Study of Microstructures and Macro-Mechanical Properties of Fluid-Saturated Porous Materials

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To understand the relations between microstructures and macro-mechanical properties of fluid-saturated porous materials, we have performed the study and obtained the results, placing an emphasis on (1) effective elastic moduli and (2) torutuosity, as follows :(1) Effective Elastic Moduli : 1. We have compared and evaluated the static self-consistent model of composite materials and the dynamic self-consistent model based on stress wave scattering ; it has been found that, as the porosity increases, difference in the values of effective elastic moduli evaluated by these two models is larger, while, as the porosity approaches 41%, the elastic moduli given by the former model go down to zero, as agrees to those obtained by the experiment. 2. We have checked the validity of the simulation method proposed in the present study by using the 2-dimensional model and found that the method proposed is very effective. 3.On the basis of this confirmation, we have started the 3-dimensional simulation resorting to the random packing of small spheres. We have constructed the random packings of equi-radial spheres in the computer and started to evaluate the spring constants of a pair of spheres by the finite element method.(2) Tortuosity : 1. We have exzmined some existing formulae of tortuosity from the view point of hydrodynamics. Thus, we have found some bad points in them, but have not succeed in proposing a new microscopic parameter. 2. Experimentally, we have accumulated the data on the tortuosity derived from the observed phase velocity of the second compressional wave.