Young's Modulus Calculus Using Split Hopkinson Bar Tests on Long and Thin Material Samples

Young's modulus is a key parameter of materials. The method of its calculation in the current paper is concerned with the mismatch of the mechanical impedance at the bar/specimen interface for a compression SHPB (split Hopkinson pressure bar) test. By using long and thin specimens, the signal recorded in the transmission bar presents itself as a multistep signal. The ratio between the heights of two successive steps represents the experimental data that are considered in the formula of the elastic modulus this article is devoted to. The oscillatory nature of the real signals on the horizontal or quasi-horizontal segments prevents a precise determination of the two successive step heights ratio. A fine tuning of this value is made based on the characteristic time necessary for the signal to rise from one level to the next one. The FEM (Finite Element Method) simulations are also used in calculation of the Poisson coefficient of the tested complex concentrated alloy.

Automated summary

This paper investigates the effect of mechanical impedance mismatch at the bar/specimen interface on the calculation of Young's modulus in compression SHPB tests. By using long and thin specimens and recording multistep signals, the elastic modulus is calculated based on the ratio between the heights of two successive steps, with fine tuning based on the characteristic time. Finite Element Method simulations are also employed to calculate the Poisson coefficient of the tested complex concentrated alloy.