In the last 10 years or so, nearly all major Chinese universities, schools and research institutes with strong Earth science programs showed strong interest in developing a new research branch of High-Pressure Earth Sciences.As a result, many young Chinese scientists with good training from the universities in the west countries were recruited.This directly led to a fast growing period of about 10 years for the Chinese high-pressure mineral physics research field.Here we take the advantage of celebrating the 30th anniversary of launching the Chinese Journal of High Pressure Physics, and present a brief summary of the new accomplishments made by the Chinese scientists in the fields of high-pressure mineral physics relevant to Earth sciences.The research fields include:(1) phase transitions in the lower mantle; (2) high spin-low spin transitions of iron in lower mantle minerals; (3) physical properties of the Earth core; (4) electrical measurements of rocks; (5) electrical measurements of minerals; (6) elasticity of minerals (especially equation of states); (7) high-pressure spectroscopic studies; (8) chemical diffusions in minerals; (9) ultrasonic measurements under high pressure; (10) physical properties of silicate melts; (11) geological fluids.In sum, the last 10 years have seen a rapid development of the Chinese high-pressure mineral physics, with the number of scientific papers increasing enormously and the impact of the scientific findings enhancing significantly.With this good start, the next 10 years will be critical and require all Chinese scientists in the research field to play active roles in their scientific activities, if a higher and advanced level is the goal for the Chinese mineral physics community.

As an effective way to realize metal hydrogen and high-temperature superconductors, the metalization and superconductivity of hydrogen-rich compounds have become one of the hot spots of physics and materials science.In practical application, hydrogen-rich compounds are also potential hydrogen storage materials.The study of the structure and properties of hydrogen-rich compounds under high pressure is considered to be an effective means to enhance their hydrogen storage performance.In this paper, high pressure experimental and theoretical researches on the second main group hydrides, a typical kind of rich hydrogen compounds, were briefly introduced, including high pressure structural phase transition, the stability of the new structure, the mechanism of metalization.The effects of different hydrogen motifs on superconductivity were also discussed.

In this study we studied the chemical reaction of the NaCl-O₂ system under high pressure and high temperature using the diamond anvil cell apparatus and the double-sided laser heating technology.The sample was heated to about 1 500-2 000 K under a pressure of 55 GPa, and then analyzed by the Raman measurement at room temperature.The determined data show that the NaCl-O₂ system undergoes a chemical reaction under the above-mentioned pressure and temperature conditions.The products include the nontraditional compounds of NaO₄ and NaCl₃, as well as a small amount of NaClO₄ and intermediate product Cl₂.The black NaO₄ powder, being apt to absorb moisture, can still exist in the ambient condition.The diagnostic zero-pressure Raman band of 1 384 cm^-1, assigned to the symmetric stretching vibration of the O₄^- anion in NaO₄, suggests the occurrence of O-O atom pair with a negative fractional valence in the structure.The orthorhombic structure of NaCl₃ exhibited a strong Raman signal, which could distinguish 10 Raman peaks in our measurements.It decomposes into NaCl+Cl₂ under about 23 GPa on decompression.The experimental results suggest that both elements of oxygen and chlorine prefer to occur in the unconventional form of pair-anions or polyanions caused by their unique chemical reactivity under high pressure, differing from that in atmospheric and lower pressure environments.It requires more robust evidences from various experimental systems to confirm whether these properties of oxygen and chlorine under high pressure are universal.Oxygen is one of the most important constituent elements on Earth, and most of the Earth is in high temperature and high pressure environment.This study provides new evidence for the possible unconventional existence of oxygen in the mantle.

In the present work we determined the sound velocities of shocked Fe_92.5O_2.2S_5.3 (in weight percent) under pressures up to 208 GPa using the reverse-impact method and the optical analyzer technique.We found that the longitudinal sound velocities of the solid Fe_92.5O_2.2S_5.3 began to decrease at 144 GPa and completely transformed to bulk sound velocity of liquid at 165 GPa, indicating that the completely melting temperature of the sample is about (3 500±400)K based on the energy conservation relation.With respect to this point as reference, the melting temperature of Fe_92.5O_2.2S_5.3 is about (5 000±400)K when extrapolated to the boundary of the inner/outer core using the Lindeman Law.Compared with the already measured melting temperatures of Fe, Fe-O, Fe-S and Fe-O-S, it shows that the oxygen has little effect on the melting of iron, and the melting depression of iron increases with sulfur content in the sample.If the mass fraction of the sulfur in the outer core is 2%-6%, the temperature is about 5 000-5 400 K at the inner core/outer core boundary of the Earth.

Based on a two-stage light gas gun and a multi-channel time-resolved pyrometer, we simultaneously measured the shock temperatures and sound velocities of B2, B2-liquid and liquid phase NaCl single crystal in the pressure range from 45 GPa to 85 GPa.According to these sound velocities, the shock melting pressure region was determined to be 58-67 GPa, and the shock melting point obtained was 3 740 K at 67 GPa.Furthermore, we calculated the isentropic bulk modulus, the Grüneisen parameter, and the specific heat capacity under constant pressure and compared the experimental results with the previously published data.The Grüneisen parameter calculated by Wuqiang model has an excellent agreement with both the shock compression experiment data in the liquid region and the diamond anvil cell experiment data and the finite strain theory calculation results in the low pressure region.

The Richtmyer-Meshkov instability of a "V" shaped air/SF₆ interface accelerated by a planar incident shock and its reshock was experimentally investigated in a shock tube.The soap film technique was adopted to form a well-controllable initial interface, and the flow field was captured by a high-speed schlieren system.Through changing the vertex angle of the interface, the initial perturbation amplitude was varied, and the effect of the initial perturbation amplitude on the wave pattern and the flow morphology was highlighted.The results show that, after the impact of the incident shock, the interface morphology is different for different vertex angles, further causing the diversity of the interface morphology after the reshock impact.For the interfaces with small vertex angles, the complicated wave patterns will emerge inside and outside the interface after the reshock, which exert an influence on the interface morphology and phase inversion phenomenon.The flow enters the turbulent mixing quickly after the reshock, and the development of interface for small vertex angles tends towards isotropy.Moreover, the mixing width after the reshock was measured from experiments and compared with the theoretical predictions.The model was found to be invalid mainly because the initial conditions of the experiments violate the requirement of the model.

Based on the stress-strain relationship in three-dimensional condition, we established a dynamic constitutive model of an anisotropic composite material using the Grüneisen, PUFF equations of state, Tsai-Hill yield criterion and the Johnson-Cook stress model and then simulated the thermal shock wave propagation induced by a high energy density X-ray impulse in a C/TF material.The results for the anisotropic constitutive model and the isotropic constitutive model were compared, and the analysis show that the anisotropic constitutive model proposed in this study can not only reflect the anisotropy of the material, but also describe the dynamic behavior of the vaporized material.Our model lays an important theoretical foundation for the application of anisotropic composite material in irradiation environment.

We used the polycrystalline cubic boron nitride (PCBN) as the anvil material based on its high hardness and strong absorption of neutrons, and designed a new type of concave-flat anvil and a hybrid gasket made of TiZr alloy, carbon fiber and teflon.The PCBN cell pressure was calibrated using the transformation points of ZnTe and ZrW₂O₈ respectively.The results show that the cell pressure reaches 9 GPa with the sample cell volume of 9 mm³ when the load pressure is 260 kN.The in-situ high pressure neutron diffraction experiments indicate that the PCBN anvil miscellaneous signal was not observed in the high pressure neutron diffraction patterns of iron.By further optimizing the PCBN cell, we expect to obtain a high-quality neutron diffraction patterns under higher pressure than 10 GPa.

A quick and practical engineering analysis model based on the reasonably simplified hypothesis is an important means to study the ballistic performance of the ceramic/metal targets.The available detailed theoretical models have to carry out complex calculation and rarely are made comparisons with the residual velocity of the projectile perforating ceramic/metal targets under the condition of ultra-high speed (with the projectile muzzle velocity greater than 1 500 m/s).In this study, considering the decrease of the strength of fractured ceramic during the penetration of the projectile into fractured conical ceramic, the effect of the projectile's initial velocity on the value of the half conical angle, and the influence of the metal plate's deflection on the long rod of ultra-high speed penetrating the fractured conical ceramic, based on the semi-fluid dynamics Alekseevskii-Tate (A-T) model, a simplified model predicting the residual velocity of the long rod of ultra-high speed perforating ceramic/metal target was proposed.By comparing with the experiment data and the simulation results of the tungsten long rod (1 800-2 600 m/s) perforating Al₂O₃/RHA steel target carried out on the LS-DYNA finite element analysis software, the correctness and applicability of the proposed simplified model, the numerical model and its corresponding parameters were validated.Furthermore, based on the simplified model, the ballistic performance of composite targets consisting of 4 ceramic facing plates (Al₂O₃, AlN, SiC, B₄C) and 2 metallic backing plates (RHA steel, aluminum), under the condition of certain thickness and certain areal density was discussed.

In this research, we carried out a systematic study of the mechanical behaviors of the 93 tungsten alloy (93%W-4.9%Ni-2.1%Fe) with a temperature range of 296-1 273 K and a strain rate range of 0.000 5-6 000 s^-1.The results demonstrate that the flow stress is highly dependent on the temperature and the strain rate:the flow stress increases with the decrease of temperature and the increase of strain rate, and the shear failure does not occur when the true plastic strain is up to 0.6.Then we introduced and established 3 constitutive models, including two phenomenological constitutive models, JC model and KHL model and one physically-based constitutive model, to fit the stress-strain relationship through a procedure of regression analysis and constrained optimization.Finally, we evaluated the fitted results of the 3 constitutive models through a fitting error analysis and a specific strain-rate jump experiment.

As an important part of high-speed trains, the axle has to withstand complex loads, especially the shock load in the train's operating conditions.To study the dynamic mechanical properties of the 42CrMo steel used in axle production, quasi-static and dynamic compression experiments of 42CrMo steel were conducted at strain rates from 0.001 s^-1 to 4 163 s^-1.The results of these experiments show that the 42CrMo steel has an effect of strain rate, strain hardening and thermal softening at high strain rate.Based on the experimental results, we improved the Johnson-Cook model by decoupling the terms of the strain and the strain rate, and also by considering the adiabatic temperature rise.The improved Johnson-Cook model has proved to be capable of describing the dynamic mechanical properties of the 42CrMo steel well and providing reference for practical engineering structural mechanics analysis.

In this research, we focused on the effect of the stiffener shape on the dynamic response of composite stiffened panels.We first established the finite element analysis model for composited stiffened structures with 3 kinds of stiffeners using the local refinement with the interface between the layers simulated by bonding interface, and then analyzed the dynamic response and the delamination damage of these composite stiffened panels.According to the results of the numerical simulation, it is found that the dynamic response is closely related to the structure stiffness, the composite stiffened panels with T-shaped and I-shaped stiffeners are warped in the region beyond the impacted part of the panels, and their damage distribution and damage area are similiar.The results also show that the layer angle of the two layers adjacent to the surface of the skin and the stiffener affects the area of the delamination damage.

In this study, the single shock mode—shock wave propagates along the hollow cylindrical shell—was established and, by introducing the modified pipe wall parameters, the axial dynamic buckling response of the graded hollow cylindrical shell was predicted and compared with that of the hollow cylindrical shell with a uniform wall thickness.The result of the modified single shock mode is in good agreement with that from the numerical simulation.Under axial impact loading, the impact resistance of the graded hollow cylindrical shell is better than that of the hollow cylindrical shell with the uniform wall thickness.

The wheel-rail interaction is a major concern in research for high-speed rail transport.As a main type of wheel/rail failure, the wheel flats exert serious restriction on the stability and safety of high-speed trains.In this study, a three-dimensional wheel-rail rolling contact model with a flat was built using the Hypermesh software, and the corresponding finite element simulation was conducted, based on the Cowper-Symonds empirical model, using the LS-DYNA 3D explicit algorithm.Influences of the train speed, flat length and axle load on the wheel-rail impact response were discussed, respectively.The simulation results indicate that the maximum vertical wheel-rail impact force is significantly larger than the corresponding static axle load due to the presence of a wheel flat, and the maximum von-Mises equivalent stress and maximum equivalent plastic strain are observed on the wheel-rail contact surface.The strain rate-dependent constitutive parameters of the wheel/rail steels have no influence on the maximum vertical wheel-rail impact force; however, due to the hardening effect of the strain rate, the maximum von-Mises equivalent stress obtained from the Cowper-Symonds model is obviously larger than that derived from the rate-independent one, while the maximum equivalent plastic strain derived from the Cowper-Symonds model is smaller than that under rate-independent one.Besides, the wheel-rail impact response is demonstrated to be sensitive to the train speed, flat length and axle load.These findings can provide technological supports for safety design and assessment of the wheel-rail system.

Carbon fiber reinforced polymer (CFRP) laminates and epoxy gels have been extensively applied to externally strengthen engineering structures to resist blast loading.In order to understand the mechanical properties of CFRP/epoxy gel composites, we carried out a series of quasi-static tensile tests and obtained the entire tensile stress-strain curve.Based on the test results, we calibrated the material parameters of the finite element model developed in LS-DYNA software.It is found that CFRP/epoxy gel composites exhibit an obvious elastic-brittle characteristic, and the mean value of the tensile strength obtained in the test is up to 4 100 MPa.Being externally attached with resin gel, the disadvantage of discrete characteristics of CFRP laminates was significantly improved, which makes the externally bonded CFRP fully effective.The initial defects of the pasted epoxy gels significantly affect the failure modes and tensile properties of the tested specimen, and the uniformity of the sprayed layer of epoxy gels is of great importance to improving the blast resistance of the retrofitted engineering structures.

To study the effect of the explosion caused vibration on the roof of the pasted backfill, which use a new cementitious material agent as the backfilled agent in substitution of cement in the downward slicing drift mining, we first conducted blasting test, theoretical analysis and test data regression analysis, and then simulated the dynamic response of the new pasted backfill under explosion loading using the FLAC^3D software.The simulation results show that, under the same explosion loading, the peak particle velocities in x, y, z directions of the new pasted backfill with cement-sand ratio 1:6 and 1:12 is slightly larger than those of the cemented pasted backfill and their difference is within 6.8%;while the peak particle velocities of the new pasted backfill with cement-sand ratio 1:8 is slightly lower than those of the cemented pasted backfill.It can thus be concluded that the new cementitious material agent can be used for backfill mining with the requirements equally well satisfied of the original engineering blasting design.

To investigate the feasibility of applying the light-initiated explosive, silver acetylide-silver nitrate (SASN), as an effective simulation of a cold X-ray blow-off event, we carried out experimental researches on the detonation property of SASN ignited by a light flash.First we presented the basic and sensitivity characteristics of SASN, and then based on the analysis of its light-initiated mechanisms, we succeeded in igniting a large area of SASN sprayed layer by a light flash with high voltage, and conducted tests on the detonation characteristics of SASN sprayed layer initiated by light.The results indicate that SASN is a relatively safe agent of light-sensitive explosive with a relatively low detonation velocity of sprayed layer capable of providing low impulsive loads.The test results confirmed that the specific impulse of explosion from SASN is almost linear to the areal density of sprayed layer under the conditions of low-level density.

In this work we presented an improved form of the drop-weight system in which, instead of being impacted directly by the drop weight, the sample was impacted by the upper anvil which was beforehand impacted by the drop weight.Based on this improved drop-weight system, the ignition and burning processes of HMX based plastic bonded explosives were recorded by a high-speed camera at the microsecond time scale.The experiment results indicate that, under low pressure and long pulse loading, heterogeneous explosives mainly undergo the process of compression→plastic flow→particle breaking→formation of local high temperature region→initiation→burning→quenching, which is a typical non-shock initiation process.But, because the explosive is heterogeneous at the mesoscale, the location of the high temperature region, the reaction duration and the reaction violence of heterogeneous explosive samples are different from each other under the same experimental conditions.