Texture and textural evolution in explosively formed jets

Abstract

The potential effects of crystallographic texture (preferred grain orientation) on the behavior of metallic shaped-charge jets are examined. There is some experimental evidence that strong initial liner textures can be beneficial to overall performance; in this paper we investigate the mode of action of such textures. A crystallographic-texture code was used to calculate the changes in preferred orientation, and the corresponding changes in yield anisotropies, for deformation paths typical of early jet formation. Simulations were performed for two different initial textures, and for two different regions in a hemispherical titanium liner. It was found that the initial texture and its corresponding pattern of anisotropy do not persist beyond the earliest stages of liner collapse; the state of the material in a well-formed solid jet reflects the most recent deformation, not the initial texture. Any initial texture effect on subsequent jet behavior would be exerted indirectly, e.g., through changes in flow patterns induced during the first few microseconds of deformation. During this time, the evolution of texture and the corresponding anisotropies were found to be significantly different, not only for different initial textures, but also for different regions of the liner. This is due to the variation in deformation paths, and, in our model for titanium, to differences in the relative importance of slip and twinning.