Alpha Sigma Mu Lecture: Prof. Robert O. Ritchie, Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Materials Science & Engineering, University of California Berkeley
Deformation and Fracture of Biological and Engineering Materials
The ability of a material to undergo limited deformation is a critical aspect of conferring toughness as this enables the dissipation of high stresses which would otherwise cause fracture. Indeed, resistance to fracture is a compromise - a combination of two, often mutually exclusive, properties of strength and deformability. It can also be considered as a mutual competition between intrinsic damage processes that operate ahead of a crack tip to promote its advance and extrinsic crack-tip shielding mechanisms that act at, or behind, the tip to locally diminish crack-tip stresses and strains. We examine here how such interplay is utilized to derive damage-tolerance in natural materials, e.g., bone, skin, fish scales, and in engineering structural materials such as aerospace ceramic-matrix composites, nuclear graphite, and advanced metallic materials, such as high-entropy alloys.