Steady-state power-law creep in inclusion matrix composite-materials

International audienceThis work is devoted to the prediction of the constitutive steady-state creep behavior of matrix inclusion composites. Both phases are characterized by power-law constitutive equations. The three phase model is extended to viscoplastic equations. If both phases have the same strain rate sensitivity, the effective behavior of the composite is characterized by an effective prefactor. If not, an effective strain rate sensitivity is defined, which is a function of the applied strain rate and of the volume fraction of the phases. All the results are compared with the classical self-consistent ones. A limit case which may be related to the grain boundary sliding accommodated by intragranular power-law creep is also studied

Developing New Components to Improve Energy Savings in Buildings by Using Phase Change Materials

In this paper is presented a general overview of studies which aim at developing new components to be used in buildings to improve energy savings without decreasing human thermal comfort. The main features of these studies are reminded and the paper is focused on the realisation and test of honeycomb panels filled with PCMs. Thermal response of panels is determined with a specific test bench and PCM effects are clearly shown. Modelling and numerical simulation allowed us to interpret experimental results

Ablative degradation of cryogenic thermal protection and fuel boil-off: Improvement of using graded density insulators

International audienceA simple modeling of the heat transfer through insulating bilayers of cryogenic reservoir subjected to surrounding environment or aerothermal flux is presented. The model permits to determine the instantaneous evolution of maximum fuel temperatures and the boil-off rate as well as the possible insulation ablation. To get a realistic estimation of the maximum fuel temperature and boil-off loss, the good knowledge of the internal convection coefficient, taking into account the possible fuel ebullition, is indispensable. The aerothermal flux provokes the insulation degradation and its ablation. Because of the ablation, the reservoir becomes less and less thermally protected, which may cause an important fuel boil-off. Compared to classical insulations with uniform density, those with spatially graded densities appear as potential insulations permitting to meet both light-weight and low boil-off requirements. (C) 2011 Elsevier Ltd. All rights reserved

Numerical study of 3D compressions of entangled materials

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Numerical study of 3D-compressions of entangled materials

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Discrete approaches for entangled materials

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An estimation of overall properties of heterogeneous Cosserat materials

In this work, we try to answer the following question : What is the effective characteristic length of a mixture of Cosserat continua ? More generally, homogenization methods for heterogeneous Cosserat media are proposed and applied to the case of linear elasticity. They first application deals with a beam network regarded as a discrete Cosserat medium and the second with a continuous heterogeneous Cosserat continuum