Micro-granular Mechanics for Deformation and Failure of Granular Materials

以往的研究表明，通常的应变概念（位移第一梯度）不能充分描述大偏差加载条件下颗粒材料的破坏前后行为。在本研究中，除了通常的应变概念外，还将探讨使用其他运动学描述符的概念。这项工作的总体目标是利用新的运动学描述符发展微颗粒力学理论，使这些理论适用于应力变形行为的整个范围。所采用的方法将基于微观-宏观方法，其中组装的行为与粒子的性质有关。实验数据和计算机模拟将构成理论发展的一个组成部分。所建立的微颗粒力学理论将应用于有限元环境。该模型将通过比较颗粒材料在不同加载条件下的实测和预测行为来验证。本研究结果将为连续介质力学中材料局部化和分岔的理论框架提供新的见解。材料的固有长度直接关系到材料的微观结构，在局部破坏区起着重要的作用。这一独特特征显著地将这一理论与基于现象学的模型区分开来。所导出的理论不仅对微颗粒力学领域，而且对分析剪切问题的有限元方法领域具有极大的价值

***9813299ChangPrevious studies have shown that the usual concept of strain (firstgradient of displacement) cannot adequately describe the near- andpost-failure behavior of granular material under large deviatoric loadingcondition. In this research, the concept of using additional kinematicdescriptors other than the usual concept of strain will be explored. Theoverall objective of the work is to develop micro-granular mechanicaltheories using new kinematic descriptors so that the theories areapplicable to the entire range of stress-deformation behavior.The approach employed will be based on a micro-macro approach in which thebehavior of an assembly is linked to the properties of particles.Experimental data and computer simulation will form an integral part in thedevelopment of the theory. The developed micro-granular mechanical theorywill be implemented to a finite element environment. The model will bevalidated by comparing measured and predicted behavior of granularmaterials under different loading conditions.The result of this research will provide insight into the theoreticalframework of material localization and bifurcation in continuum mechanics.The intrinsic length of material, which plays a major role in localizedfailure zones, will be directly related to the micro-structure. Thisunique feature significantly distinguishes this theory fromphenomenologically based models. The derived theories are expected to beextremely valuable not only to the field of micro-granular mechanics butalso to the field of finite element methods in the analysis of shearproblems.***