An interactive Lagrangian approach to two dimensional penetration analysis

Results from a numerical calculation of a low velocity missile impacting a thin target were presented at the 8th SMiRT Conference (Itoh and Obata 1985). Mesh distortions of the Lagrangian grid used in this calculation were moderate and penetration of the target plate did not occur. At higher velocities large localized shear flows can be expected in the impact region, possibly resulting in target penetration. The severe material distortion and fragmentation that occurs in these situations has historically been very difficult to compute using a Lagrangian frame of reference. Usually investigators opt for an Eulerian approach with either finer zoning or a higher order solution compensating for the increased diffusion inherent in such formulations. This paper describes a technique for performing high velocity impact and penetration analyses using an interactive Lagrangian method. The method has been implemented in AUTODYN, an interactive computer program which uses a predominantly finite difference approach to solve problems in non-linear continuum mechanics. (orig./GL)