Recent progress in ALEGRA development and application to ballistic impacts

Abstract

, Summary-ALEGRA is a multi-material, arbitrary-Lagrangian-Eulerian (ALE) code for solid dynamics being developed by the Computational Physics Research and Development Department at Sandia +tionat Laboratories. It combines the features of modem Eulerian shock codes, such as CTH, with modem Lagrangian structural analysis codes. With the ALE algorithm, the mesh can be stationary (Eulerian) with the material flowing through the mesh, the mesh can move with the material (Lagrangian) so there is no flow between elements, or the mesh motion can be entirely independent of the material motion (Arbitrary). All three mesh types can coexist in the same problem, and any mesh may change its type during the calculation. In this paper we summarize several key capabilities that have recently been added to the code or are currently being implemented. As a demonstration of the capabilities of ALEGRA, we have applied it to the experimental data taken by Silsby.

ALEGRA : version 4.6.

“…For parallel simulations a single block per processor will also limit communications overhead, however more blocks per processor will allow flexibility for upcoming dynamics load balancing capabilities. [8,37] is an ALE (Arbitrary Lagrangian-Eulerian) multi-material finite element code that emphasizes large deformations and strong shock physics. As an effort to combine the modeling features of modern Eulerian shock codes with the improved numerical accuracy of modern Lagrangian finite element codes, alegra is a descendant of the pronto transient dynamics code [38,39] and contains elements of the cth family of shock wave codes [25,7].…”

Megaamps, megagauss, and megabars: Using the Sandia Z Machine to perform extreme material dynamics experiments

“…Both one-and twodimensional Eulerian simulation platforms have been developed using the finite element, arbitrary Lagrangian-Eulerian, MHD code ALEGRA [5] to solve the MHD equations for a compressible material with material strength. In these simulations, a complete equation of state valid for a wide range of pressures, densities, and temperatures is used for the conductor materials, in addition to physical models for thermal and electrical conductivities.…”

ALEGRA Validation Studies for Regular, Mach, and Double Mach Shock Reflection in Gas Dynamics

“…ALEGRA (Summers, et al, 1997) is a multi-material, multi-physics Arbitrary Lagrange Eulerian (Peery and Carroll, 2000) shock wave physics code. This computer code uses a finite element grid for spatial discretization and a matched time-stepping method for performing shock wave physics calculations (Hughes, 1987).…”

“…A validation assessment activity that is important for applications of the ALEGRA shock wave physics code (Summers, et al, 1997) to High Energy Density Physics (HEDP) is to assess validation of the code for strong shock wave applications. While such an assessment contributes to overall validation of application of ALEGRA in a variety of shock hydrodynamics applications, success in this endeavor is far from sufficient for achieving appropriate confidence in compressible multi-material shock wave simulations for complex HEDP applications.…”