Double-peaked impact force of very soft gel balls

概要

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We measure the time change of the contact force F(t) during the impact between very soft gel balls and a rigid substrate. For low-impact velocities V-i, F(t) is single-peak functions as intuitively expected; and the relation between V-i and the peak value F-m [of F(t)] obeys the prediction of the standard theory for the impact in the linear elastic regime (i.e., the Hertz theory). On the other hand, for large V-i, where the gel ball deforms into thin pancakelike shapes, F(t) becomes double-peak functions. We compare the data of F(t) for large V-i with a prediction of a model proposed in our previous study [Tanaka, Europhys. J. E 18, 95 (2005)]. The model can quantitatively reproduce the experimental F-m-V-i relation, and shows that the double-peak behavior of F(t) is a consequence of the expanding deformation of the pancake-shaped gel, i.e., spreading motion parallel to the substrate.
American Physical Societyの論文
2006-03-08