Spall and Damage Behavior of S200f Beryllium

Abstract

We have perfonned a eries of plate impact experiments to study the strength and spall damage behavior of S200F Be. Peak stresses achieved were in th e range from 5.6-19.2 GPa VISAR data show long rise times in the approach to the shocked state believed to be the result of twinning occurring alongside. or in defference to slip, in this hcp material, wi th its free surface never achieving a steady velocity. This data indicate brittle spall behavior with spall strengths in the range of 0.8-0.9 GPa. In experiments where target thicknes. is varied, we see evidence of precursor decay and present calculations of the Hugoniot Elastic Limit (HEL).

Spall fracture of beryllium under shockwave loading

“…The value of the Hugoniot dynamic yield strength of the investigated Be is significantly higher than Be of the type S200F [6], namely more than 2 times higher. As it is possible to see from the data of Table 3, thicknesses of spalls, which are measured by three techniques, coincide within the experimental error, and they are equal to ~1 mm in each performed test.…”

“…with the value of σ p for Be of the type S200F (0.8-0.9 GPa), which was obtained in [6] under loading by impactor in the conditions of, probably, higher values of ε , but it is much lower than the value of σ p for Be of the same type, loaded by detonation wave [1]. The value of the Hugoniot dynamic yield strength of the investigated Be is significantly higher than Be of the type S200F [6], namely more than 2 times higher.…”

“…Strain rate dependence of Be spall strength within the release wave: 1 -Be of type S200F, loading by detonation wave, L. M. Hull [1]; 2 -Russian Be, this work; 3 -polycrystalline Be, loading by impactor, Yu. I. Meshcheryakov [7]; 4 -Be of type S200F, loading by impactor, George T. Gray III [6]; 5 -interpolation curve σ p ( ε ) for Be S200F, L. M. Hull [1]; 6 -interpolation curve σ p ( ε ) for Russian Be, this work.…”

Beryllium strain under dynamic loading

“…[4][5][6]. For today the model description of this complex metal behavior does not have a reasonable agreement with the experimental data [4], [6], thus a wider spectrum of experimental data is required.…”

“…A number of data on deformation curves for different types of beryllium, in particular S200F (USA) at strain rateś ε = 1500 − 8000 s −1 are given in [3,4]. For the same type of beryllium, mechanical characteristics at higher strain ratesέ = 10 4 − 10 5 s −1 (spall strength) [4,5] as well as fracture and structure responses of shock loaded beryllium [6] are known. In [7][8][9] the data are given on investigation of spall and shear strength of Russian beryllium at strain ratesέ· ∼ 10 4 − 10 5 s −1 using various methods.…”