SIMULATION AND MODELING OF 3-DIMENSIONAL PERCOLATING STRUCTURES - CASE OF A LATEX MATRIX REINFORCED BY A NETWORK OF CELLULOSE FIBERS

The composite presented here, which is made of cellulose whiskers embe dded into a latex matrix, shows quite surprising elastic properties du e to the fact that a continuous skeleton of hard whiskers is formed wi th some tight interactions. The work shows that the classical homogeni zation techniques are not applicable here, in particular because those techniques do not make any difference whether or not tight interactio ns are considered. The percolation problem is investigated by means of numerical simulations to quantify the percolation threshold and the m echanical properties are obtained by means of the Percolation Theory a nd a simple Voigt model. Finally, a continuous description is proposed , using Cosserat Continua, where the material's behavior exhibits a le ngth scale. Ail the elastic parameters associated with this descriptio n are determined by Finite Element simulations. An attempt is made to understand the physical meaning of this length scale. (C) 1997 Acta Me tallurgica Inc.