A thermodynamic approach is used to develop a framework for modeling uranium-niobium alloys under the conditions of high-strain rate. Using this framework, a three-dimensional phenomenological model, which includes nonlinear elasticity (equation of state), phase transformation, crystal reorientation, rate-dependent plasticity, and porosity growth, is presented. An implicit numerical technique is used to solve the evolution equations for the material state. Comparisons are made between the model and data for low-strain rate loading and unloading as well as heating and cooling experiments. Comparisons of the model and data also are made for low- and high-strain-rate uniaxial stress and uniaxial strain experiments. A uranium-6 wt niobium alloy is used in comparisons of the model and experiment. (C) 2003 American Institute of Physics. References: 53
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