Presented are several a!gorlth~s that allow a Lagrang!an hydrodynamic computer code to simulate hyperveloclty impact.
Such impacts typically involve very large material deformations and ordinarily can be handled only by Eulerlan codes, in which the materials flow through a stationary grid.
In Lagranglan codes, the mesh is attached to the material and deforms with it: in problems involving severe distortlons, the mesh can become tangled, resulting in loss of accuracy or even a breakdown of the computational scheme.
However, Lagranglan codes present several advantages in economy, ease of programming and use, and interpretation of results. This paper describes several modifications of the DEFEL code (Flls, Miller, and Clark, 1984).
This code, a descendant of EPIC-2 (Johnson, 1976), was originally developed to simulate low-to medlum-velocity impact and exploslve-metal interaction.
Modifications include automatic rezoning, a surface-eros!on model, and treatment of fracture (cracking) by automatic introduction of sliding lines between elements.
These features allow DEFEL to handle a variety of problems in the hyperveloclty regime.
Included are discussions of several example problems.