A Desktop Tensile Kolsky Bar for the Dynamic Testing of Metallic Foils

Abstract

A miniature tension Kolsky (split-Hopkinson) bar has been developed to facilitate measurement of the uniaxial stress–strain constitutive response of metallic foils at strain rates on the order of 104 s−1. The system utilizes a cylindrical launch tube with an internal striker to generate the loading pulse. This launch tube set-up allows for the use of traditional disk shaped pulse shapers which may be required to ensure that the specimen in deformed under force equilibrium and at a nearly constant strain rate. Unlike most traditional Kolsky bar systems, incident and transmitted bars with rectangular cross-section are used to facilitate specimen and strain gage mounting. The rectangular bar cross-section also provides a reduced cross sectional bar area when compared to an equivalent diameter circular section which increases the system sensitivity. The system was used to perform dynamic tests on 99.9 % magnesium specimens, illustrating the ability to measure the high-rate response of ductile metals under equilibrium and constant strain rate conditions.