Obtain Hugoniot Data Research Articles

Shock Response of Lightweight Adobe Masonry

The behavior of a low density and low-strength building material under shock loading is investigated. The considered material is lightweight adobe masonry characterized by a density of 1.2 g/cm3 and a quasi-static uniaxial compressive strength of 2.8 MPa. Planar-plate-impact (PPI) tests with velocities in between 295 and 950 m/s are performed in order to obtain Hugoniot data and to derive parameters for an equation of state (EOS) that captures the occurring phenomenology of porous compaction and subsequent unloading. The resulting EOS description is validated by comparing the experimental free surface velocity time curves with those obtained by numerical simulations of the performed PPI tests. The non-linear compression behavior, including the pore compaction mechanism, constitutes a main ingredient for modelling the response of adobe to blast and high-velocity impact loading. We hence present a modeling approach for lightweight adobe which can be applied to such high rate loading scenarios in future studies. In general, this work shows that PPI tests on lightweight and low-strength geological materials can be used to extract Hugoniot data despite significant material inhomogeneity. Furthermore, we demonstrate that a homogenous material model is able to numerically describe such a material under shock compression and release with a reasonable accuracy.

Softening of sound velocity and Hugoniot parameter measurement for shocked bismuth in the solid-liquid mixing pressure zone

Polymorphic phase transformation and melting under shock wave loading are important for studying the material dynamic mechanical behavior and equation of state in condensed matter physics. In this paper, the accurate Hugoniot parameter and sound velocity of shocked pure bismuth (Bi) in a pressure range of 17.3-28.3 GPa are obtained by using flyer impact method and rarefaction overtaking technique, respectively, and the sound velocity softening trend in shock-induced melting zone and the melting kinetics of Bi are then analyzed. In each experiment, six Bi samples with different thickness values are affected by oxygen-free-high-conducticity copper flyer fired through power gun. Shock wave velocity and particle velocity in Bi are experimentally determined through measuring the impact velocity and shock wave time in the thickest sample by photon Doppler velocimetry (PDV) technique. The velocity profiles on each interface between Bi and lithium fluoride (LiF) window are measured by displacement interferometer system of any reflector (DISAR), and then the sound velocity of shocked Bi is determined using the rarefaction overtaking method. The analyses of our results show that the softening of sound velocity of Bi approximatively satisfies the linear relation of Cs=3.682-0.015 p in the solid-liquid coexistence zone, and the pressure zone of the solid-liquid coexistence phase is further affirmed to be in a range of 18-27.4 GPa. Additionally, the obtained Hugoniot data for Bi in this paper supply a gap in the pressure zone of solid-liquid mixing phase. The quadratic equation with the expression of Ds=0.401+ 3.879 up-0.876 up2 can better demonstrate the relation between shock wave velocity and particle velocity than a linear one when the particle velocity lies in a range of 0.5-1.0 km/s, and this non-linear property maybe has a relationship with the shock-induced melting of Bi. Finally, our wave profile measurement of the Bi/LiF interface shows peculiar ramp characteristics in the expected velocity plateau zone in the pressure zone of solid-liquid coexistence phase, which may be associated with both the nonhomogeneous melting kinetics and the long time scale of melting for bismuth.

A cold energy mixture theory for the equation of state in solid and porous metal mixtures

Porous or solid multi-component mixtures are ubiquitous in nature and extensively used as industrial materials such as multifunctional energetic structural materials (MESMs), metallic and ceramic powder for shock consolidation, and porous armor materials. In order to analyze the dynamic behavior of a particular solid or porous metal mixture in any given situation, a model is developed to calculate the Hugoniot data for solid or porous mixtures using only static thermodynamic properties of the components. The model applies the cold energy mixture theory to calculate the isotherm of the components to avoid temperature effects on the mixtures. The isobaric contribution from the thermodynamic equation of state is used to describe the porous material Hugoniot. Dynamic shock responses of solid or porous powder mixtures compacted by shock waves have been analyzed based on the mixture theory and Hugoniot for porous materials. The model is tested on both single-component porous materials such as aluminum 2024, copper, and iron; and on multi-component mixtures such as W/Cu, Fe/Ni, and Al/Ni. The theoretical calculations agree well with the corresponding experimental and simulation results. The present model produces satisfactory correlation with the experimentally obtained Hugoniot data for solid porous materials over a wide pressure range.

Measurement of low-pressure Hugoniot data for bismuth with reverse-impact geometry

Hugoniot data for Bi are determined through measuring the impact velocity and the particle velocity at the sample/window interface on a powder gun or a two-stage light gas gun in a shock pressure range from 10 to 45 GPa, using reverse-impact geometry. The used experimental technique avoids the difficulty in accurately measuring the shock wave velocity resulting from the poor start synchronigm of electric pins under low shock pressure. The obtained Hugoniot data (shock wave velocity D versus particle velocity u) indicates that the D-u curve does have a discontinuity at a particle velocity of ~0.9 km/s, which is likely to be caused by the shock-induced solid-liquid phase transformation.

Shock melting of cerium

Shock-wave experiments were performed to examine the melt transition for cerium. Despite past work which points to a higher-pressure transition, the large volume collapse associated with the low-pressure $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\alpha}$ phase transition is expected to result in a low-pressure melt transition. Multiple experimental configurations including front-surface impact and transmission experiments using velocimetry were used to obtain Hugoniot data and sound-speed data for impact stresses up to approximately 18 GPa. Sound-speed data exhibit a structured release consisting of a longitudinal wave followed by a slower plastic wave. The difference between these two wave speeds is observed to decrease with increasing impact stress until a single shock wave is observed indicating the onset of the melt transition which was estimated to be $10.24\ifmmode\pm\else\textpm\fi{}0.34\text{ }\text{GPa}$. Additional data show that the sound speed is in agreement with liquid data at approximately 18 GPa likely indicating the completion of the melt transition. Further results and implications are discussed.

Hugoniot measurement of diamond under laser shock compression up to 2TPa

Hugoniot data of diamond was obtained using laser-driven shock waves in the terapascal range of 0.5–2TPa. Strong shock waves were generated by direct irradiation of a 2.5ns laser pulse on an Al driver plate. The shock wave velocities in diamond and Al were determined from optical measurements. Particle velocities and pressures were obtained using an impedance matching method and known Al Hugoniot. The obtained Hugoniot data of diamond does not show a marked difference from the extrapolations of the Pavlovskii Hugoniot data in the TPa range within experimental errors.

Shock Hugoniot compression curve for water up to 1 GPa by using a compressed gas gun

A shock Hugoniot compression curve for water has been measured up to less than 1 GPa. A plane and steady shock wave is produced in water by the flat plate impact of a projectile accelerated by a compressed gas gun. A new experimental procedure was proposed to detect the shock wave front sensitively, which makes it possible to measure shock Hugoniot in higher precision than the previous method. The present method is based on the very large pressure dependence of the refractive index of water upon compression. By using this method, the shock compression curve was determined within the precision of 2% to 3% of the estimated shock pressure. The precision is better than that of the previous data. It was confirmed that within the pressure range covered in this experiment, the shock-particle velocity Hugoniot can be described by a linear relation with a large slope. Shock Hugoniot states on the pressure–temperature plane were calculated by using the obtained Hugoniot data combined with the values of thermodynamical variables. Thermodynamic analysis of the shock compression process was developed to estimate the contributions of irreversible heating by shock compression.

Shock compression measurements at 1 to 7 TPa

A shock wave generated by an underground nuclear explosion was used to perform impedance-matching experiments for several different materials at pressures from 1 to 7 TPa. The nearly planar shock passed through a 180-mm-diam by 12-mm-thick molybdenum standard and into stacks of 10-mm-thick samples of the following adjacent pairs of materials: LiD-Be, Be-LiD, Al-Mo, Pb-quartz, W-Mo (low density, ${\ensuremath{\rho}}_{0}=8.29$ g ${\mathrm{cm}}^{\ensuremath{-}3}$), U-Mo, and Fe. An array of 75 electrical contact pins was used to determine the shape of the shock front and the shock velocities in the standard and in the samples with uncertainties ranging from 1.5 to 2.5%. The measured shock velocity of 27.30 km/s (\ifmmode\pm\else\textpm\fi{}1.5%) in the molybdenum standard corresponds to a pressure of 4.95 TPa (\ifmmode\pm\else\textpm\fi{}3.5%) based on a theoretical equation of state (EOS) that includes electronic-shell-structure effects. An impedance-matching analysis was performed for each sample stack to obtain Hugoniot data for all samples except those in the U-Mo stack; neutron-induced fission heating in the uranium perturbed the initial state and produced inconclusive results. Predictions, based on the SESAME EOS library, of shock velocities in most samples agree with the experimental results within the uncertainties. For the quartz and low-density molybdenum, the SESAME-predicted shock velocities are too large by 5 to 10%. The following Hugoniot points in pressure ($P$)-particle-velocity ($u$) coordinates were determined for the indicated samples: LiD ($p=0.946$ TPa, $u=29.39$ km/s), Be (1.46, 22.69); Be (1.79, 25.42), LiD (1.038, 31.23); Al (2.23, 23.89), Mo (4.03, 16.05); Pb (4.80, 17.84), quartz (1.66, 23.64); W (6.51, 15.10), and Mo (${\ensuremath{\rho}}_{0}=8.29$ g ${\mathrm{cm}}^{\ensuremath{-}3}$) (3.68, 18.27). The results for iron have a larger uncertainty but are consistent with the SESAME predictions.