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Colloquium: Prof. Kenji Urayama, Multiaxial Fracture of Elastomers: Energetic Criteria and Biaxiality-Controlled Structural Transformations
Elastomer fracture is often described by a critical energy release rate from uniaxial tests, but its relevance under multiaxial loading and evolving microstructure is unclear. We quantify crack-growth onset in biaxially stretched sheets using energetic analysis and near-tip deformation measurements. For elastic elastomers without deformation-induced structural evolution, cracks initiate at a material-specific critical energy release rate independent of biaxiality. Strain-induced crystallizing elastomers such as natural rubber break this universality. Their response is controlled by a biaxiality-dependent transition near the crack tip: below a critical deformation state, crystallization stays confined and adds little resistance; above it, crystallization spreads around the tip, reinforcing the material and increasing crack-opening displacement and critical energy release rate. Thus, fracture resistance is no longer an intrinsic material constant, but set by the crystallized zone, guiding robust elastomer design including tires, soft robotics, and biomedical devices.
14.09.2026