2017 Insensitive Munitions & Energetic Materials Technology Symposium
Double Tree by Hilton Portland, Portland, OR, USA, April 23-26, 2018
Filling the Gap between the Initiation Behavior
of Shaped Charge Jets and Fragments
Werner Arnold
1
, Thomas Hartmann
2
, Ernst Rottenkolber
2
1
MBDA-TDW Gesellschaft für verteidigungstechnische Wirksysteme mbH, Hagenauer
Forst, D-86529 Schrobenhausen, Germany,
2
NUMERICS GmbH, Mozartring 6, D-85238 Petershausen, Germany
Abstract
In the previous IMEMTS paper [10] the findings showed that for shaped charge jet (SCJ)
attacks the critical stimulus S = v²∙d (v = jet velocity; d = jet diameter) for the initiation of a
munition is no longer constant (S ≠ const.) an therefore a new initiation model is necessary.
In this work the initiation scope should be extended from SCJs to fragments represented by
STANAG projectiles. The original STANAG projectile with L/D = 1 and elongated ones with
L/D = 3 made out of steel and copper were shot with a EMI powder gun against the TDW
standard charge with the PBX KS32 (HMX/PB 85/15, = 1.64 g/cm³). The results were in
good agreement with those achieved during the SCJ trials. A new linear initiation model was
proposed: v = A - B∙d.
1 Introduction
During more than one decade of studying initiation phenomenology numerous papers at
previous IMEMTS and other symposia ([1] - [11]) were published. Most of them dealt with
the hypervelocity impact initiation of plastic bonded high explosive charges by shaped
charge jets (SCJ) and a few ones reported results in the ordnance velocity impact regime
with STANAG projectiles [9] and explosively formed projectiles (EFP) [2]. A recent finding of
our investigations of charge jet (SCJ) attacks suggests that the critical stimulus S = v²∙d (v =
SCJ / projectile velocity; d = SCJ / projectile diameter) for the initiation of a munition can no
longer be seen as a constant (S ≠ const.) Also, known equations, e.g. Jacobs-Roslund, are
not capable to describe low velocity and hypervelocity impacts with the same parameter set.
Consequently, a new initiation model is needed taking these findings into account. The pre-
sented study shall therefore continue the investigations already launched in [10] under the
title “Towards a Unified Initiation Model”. On the way to such a new unified model further
work has to be done trying to realize a “unifying link” between the initiation phenomenology
of shaped charge jet impacts (in the hypervelocity regime) and of projectile impacts (in the
lower velocity regime). The situation of today is that a larger number of experimental results
are available in the hypervelocity regime of the SCJs and only a few ones in the lower veloci-
ty regime of STANAG / EFP projectiles. Therefore, a series of trials were planned and con-
ducted to close the data gap in the low velocity regime.
2 From Shaped Charge to Fragments
For fragments the STANAG projectile is representative according to [12]. While making the
transition from SCJ towards STANAG projectile impacts several changes of initiation phe-
nomena are expected. This transition process starts from a continuous copper jet and ends
up with the standard steel STANAG projectile with L/D = 1. The individual steps include:
