摘要
研究发现,颗粒物质层被匀速推移挤压过程中,所需推移力先以线性规律增加,在某一确定点后,则会以指数规律增加.而颗粒物质是由众多离散颗粒组成的软凝聚态物质,其宏观上反映的是离散颗粒的个体性质和凝聚态物质的集体效应.颗粒与颗粒之间以及颗粒与边界之间的细观尺度接触力链的构成以及演变规律将会直接影响各种宏观受力情况,其摩擦力与挤压力便是力链的主要构成形式.围绕着定量描述细观力链特征,从而揭示力的变化规律这一目标,采用计算机模拟的方法,依照球形颗粒Hertz法向接触理论和Mindlin-Deresiewicz切向接触理论,对重力作用下不同数目的三维等径球体颗粒层的推移情况进行了离散元仿真模拟,量化分析了推移力变化规律、各摩擦力变化规律以及力链分布规律,发现摩擦力与挤压力在颗粒堆积的不同阶段对力链的构成起到了不同的主次作用,使得力链发生强弱演变,从而发现了推移颗粒物质层时推移力的变化规律及原因.这些结果有利于从力链角度揭示颗粒内部和颗粒与各边界之间的受力情况.
Granular matter shows macroscopically the collective effects of individual characteristics of solid grains because it is the soft condensed state of a large assemblage of individual solids. The composition and evolution laws of contact force chains that exist between the particles as well as that between the particles and the boundaries have a direct impact on different macro-forces. Among these force chains, macro friction force and thrust force are the main component. Although the research indicates that the thrust force increases linearly during the process of the granular matter layer that is pushed horizontally, this force increases exponentially when the granular matter layer reaches a determined position. In order to achieve the aim of quantitative description of microscopic characteristics for the force chains and the macro force rules, a discrete element model based on rigorous Hertzian contact law and Mindlin-Deresiewicz contact theory for normal and tangential contact forces has been suggested. The push process is simulated for different quantity of uni-diameter 3D balls under gravity loads by using this model. The pushing force rules, friction force rules and the distribution rule of force chains are discussed quantitatively. The indications are that the effects of the friction force and the thrust force differs in different stages during the pushing process. It leads to the strength changing of force chains. Moreover, the reason of inflection for pushing force increasing rule is discovered. These results help to reveal the internal forces between the particles and particle boundaries.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第9期366-371,共6页
Acta Physica Sinica
关键词
颗粒物质层
力链
离散元法
granular matter layer
force chain
discrete element method
作者简介
通讯作者．E—mail：lixingxiangstar@126．com
