Anelasticity and Phase Transition During Ramp-Release in Tin
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Anelasticity and Phase Transition During Ramp‑Release in Tin W. Schill1 · R. Austin1 · J. Brown2 · N. Barton1 Received: 17 July 2020 / Accepted: 9 October 2020 © Society for Experimental Mechanics, Inc 2020
Abstract This article examines the qualitative features of an anelasticity model associated with the bowing of dislocations in the presence of phase transition. A simple physically plausible mechanism is introduced to describe the interaction of anelasticity and the transformation. Varying the anelastic parameters results in strong differences in the deviatoric stress response. The model is applied to study the behavior of tin (Sn) and compared to data from ramp driven compression-release experiments. Tin exhibits a complex phase diagram within a relatively accessible range of temperature and pressures and the characterization of its phases is considered an open problem with significant scientific merit. The coupling between anelasticity, plasticity, and phase transformation contributes to release wave features traditionally associated with the phase transition effect alone suggesting the importance of accounting for the effects jointly. Posterior distributions of the plastic and anelastic parameters are computed using Bayesian-inference-based methods, further highlighting the importance of anelasticity in this regime.
Introduction Ramp-driven dynamic experiments probe material response under varied conditions including off-Hugoniot portions of the thermodynamic phase space and kinetic processes inaccessible via shock-driven loading. The idea is to utilize velocimetry [1, 2] to make inferences regarding aspects of a model for the material behavior such as equation of state (EOS) and flow strength properties of the material. In this article, we examine a ramp-release loading-unloading path where the pressure is driven to a maximum value without shocking the material and then smoothly decreased. We advance a forward model of the experimental configuration and draw conclusions based on direct comparison of simulated velocity profiles against experimental data. This * W. Schill [email protected] R. Austin [email protected] J. Brown [email protected] N. Barton [email protected] 1
Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550, USA
Sandia National Laboratory, 1611 Innovation Pkwy SE, Albuquerque, NM 87123, USA
2
enables a proper accounting of experimental uncertainties while incorporating material model form assumptions in a direct manner. In some materials, modeling of the release wave presents several additional potential complications beyond conventional notions of EOS and flow strength. First, it has been observed that many metals exhibit anelastic behavior [3, 4], with the anelasticity associated with dislocation motion occurring during loading transients such as those in ramp compression-release [5]. Thus, it can be important to explicitly include a deformation mechanism that arises from this kind of physics. Second, for a material undergoi
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