Toughness by Design

这笔赠款的研究目的是了解和开发非均质性在创造独特的裂缝特性方面的作用。虽然脆性断裂的研究已经有很长的历史，但对显微组织和整体韧性之间的关系的理解是不完整的。最近的研究表明，通过利用定义明确的复杂异质性，有极大地影响韧性的特殊机会。具体地说，初步工作表明，设计良好的非均质性可以显著提高整体韧性，并引入显著的不对称性，其中从左向右扩展的裂纹前沿的阻力与从右向左扩展的裂纹前沿的阻力不同。与此同时，包括数字制造和自组装在内的新兴材料合成方法正在创造一种非凡的新能力，可以合成具有任意复杂但精确的异质结构的材料和部件。拟议的研究将以此为基础，系统地审查一系列理想化但日益复杂的配置中的关键问题。提出了一系列的理论、全面表征和先进的原位方法。这些研究的结果将被用于利用快速原型技术设计和合成复杂的微结构。如果成功，这笔赠款将使设计和合成具有规定韧性的材料以及故障安全部件成为可能，在这些部件中，如果发生裂缝，可以被固定在陷阱中，或者被偏转到造成最小损害的区域。该项目将在理论、计算和实验相结合的高度协作的环境中培养一名博士生。该项目还将为每年夏天的本科生创造研究机会。本文提出的研究结果将积极纳入课程。

The research objective of this grant is to understand and exploit the role of heterogeneities in creating unique fracture properties. While the study of brittle fracture has a long history, an understanding of the relation between microstructure and overall toughness is incomplete. Recent work has shown that there are exceptional opportunities to dramatically affect toughness by exploiting well-defined complex heterogeneities. Specifically, preliminary work suggests that well-designed heterogeneities can dramatically enhance the overall toughness, and introduce a significant asymmetry where the resistance of a crack front propagating from left to right is different from that of a crack front propagating from right to left. Simultaneously, emerging methods of materials synthesis including digital manufacturing and self-assembly are creating an extraordinary new ability to synthesize materials and components with arbitrarily complex but precise heterogeneities. The proposed research will build on this by systematically examining critical issues in a series of idealized but increasingly complex configurations. A range of theoretical, overall characterization and advanced in-situ methods are proposed. The results of these studies will be used to design and synthesize complex microstructures using rapid prototyping. If successful, the grant will enable the design and synthesis of materials with prescribed toughness as well as fail-safe components where a crack -- if it were to occur -- could either be pinned in traps or be deflected into regions where it causes minimal damage. This project will train a doctoral student in a highly collaborative setting that combines theory, computation and experiment. This project will also create research opportunity for an undergraduate student each summer. The results of the research proposed here will be actively incorporated into the curriculum.