Speaker: ShihengZhao，Max-Planck Institute for the Physics of Complex Systems

Title: Mechanics of Poking a Cyst

Language: Chinese

Time & Venue: 2025.11.06 14:00-15:00 思源楼315会议室

Abstract: Biological tissue are very soft materials: Their linear elastic constants tend to be several orders of magnitude smaller than those of conventional soft materials. Here, we consider the simplest model of an elastic material with zero linear shear modulus (a purely nonlinearly elastic material). We extend the paradigmatic "Pogorelovdimple" problem of classical elasticity to such material. Strikingly, our numerical calculations reveal novel scaling behaviourof the force-displacement relation, with an exponent 3/2 for this "supersoft" material, different from the classical exponent 1/2. We develop an elastic shell theory and a scaling argument to explain this exponent, and we characterisenumerically the transition between the two scaling regimes as a small, nonzero linear shear modulus is added. Excitingly, the results suggest that the nonlinear contributions to tissue elasticity can be measured from the scaling behaviourin poking experiments.