Plane impact response of PBX 9501 and its components below 2 GPa

Dick, J. J.; Martinez, A. R.; Hixson, R. S.

doi:10.2172/663187

Cited by 21 publications

(12 citation statements)

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“…Figure 7 presents plots of the average resistance change for each gauge as a function of calculated impact stress for each shot. The impact stresses given in Table 1 and Figure 7 are calculated from the measured projectile velocity and the intersection of a Hugoniot with itself for symmetric impact where particle velocity is assumed to be ½ of the flyer velocity (PBX 9501: ρ = 1.83, c = 2.41, s = 2.39 35 ; PMMA: ρ = 1.186, c = 2.774, s = 2.182, q = -2.014 40 ). A time of impact can be calculated from the projectile velocity and the trigger standoff, and with this information and the initial response time of the gauges, an apparent shock velocity in PBX 9501 can be inferred.…”

Section: Resultsmentioning

confidence: 99%

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Stress Measurements in Shock-Loaded PBX 9501 with Embedded Longitudinal and Lateral Piezoresistive Ytterbium Gauges

Hooks¹

2004

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A series of light gas gun impact experiments were performed with piezoresistive ytterbium (Yb) gauges in longitudinal and lateral orientations embedded in the plastic bonded explosive PBX 9501. These experiments were performed to evaluate the feasibility of using this method to measure lateral stresses and shear strength dynamically in PBX 9501. Ytterbium was chosen as a gauge material based on its high piezoresistance changes at low stress levels. Experiments were performed at longitudinal impact stresses of approximately 0.6 GPa, which is above the yield point of Yb, near the dynamic yield point of PBX 9501, at a level that is comparable with other impact data, and relevant to several multidimensional safety tests. Results show that PBX 9501 does maintain strength throughout compression. Because of poor reproducibility observed in the experiments presented, it appears unlikely that stress extraction from these gauge results would yield an estimate of shear strength at this impact stress with acceptable error.

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Section: Resultsmentioning

confidence: 99%

“…The Hugoniot elastic limit of PBX 9501 is 0.14 GPa, as estimated from embedded electromagnetic gauge data for impact at 0.29 and 0.56 GPa. 35,36 Lagrangian analysis performed on this data to produce stress-strain information is available also. 37 Piezoresistance gauges are used under the assumption that gauge response is perfectly plastic.…”

Section: Introductionmentioning

confidence: 99%

Stress Measurements in Shock-Loaded PBX 9501 with Embedded Longitudinal and Lateral Piezoresistive Ytterbium Gauges

Hooks¹

2004

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“…Likewise, Dick et al 20 report the bulk wave speed for PBX 9501 as 2500 m/s. Accordingly, the excitation wavelength approaches the particle size of HMX for frequencies on the order of 10 MHz.…”

Section: B Thermal Responsementioning

confidence: 96%

Thermal and mechanical response of PBX 9501 under contact excitation

Mares

Miller

Sharp

et al. 2013

Journal of Applied Physics

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The thermal and mechanical responses of a cyclotetramethylene-tetranitramine-based explosive (PBX 9501) and two non-energetic mock materials (900-21 and PBS 9501) under high-frequency mechanical excitation are presented. Direct contact ultrasound transducers were used to excite samples through a frequency range of 50 kHz to 40 MHz. The mechanical response of each sample was approximated from a contact receiving transducer and trends were confirmed via laser Doppler vibrometry. The steady-state thermal response of the samples was measured at discrete excitation frequencies via infrared thermography. A maximum temperature rise of approximately 15 K was observed in PBX 9501, and the mock materials exhibited similar thermal characteristics. Temperature gradients were calculated to estimate the total heat generated within the samples due to the mechanical excitation. The active heating mechanisms were found to be highly dependent on the frequency of excitation. Possible mechanisms of heating at frequencies below 1 MHz are likely related to bulk motion. Above this frequency, the active heating mechanisms are likely related to particle-scale processes. The observed phenomena may prove useful in the aid of current trace vapor detection methods for explosives. V C 2013 American Institute of Physics.

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“…For a grain volume fraction of 0.95, such as that used in PBX9501, the average stress is predicted to be $457 MPa, which is within 3.3% of the value obtained from experiments. 47 FIG. 7.…”

Section: Large Samples Without Wave Reflectionsmentioning

confidence: 99%

Ignition criterion for heterogeneous energetic materials based on hotspot size-temperature threshold

Barua

Kim

Horie

et al. 2013

Journal of Applied Physics

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A criterion for the ignition of granular explosives (GXs) and polymer-bonded explosives (PBXs) under shock and non-shock loading is developed. The formulation is based on integration of a quantification of the distributions of the sizes and locations of hotspots in loading events using a cohesive finite element method (CFEM) developed recently and the characterization by Tarver et al. [C. M. Tarver et al., "Critical conditions for impact-and shock-induced hot spots in solid explosives," J. Phys. Chem. 100, 5794-5799 (1996)] of the critical size-temperature threshold of hotspots required for chemical ignition of solid explosives. The criterion, along with the CFEM capability to quantify the thermal-mechanical behavior of GXs and PBXs, allows the critical impact velocity for ignition, time to ignition, and critical input energy at ignition to be determined as functions of material composition, microstructure, and loading conditions. The applicability of the relation between the critical input energy (E) and impact velocity of James [H. R. James, "An extension to the critical energy criterion used to predict shock initiation thresholds," Propellants, Explos., Pyrotech. 21, 8-13 (1996)] for shock loading is examined, leading to a modified interpretation, which is sensitive to microstructure and loading condition. As an application, numerical studies are undertaken to evaluate the ignition threshold of granular high melting point eXplosive, octahydro-1,3,5,7-tetranitro-1,2,3,5-tetrazocine (HMX) and HMX/Estane PBX under loading with impact velocities up to 350 ms À1 and strain rates up to 10 5 s À1. Results show that, for the GX, the time to criticality (t c) is strongly influenced by initial porosity, but is insensitive to grain size. Analyses also lead to a quantification of the differences between the responses of the GXs and PBXs in terms of critical impact velocity for ignition, time to ignition, and critical input energy at ignition. Since the framework permits explicit tracking of the influences of microstructure, loading, and mechanical constraints, the calculations also show the effects of stress wave reflection and confinement condition on the ignition behaviors of GXs and PBXs.

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Plane impact response of PBX 9501 and its components below 2 GPa

Cited by 21 publications

References 1 publication

Stress Measurements in Shock-Loaded PBX 9501 with Embedded Longitudinal and Lateral Piezoresistive Ytterbium Gauges

Stress Measurements in Shock-Loaded PBX 9501 with Embedded Longitudinal and Lateral Piezoresistive Ytterbium Gauges

Thermal and mechanical response of PBX 9501 under contact excitation

Ignition criterion for heterogeneous energetic materials based on hotspot size-temperature threshold

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