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The present paper deals with a novel method to predict the effective elastic behavior of heterogeneous continuous materials using discrete element method. This work uses a numerical approach based on a hybrid particulatelattice model in which discrete elements are linked by cohesive forces through beam elements. Mechanical tests, carried out on particulate composite material, are performed in terms of effective elastic properties and stress fields which exhibit a good adequation with other numerical and analytical approaches such as the finite element method and the Fast Fourier Transform based method. As an example, the proposed approach is performed to predict the elastic properties of a ceramic/resin composite as well as the local effects by means of equivalent Von Mises stress.

This work examines the synthesis of polyurethane (PU)—polydimethylsiloxane (PDMS) hybrid in order to provide low flammability to PU. Chemical characterization of PU/PDMS hybrid by solid state NMR of carbon and FT‐IR shows that some PDMS segments are incorporated in the macromolecular chains of PU. Heat stability of PU (thermo‐oxidative decomposition) is not enhanced by the incorporation of PDMS except that the amount of the high temperature residue is improved and depends on the amount of PDMS incorporated in the PU chains. It is explained by the formation and the accumulation of silica. On the contrary, thermal stabilization (charring) occurs in the pyrolytic conditions when incorporating PDMS. The accumulation of silica as well as charring enhancement enables the flammability properties of the PU/PDMS hybrid to form a protective layer limiting heat transfer between the flame and the substrate. The heat release rate measured by cone calorimetry of PU/PDMS hybrid is significantly decreased compared to virgin PU and temperature of the back of the sample is comparatively low compared to virgin PU. Copyright © 2006 John Wiley & Sons, Ltd.

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This article describes a novel technique for manufacturing functionally graded materials with tailored properties for thermal management. These materials are ceramic/metal composites with a gradient microstructure, elaborated by producing a porosity gradient preform made of alumina phase subsequently infiltrated by the molten aluminum alloy (Al) phase. In order to model these particulate composites and to evaluate their effective thermal conductivities, a numerical approach based on both discrete element method and finite element method has been developed. The study presented here deals with alumina/Al composites without gradient microstructure and is conducted to numerically investigate the effects of the particle size distributions and the interconnection sizes between particles on the effective thermal conductivity. The situation in which an interfacial thermal resistance is present between both phases of composites to simulate a non ideal contact has also been considered.