Virtual Experiments and Design of Particulate Composites with the Inclusion-based Boundary Element Method (iBEM)

本项目旨在为颗粒复合材料的设计和制造建立一种新的计算方法。复合材料的性能受多种因素的影响，因此采用参数化实验方法开发一种新型复合材料通常需要进行大量的实验来优化制造参数。通过虚拟实验精确再现复杂的材料加工和测试过程，可以在计算机上可靠地模拟物理实验，从而大大减少材料开发时间和成本。应用基于内含体的边界元方法（iBEM）建立高保真的材料行为模拟，并将用于颗粒复合材料的虚拟实验。虽然开发的原理和方法可以应用于一般复合材料，但该项目侧重于轻质混凝土（LWC），它是由泡沫颗粒混合在水泥浆中制成的。其独特的热学、声学和轻质性能使其成为节能建筑围护结构的优良材料。这个项目将产生一种新的工具来加速先进材料的设计和开发周期，这将为我们的制造业和美国经济带来巨大的利益。涵盖理论、数值和实验方面的多学科研究将促进我们的学生在科学、技术、工程和数学（STEM）方面的研究和教育。本项目将计算、实验和微观力学相结合，建立了一种新的设计范式，在以下几个方面推动了颗粒复合材料设计的发展：1)随机颗粒微观结构生成算法将为构建数字复合材料提供一种实用的方法；2) iBEM通过Green函数技术将每个非均匀性模拟为具有特征应变的包体，避免了代表性体积元（RVE）内部的网格划分，能够模拟1000个非均匀性，从而提供了更客观、更真实的材料样品描述；3)评估两个长度尺度（微米和毫米）上的非均匀性相互作用，通过复合材料的微观组织演化来预测破坏过程；4)虚拟实验经过少量实际实验的验证，将在计算机上再现材料的力学行为，加速材料设计和新型复合材料的优化过程。该项目的成功不仅将建立我们的LWC设计方法，而且将导致颗粒复合材料计算机辅助设计（CAD）的突破。此外，它将证明iBEM作为一种新的连续体方法来研究多粒子系统的粒子相互作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project is to establish a new computational approach to the design and manufacture of particulate composites. The performance of a composite changes with many factors, so developing a new composite commonly requires a large number of experiments to optimize the manufacture parameters if a parametric experimental approach is adopted. Through accurately reproducing the complex material processing and testing by virtual experiments, physical experiments can be reliably simulated on the computer, and thus significantly reduce both the material development time and cost. Application of the inclusion-based boundary element method (iBEM) is planned to create high fidelity simulation of the material behavior and will be used for the virtual experiments of the particulate composites. While the principles and methodologies developed can be applied to general composites, this project focuses on lightweight concrete (LWC), which is made of foam particles mixed in a cement paste. Its unique thermal, acoustic and lightweight properties make it an excellent material for energy efficient building envelope. This project will produce a new tool to accelerate the design and development cycle of advanced materials, which will produce significant benefits to our manufacturing industry and thus to the U.S. economy. The multidisciplinary research covering theoretical, numerical and experimental aspects will promote our student research and education in science, technology, engineering, and mathematics (STEM). This project integrates computation, experiments, and micromechanics together to establish a new design paradigm that advances the state-of-the-art of the design of particulate composites in the following aspects: 1) The random particulate microstructure generation algorithm will provide a practical method to construct digital composite materials; 2) The iBEM, simulating each inhomogeneity as an inclusion with an eigenstrain through the Green function technique, will avoid meshing inside the representative volume element (RVE), enable the simulation of 1000 inhomogeneities, and therefore provide a more objective, realistic description of material samples; 3) Interactions of inhomogeneities across two length scales (micron and millimeter) will be evaluated to predict the failure process through the microstructural evolution of the composite, and; 4) The virtual experiments, validated by a few actual experiments, will reproduce the mechanical behavior on computer and accelerate material design and the optimization process of new composite materials. The success of this project will not only establish our LWC design method, but also lead to a breakthrough in computer-aided design (CAD) of particulate composites. In addition, it will demonstrate the iBEM as a new continuum method to study particle interactions of many-particle systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.