Multiple impacts of two concentric hollow cylinders with zero clearance

impact problem of two concentric, hollow, circular, elastic cylinders of same materials with zero clearance is studied, where the interior hollow cylinder is subjected to different uniformly distributed, exponentially decaying, interior pressures. The structural sizes and material parameters of the impacting system are unchanged. The influences of multiple collisions and multiple separations on interface impact pressures, dynamic radial displacements and stresses, are considered in the present investigation. The global histories of interface impact pressure have similar decay tendencies, and there exist three types of interface impact pressure branches. A so called ‘group’ phenomenon occurs in the histories of interface impact pressure, where several collisions take place closely together to form a cluster of interface impact pressure branches. Two neighboring cluster have an approximately constant time interval. The quasi-periodic growing of clusters means the impacting system is stable, and will result in quasi-periodic motions. A main frequency exists in the impacting system as well, which is different from the natural frequencies of two hollow cylinders. Q 1997 Elsevier Science Ltd.