An investigation of the deformation of a 38-O sheet specimen during tensile failure

摘要

It is recognized that the "necking down" of a tensile specimen which occurs prior to failure is essentially a plastic flow phenomenon. Careful observation of this flow could conceivably be used to determine the plasticity properties of various metals and also to check the applicability of some of the assumptions in the theory of plasticity.The present preliminary tests were carried out primarily for the purpose of developing an experimental technique. A motion picture camera was used to photograph a deforming grid in the neck of a sheet tensile specimen while the load was simultaneously recorded on a recording oscillograph. This technique yielded two-dimensional strain data on one surface of the specimen and the total load as functions of time. This is admittedly not all the information desired on the plastic flow, but it does allow a partial correlation of strain rate with rate of loading, and a determination of the extent of elastic and plastic deformation on one surface of the specimen.