COMPACTION OF POWDERS CONTAINING HARD INCLUSIONS - EXPERIMENTS AND MICROMECHANICAL MODELING

The effect of reinforcements in powders during hot compaction is studi ed with the help of model materials. The matrix is a polymethylmethacr ylate (PMMA), which exhibits a nonlinear viscoplastic behavior at 110 degrees C. The inclusions are spheres of glass with different sizes. T he samples an compacted in a triaxial cell. In situ measurements of de nsity variations are made with an X-ray tomograph which allows, in add ition, continuous measuring of the diameter of the samples. Different volume fractions and sizes of inclusions are considered. The experimen ts are modeled by means of a micromechanical procedure based on recent ly proposed nonlinear variational procedures. An original multi-scale scheme is proposed to account for the relative size of the inclusions compared to the particles of matrix. (C) 1998 Elsevier Science Ltd. Al l rights reserved.