FOR 5657:  Bioinspired anti-fatigue: enhancing materials science structural properties by abstracting naturally-grown fatigue resistance

• Subject Area: Materials Science and Engineering
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 516930787

Fatigue failures are often experienced as "sudden" fracture events, because damage develops without macroscopically visible signs during thousands or millions of cycles, at loads below the quasistatic strength and often even below the elastic limit. Fatigue resistance is modulated by microstructural features, such as soft interfaces, precipitates, or grain/particle size. These increase toughness, strength or plastic deformability, thus hindering microcrack formation and growth, elevating the fracture energy. Here we explore the interaction between microstructural features and fatigue in different synthetic composites inspired by a range of natural materials with remarkable fatigue resistance. Our research group seeks inspiration from fatigue resistance of biological materials that survived long processes of natural selection, a topic that has rarely been addressed as source of bio-inspiration. Coordinated by the spokesperson, the consortium comprises four tightly interwoven projects, each led jointly by a "biological" and an "engineering" materials scientist. The projects concentrate on diverse, widely encountered fatigue loaded, biological, stiff structures, and complementary engineering composites. On the one hand, we explore evolutionary-grown fatigue resistance in a series of biological, long-term cyclically loaded systems: coral, tooth enamel, fishbone, and wood. All our biological blueprints share long-term survival of cyclic loading, but none of them possesses biological remodeling processes that might replace fatigue damaged tissue by healthy, new material. They further span a wide range of compositional and structural features. On the other hand, we harness modern additive manufacturing and synthesis approaches for structuring and templating intricate artificial nanocomposite systems. The engineering material scientists will use a variety of material compositions and fabrication methods to introduce microstructural features identified as advantageous in the biological blueprints. The approaches of the partners differ by material composition and the introduced core features. An important aspect is the exchange of materials and processing methods between the projects to jointly elucidate the influence of processing on material properties and the applicability of complementary processing methods to the design of different bioinspired composites. Our overarching goal is to explore structural features on different length scales and how they can be transferred from the biological systems into engineering structures to increase fatigue resistance.

• DFG Programme: Research Units
• International Connection: Israel

Projects

• Coordination Funds (Applicant Fleck, Claudia )
• P1 Coral secrets - how do glass flowers of the ocean resist sea wave fatigue (Applicants Schmidt, Franziska ;  Zaslansky, Paul )
• P2 “Enamel”: Natural enamel and water-glass based composites – decoding structure-function relationship regarding fatigue resistance of two complementary systems (Applicants Fleck, Claudia ;  Görke, Oliver ;  von Stein-Lausnitz, Manja )
• P3 - Fishbone: Bones without cells as blueprints for durable, cyclically loaded nanocomposites: how does anosteocytic fishbone cope with fatigue? (Applicants Boccaccini, Aldo ;  Fleck, Claudia )
• P4 "Wood": Fatigue-related failure resistance in living trees and harvested wood as inspiration for hydration-responsive minerals and bilayer composites (Applicants Eder, Michaela ;  Schenk, Anna Sophia )

• Spokesperson: Professorin Dr.-Ing. Claudia Fleck