CAMCS
Materials Characterization at Ultra-High-Strain-Rates
Measuring the strength properties of materials under dynamic loading conditions is an important aspect of the Stockpile Stewardship Program. Traditional testing techniques such as the Split Hopkinson Pressure Bar (also known as the Kolsky Bar) can provide experimental data up to strain rates that are on the order of 10^4 s-1. Recently, laser strength experiments have been conducted at Lawrence Livermore National Laboratory (LLNL), which can probe the strength of materials deformed at strains rates on the order of 10^7-10^9 s-1. There is, therefore, a strain rate regime of 10^4-10^6 s-1 where the capabilities at LLNL to measure the strength properties are limited. The two primary techniques for attaining this strain rate range are the miniaturized Kolsky bar and high-strain-rate pressure-shear plate impact.
A second issue that is of great importance in the characterization of materials under dynamic loading conditions is an understanding of the separate and coupled effects of pressure and strain-rate. There are few experimental techniques that have independent control of these two variables. Therefore, a well-designed suite of experiments is needed to explore material behavior in this regime.
This thrust uses the techniques of miniaturized Kolsky bars, high-strain-rate pressure-shear plate impact and modifications of these two techniques to explore the properties of materials at very high strain-rates.
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