The Detonation Properties of Combined Effects Explosives

  • PDF / 524,504 Bytes
  • 6 Pages / 612 x 792 pts (letter) Page_size
  • 5 Downloads / 184 Views

DOWNLOAD

REPORT


The Detonation Properties of Combined Effects Explosives Paul Anderson,1 Paula Cook,1 and Wendy Balas-Hummers,1 Andy Davis,2 and Kyle Mychajlonka2 1 Explosives Research and Development Branch, US Army ARDEC, Picatinny Arsenal, NJ 07806 USA 2 Nammo Talley, Research and Development, Mesa, AZ, 85277 USA ABSTRACT In development of new explosives, it is often necessary to balance a number of attributes in performance while certain formulation constraints exist. Statistical design of experiments (DOE) is a valuable tool for rapid formulation optimization and minimization of costly and hazardous testing. During the development of metal-loaded explosives designed for enhanced blast, it was discovered that upon proper formulation, aluminum additives obtained full reaction by 7 volume expansions, which resulted in extremely high Gurney energies equivalent to LX-14 and PBXN-5 but with lower loading of nitramines. The early aluminum oxidation can be described by Eigenvalue type detonations, where the fully reacted Hugoniot of the condensed phase aluminum oxide and explosive products lies below the unreacted aluminum Hugoniot. Such an analysis describes fully the agreement of aluminum consumption by 7 volume expansions from 1-inch copper cylinder expansion tests and an analytic cylinder model, as well as detonation calorimetry. With the early reaction of aluminum also comes a shift in the gaseous reaction products to higher enthalpy species such as CO and H2, leading to further augmentation of blast. Thus, both the mechanical energy (for fragmentation or “metal pushing”) and blast (for structural targets) are available in a single explosive fill. This provides capability for combined metal pushing and blast in a single explosive that was not previously possible. Development of such explosives and the importance of modern statistical design of experiments will be shared. INTRODUCTION Enhanced blast explosives have generated much interest in recent years due to their effectiveness in buildings, bunkers, caves and other enclosed structures. However, with enhanced blast often comes a decrease in the ability of the explosive to push metal, i.e. a decreased Gurney constant. This is due to the delayed oxidation of aluminum until later in the fireball expansion, generally well above 10-50 volume expansions. Recently, Picatinny Arsenal developed a new generation of explosives deemed “combined effects”, which utilize an energetic binder system and small aluminum particles [1]. The term “combined effects” is used because the formulations show both enhanced blast and impressive Gurney constants at volume expansions V/Vo < 10. While the systems were optimized for metal pushing according to particle size, binder content, and other parameters, the exact mechanism of how aluminum reacts early in the detonation event is still under scrutiny. Previous investigators hypothesized that higher oxygen balance materials led to early aluminum reaction as well as proper choice of aluminum particle size [2]. While oxygen balance may be a contributing fact