Numerical study of structural evolution in shear band
Numerical study of structural evolution in shear band
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剪切带结构演化的数值研究
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
H. Muhlhaus
中科院分区：
文献类型：
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作者：
Xiaoxing Liu;A. Papon;H. Muhlhaus
在较高的应力水平下，颗粒集合体的变形倾向于局部化在狭窄的剪切带。最近的研究工作在粒状材料社区集中在变形模式的形态带内。了解变形机制是量化能量耗散，硬化和软化后本地化范围内的先决条件。尽管大量的实验研究工作，一个清晰的理解剪切带内的流动特性和本构行为仍然是难以捉摸的。这可能主要归因于剪切带是薄的物体，使得难以详细描述颗粒的行为及其在剪切带内的相互作用。离散元法（DEM）作为一种数值方法，由于其固有的跟踪颗粒行为的特性，已经证明了它解决这一问题的能力。本文介绍了应用离散元法模拟二维、密排、无粘性、多分散颗粒集合体在简单剪切作用下的结果。对位移场等中尺度运动学信息进行了评价。在剪切带内，变形场显示出涡旋状结构，并且这种涡旋结构伴随着剪切带内强烈的孔隙空间产生。局部剪切带内部力链的历史分析表明，涡旋结构的形成与力链的建立、屈曲和崩溃的循环的运动学演化有关。
At elevated stress levels, the deformation of granular assemblies has the tendency to localize in narrow shear bands. Recent research efforts within the granular material community are focusing on the morphology of deformation patterns within the bands. Understanding of the deformation mechanisms is a prerequisite for the quantification of energy dissipation, hardening and softening in the post-localization range. Despite significant experimental research efforts, a clear understanding of the flow properties and constitutive behaviours within the shear band is still elusive. This could mainly be attributed to the fact that shear bands are thin objects, making a detailed characterization of the particles’ behaviour and their interactions within shear bands difficult. As a numerical method, the Discrete Element Method (DEM) has demonstrated its ability to address this problem, owing to its intrinsic characteristic of tracing particle behaviour. This paper presents the results of application of DEM to model two-dimensional, densely packed, cohesionless, polydisperse granular assemblies under simple shear. Meso-scale kinematical information such as displacement field is evaluated. Within the shear band, the deformation field displays a vortex-like structure, and such vortex structures are accompanied by strong pore space production within the shear band. Analysis of the history of force chains inside the localized shear zone reveals that the formation of vortex structures is related to the kinematical evolution of a cycle encompassing buildup, buckling and collapse of the force chains.