En este trabajo se compararon las sensibilidades al choque de muestras nuevas y envejecidas de una misma composición de propulsante doble base. Se determinó que la presión crítica era menor para propulsantes envejecidos, aunque no suficiente para cambiar la clasificación internacional de estas sustancias de deflagración masiva a detonación masiva. Estos resultados demuestran cómo es posible modelizar el comportamiento de cantidades grandes de propulsantes usando pequeñas muestras con las debidas consideraciones sobre choque, detonación y ciencia de los materiales.
Abstract
Shock sensitivity of a double-base propellant (nitroglycerin and nitrocellulose with smaller quantities of other ingredients) was compared for fresh and aged samples. Because the available amount of propellant was less than that needed for extrusion, most samples were pressed. The large-scale gap test (LSGT) was consistent for 240-g samples of fresh propellant whether extruded as one piece or ~6-mm pieces pressed together directly into the confinement tube. The latter had the same density but with microscopic gaps between pieces and nitrocellulose fibers randomly oriented instead of being aligned with the extrusion axis. In a further reduction of the amount of required propellant, 11-g samples pressed from ~3-mm pieces had the same critical shock pressure in the Insensitive High Explosive gap test (IHEGT), which has a LSGT donor and replicates its confinement. There was just enough propellant aged for ~13 and ~16 years to press several IHEGT samples each. The critical shock pressure was somewhat lower for aged propellant. These results demonstrate how smaller tests can mimic results in larger ones upon proper consideration of shock, detonation, and material science.
Fuente: http://aip.scitation.org
