Abstract
Explosively driven arrested beryllium experiments were performed with post mortem characterization to evaluate the failure behaviors. The test samples were encapsulated in an aluminum assembly that was large relative to the sample, and the assembly features both axial and radial momentum traps. The sample carrier was inserted from the explosively-loaded end and has features to lock the carrier to the surrounding cylinder using the induced plastic flow. Calculations with Lagrangian codes showed that the tensile stresses experienced by the Be sample were below the spall stress. Metallographic characterization of the arrested Be showed radial cracks present in the samples may have been caused by bending moments. Fractography showed the fractures propagated from the side of the sample closest to the explosives, the side with the highest tensile stress. There was evidence that the fractures may have propagated from the circumferential crack outward and downward radially.
Highlights
Beryllium has many unique properties, there is surprisingly little recent literature on its dynamic behavior [1,2,3,4,5]
This geometry can be used to study the strength, fracture behavior (in compression or tension), and Equation-of-State (EOS) [4, 5]. These experiments showed a brittle spall behavior with spall strengths in the range of 0.8-0.9 GPa. The results of these plate impact experiments were compared to simulations using both an Arbitrary Lagrangian Eulerian (ALE) and a Lagrangian analysis to interrogate the performance of the EOS and strength models
It appears that the spall strength of beryllium does not appear to be dependent on either strain rate or the shape of the incident wave implying that the kinetics of the failure mechanism is rapid
Summary
Beryllium has many unique properties, there is surprisingly little recent literature on its dynamic behavior [1,2,3,4,5]. This work addresses the shock peak stress for damage and spall to initiate, the shock strength of Be, and the ability for a damaged ensemble of fragments to support a shear stress when re-shocked [4,5,6]. These experiments show the behavior of Be under different loading conditions. The “arrested”, explosively driven shock experiment was first conceptually designed to provide insight into the ability of the equation of state (EOS), plasticity models, and damage models to capture the high-rate deformation characteristics of Be and to assess the probability of material failure under characteristic states of loading. Post test characterization of the Be samples in the “arrested” shock experiments was performed to evaluate the microstructure and failure behaviors seen in these experiments
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