Bertram Hopkinson was prescient in writing of the importance of better measuring, albeit better understanding, the nature of high rate deformation of materials in general and, in particular, of the importance of heat in initiating detonation of explosives. This report deals with these subjects in terms of post-Hopkinson crystal dislocation mechanics applied to high rate deformations, including ...

expansion equal channel angular extrusion (exp-ecae) is a severe plastic deformation (spd) operation for processing bulk materials. in the current study, aa7075 al was spd-processed by expansion equal channel angular extrusion (ex-ecae) at various temperatures and ram velocities. then, using split hopkinson pressure bar (shpb), the severely deformed products were compressed at room temperature ...

Direct impact Hopkinson pressure bar systems offer many potential advantages over split Hopkinson pressure bars, including access to higher strain rates, higher strains for equivalent striker velocity and system length, lower dispersion, and faster achievement of force equilibrium. Currently, these advantages are gained at the expense of all information about the striker impacted specimen face,...

The compressive split Hopkinson pressure bar (SHPB) technique allows the stresses on each end of the specimen to be measured individually. Results are presented showing a large difference between these end pressures, depending on specimen length and loading rate. The mechanisms responsible are shown to be a combination of inertial forces and non-uniform deformation due to wave propagation. Impl...

All materials have been historically tested at static loading conditions. With the advent of technology, the study of behaviour of materials at high strain rate was done using various methods. The principle of split Hopkinson bar was used to study high strain rate of material in the range of 102s-1 to 103s-1. Split Hopkinson bars were designed for all three modes of deformation and extensively ...

Elastic theory shows that wide spectrum signals in the Hopkinson pressure bar suffer two forms of distortion as they propagate from the loaded bar face. These must be accounted for if accurate determination of the impact load is to be possible. The first form of distortion is the well-known phase velocity dispersion effect. The second form, which can be equally deleterious, is the prediction th...