(274g) Quantification of Stress Fields Ahead of a Cutting Blade Via Mechanophores

Fracture initiated by contact with a sharp object is a concern in many industries. No matter whether fracture is desired or unwanted, understanding the effects blade and material properties have on the fracture and stress responses of the material is critical to enable better design of products. This research aims to describe fracture and stress fields inside elastomers due to cutting and the effects blade radius has on these properties. The methodology to accomplish this utilizes a Y-shaped cutting apparatus to quantify fracture toughness and mechanophore incorporation coupled with confocal microscopy to visualize stress in situ. Elastomer samples are cut using blades of varying radii to highlight the differences between blades of different cutting aptitudes. Cutting force measurements are used to determine the fracture toughness of the elastomer and to ensure that cutting is performed at steady state. Within this steady state regime, mechanophore activation ahead of the propagating crack tip describes the behavior of fracture induced by different radii blades. The magnitude and distribution of stress ahead of the crack tip is discussed and compared for the different blades. The fluorescent response of the activated mechanophore is mapped to calculated stress using finite element analysis, quantifying the stress distribution in the material during cutting. These results demonstrate the importance of using cutting implements designed for the task and a way to quantify the interactions of these cutting tools against elastomers.