Mercredi 2 juillet 2025 à 14h30 ; salle 259 - IUSTI
The prevailing theory for crack propagation is strictly focused on planar cracks – cracks where a unique crack plane exists, and can easily be identified; however, most cracks are not planar symmetric, but instead have complex geometry at the crack front, or variation of the near-tip fields along the crack front due to finite sample geometry. Here, we probe cracks in brittle hydrogels that have broken planar symmetry, either by geometry of the crack front, or by pore fluid fluxes. We find that these deviations from planar symmetry have consequences for the stability of the crack front, and can even enhance effective toughness. To characterize the near crack-tip fields, we use high-resolution microscopy to analyze the crack tip opening displacement and particle tracking methods. Using these direct observations, we identify novel directions for the characterization of poroelastic fracture mechanics, and identify a key shortcoming in 3D fracture theory when the planar symmetry of a crack is broken. Our measurements highlight the need for further development to address crack propagation of non-planar crack tips. A perspective direction to fill this gap will be discussed prior to the conclusion of the talk.