Effect of Elasticity, Viscosity, External Dissipation and Structures on Impulsive Elastic Energy Release in Polymers

Impulsive elastic energy release in materials have been widely adopted in small organisms and engineered micro-robotic devices to achieve high speed motion. The kinematics of impulsive motion are well characterized through high speed camera imaging, but the mechanics of the materials under large deformation and high strain-rate deformation is not yet established. Here, we present a theoretical and experimental study about the effects of material properties, environmental interactions and structures of synthetic polymers for the performance of a free retraction. Building upon the 1D elastodynamics and nonlinear mechanics, we discover that kinematics of impulsive recoiling can be described through a power-law constitutive model, and the residual strain after retraction determines the maximum center-of-mass velocity. The viscous losses in the materials and frictional force in the environment are shown to significantly affect the center-of-mass velocity. Finally, we explore how topologies in mechanical metamaterials can lead to control of impulsive elastic energy release.