Effective permittivity of compacted granular materials:Effects ofinterfacial polarization and pore-filling fluids  

作　　者：Xu Wang Chongpu Zhai Yixiang Gan 

机构地区：[1]School of Civil Engineering,The University of Sydney,Sydney NSW 2006,Australia [2]State Key Laboratory for Strength and Vibration of Mechanical Structures,School of Aerospace Engineering,Xi’an Jiaotong University,Xi’an 710049,China [3]The University of Sydney Nano Institute(Sydney Nano),The University of Sydney,Sydney NSW 2006,Australia

出　　处：《Theoretical & Applied Mechanics Letters》2024年第6期441-449,共9页力学快报(英文版)

摘　　要：Interfacial polarization dominates the permittivity spectra of heterogeneous granular materials for the intermediate frequency range(i.e.,from kHz to MHz).In this study,we examine the corresponding dielectric responsesof compacted glass sphere packings saturated with pore-filling fluids under various compressive stresses.Theeffective permittivity spectra are observed to exhibit consistently a plateau-to-plateau drop,described by lowfrequency permittivity,characteristic frequency,and high-frequency permittivity.The permittivity spectra underdifferent compressive levels are found to be influenced by the packing structure,compressive stress,and electricalproperty contrasts between solid and fluid(specifically permittivity and conductivity).For considered measure-ment conditions,the variation of packing structure and its associated porosity is found to be more significantthan the stress evolution in controlling the interfacial polarization,thus the permittivity spectra,as supportedby analytical and numerical results for unit cells.Furthermore,to gain a general rule for dielectric responses forsaturated granular materials,we train multi-layer artificial neural network(ANN)models based on a series ofsimulations for unit cells with various structures,stresses,and electrical and dielectric properties.The predictions with two-layer ANN agree well with experimental measurements,presenting errors smaller than 5%forboth low-frequency and high-frequency permittivity.This study offers an effective predicting approach for thedielectric behaviour of heterogeneous and multiphase materials.

关 键 词：Interfacial polarization Volumetric compression Packing structure Pore deformation Artificial neuron network 

分 类 号：G63[文化科学—教育学]