Oh snap! Ultrafast snapping recoil of elastic materials

Elastic biological materials like tendon play a vital role in animal locomotion, yet their complexity makes their mechanical characterization challenging. These materials often have a highly non-linear mechanical response in which stress has a complicated dependence on the amount of applied deformation. Further, these elastic biological materials are highly rate-dependent due to complex dynamic relaxation processes. Traditional testing of elastic biological materials typically focuses either their large deformation behavior or their high-rate properties -- not both aspects simultaneously. But for ultrafast movements in biology, these materials experience both extremes at the same time.

In our work, we perform recoil experiments to characterize the high-rate, large deformation response of elastic materials. In a recoil experiment, a clamped material is first slowly stretched while measuring force and displacement to calculate the elastic energy stored in the material. Then the material is suddenly released from its clamped state, and the material recoils (retracts) back towards its unstretched original state. By measuring the recoil using high speed videography, we measure the dynamics of the elastic energy release, and ultimately, infer the high-rate and large deformation mechanical properties of the material. The details of how to successfully infer these properties from a recoil experiment are still largely unresolved, but steps towards this goal would enable the characterization of elastic biological materials to understand their unique properties during ultrafast movement.

Essay Prompt: What interests you about this research and what do you hope to get out of the research experience?