Anomalous Frictional Behavior in Collisions of Thin Disks Revisited

In prior work, Calsamiglia et al. (1999, “Anomalous Frictional Behavior in Collisions of Thin Disks,” ASME J. Appl. Mech., 66, pp. 146–152) reported experimental results of collisions between thin plastic disks and a relatively rigid steel barrier. In those experiments, it was observed that, contrary to a commonly held assumption in rigid body collision modeling, the ratio of tangential to normal components of the contact impulse could be substantially less than the friction coefficient even for collisions where the disk contact point did not reverse its velocity direction (i.e., for sliding collisions). In those experiments, the disk’s edges were rounded to make the contact less sensitive to machining imperfections. While such impact/contact is nominally at a single point, the rounded edges make the interaction three dimensional (from the view point of analyzing deformations). Here, we revisit that problem computationally, but model the edges as flat, making the problem two dimensional. Our finite element calculations (ABAQUS) do not reproduce the anomalous frictional interactions observed in those experiments, suggesting that rounding of the edges, among other possibilities, may have played a significant role in the experimental results.