CTH is a family of codes developed at Sandia N_onal Laboratories for modelling complex " multi-dimensional, multi-material problems that are characterized by large de/Ormationsand/or strong shocks. A two-s_p, second-order accurateEulerian solution algorithm is used to solve themass, momen-_...._'_ C_[ mm, and energy conservation equations. CTH includes models for material strength, fracture, porous t_ "-_ materials, and high explosive detonation and initiation. [/ft.,' !.,., or rate-dependent models of material strength have been added recently. The formulations _U0 of Johno_3n-Cook,Vise°pla_c Zerilli-Annstrong, and Steinberg-Guina_|-Lundare standard options within CTI-LThese _ _ models rely on the use of an internal state variable (typically the equivalent plastic strain) to account for the histoq dependence of material response. The implementation of internal state variable models will be O _ T [ discussed and several sample calculations will be presented. Comparison with experimental data will be made among the various material strength models. The advancements made in modelling material response have signiticanfly improved the ability of CrH to model complex large-deformation, plasticflow dominated phenomena. The detonation of energetic material under shock loading conditions has been an area of great interest. A recently developed model of reactive burn for high explosives 0-lE) has been added to CTH. This model along with newly developed tabular equations-of-state for the HE reaction by-products has been compared to one-and two-dimensional explosive detonation experiments. These comparisons indicate excellent agreement of CTH predictions with experimental results. The new reactive bum model coupled _cg ___ g _ _ _ _ with the adw,pces in equation-of-state modeling make it possible to predict multi-dimensional bum phe-_. _-_ _ _ 8 _: _ _, _" nomena without modifying the model parameters for different dimensionality. Most current bum models 2. _o _, _ _ _ _., ,, = ct __g"g'_ _ o _ 8 _.__ do not accurately predict both one-dimensional plate acceleration experiments and two-dimensional cylin-_-_"._ _ _. _ _. :" b_" = der expansion experiments simultaneously. Our implementation is significant because it represents the _ _ o _ _ _ _ _ "first time a multi-dimensional model has been used to successfully predict multi-dimensional detonation _ o .., o ,_ _ _ _ z effects without requiringa modification of the model parameters.

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The PANDA code is used to build a tabular equation of state (EOS) table for carbon. The model includes three solid phases (graphite, diamond, and metallic) and a fluid phase mixture containing three molecular components (C 1 , C 2 , and C 3). Separate EOS tables were first constructed for each solid phase and for each molecular species in the fluid phase. Next, a mixture/chemical equilibrium model was used to construct a single multicomponent EOS table for the fluid phase from those for the individual chemical species. Finally, the phase diagram and multiphase EOS were determined from the Helmholtz free energies. The model gives good agreement with experimental thermophysical data, static compression data, known phase boundaries, and shock-wave measurements. This EOS covers a wide range of densities (0-100 g/cm 3) and temperatures (0-1.0×10 8 K). The new EOS table can be accessed through the SNL-SESAME library as material number 7830.

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