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.
