Kenneth C. Walls

Validation of the Kerley Soil Model in CTH

Recently Kerley has developed a soil model suitable for implementation in Eulerian hydrocodes. The model has been installed into CTH [1]. While basic features of the model suggest it may be suitable for modeling ground shock and cratering problems, it has not been extensively validated. As such, in order to provide more confidence in the use the model, a series of calculations was conducted to compare Kerley’s model to the Hybrid Elastic-Plastic (HEP) model.Copyright

On Determining Conditions for Optimal Performance of Cased Munitions

In order to make the process of fragmentation of warhead cases more systematic, we have developed a procedure that makes use of nonlinear optimization to derive optimal values for case design parameters subject to various design constraints. A framework has been developed that makes use of the optimization software package LS-OPT driving the hydrocode CTH (CTH is developed and maintained at Sandia National Laboratories, LS-OPT is commercially available from Livermore Software Technology Corp.). CTH was used to model the explosive detonation and determine the resultant kinetic energy delivered to the case by the energetic material. In this follow-on effort to a previous study [1], the range of constraints and free parameters used in the optimization study was expanded.Copyright

Coupling EPIC to LS-DYNA for Simulation of Blast-Structure-Fragmentation Interaction

In this work we have coupled the EPIC code to the LS-DYNA code to provide a high-fidelity simulation framework for simulation of blast-structure-fragmentation interaction. The coupled code exploits the strengths of the two original codes: EPIC, which has special algorithms and models for weapons effects analysis, and LS-DYNA, which is a general purpose finite element code for modeling large-scale structural deformation. Example problems are shown which illustrate the advantages of this approach.Copyright

Maximizing the Performance of Cased Munitions Under Realistic Constraints

In order to make the process of fragmentation of warhead cases more systematic, we have developed a procedure that makes use of nonlinear optimization to derive optimal values for case design parameters subject to various design constraints. A framework has been developed that makes use of the optimization software package LS-OPT driving the hydrocode CTH (CTH is developed and maintained at Sandia National Laboratories, LS-OPT is commercially available from Livermore Software Technology Corp.). CTH was used to model the explosive detonation and determine the resultant kinetic energy delivered to the case by the energetic material. As an example of application of the framework, a test problem was run using a case configuration consisting alternating titanium alloy and polymer layers.Copyright

Development of Reactive Flow Models for Energetic Materials

In order to make the process of material model development more systematic for energetic materials, we have developed a procedure that makes use of nonlinear optimization to derive optimal values of parameters in the material models. A framework has been developed that makes use of the optimization software package DAKOTA driving the hydrocode CTH (both CTH and DAKOTA are developed and maintained at Sandia National Laboratories). CTH was used to model a set of characterization experiments that were used as the basis for the calibration of a particular model; for example, the cylinder test was used to calibrate the JWL equation of state, and the wedge test for the HVRB reactive burn model. As a verification test of the framework, we have determined material model constants for TNT and compared them to values published in the literature.Copyright