![]() 26,27 These initiation experiments 11 were generally carried out well below the Chapman–Jouguet (CJ) pressure ( ≈ 28.5 GPa). For subsequent modeling efforts, this provided some justification to generate a single model calibration rather than lot-specific variants in the shock initiation regime. 11,17 found little lot-to-lot variability on the initiation characteristics (at least to the level of accuracy of the experiments). The latter, mixed composition of the recycled lots tends to include many more fine particles, which are generally expected to promote or enhance reaction. The diagnosis of the lot effect was achieved via comparison of virgin material results vs recycled (which includes a mixture of virgin prills and reprocessed scrap material from previous machining). This work provided a wealth of data contributing to the equation of state (EOS) and reactive flow model development in this regime. In this scenario, the impact of high-speed projectiles initiates the decomposition of reactant material in the HE and, if of sufficient strength, generates an acceleration of the resulting shock into a detonation wave. 11 on the plate impact shock initiation of PBX 9502, with an emphasis on the effects of differing material lots. Here, we are focused on the shock initiation of PBX 9502 and extend a number of previous characterization studies for this material for example, an extensive body of work was carried out by Gustavsen et al. 18–20 Related TATB-based explosives have also been studied by other laboratories and institutions. In addition, the Lawrence Livermore National Laboratory (LLNL) analog explosive LX-17 has also been subject to in-depth experimental and modeling studies. To generate needed information for explosive modeling in relevant engineering geometries, the detonation performance 2–9 and shock-to-detonation transition or shock sensitivity characteristics 10–17 of the explosive have been experimentally studied across different initial temperatures, initial pressing densities, and source material lots (which introduces a degree of microstructural variation). Like other polymer-bonded explosives (PBXs) used in HE engineering, PBX 9502 is composed of discrete explosive crystals, heterogeneously and bi-modally distributed across a spectrum in size 1 (with maxima at ≈ 5 μm and 50 μm in particle diameter). PBX 9502 is an insensitive high explosive (HE) consisting of 95% dry-aminated triaminotrinitrobenzene (TATB) explosive crystals and 5% Kel-F 800 polymeric binder by weight. This new experimental information will provide a platform for both improved physics and model parameterizations for this well-studied explosive. ![]() As a result, the present experiments provide a novel platform to evaluate the quantitative and qualitative consequences stemming from these modeling choices in a challenging initiation scenario, largely beyond the chosen calibration range of either model. The employed model variants crucially differ in their definition of each model’s empirical reaction rate functional form, utilization of shock state quantities, and local flow variable dependencies. Finally, a pair of previously established continuum-level detonation performance modeling approaches for PBX 9502 were used to analyze the experiments. ![]() To address this, the thin samples are also characterized via x-ray micro-computed tomography. Samples at these thicknesses also provide an opportunity for evaluation of potential micro-structure effects on the resulting shock-to-detonation-transition measurements. These observations necessitate extremely thin explosive samples, and the high rates of reaction provide a considerable challenge to optical diagnostics. Our experiments capture the transient buildup of a shock-induced reaction via measurement of HE and polymethyl methacrylate window interface particle velocity profiles for a variety of sample thicknesses for this insensitive HE. These include both slightly sub-Chapman–Jouguet and overdriven input pressure conditions, namely, ∼ 25 and ∼ 31 GPa, respectively. The shock-to-detonation transition properties of the triaminotrinitrobenzene based PBX 9502 high explosive (HE) are experimentally and computationally explored in extremely high input pressure conditions.
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