DYNA-modelling of the high-velocity impact problems with a split-element algorithm

The present work addresses the implementation of a split-element algorithm for modelling fracture in terminal effects (TE) problems. The algorithm is incorporated within Vec-Dyna3D hydrocode (Technical report DSWA-TR-96-95. Alexandria (VA): Defense Special Weapons Agency, 1998), which is a prototype of LS-DYNA3D (Version 950. Livermore: Livermore Software Technology Corporation, May 1999). This algorithm has also been implemented in LS-DYNA2D (UCID-18756, Rev. 2. Livermore: Lawrence Livermore National Laboratory, 1984.) and it is verified numerically in the present paper. In doing so, tensile and shear modes of fracture due to high velocity impact are analysed in detail. Plate collision (the spallation problem) may be considered as a test problem for achieving the tensile mode of fracture. Encounter of a compact projectile with a plate (the plugging problem) plays similar role for the shear mode. Influence of choice of effective (equivalent) stress involved in a 3D-extension of a fracture criterion is analysed from two points of view: (i) the mesh effects, and (ii) a role of the complex stress state. The strain-rate sensitive Maxwell-type model (J. Appl. Mech. Tech. Phys. 13(6) (1972) 868.) is employed as a constitutive model. Workability of the algorithm in 3D case is illustrated with a numerical example for the plugging problem. The calculations being conducted show an appropriateness of the present approach for TE problems.

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