New Approaches for the Design of Particulate Media

CBET-1605075PI：积家，海因里希颗粒介质，或颗粒状材料，是大量固体颗粒的随机集合体。它们有各种大小，包括各种天然材料，如砾石、沙子和土壤，以及各种工农业产品，如谷物、化肥、粉末和颜料。这些材料对大规模处理提出了特殊的挑战，因为它们可以表现出一系列类固体和类流体的行为。设计此类材料的一个关键问题是如何选择组成颗粒以获得所需的骨料材料特性。该项目将开发一种新的方法，允许从业者设计粒子类型，从而为聚集体的行为产生预定的目标结果。该项目将包括计算和实验相结合，以解决颗粒设计问题，并制定一套通用的设计规则。该项目将为所有学术水平的学生提供参与研究的机会。研究人员将参加一个桥梁计划，该计划鼓励本科生，特别是那些来自代表不足的群体的本科生，继续毕业工作。此外，团队还将参加几项外展活动，以增加公众对科学和工程的欣赏，其中包括与爆炸有关的物理！为了解决为给定的性能目标确定合适的粒子形状的反问题，该项目实施了一种计算机辅助设计和优化方法，该方法利用进化计算的思想。该项目不仅为特定的设计目标设计特定的解决方案，还通过开发一般设计规则引入了新的功能。这样的规则适用于所有相关的目标，一旦建立，就可以通过提供从颗粒介质的整体行为到颗粒级属性(如形状)的映射来实现合理的设计。对于具有复杂颗粒形状的随机复合材料或颗粒系统的设计，这是一种具有变革潜力的新方法。在这个项目中，任意的凸形和非凸形将由一组不同半径和重叠的粘合球体来表示，这些粘合球体的形状可以通过变异和进化来优化性能。研究方向包括颗粒大小和形状的分布、颗粒破碎、颗粒结合软硬材料、设计早期破坏非线性区域的应力响应、不仅优化颗粒而且优化加工路径。在项目的第二阶段，这一方法被扩展到设计流动行为，重点是浓缩颗粒悬浮。为了校准和验证，计算工作与使用高分辨率3D打印来制造颗粒并使用X射线和超声波进行非侵入性成像的系统实验密切相关。

CBET - 1605075PI: Jaeger, HeinrichParticulate media, or granular materials, are random aggregates of a large number of solid particles. They come in all sizes and encompass a broad range of naturally occurring materials, such as gravel, sand, and soil, and a broad range of industrial and agricultural products, such as grains, fertilizers and powders, and pigments. These materials pose special challenges to handle on a large scale because they can exhibit an array of solid-like and fluid-like behaviors. A key question in designing such materials is how to pick the constituent particles to achieve desired material properties of the aggregate. This project will develop a new approach that will allow practitioners to engineer particle types that will yield predetermined, target outcomes for the behavior of the aggregate. The project will involve a combination of computations and experiments to solve the problem of particle design and to develop a set of general design rules. The project will provide opportunities for students at all academic levels to participate in research. The researchers will participate in a Bridge Program that encourages undergraduates, especially those from underrepresented groups, to continue to graduate work. In addition, the team will participate in several outreach activities to increase the public's appreciation of science and engineering, including the Physics with a Bang! event, which demonstrates science principles to broad audiences.To tackle the inverse problem of identifying appropriate particle shapes for given performance targets, the project implements a computer-aided design and optimization method that makes use of ideas from evolutionary computation. Going beyond devising specific solutions to specific design targets, the project introduces new capabilities by developing general design rules. Such rules apply across a whole range of related targets and, once established, enable rational design by providing a mapping from overall behavior of the particulate medium to particle-level attributes, such as shape. For the design of random composite or particulate systems with complex particle shapes this is a new approach with transformative potential. In this project,arbitrary convex and non-convex shapes will be represented by sets of bonded spheres of varying radius and overlap, whose configuration can be mutated and evolved to optimize performance. Directions to be investigated include distributions of particle sizes and shapes, particle breakage, particles combining hard and soft materials, designing the stress response in the nonlinear regime of incipient failure, and optimizing not only the particles but also the processing pathway. In a second stage of the project this methodology is extended to designing flow behavior, focusing on concentrated particle suspensions. For calibration and validation the computational effort is closely coupled to systematic experiments that use high-resolution 3d-printing to fabricate particles and use x-rays and ultrasound for non-invasive imaging.