Abstract
The effect of mechanical impedance of loading bars in the Split-Hopkinson pressure bar testing system is numerically clarified based on the one-dimensional elastic stress wave theory. Uniformity of the stress distribution in a specimen depends on difference of mechanical impedances between the loading bars and the specimen. From a practical point of view, almost uniform stress distribution in the specimen is obtained after several reverberations of stress waves even in the case of the high mechanical impedance loading bars. Applying ramp incident wave is a useful method to realize uniform stress distribution at relatively low stress level and consequently, it is available to high strain rate deformation. For soft materials with low mechanical impedance a flanged loading bar system is proposed to measure the flow stress accurately under a uniform stress distribution in the specimen. The effect of mechanical impedance of loading bar on the strain rate is also discussed.
