Squeaking

Why do our sneakers give off annoying squeaks, especially when you return home on a rainy day? Collaborating with material scientists from Harvard University, we recently discovered an interfacial contact mode between elastomeric materials and hard floor that could be related to the generation of high-frequency noises.

Schematics of the experimental setup and spatiotemporal recordings of the contact area change during sliding. The finite-element modeling shows an intersonic wave propagating along the contact interface. (Du et al., 2021)