Abstract
In this paper, we demonstrate by a Bayesian approach the incapacity of the Preston-Tonks-Wallace (PTW) strength model to represent, with the same set of parameters, the flow stress of beryllium in both moder-ate and highly dynamic experiments, and suggest hypotheses explaining that limitation. Usual plasticity models such as Johnson-Cook (JC) and PTW are mostly adjusted onto quasi-static and dynamic uni-axial compression data acquired thanks to compression machines and split Hopkinson pressure bars. Nonetheless, they may be used beyond the range of mechanical loading in which they have been fitted. This is the case of the simulations of solid Rayleigh-Taylor instabilities (RTI) driven by high explosives. A recent work of Henry de Frahan et al. noticed the inability of various plasticity models to stand for the growth of beryllium RTI. Amongst them, the PTW model has been particularly examined through four different sets of parameters, each of them largely un-derestimates the growth of the experimental instability. Thus, this work is an attempt, regarding the plastic flow modeling of beryllium, to conciliate uni-axial compression tests (CT) and RTI by means of a crossed Bayesian analysis.
Highlights
In 1974, Barnes et al [1] demonstrated the relevance of Rayleigh-Taylor instabilities (RTI) driven by high explosive (HE) to examine the dynamic plastic behavior of metals
It consisted in using the detonation products of high explosives to accelerate without shock metallic plates with sinusoidal perturbations machined on the surface facing the HE
The plasma generated by the interaction of a CH reservoir and the laser beam acted as the light medium accelerating the heavy one
Summary
In 1974, Barnes et al [1] demonstrated the relevance of Rayleigh-Taylor instabilities (RTI) driven by high explosive (HE) to examine the dynamic plastic behavior of metals (aluminum or steel) It consisted in using the detonation products of high explosives (the light medium) to accelerate without shock metallic plates (the heavy medium) with sinusoidal perturbations machined on the surface facing the HE. PTW takes into account the effects of strain hardening, strain rate and temperature and possible athermal plateau, thermally activated phenomena and phonon drag regime It is well suited for BCC materials such as iron (or steel), tantalum and molybdenum but can be used for FCC materials such as aluminum and copper.
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