Distribution A: Approved for public release
1
2018 Insensitive Munitions & Energetic Materials Technology Symposium
Portland, OR
Fragment Impact Standardization Historical Review
Kathryn E. Hunt
1
and Ernest L. Baker
2
1)
OUSD/AT&L, Land Warfare and Munitions, Pentagon, Washington DC, USA
2) Munitions Safety Information Analysis Center (NATO), Brussels, Belgium
This report describes the results of a review of the history and development of NATO
STANAG 4496 Fragment Impact Munitions Test Procedures related to the origin of the
threat fragment characteristics and requirements that were first cited in the initial edition
of STANAG 4496. The review was performed by completing a literature search of
historical papers and documents surrounding the original development for the STANAG.
The purpose of the fragment impact test is to assess the reaction, if any, of munitions and
weapon systems to impact by a high velocity fragment. The review discusses the
technical rationale behind the following aspects of the STANAG requirements: (1)
Fragment shape, both a discussion of the effect of yaw at impact as well as a discussion
of the merit of various designs and shape factors (2) Fragment size (3) Fragment velocity
and (4) Multiple fragments. This study was used to inform the NATO AC/326 SG/B
Fragment Impact Custodial Working Group (FI CWG).
INTRODUCTION
As part of the documentation for a revised edition of NATO STANAG 4496 Fragment Impact
Munitions Test Procedure, it is important to recognize the basis for previous decisions on
modifications of the standard. To that end, this paper covers some historical fragment impact (FI)
information as well as the origin of the threat fragment characteristics and requirements that were
first cited in the initial edition of STANAG 4496. Prior to the publication of the standard, a variety of
different test methodologies existed for evaluating fragment impact.
Number, size, shape, velocity, and the method for projecting the fragment(s) have long been the
dominate considerations when discussing fragment impact testing. The earliest fragment impact
safety requirement appeared in NAVSEA Instruction 8010.5 in 1985. Multiple half-inch square mild
steel cubes were required to be projected at the test item with 3-5 hits recorded and a striking
velocity of 8300 fps. This was intended to simulate general purpose bomb fragments [1]. The most
commonly used procedures in the 1980’s and 90’s relied on explosively projected the fragments.
A mat of preformed fragments were placed on the front face of the explosive charge which was
detonated. Neither number of fragment hits nor the fragment orientation were controlled, leading
to inconsistent test results. Starting in the mid-1990s the test methods were improved to use gas
guns to launch individual fragments to the target.
Table 1 gives an overview of various NATO nations FI test policy and procedure requirements that
were in place in 2001 [2]. This represented the Nations’ baseline for the evolution of STANAG
4496.
