233 / 2019-09-02 21:55:34

Generic theoretical framework for percolation threshold, tortuosity and transport properties of anisotropic porous composites via finite-size scaling analysis

porouse materials,Percolation,Tortuosity,transport properties,finite-size scaling

计算力学在工程中的应用 > 复合材料力学

Continuum percolation of randomly orientated anisotropic-shaped pores is first studied. The percolation threshold ϕc, percolation transition width Δ, and correlation-length critical exponent  for pores are determined with hitherto unattained accuracy via extensive finite-size scaling analysis. A novel generalized excluded-volume approximation for percolation threshold is proposed and shown to yield accurate predictions of ϕc based on available numerical and experimental data. Then, a percolation-based tortuosity model is proposed by using the proposed finite-size scaling method and percolation theory. The tortuosity model suggests the geometrical tortuosity is strongly related to the percolation threshold, porosity and fractal dimension of porous networks, which possesses clear physical meanings, rather than those empirical and quasiphysical tortuosity studied in the past. A powerful percolation-based conductivity model that couples the percolation threshold model with the generalized effective medium approximation to developed to predict the effective conductivity of porous composites. We validate the proposed percolation-based models with excellent accuracy by comparing with available numerical simulations and experimental data reported in literature. Our results shed light on the intrinsic interactions of component-structure-transport property in porous composites, which may provide guidance for understanding degradation essence of porous materials in practical applications.