X-0557 MODIFIED STEVEN TESTS

摘要

Low-velocity mechanical impact leading to unintentional reaction is of concern in accident scenarios involving the handling, transport, and storage of high explosives (HE). Various experimental techniques, from small- to large-scale, have been used to investigate the potential conditions leading to a high explosive violent reaction (HEVR) for pristine as well as aged materials. PBX 9501, one of the Los Alamos National Laboratory (LANL) HE formulations, is routinely evaluated for potential aging mechanisms that may influence performance and or safety criteria. Ultimately, the data derived from the aging analyses will be used to further advance 3-D finite element analysis predictive capability with improved bulk constitutive HE models for the assessment of HE response to mechanical insult. The Modified Steven test geometry was used to investigate the mechanical loading behavior and response of baseline and virtually-aged PBX 9501 lots. The PBX 9501 binder system is composed of nitroplasticized Estane 5703,™ a polyester polyurethane copolymer. The nitroplasticizer (NP) can migrate out of the PBX 9501 as a function of time, resulting in increased brittle behavior and response. To mimic extreme NP depletion four lots of X-0557 were formulated with reduced NP concentrations for comparison to the baseline PBX 9501. Changes to the mechanical behavior response of the PBXs as a function of plasticizer loss may eventually affect the response of the HE to low amplitude impact. The threshold velocity to reaction, and energy release for the different lots are reported, compared and evaluated for trends as a function of NP weight percent.