Micro-granular Mechanics for Deformation and Failure of Granular Materials

* 9813299 Chang以往的研究表明，通常的应变（第一位移梯度）概念不能充分描述大偏载条件下粒状材料的近破坏和破坏后的行为。 在这项研究中，将探讨使用额外的kinematicdescriptors比通常的应变概念的概念。 这项工作的总体目标是使用新的运动学描述符发展微观颗粒力学理论，使理论适用于整个应力-变形行为范围。所采用的方法将基于微观-宏观方法，其中组件的行为与颗粒的性质有关。实验数据和计算机模拟将形成理论发展的组成部分。 所发展的细观颗粒力学理论将在有限元环境中实现。 通过比较不同加载条件下颗粒材料的实测和预测行为，验证了该模型的正确性，研究结果将有助于深入理解连续介质力学中材料局部化和分叉的理论框架，材料的内禀长度在局部破坏区中起主要作用，它与材料的微观结构直接相关. 这一独特的特征使这一理论区别于现象学模型。 所导出的理论不仅对细观颗粒力学领域，而且对剪切问题的有限元分析领域，都是极有价值的。

***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.***