April 23rd (Thursday) Randy Ewoldt (Mechanical Engineering, MIT)
Nonlinear viscoelastic soft materials: bioinspired applications and new characterization measures
Abstract:
Nonlinear mechanical properties play an important role in numerous biological functions. For example, the strain-stiffening of artery walls enables stability to inflation over a range of pressures, and the dramatic viscous shear-thinning of snail pedal mucus (the biopolymer gel slime trail) enables wall-climbing adhesive locomotion. I will discuss our pursuit of an engineered system which imitates native pedal mucus and enables adhesive locomotion of a mechanical crawler (Robosnail). Our studies have revealed the difficulty of appropriately describing nonlinear viscoelastic material responses. I will present a new framework for describing and understanding such nonlinear viscoelastic behavior, outlining new material measures and clearly defining language such as strain-stiffening/softening and shear-thickening/thinning. Interest in soft materials is increasing within the engineering field. A better understanding of complex viscoelastic materials will help the engineering community integrate soft solids and complex fluids into the working components of devices.