This Faculty Early Career Development (CAREER) project aims to study the size-scale dependence of toughness in multilayered structures. The superior mechanical properties of layered biological materials relates to its hierarchical structure and nature?s ability to design these materials with nanoscale structural components. This project establishes a link between toughening mechanisms in biological materials and the design of robust structural composites. To achieve this goal, toughening mechanisms in biological and bio-inspired multilayers will be studied using a novel experimental technique that allows measurement of crack growth in real time at nanometer scale. Using the knowledge of the origin of toughness, a freeze-casting technique will be used to make nature-inspired layered hybrid composites. Mechanics models will be developed to understand the toughening mechanisms such as viscoelastic crack bridging, crack deflections and twisting in biological and bioinspired multilayered materials. The models will be used to optimize the toughness of nature-inspired composites as well as to design tailored composite materials for a wide range of structural applications. The educational plan contributes to and draws upon the research plan. The outreach program collaborates with a university in Africa and locally with a community college. The curriculum development includes inductive team-teaching of multidisciplinary engineering courses.
Strength and toughness are both vital properties for most structural materials. Although there has been success in the development of stronger and harder materials, these materials have little to no use as bulk structural materials without appropriate fracture resistance. Understating the mechanical behavior of biological materials is a crucial step in the design of robust structural materials. The objective of this project is to study toughness in biological multilayer materials. The experimental techniques and theoretical findings from this fundamental research will have a direct impact on the improvement of much needed sustainable infrastructure in the United States. The resulting models can be used to optimize the properties of bio-based composite materials. The educational initiatives will involve participation of underrepresented groups through collaborations with local a community college and Citizen schools.
