THE INHOMOGENEOUS DEFORMATION OF HOLLOW CYLINDERS SUBJECTED TO STATIC AND DYNAMIC AXIAL COMPRESSION

Abstract

Experiments are described in which hollow cylinders of mild steel were subjected to stalic compression, both where the operation was stopped freqnenily to effect re-lubrication, and where the operation was continuous. Previous observations relating to the rolling of material from the walls of the specimen onto the compression plaiens are illustrated and discussed. The effects of specimen/platen friction on the interpenetration of the “dead meta zones“ or “pressure cones“ and the resultant effects upon force-displacement characleristics and axially inhomogeneous deformation of the specimen are demonstrated. Further tests carried out dynamically at both room and elevated temperature are described. The mechanism whereby a sharp “tongue“ of material is caused to project from the inner wall at high fractional reductions —also observed in ihe use of Plasticenef specimens—is illustrated.