Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session L01: Model Calibrations and MethodologiesFocus Recordings Available
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Chair: Robert Dorgan, Air Force Research Laboratory Room: Anaheim Marriott Platinum 5 |
Tuesday, July 12, 2022 2:00PM - 2:15PM |
L01.00001: Short Pulse Planar Impacts - Initiation Data, Extended Run Distances, and Pulse Attenuation Christopher Neel, David Lacina, Peter A Sable Thin impactor plates were utilized to produce short-duration planar impacts on a generic RDX-based explosive. In some cases, the explosive was a small solid pellet, resulting in go/no-no initiation data, and in other cases the explosive was a large disc containing embedded particle velocity tracking gauges to additionally determine shock-to-detonation run distance. The results show excellent agreement with complementary data on pellet initiation, and substantially extend the data to lower pressures and longer pulse durations. With the embedded gauges, extended run distances were observed as the ignition threshold was approached. Based on these experiments, a simple linkage between the pop-plot and the initiation curve is proposed. The linkage, based on a simple approximation of input pulse attenuation, provides an explanation for previous time-scaling observations between the pop-plot and the initiation curve and provides an estimation of the critical input pulse duration in the absence of initiation data. This critical pulse duration serves as a scaling factor to allow a dimensionless relationship between input pulse duration and extended run distance. |
Tuesday, July 12, 2022 2:15PM - 2:30PM |
L01.00002: Davis EOS and AWSD rate-law calibration for PBX 9012 Jeffery A Leiding, Tariq D Aslam, Stephen A Andrews, Christopher C Ticknor We will present a full model calibration of the AWSD (Arrhenius Wescott-Stewart-Davis) rate law, and associated Davis reactants and products equations of state for the high explosive, PBX 9012. The reactants and products EOS were calibrated using a combination of experiment, theoretical (density functional theory), and thermochemical data (as calculated with Magpie, LANL’s thermochemical code). The AWSD rate law was calibrated to shock-to-detonation transition embedded-gauge experiments, as well as diameter-effect and front-curvature data. Optimal results will be compared to experimental and theoretical data, and the optimization framework will be briefly discussed. |
Tuesday, July 12, 2022 2:30PM - 2:45PM |
L01.00003: A CREST reactive burn model for LX-14 Caroline Handley, Nicholas J Whitworth CREST is an entropy-dependent reactive burn model that has had considerable success in modeling a wide range of shock initiation and detonation behavior in explosives [1]. This paper will describe the development and initial testing of a CREST model for the HMX-based explosive LX-14, for which a suite of gas-gun data have become available in recent years [2,3]. The new model has been calibrated to a sub-set of the available data using a semi-automatic method consistent with other recent CREST models, and the fit to the calibration data for LX-14 is universally good. It will be shown that CREST accurately predicts the behavior of nominal-density LX-14 in experiments [3,4] but, consistent with other reactive burn models, it fails to match the low-density gas gun data. Possible ways to improve the reaction rate in future will be discussed. |
Tuesday, July 12, 2022 2:45PM - 3:00PM |
L01.00004: Full Calibration of an Equation of State for Composition B Ryan B Jadrich, Dana M Dattelbaum, Lee L Gibson, Tariq D Aslam, Jeffery A Leiding Hydrodynamic simulations involving high explosives require an equation of state (EOS) for the unreacted material, the products of the explosion, and a burn model that governs the transition from the reactant to product state. While the functional forms of the EOS models are informed by physics, the parameters of the EOS models must be calibrated to experimental data. In this talk, we present a new calibration for Composition B (Comp B), using the Davis model for the reactants and products and the AWSD model for the burn. New shock to detonation experimental data is leveraged to tune the AWSD model. The wide use of Comp B necessitates accurate modeling of the behavior in hydrodynamic simulations to address issues regarding the safety and performance for use in energetic devices. |
Tuesday, July 12, 2022 3:00PM - 3:30PM |
L01.00005: The calibration of the products equation of state for high explosives Invited Speaker: Carlos Chiquete The most accurate determination of a detonating high explosive’s (HE) products equation of state (EOS) requires calibration to experiment, usually via simulations of cylinder expansion tests where isentropic expansion of the products drives the motion of metal confiners. Typically, simplified representations of the detonation structure are used to refine the relevant EOS parameters. These programmed burn (PB) calculations typically assume an instantaneous reaction which results in a computationally efficient limit where solid reactant material is immediately converted to product gas, a uniform end state of the reaction across the front and a constant normal detonation speed. Recently, we have made a series of calculational improvements via introduction of finite reaction zone effects on both energy delivery and propagation, while maintaining instantaneous reaction. For energy release, we have used a velocity-adjusted method which modifies the post-wave arrival end states at each HE cell, sensitizing the flow to the reduced shock strength due to wave curvature. However, we also have relaxed the basic assumption of instantaneous reaction in favor of the more realistic Pseudo-Reaction Zone (PRZ) energy release PB model. The latter approach features a finite reaction rate and importantly, a finite reaction zone length scale. This advanced PB methodology can then be applied to the calibration of any products EOS form and is independent of any base parameter adjustment strategy as in the velocity adjusted methodologies. This then supports the generation of paired PB and reactive burn models possessing equivalent energy release properties but very distinct wave propagation characteristics. In this study, we discuss the relative merits of each calibration methodology to determine the importance of the reaction zone in the EOS parameterization process and also present selected applications of the resulting detonation performance models. |
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