AN EXPERIMENTAL IMPACT OSCILLATOR

The present work considers the impacting behavior of a piecewise linea r experimental system, a previous version of which has successfully di splayed a wide variety of non-linear, including chaotic, behavior in o ther previous experiments [1-3]; making use of the 'ball rolling on a hill' concept, a cart is constrained to roll along an 'energy well' tr ack, shaped in the form of a parabola such that the governing equation s of motion of the cart are almost linear. In contrast to previous stu dies, where the impact condition was fixed (usually at equilibrium), t he rigid barrier is placed at varying positions along the track in thi s study to provide a displacement constraint that gives rise to a disc ontinuity in the restoring force on the cart (provided solely by gravi ty in the non-impacting region). Varying the position of the impact ca n significantly change the overall behavior of the system, and this ex perimental study will concentrate on behavior where the impact point i s varied among three different positions along the parabolic track, on e chosen at a position less than equilibrium, one chosen at equilibriu m, and one chosen greater than equilibrium; wide and varied responses are observed for these cases. Data were collected with the LabVIEW obj ect-oriented, programmable interface, about which a few salient featur es are also discussed. (C) 1997 Elsevier Science Ltd.