Research On Resistance Of Granular System Response With Compresive Stress

Granular materials is a kind of aggregation state which size from 10-4m-104 m. It is different from solid, liquid and gas, which have strong inner dissipate and nonlinear special characters. Granular material is a branch of soft materials, whic h is general in industry and daily life, from concrete to sand in construction to corn and fruit in agriculture, to dust and soil in nature environment. Granular materials impact many natural phenomenon, from sand storm to debris flow, from corn storage to fruit transportation, they are tightly related to granular materials. It is meaningful to research and solve these kind of problems.Recent years, the special characteristics of Granular Materials attract many outstanding scientists devote themselves into this field, research is hot. But now, research on electrical conductive characteristics is limited. Resistance of granular material is not only related to the materials resistivity, but also affected by their assembly states, surface states and interactivity with extra container. It is unclear of inner conductive mechanism, researches are focus on metal, but nonmetal is limited. It is necessary to research how stress influence granular materials’ conductivity.In this work, based on Hertz contact resistance theory and Janssen Model, we deduced resistance of granular system change with the co mpressive stress and pressure on bottom change with granular thickness. We also combined two theories, represent pressure of bottom as a function of thickness, then deduced granular system resistance change with thickness. To test the validity of theory, we me asured resistance of granular change with continual compressive stress. First, we measured the axial resistance change with pressure, observed the experiment phenomenon and concluded experimental regularities. To verify regularities in different materials, we measured and compared resistance change with pressure in bamboo-charcoal and conductive plastics. Furthermore, we measured transverse resistance change with compressive stress, and fitted experimental data with power-law function. We found use two part power-law functions could fit data better. At last, we separate granular system into layers, measured resistance of each layer. We found resistance change with compressive stress is inhomogeneous in different layer. In addition, we measured resistance change with thickness, and found pressure saturation. After processing, experimental data could fit theory well.