"Soft materials resist fracture by deconcentrating stress"

Abstract: Fracture occurs because cracks concentrate stress. Materials resist fracture by deconcentrating stress near cracks. For example, structures such as polymer chains and stiff phases carry stress away from a crack tip, and in soft materials, large deformation itself can remove stress concentrations. Furthermore, soft materials can contain structures spanning multiple length scales. In a recent work, multiscale stress deconcentration was used to amplify the fatigue resistance of rubber by an order of magnitude. This talk will teach methods for creating soft materials that deconcentrate stress, as well as the mechanics underlying their performance. Examples include particle-filled rubbers, hydrogels, and soft adhesives. Applications of such materials include car tires, tissue adhesives, and sustainable polymers.