assemblies. Moreover these structural arrangements play critical role in forming preferred paths of heat transport. In spite of the recent experimental and theoretical studies on the evolution of force chains, the formation of heat chains and the correlation between the heat and force chains still remain unclear. In this study two-dimensional numerical simulations are demonstrated to un- derstand some of the fundamental concepts such as: (i) formation of force and heat chains (ii) formation of localized hot zones, (iii) cross-property relations between contact force distribu- tions and heat transported at the contact surfaces, (iv) influence of system characteristics such as diverse size distribution of particles, binary material constituents and different boundary conditions. KW - Mechanical and Aerospace Engineering KW - Granular materials KW - Compacting--Mathematical models KW - Expansion (Heat) LA - eng ER -