Effects of polydispersity on the micro–macro behavior of granular assemblies under different deformation paths

查看全文 作　　者：Nishant [1]Kumar;Olukayode [1]I.Imole;Vanessa [1]Magnanimo;Stefan [1]Luding

机构地区：[1]Multi Scale Mechanics(MSM), Faculty of Engineering Technology, MESA+, University of Twente

出　　处：《Particuology》索引2014年第12卷第1期,共16页

基　　金：financially supported by the European Union funded Marie Curie Initial Training Network,FP7(ITN-238577) 摘　　要：The micromechanical and macromechanical behavior of idealized granular assemblies, made by linearly elastic, frictionless, polydisperse spheres, are studied in a periodic, triaxial box geometry, using the discrete element method. Emphasis is put on the effect of polydispersity under purely isotropic loading and unloading, deviatoric(volume conserving), and uniaxial compression paths.We show that scaled pressure, coordination number and fraction of rattlers behave in a very similar fashion as functions of volume fraction, irrespective of the deformation path applied. Interestingly, they show a systematic dependence on the deformation mode and polydispersity via the respective jamming volume fraction. This confirms that the concept of a single jamming point has to be rephrased to a range of variable jamming points, dependent on microstructure and history of the sample, making the jamming volume fraction a state-variable.This behavior is confirmed when a simplified constitutive model involving structural anisotropy is calibrated using the purely isotropic and deviatoric simulations. The basic model parameters are found to depend on the polydispersity of the sample through the different jamming volume fractions. The predictive power of the calibrated model is checked by comparison with an independent test, namely uniaxial compression. The important features of the uniaxial experiment are captured and a qualitative prediction for the evolution of stress and fabric is shown involving a 'softening' regime in both stress and fabric – stronger for the latter – that was not prescribed into the model a priori. 关键词：多分散性变形路径力学行为颗粒状宏观组件体积分数微观

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Effects of polydispersity on the micro–macro behavior of granular assemblies under different deformation paths

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