New Trends in Research of Energetic Materials, Czech Republic, 2016 Posters 947 Thermobaric effect comparison of cast thermobaric PBX and TNT in enclosure test Danica Simić*, Radoslav Sirovatka*, Uroš Andjelić*, Jovica Bogdanov** and Slavica Terzić* * Military Technical Institute, Belgrade, Serbia ** University of Defence, Military Academy, Belgrade, Serbia simic_danica@yahoo.com Abstract: This paper reports on the examination of the thermobaric effect of explosives by measuring the shockwave parameters at different distances in a reinforced enclosure. Shockwave overpressure, minimum underpressure, positive phase duration and pressure impulse are measured and compared for the cast TNT and cast cured thermobaric PBX explosives. Thermobaric explosives containing HMX, ammonium perchlorate, aluminium, magnesium and HTPB binder are prepared using casting technology. Experiments were done with 400g , 50 mm in diameter samples without casing. Density and detonation velocity for the examined cast explosives are determined. Pressure-time profiles were measured using pie- zoelectric probes placed at the same height as the explosive samples. Keywords: thermobaric explosive; PBX; TNT; enclosure test; shockwave overpressure 1 Introduction Thermobaric explosives (TBE) combine thermal and pressure effects (Greek: thermo – θερµός, baric – βάρος), and give improved incendiary and blast effects, compared to conventional high explosives. They belong to a group of volumetric weapons [1-3]. TBE produce additional heat and sustained blast overpressure due to combustion of metallic fuels and gaseous detonation products with oxygen in the air. They can, thus, be optimized for high heat output, high blast output or both [4, 5]. In confinement, thermobaric detonations cause a series of reflected shock waves (Fig.1), which maintain the fireball and can extend its duration to between 10 and 50 ms, as exothermic reactions occur. Further damage can occur as the gas- es cool and the pressure drops sharply, causing additional physical damage to people and struc- tures. They are highly effective against soft targets in tunnels, bunkers, underground structures, buildings, field fortifications, etc [1-3, 5, 6]. The most prominent type of TBE is the solid composite type, which consists of polymer based binder, explosive, metallic powder and oxidizer. They belong to the group of PBX explosives (Plastic Bonded eXplosives). These compositions are produced either by casting or extrusion technologies. Thermobaric explosion can be divided in stages: first, a cloud of flammable vapour or flammable metal is released (such as a mixture of finely powdered aluminium and ammonium perchlorate), then that cloud is ignited. The resulting explosion has fragmentation, concussion, and incendiary effects. Detonation of thermobaric explosives can be partially described by ZND (Zeldovich-von Neumman-Döring) model of non-ideal explosives detonation [3, 4].