ROUTES TO CHAOS IN BALL-BEARINGS

The dynamic motion of a lightly loaded ball bearing is studied in order to show and to gain an understanding of the different mechanisms involved in transitions to chaotic behaviours. By varying a control parameter, different routes to chaos are described. The most widely known is the subharmonic route, which is characterized by an increasing number of subharmonics of the driving frequency. Alternance of period doubling and tripling has been noticed, as the ball pass frequency is around the first resonance of the bearing. The second route is a quasi-periodic route. It is characterized by competition between the second resonance of the bearing and the ball pass frequency. It results in an increasing number of combinations of two incommensurate frequencies. During the quasi-periodic sequence, mode-locking occurs each time the two frequencies are locally commensurate. The last type of chaos that is observed is involved by the quasi-periodic breakdown of an attractor. It looks like intermittency and, in the present case, it is obtained by introduction of some over-sized balls. Finally, the occurrence of loss of contact between balls and raceways is studied and related to the existence of chaos. © 1993 1993 Academic Press Limited.