Soft Matter Seminar: “Fracture, Instability and Phase Transitions via Constrained Expansion”

The Syracuse University Department of Physics Soft Matter Group is pleased to welcome Dr. Abigail Plummer, Assistant Professor of Mechanical Engineering at Boston University.

Title: “Fracture, instability and phase transitions via constrained expansion”

Abstract:

Consider an elastic material that increases in size due to growth or swelling. If the material is unable to expand freely, stresses develop. In this talk, Dr. Plummer will present two systems in which stresses due to constrained expansion can generate dramatic and complex responses. First, it will be described how hydrogels, polymer networks that imbibe large amounts of water, behave when forced to swell around rigid obstacles. We identify a regime in which stresses due to obstacles cause swelling hydrogels to fracture, tearing themselves apart as they expand. Second, she will discuss the mechanics of thin sheets that have been locally dilated at a periodic array of sites. When the dilations are sufficiently large, the affected sites buckle either above or below their surroundings. These bistable dilations form a mechanical analog of the Ising model with curvature acting as an external field.