Breakage mechanics - Part II: Modelling granular materials
Breakage mechanics - Part II: Modelling granular materials
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DOI：
10.1016/j.jmps.2006.11.004
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发表时间：
2007-06-01
影响因子：
5.3
通讯作者：
Einav, Itai
中科院分区：
文献类型：
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作者：
Einav, Itai
传统上，颗粒材料的压缩模型具有经典弹塑性的局限性。能量被隐含地假设为从粒子的摩擦相互作用中耗散。然而，脆性颗粒材料破碎的事实表明，能量也必须从颗粒的断裂中耗散，如断裂力学中那样。在第一部分[Einav，1.，2006.断裂力学.第1部分：理论J.Mech.Phys.Solids00，000 -000）来描述断裂机制。该理论允许处理理想的理论材料，这些材料纯粹从断裂中耗散，没有其他机制允许能量消耗。然而，在弹塑性中，耗散也必须从颗粒的摩擦重排中发生。因此，必须研究断裂和塑性这两种耗散机制的结合，正如我们在本文中所做的那样。这两种机制通常是耦合的，因为当另一种机制发展时，一种机制不可避免地出现。塑性耗散作为破碎耗散的副产品出现，因为颗粒破碎后，必须发生局部重排。这种情况可以被称为“主动断裂机制”，并代表压缩变形。在剪切过程中，塑性耗散占主导地位，但由于磨粒磨损，不可避免地会出现破碎。这种情况可以被称为“被动断裂机制”。基于耦合假设，模型的粒状材料。特别是，我们表明，在压缩各向同性硬化的砂可能会出现不涉及塑性应变，即，与摩擦耗散无关。这种对硬化的解释不同于经典临界状态土力学中所用的解释。然而，摩擦耗散导致塑性应变，这对于模型在卸载中的预测是必要的。(c)2006爱思唯尔有限公司保留所有权利。
The compression of granular materials has been traditionally modelled with the limitations of classical elasto-plasticity. The energy was implicitly assumed to dissipate from the frictional interaction of particles. However, the fact that brittle granular materials crush suggests that energy must also be dissipated from the fracturing of the grains, as in fracture mechanics. The concept of breakage as a thermornechanical internal variable was introduced in Part I [Einav, 1., 2006. Breakage mechanics-Part 1: theory. J. Mech. Phys. Solids 00,000-000) to describe the fracturing mechanisms. The theory allows to treat ideal theoretical materials that undergo dissipation purely from breakage with no other mechanism allowed for the energy consumption. However, as accounted for in elasto-plasticity, dissipation must also occur from the frictional rearrangement of grains. The combination of the two dissipative mechanisms of breakage and plasticity must therefore be investigated, as we do in this paper. Those two mechanisms are generally coupled, in the sense that one inevitably appears when the other develops. Plastic dissipation emerges as a by-product of breakage dissipation because after grains crush, local rearrangement must occur. This scenario may be termed an 'active breakage mechanism', and typifies compression deformations. In shear the plastic dissipation is dominant but breakage appears inevitably from grains abrasion. This scenario may be called a 'passive breakage mechanism'. Based on the coupling assumption, models are developed for granular materials. In particular, we show that in compression isotropic hardening of sands may appear without involving plastic strains, i.e., independent of frictional dissipation. This interpretation of hardening is different from the one used in classical critical state soil mechanics. However, frictional dissipation leads to plastic straining that are necessary for the models to be predictive in unloading. (c) 2006 Elsevier Ltd. All rights reserved.