Using diamond anvil cell (DAC) combined with synchrotron axial X-ray diffraction (AXRD) techniques, the stress transmission behavior among materials with different strengths was investigated under non-hydrostatic compression. In our experiments, powder mixtures of platinum (Pt) and cubic silicon carbide (β-SiC), Pt and tungsten carbide (WC), as well as WC and β-SiC, were compressed up to 56, 61, and 25 GPa, respectively. We found that the stress transmission among the grain boundary of two different materials is discontinuous due to their strength difference, and the observed stress difference increases with the strength difference. The stronger material has a smaller observed stress near the minimum stress direction under non-hydrostatic compression in DAC at the same loading.

The tungsten alloy melting behaviors under high-velocity shock loading is investigated by Molecular Dynamic (MD) method combined with Embedded Atom Method (EAM) potential of tungsten alloy. First, the shock model of tungsten alloy is set up and the numerical simulations of lattice planes (100), (110), (111) under the shock loadings with the same velocity are conducted respectively. The Hugoniot curve and the relative data of pressure, temperature, volume and particle velocity behind the shock wave are obtained. Based on the analyses of the data and the curve, it is found that the shock pressure is in proportion to the shock temperature and inversely proportional to the shock volume. The above conclusions fit to experimental data well when the loading velocity is low, which are extended to the high-velocity impact field. The calculations show the plasticity of tungsten under high-velocity impact in qualitative description.

The basic principle and the parallel design strategy of the PMMIC-3D parallel program which using Euler method based on the message passing interface (MPI) mode were stated. After numerically stimulating the fortification mode, it can be seen that the results of numerical stimulation basically match with the reality and the physical laws. The shock waves of explosive detonation in fortifications not only had a higher peak overpressure, but also had a longer duration of action. When the shock wave met the wall, it would reflect and produce the reflected high pressure. Because of the diffraction convergence, the local high pressure would be brought about in a certain region behind the wall, in which the destructive effect was much larger compared with the shock waves of air explosion. The propagation process and the interaction of shock waves can be seen clearly by the numerical stimulation, which can determine the arrival time of the shock waves at various positions. The optimal explosive charge can be ensured by comparing the overpressure value of shock waves at different places.

High-pressure and high-temperature (HPHT) synthesis has play growing importance in exploring new materials. It has the merits of producing many new compounds that otherwise could not be synthesized at ambient conditions. The conventional HPHT facilities are based on so called one stage model reaching pressures up to 10 GPa. It is well understood that the higher synthesis pressure is, the more new compounds will be obtained. Here we introduce a state of the art new type high pressure synthesis facility based on double stage model of the six over eight multi anvils large volume high pressure machine that can reach unprecedented 20 GPa and 2 000 ℃. With the six over eight double stage facilities, much more new high pressure compounds are expected.

We report here the additive Runge-Kutta methods for computing reactive Euler equations with a stiff source term, and in particular, their applications in gaseous detonation simulations. The source term in gaseous detonation is stiff due to the presence of wide range of time scales during thermal-chemical non-equilibrium reactive processes and some of these time scales are much smaller than that of hydrodynamic flow. The high order, L-stable, additive Runge-Kutta methods proposed in this paper resolved the stiff source term into the stiff part and non-stiff part, in which the stiff part was solved implicitly while the non-stiff part was handled explicitly. The proposed method was successfully applied to simulate the gaseous detonation in a stoichiometric H₂-O₂-Ar mixture based on a detailed elementary chemical reaction model comprised of 9 species and 19 elementary reactions. The results showed that the stiffly-accurate additive Runge-Kutta methods can well capture the discontinuity, and accurately describe the detonation complex wave configurations such as the triple wave structure and cellular pattern.

The measurement of sound velocity of materials under high temperature and high pressure (HTHP) is an important research content in high pressure science. As a fundamental physical property of liquids, velocity of sound wave in liquids is very important and useful, for many thermodynamic parameters may be derived from sound velocity. However to date, there is little direct experimental information on macroscopic thermodynamic properties of liquids or melts under high pressure, especially the experimental technique to measure sound velocity of liquid has not been well established. The purpose of this paper is to give a brief review on various sound speed measurement techniques of liquid materials under high pressure and a detailed introduction on some new breakthroughs nearly, and finally to point out some expectations in this research field.

The inversion of visco-elastic constitutive relation from the measured data of a spherical wave experiment is a challenging research. Starting from the governing equations for linear visco-elastic spherical waves which are based on the ZWT visco-elastic constitutive relation, the analytical expression for the attenuation of strong-discontinuous visco-elastic spherical wave front is derived, and consequently a new method is proposed, by which the high-strain-rate visco-elastic parameters could be inversed from a series of particle velocity profiles measured in a spherical wave experiment. The first step is to determine the high-strain-rate elastic module from wave velocity measurements when the quasi-static material parameters are known. Then the high-strain-rate relaxation time can be determined from the attenuation factor. Thus the required visco-elastic constitutive relation can be obtained. Using those material parameters obtained by such a new inversion method, the visco-elastic spherical wave profiles are calculated by the characteristics method. The good agreement between the numerical predictions and the experimental results well supports this proposed new inversion method.

In-situ pressure-induced phase transition of ionic liquids [Emim][PF₆] and [Bmim][PF₆] have been studied under high pressure and room temperature by using Raman spectroscopy and high-pressure diamond anvil cell (DAC) apparatus. With the increase of pressure, [Emim][PF₆] experiences the solid-solid phase transition at about 0.86 GPa, and [Bmim][PF₆] experiences the liquid-solid phase transition at about 0.62 GPa and the solid-solid phase transition at about 1.45 GPa. Furthermore, the decrease of pressure of [Bmim][PF₆] has also been discussed in details. Pressure-released Raman spectra shows that the phase transition of [Bmim][PF₆] is reversible under pressure up to 2 GPa.

We used high resolution 5th-order WENO (Weighted Essentially Non-Oscillatory) scheme, Level Set method and interface treatment method-RGFM (Real Ghost Fluid Method) in simulating compressible multi-medium flow with high density and high pressure ratio. Simulation of one-dimensional gas-water interaction problem was performed, and the accuracy and reliability of the method was verified. This method is applied to two-dimensional deep water and near free surface explosion simulation. From the simulation results of underwater explosion, it indicates that this method can simulate the shock wave generation, propagation, reflection and transmission after interation with the interface in underwater explosion. This method is strongly advantageous in simulating compressible multi-medium flow with high density ratio, high pressure ratio and strong discontinuity.

The pressure chamber of “600 ℃ and 20 MN servo-controlled triaxial rock testing system with high temperature and high pressure” has adopted the piston- thick-walled cylinder structure. Compared with normal pressure chamber, the inner diameter rises to 300 mm, the outside diameter becomes 1 060 mm and the height grows to 1 100 mm. The size of test specimen also amounts to Ø200 mm×400 mm. The calibration test applies internal heating type and electronic heating approach with low voltage and high current. Before the system is put into use, the reference temperature point should be calibrated. Thus, nine thermocouples were placed in and outside the specimen to observe the temperature variation at these observation points, and to study temperature field characteristics inside of specimen, as well as its relationship with reference point temperature. The calibration experiment results indicate that, the temperature data collected from the middle of the junction of NaCl and micanite paper are stable and reliable, and are in a favorable linear relationship with the inner temperature. Therefore, the place is qualified to be the reference temperature point in the heating process. The test results show that the inner temperatures of the specimen are higher than the temperatures of the junction of NaCl and micanite paper in the same cross section, the middle temperatures of whom are higher than those on both ends. In the inner axial direction, the upper end and the bottom temperature are symmetric to the middle of the specimen whose temperature is higher than either of those of the both ends. The disparity from middle to end grows bigger as the heating temperature increases, the maximum gradient is 0.85 ℃/mm. In the radial direction, the larger distance from the central point, the greater trend of linear temperature distribution. While the central temperature is the lowest, the surface temperature is the highest. The biggest temperature gradient is about 0.5 ℃/mm. The temperature at the central point, 40 mm from the central point, 80 mm from the central point and on the surface of the specimen are respectively larger than the reference temperature by 21%, 27%, 28% and 29%. Whereas, in the inner axial direction, the upper end temperature and the bottom temperature are close, only 1.5% lower than the reference temperature. It is testified that the heating approach is reasonable, and the accuracy of temperature control is high and the temperature of test specimen is well-distributed.