Non-classical Micromorphic Continuum Model for Granular Microstructure Design

该奖项支持开发新分析方法的基础研究，这些方法将准确有效地描述颗粒固体的力学行为及其与微观结构和颗粒相互作用的关系。颗粒状固体无处不在，影响着工程和科学的各个领域，如材料开发，运输和基础设施系统，制药和药物输送以及物理学中的自然过程。 这些材料跨越了从由颗粒前体形成的高度固结的致密固体到非粘性颗粒的受限填料的范围。 这些材料对施加的机械载荷的响应典型地表现出一系列复杂的行为。 通过操纵微观结构和颗粒相互作用，可以控制机械行为，并且可以利用增材制造来制造具有可预测特性的此类材料。 目前用于预测这些材料的机械性能的方法效率低且不准确。这些知识将为设计具有上级重量-刚度/强度比、振动控制能力和其他不寻常性能的新型颗粒固体打开大门。 在基础设施、航空航天、生物医学和汽车工业中，对加速开发此类材料的需求日益增加。 因此，这项研究的成果将对美国经济和社会产生有益的影响。 这项跨学科研究将借鉴包括制造，数学，材料科学和工程在内的多个学科。 研究成果和技术将在校园外展活动中突出显示，旨在吸引学生进入STEM学科，并招收学生进入研究生课程。 该项目的跨学科性质将有助于吸引代表性不足的群体的参与，并将更高层次的力学概念引入工程教育。颗粒对相互作用和颗粒结构对颗粒固体中颗粒的集体行为有很大的影响。 因此，需要的方法是不同的许多微机械或多尺度的方法，已设想在传统的连续介质和离散粒子力学的框架内。 该研究项目的目的是发展一种新的非经典微观连续体模型使用颗粒微观力学范式。 该项目的成果将是开发用于描述这些材料力学的工具和方法，并将产生以下成果：（1）具有颗粒微观结构的材料的连续体模型，该模型在颗粒微观力学框架内解释了颗粒位移和颗粒旋转的波动;（2）需要根据经验数据加强连续体方法的理由;以及（3）这些模型实际应用的验证方法。

This award supports fundamental research for development of new analyses methods that will accurately and efficiently describe the mechanical behavior of granular solids and its relation to microstructure and grain-interactions. Granular solids are ubiquitous and impact diverse areas of engineering and science such as material development, transportation and infrastructure systems, pharmaceuticals and drug delivery, and natural processes in geophysics. These materials span the spectrum from highly consolidated dense solids formed of particulate precursors to confined packings of non-cohesive particles. The response of these materials to imposed mechanical loads characteristically exhibits a range of complex behavior. By manipulating the microstructure and grain-interactions the mechanical behavior can be controlled and additive manufacturing can be exploited to fabricate such materials with predictable properties. The current methods used for the predicting the mechanical performance of these materials suffer from inefficiencies and inaccuracies. Such knowledge will open the door for the design of novel granular solids that have superior weight-to-stiffness/strength ratio, vibration control capabilities and other unusual properties. There is an increasing demand for accelerated development of such materials in infrastructure, aerospace, biomedical and automotive industries. Consequently, the results of this research will have beneficial impact upon the U.S. economy and society. This interdisciplinary research will draw from a number of disciplines including manufacturing, mathematics, material science and engineering. The research results and techniques will be highlighted at the campus outreach events designed to attract students into STEM disciplines and recruit students into graduate programs. The interdisciplinary nature of the project will help attract participation from underrepresented groups and introduction of higher-level mechanics concepts into engineering education. The grain-pair interactions and granular structures have a strong effect upon the collective behavior of grains in granular solids. Therefore, approaches are needed that are different from the many micromechanical or multi-scale methods that have been conceived within the framework of conventional continuum and discrete particle mechanics. The research project is aimed at developing a novel non-classical micromorphic continuum model using the granular micromechanics paradigm. The outcome of the project will be the development of tools and methodologies for describing mechanics of these materials and will result in following: (1) continuum model of materials with granular microstructures accounting for fluctuations in grain displacements and grain rotations in the framework of granular micromechanics; (2) rationale for the need for enhanced continuum approach based upon empirical data; and (3) validated methodology for practical application of these models.