In situ angle dispersive X-ray diffraction measurements for a natural epidote were performed with diamond anvil cell instrument and synchrotron radiation at NSLS (National Synchrotron Light Source).The maximal pressure in the experiment was 9.16 GPa.At experimental pressures, no evidence of phase transition of the epidote was observed.A fit to the third-order Birch-Murnaghan equation of state yielded an isothermal bulk modulus of 116(7) GPa and its pressure derivative of 7.8(8).The isothermal bulk modulus of epidote is determined to be 132(4) GPa, assuming that its first pressure derivative is 4.Furthermore, we confirm that the linear compressibilities along a, b, and c directions of epidote are elastically anisotropic.Consequently, it can be concluded that the compressibility of epidote under high pressures has been accurately constrained.

Piston-cylinder apparatus is widely used for high-pressure and high-temperature experiments.Its thermal structure in the pressure chamber depends mainly on design and materials of the sample assembly.Here we present a thermal structure analysis on the 13 mm pressure assembly of a QUICKpress piston-cylinder apparatus on the basis of the experimental temperature measurements using the double thermocouple determination, the spinel reaction progress thermometer, and heat conduction simulation by Fourier's law.The temperature measurements were conducted at 0.5 GPa, 1.0 GPa and 1.5 GPa with the control thermocouple in a temperature range of 800-1 400 ℃.The major results are summarized as follows:(1) the hot spot is always located at a position below the midpoint of effective furnace (this means that it is close to the steel base plug); (2) the hot spot region with a temperature variation within 20 ℃ possesses a width of 2.8 mm to 5.2 mm, showing a low thermal gradient of 7.7-13.0 ℃/mm while the region far from hot spot shows a much higher thermal gradient of 42-83 ℃/mm; (3) the position of hot spot moves toward the center or midpoint of effective furnace with pressure or temperature increasing, but the temperature profile is main determined by the temperature of hot spot, with the hot spot region becoming narrower and the thermal gradients for both the hot spot region and the region far from hot spot becoming larger with temperature increasing.On the basis of our experimental and numerical simulation results, effective factors controlling the thermal structure of pressure assembly of a piston-cylinder apparatus and other issues are further discussed.

The microstructures of MgSiO₃ melt and their variation with temperature and pressure were investigated based on first-principles molecular dynamic simulations at high pressures (0-144 GPa) and high temperatures (2 000-6 000 K).The calculated first peak positions of the pair correlation function of O—Si, O—Mg and O—O under the condition of 0 GPa and 2 000 K are 0.163 5, 0.1 970 and 0.269 5 nm, respectively, which are consistent with the previous experimental values.As the pressure and temperature change, the structure of MgSiO₃ melt undergoes a significant change.Especially when the pressure increases, the structure becomes denser.When the temperature is below 5 000 K, the average bond lengths between two atoms decrease with the increasing temperature with density 4.59 g/cm³.While under nomal or higher pressure, the average bond length change with the increasing temperature is not obvious.At 133 GPa and 4 000 K, the average bond lengths of O—Si, O—Mg and O—O are 0.161 0, 0.183 5 and 0.230 0 nm, respectively; the average Si—O coordination number increases from 4 to 6, and the number of bridging oxygen ratio increases from 31.3% to 72.9%, from atmospheric pressure to the core-mantle boundary.The knowledge of MgSiO₃ melt microstructure is important to understand the mantle silicate fluid nature of mantle dynamics.

According to crystal lattice structures, a three-dimensional lattice physical mechanics model in constant volume state was built up to study the atom thermal vibration.The equation of thermal energy and external force on the thermal vibrating lattice was deduced absolutely from the principle of mechanical vibration.By introducing macroscopic physical statics into microscopic atomic thermal vibration equation, Mie-Grüneisen equation of state for solids and the formula of Grüneisen parameter were deduced directly from the physical mechanical model.Finally, based on the arrangement of atoms in simple cubic, face-centered cubic, body-centered cubic, diamond cubic and close-packed hexagonal crystal, it was proved that the Grüneisen parameters of these symmetrical crystals can be expressed in a uniform formula, irrelevant to their actual arrangement of atoms.

Based on the fact that the Lagrangian bulk moduli of many materials can be expressed as a second order expansion with respect to pressure, a four-parameter equation of state has been proposed which, in comparison with the three-parameter equation of state, can be applied to a wider pressure range and has higher fitting accuracy and good extrapolation behavior.The parameters in the equation are dependent on the first, second and third order derivatives, hence, by using the derivative relations of the Hugoniot and isentropic equations, one can verify if the dynamic high-pressure experimental data match the static high-pressure experimental data.The equation describes shock, isentropic and isothermal compression states in a unified form, is suitable for a variety of materials in a wide pressure range, and therefore can be considered as a universal equation of state.Being simple and easy to operate, our equation overcomes the weakness of conventional four-parameter equations of state which are of no practical use due to their complicated structure, lengthy formula, and high correlation between parameters.

This paper studied the 3D Euler method of elastic-plastic hydrodynamics with the ideal elastic-plastic constructive model for debris clouds produced by hypervelocity impacts.Two cases were simulated that sphere and oblique cylinder impacting single plates.The simulation results were compared with experimental results.The numerical simulating cloud shapes agreed very well with experimental results.The hole diameter of hypervelocity impact of projectile was also studied.It shows that the Eulerian numerical method is validate for simulating debris clouds produced by hypervelocity impacts.

In order to overcome the shortcoming of multipoint laser velocimetry such as low spatial resolution, system complexity and expensive cost, a high time-space resolution line-imaging VISAR for detonation physics was implemented, which was with response time of 400 ps and space resolution of 100 μm.This line-imaging VISAR was used to measure the free surface velocity of four different configuration samples driven by explosive with or without a cavity.These experiment results mostly manifested the high spatial resolution ability of line-imaging VISAR.In the future, the line-imaging VISAR would be indispensable to some special studies of detonation physics.

The reflection bunching characteristics analysis of underwater plasma sound source has an important guiding significance on the research and application of underwater directional radiation technology.The reflection rules of different surfaces were analyzed, and the bunching sound field distribution model of underwater plasma sound source based on the Euler equation was established, which was solved by unwind WENO pattern.The intense pulsed acoustic wave bunching and the sound field distribution were analyzed by simulation, and the sound field charts illustrated the reflection bunching characteristics of the sound source.Some related experiments to verify the simulation results were designed.The simulation results are basically identical to the experimental results.It shows that the simulation model is reliable; this information is critical and lays the foundation for the further research on underwater directional radiation technology and the improvement of the source level.

In order to synthesize nano-ceria by detonation method, 5 kinds of emulsion explosives in which Ce(NO₃)₃·6H₂O acted as main oxidant were designed and prepared.Considering the effects of the content of Ce(NO₃)₃ on the detonation velocity of emulsion explosives and the yield of nano-ceria, the formulas of emulsion explosives for preparing nano-ceria were screened.Nano-ceria was synthesized by initiating the emulsion explosive in explosion vessel.The as-synthesized products were characterized by XRD and TEM.The result from XRD test indicates that the nano-ceria belongs to cubic phase.The mean size of ceria grain is 74 nm based on the calculation result according to Scherrer equation.The result from TEM test presents that the as-synthesized ceria particles are spherical by appearance, they have well dispersion and the size was uniform.According to TEM test result, the mean diameter of ceria particles is about 70 nm, which coincides with the calculation result perfectly.

In order to study the reliability of underwater target structure subjected to underwater explosion, reliable sample data were obtained through many groups of experiments.Two methods including the stepwise polynomial regression method and the BP neural network method were presented to fit to these samples, and the approximate analytic expressions were achieved between the structural response variables and the input variables.Then Monte-Carlo method was used to obtain the statistical characteristics and distribution function of the structural response variables, through which the structure reliability could be calculated.Results show that the invalidation probability of target with explosion centre changing can be displayed, and this method provides reference for the defensive structure.

A kind of copper wire closed-packed structure was compressed by one-dimensional strain impacting and the dynamic process was numerically simulated.The laser displacement interferometer was used to measure the interface particle velocity profile and the effective experimental data of structure impact compression were obtained.It can be inferred from the interface velocity curve that no compact structure was formed in the sample during the shock compressing progress, and the delamination of sample happened during the unloading progress.The three-dimensional numerical model of plane copper wire closed-packed structure was built by using smoothed particle hydrodynamics (SPH) method, and the shock compression properties of sample were obtained.The interface particle velocities and pressure of the sample were in good agreement between experiments and simulations.

A study on hypervelocity launcher techniques was carried out on the two-stage light-gas gun with quasi-isentropic compression of the flier-plate material with graded impedance.A 25-millimeter diameter aluminum alloy projectile was accelerated over 11 km/s using the hypervelocity launcher, and a 10-millimeter diameter titanium alloy projectile was accelerated over 15 km/s using the enhanced hypervelocity launcher.The hypervelocity launcher techniques using a three-stage gas gun was suitable for researches on the hypervelocity impact effect of spacecrafts.

The 3D elastic-plastic hydrodynamic Lagrangian-Remapping two-step Euler method was used for the micro ejection simulation of aluminum.The micro ejection calculation models have grooves on the aluminum interface with the same depth and different angles, and the numerical results of the micro-jet mass and maximum velocity thus accorded with Asay's experiment results.And then, the micro ejection calculation models with the same groove depth but much larger angle range were calculated.By the analysis of the numerical results, it is showed that the maximum velocity of the micro-jet decreases linearly with the increase of the groove angle, and the curving contour of the ejected factor versus groove angle is given.Because of the influence of metal strength and groove angle on the wave relations, the micro-jet coefficient curve is obviously nonlinear with the groove angle.

The interaction of shock waves in ground burst was studied by experiment with various experiment layouts.Parameters of shock waves of two or three charges exploding simultaneously were measured using air explosion test system.The results show that the shockwave overpressure and impulse are enhanced greatly, blasting power increased.The change of shockwave parameters was significant for various experiment layouts, where the amount and orientation of explosive source increasingly effected the magnitude of shockwave parameters.Shock waves collision with rigid wall can be used to approximately calculate the interaction of two equal-intensity shock wave.

The experimental and simulation studies were carried out for the 4 different nose structures of rod penetrator oblique penetrating into three-layer laminated target.For the different types of nose structures, the ability of their penetration was assessed by crater formed in the erosion of quality as well as the kinetic energy behind target.Through the description of the penetration, the changing rules of kinetic energy with time were obtained for different nose structural penetrators respectively.The experimental and simulation results indicate that the nose structures are influential for crater forming, and then the process of crater formation will directly affect the subsequent process of penetration.From the investigation, it is found out that the aluminum ogive armor-piercing block nose of structure is the most favorable in the three-layer laminated targets of penetration, and we also have analysised the penetration advantage of this nose structure, which will serve as a reference to optimize the structure of other similar penetrators.

The mechanism and damage evolution of high pressure water impaction on coal were numerically simulated using the method of coupling smoothed particle hydrodynamics(SPH) method with standard finite element method (FEM).The numerical computation model of high pressure water was a cylinder whose length is 5 mm and radius is 2 mm.According to numerical results, the coal damage evolution and stress wave propagation were studied.Meanwhile, the crushing strength of coal was obtained on foundation of numerical simulation.

High-density polyethylene (HDPE) melt and linear low-density polyethylene (LLDPE) melt were solidified through three kinds of experimental processes, including rapid compressing, natural cooling and quenching, and then the microstructure of samples was investigated.The results show that the crystallinity distribution of rapid compressing samples was more uniform regardless of low thermal diffusivity of polymers, so the "skin-core" type of crystallinity distribution was not found in RC samples.In addition, compared with quenching, rapid compressing can also hinder the crystallization of the polymer melt effectively, especially for LLDPE with low mobility of molecular chains.

In order to research the characteristic of how the scale of series composite charge explosives (JO-9159/JB-9014) affect energy output, FEM software AUTODYN was used to simulate the plane flyer test, and relevant experiments were carried out to verify the result of analog.It is showed that the relative error of the velocity of the flyer between experimental value and calculated value is 0.2%-3.0% and the relative error of the ratio dynamic energy is 0.4%-6.0%.Therefore, the simulation model is reasonable.And then the model and the material parameters were applied to calculate the structures of series composite charge explosives in different height ratios.From the calculation, the relation of structure size and energy output was studied and the exponential function between the size of the explosives and the velocity of the flyer was obtained.In conclusion, the first peak velocity of the flyer grows closer to the second as the high explosive composition increases.In contrast, the first peak velocity is less than the second as the insensitive explosive composition increases, and the velocity has a major zoom during the whole process.