On the walking stick-slip problem

The friction-excited dynamics of a two-sided interface are examined experimentally, and complementary modeling and simulation efforts are used to understand the experimental observations. The experiment uses a thin fiber pulled from between two clamping pads. The experiment shows that stick-slip behaviors of the two clamping pads are periodic but out of phase, a behavior dubbed walking stick-slip, because the pullout specimen pulls out of the fixture in discrete, alternating steps. The friction behavior is understood using two dynamic models: (i) a three degree-of-freedom translational model, and (ii) a model augmented with rotational degrees-of-freedom. The out-of-phase walking arises from the component rotations. Walking stick-slip (to our knowledge) is a previously unreported phenomenon which may have implications in a variety of other situations. (C) 2014 Elsevier Ltd. All rights reserved.