CAREER: Achieving Resilience in Brittle Materials Through Bio-inspired Nested Cylindrical Structures

Ceramics and brittle polymers play a pivotal role in biomedical, automotive, and aerospace applications. Their catastrophic failure when undergoing thermal and mechanical stresses is a concern. In contrast, although marine spicules are also made of a brittle ceramic (silica), they show unusual toughness and flexibility due to their nested cylindrical structure. This Faculty Early Career Development (CAREER) award will initially focus on investigating the microstructure, micromechanical properties, and crack development patterns and mechanisms in marine spicules found in a marine sponge, Euplectella aspergillum. The research findings will be subsequently used to design and fabricate similar structures from brittle materials such as rigid polymers and ceramics and explore their potential for bone tissue engineering and other applications. As part of the project, research will be integrated in the curriculum to train next-generation engineers. Undergraduate and graduate underrepresented minority and female students will be recruited into the research effort. There will be summer programs and workshops for K-12 students to learn about additive manufacturing. Lastly, high school teachers will be invited to summer research programs and industrial connections will be strengthened through collaborative research.

The objective of this research is to investigate the role of architecture in the facture behavior of bio-inspired nested cylindrical structures made of brittle materials. The inspiration comes from marine spicules composed of silica that resist the propagation of cracks due to the layered structure. The plan is to mimic and engineer similar structures with lower weight and improved fracture performance. First, a combination of scanning electron microscopy and finite element modeling will be used to extensively examine the toughening effect of various geometrical configurations, roughness, and morphology of the surface of cylinders and materials properties of marine spicules. These findings will form the basis of various spicule-inspired structural configurations made of tough polymers and ceramics, which will be fabricated with stereolithography 3D printing processes. An extensive experimental program based on the Taguchi method and finite element analysis will be used to understand the operative deformation mechanisms. Lastly, the analysis of variance will be performed to find the critical parameters most affecting the fracture behavior.

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.