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An Application Of High Speed Photography To The Measurement Of Dynamic Material Properties

This paper describes a technique for measuring the compressive stress-strain relations of very strong materials at high rates of strain (up to 105 s-1, corresponding to test durations of a few microseconds). The specimen is a small, flat cylinder supported on an instrumented pressure bar and impacted directly by a projectile from a gas gun. High speed photography is employed to monitor specimen strain, and a simple optical component is describ-ed which greatly increases the accuracy of the records. This photographic technique also allows nonuniformities of deformation to be detected and eliminated. An accurate synchronisation technique is described, and examples of high speed sequences are included.