The design, construction and experimental verification of a split hopkinson bar

This thesis presents the design considerations for a dynamic loading device utilizing a projectile fired from a tube. Also included is a preliminary investigation of the stress-strain relation, under dynamic loading with the device, for a plaster known as Hydrostone. Design of the unit is based on the split Hopkinson pressure bar originally developed by Kolsky and on a similar unit in use at the Lawrence Radiation Laboratory, Livermore, California. The strain pulses along the pressure bars are sensed by resistance wire strain gages and displayed on an oscilloscope. The oscilloscope traces are photographed and manually digitized for insertion into a computer program which gives results in terms of specimen stress, strain and strain rate. The recorded information applied for times of the order of 100 microseconds. All equations in this thesis are based on the one-dimensional theory of stress wave propagation. Further, the material tested is shown to be reasonably isotropic and homogeneous. The design of the loading device and attendant instrumentation has proven to be successful. Experiments were conducted on 1100-0 aluminum samples and Hydrostone plaster. Curves of results are included in the work --Abstract, page ii