Energy Release and Fragmentation of Brittle Aluminum Reactive Material Cases

• Published in: Propellants, explosives, pyrotechnics Vol. 46; no. 8; pp. 1324 - 1333
• Main Authors: Kline, Jacob C., Mason, Brian P., Hooper, Joseph P.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.08.2021
• Subjects: Aluminum; Brittleness; Chambers; Combustion efficiency; Energetic Materials; Fragmentation; Fragments; Metal combustion; Nitromethane; Overpressure; Reactive Materials; Tensile strength
• ISSN: 0721-3115; 1521-4087
• DOI: 10.1002/prep.202100014

Cylindrical reactive material cases produced by the consolidation of an aluminum powder were tested via explosive launch in a closed chamber. One configuration measured the quasistatic overpressure generated by the case and explosive, and two further tests focused on soft‐catch of fragments before and after striking the chamber walls. On a volumetric basis, the reactive material cases produced two to three times the combustion energy of an aluminum 6061 alloy case or a bare nitromethane explosive that was tested as comparisons. The metal combustion primarily occurs after case fragments impact the walls. Increasing the reactive material case thickness produces a higher pressure but lower combustion efficiency per unit mass, despite producing comparable or slightly more fine fragments on a per gram basis. Though the brittle, pressed aluminum cases have low toughness and tensile strength, recovered fragment patterns show a range of fragment sizes up to 1 mm, with approximately one‐third of the mass below 100 μm.