With-Fracture Gurney Model to Estimate both Fragment
and Blast Impulses

 

Michael D. HUTCHINSON
Hydrodynamics Department, AWE Aldermaston,
Reading RG7 4PR, UK

Abstract: Work to extend Gurney’s model for fragment velocity to predict blast
impulse is ongoing by means of analytical calculations, based on gas and casing
dynamics, with comparisons to available experimental data. The issue of early
case fracture, with release of explosive gases thus retaining a greater degree of
momentum, is also addressed. The method is based on that of G.I. Taylor and can
include both case material compressive fow stress and explosive properties such
as Chapman-Jouguet pressure. Comparisons between this new Taylor-based theory
and blast data from studies of cased charges are shown. The potential effects on blast
output of casing dynamic material properties appear considerable. Dynamic testing
of case metals is needed to confrm the yield stresses implied by the blast data. It
is expected that this method will be useful to the researcher in a number of roles.

Keywords:
Gurney, Taylor, casing, fracture, explosive