Water is not only omnipresent on the Earth but also ubiquitous in the solar system such as on comets, asteroids, or icy moons of the giant planets. Hence, exploration of different forms of ice in different environment has significant implication to physical science, chemical science, bioscience, geoscience and planetary science. Depending on the surrounding conditions of pressure and temperature, water ice exhibits an exceptionally rich and complicated phase diagram. To date, at least eighteen crystalline ice phases (ice Ih, Ic, ice II to ice XVII) have been identified under laboratory conditions. In addition, there are many hypothetical ultralow-density ice phases from clathrate hydrates, such as structure I (s-I), structure II (s-II), structure H (s-H), structure K (s-K) and structure T (s-T) ices. Recently, the s-II clathrate ice (ice XVI) produced in the laboratory emerges in the negative pressure part of phase diagram, which stimulates greatly people to explore the other low-density clathrate ices. Using extensive Monte Carlo packing algorithm, classical molecular dynamins simulations, and dispersion-corrected density functional theory optimization, we predict two cubic clathrate ices with ultralow densities, and name them as s-III (ρ=0.593 g/cm³) and s-IV (ρ=0.506 g/cm³) clathrate ices. The unit cell of s-III clathrate ice is composed of two large icosihexahedral cavities (8⁶6⁸4¹²) and six small decahedral cavities (8²4⁸), while the unit cell of s-IV clathrate ice is constructed by eight large icosihexahedral cavities (12⁴6⁴4¹⁸), eight intermediate dodecahedral cavities (6⁶4⁶), and six small octahedral cavities (6²4⁶). For these two clathrate ices, the large-sized icosihexahedral cavities and the unique packed patterns among different cavities result in their record low densities. Considering all the low-density (lower than ice XI or equal to ice XI) ices, we construct a new p-T (pressure-temperature) phase diagram of water with TIP4P/2005 model potential under negative pressures. Below the deeply negative-pressure region of s-II clathrate ice, s-III and s-IV clathrate ices replace s-H clathrate ice, arising as the most stable ice phases in the high-temperature part and the low-temperature part, respectively. As a result, a triple point (T = 115 K, p = –488.2 MPa) appears in the phase diagram. The density functional theory calculations suggest that the s-III and s-IV clathrate ices can be fully stabilized by encapsulating an appropriate guest molecule such as dodecahedrane molecule (C ₂₀H₂₀) and fullerene molecule (C₆₀) in the large cavity, respectively. Considering that the guest-free s-II clathrate ice has been produced in the laboratory, which is also recognized as ice XVI, both the s-III and s-IV clathrate ices can be viewed as potential candidates of ice XVIII or ice XIX. Computations show that the hydrogen storage capacities of s-III ice clathrate amount to nearly twice of those for the s-II ice clathrate at low temperature and room temperature, which satisfies the DOE ultimate target for on-board hydrogen storage.

High pressure shock and α-decay radiation are two extreme conditions capable of leading to damages on crystal lattices of solid materials. The present work investigated the influence of shocking on the structural variations of titanite (CaTiSiO₅) using a gas gun shock-wave technology. The results were used to compare the similarities and differences in spectral and structural changes between shocked and α-decay radiation damaged titanite, as α-decay radiation process was considered as involved in a fast high pressure process. The results showed that high pressure shock and α-decay radiation can both produce defective crystal lattice and even amorphous phases in titanite, resulting in a decrease in band intensity, a line boarding and a loss of spectral details in X-ray diffraction patterns, infrared and Raman spectra. However, there are distinct differences in the detailed processes and damage mechanisms between the two processes. High-pressure shock causes the main peak of the Ti-O stretching vibration in titanite shifts to a lower frequency, which is opposite to its behaviour in radiation damaged samples. Furthermore, shocking leads to a reduction of unit cell parameters a, b, c and cell volume V, quite contrary to a unit-cell swelling caused by radiation damage.

Lead selenide (PbSe) has received extensive attention in recent years as a non-tellurium thermoelectric material. In this paper, PbSe-PbS solid solution alloys (PbSe_1–xS_x) were prepared by mechanical alloying combined with high pressure sintering method. The influence of Se/S content on its structure and thermoelectric properties was studied. The results demonstrate that the mechanical alloying method can rapidly synthesize PbSe_1–xS_x solid solution alloy powder, and achieve rapid densification by high pressure sintering. The electrical transport properties and conductivity type of PbSe_1–xS_x powder can be controlled by adjusting the Se/S ratio; solid solution alloy can realize short-wave phonon scattering, which significantly reduces the thermal conductivity of PbSe material. When x = 0.5 and the temperature is 600 K, the highest quality factor of PbSe_1–xS_x is 0.54, which is 64% higher than that of PbSe (0.33@450 K).

The crystals of Ir₂P were predicted under the pressure ranging from 0 to 100 GPa using the CALYPSO structure exploration technique with the first-principles method based on the density functional theory. The predicted physical properties and crystal structures were examined in detail. At ambient pressure, the predicted α-Ir₂P phase was found to have a cubic structure with Fm3m space group, which is consistent with the experimental structure. The pressure-induced structural transformations were unraveled, from the α-Ir₂P phase to the β-Ir₂P phase at 86.4 GPa. The predicted β-Ir₂P phase has I4/mmm space group. In the process of phase transition, the volume of the crystal collapses and a discontinuous first order phase transition occurred. The calculation of the electronic properties showed that the predicted conduction bands and the valence bands of the β-Ir₂P phase overlap near the Fermi surface at 86.4 GPa, indicating that the structure of the β-Ir₂P phase has metallic properties. The electron localization function revealed that the β-Ir₂P phase has a polar covalent bond, a metallic bond and an ionic bond. The Bader charge transfer calculations showed that each P atom transfers 0.19e to Ir atom, mainly due to the strong electronegativity of the Ir atoms.

The evolution processes of metal/gas (Li/H₂) interface at extreme impacting conditions (22.50–78.75 km/s) were numerically studied by molecular dynamics (MD) method incorporated with the electron force field (eFF) model. It was found that the strong shock compression leads to ionization and the electron/ion separation is produced due to different diffusivities of ions and electrons. Then a strong extra electric field was established adjacent to shock font. Through 1D statistic along shock propagating direction from MD results and theoretical analysis, it was found that the electron/ion separation is moving with shock and the intensity and width of electron/ion separation zone are kept to be constant during shock propagating process and determined by shock strength. Further integrating the extra electric field and extra acceleration of metal material adjacent to the interface, the time histories of material acceleration were obtained. It was found that the extra material acceleration curves were in accordance with Rayleigh model. The key parameters were fitted based on computation results. Finally, an empirical extra acceleration evaluation model of metal material on Li/H₂ interface under impact velocity range of 20–80 km/s was established.

By using our in-house large-eddy simulation code, the MVFT (multi-viscous-flow and turbulence), we simulated the Richtmyer-Meshkov (RM) instability and turbulent mixed with the inverse chevron interface on a 3D large scale on the HPC (high performance computing) platform. The results revealed the propagations of the decomposed shock wave, the rarefaction wave, the compression wave and the interactions between the waves and the perturbed interface. Each impact of on the wave on the interface accelerates the evolution of the turbulent mixing zone and the materials’ mixing. The inverse chevron interface inverts its phase after the first transmitted shock wave in the SF₆ zone hits it, then two wall bubbles and a centerline spike with large scale develop gradually. The averaged geometry feature and the envelop of turbulent mixing zone are determined by the large-scale wall bubbles and the centerline spike and are independent of the mesh. But with the higher grid resolution, more subtle small scale turbulent eddies and intense turbulent fluctuations are captured, characterizing the turbulent mixing zone as possessing a complex structure.

Diamonds with excellent performances were used widely in national defense construction, mechanical processing, electronic science and technology, and so on. The demand for diamonds at home and abroad is also increasing. Finite element method (FEM) is suitable for simulation analysis of complex geometric structure and physical problems. FEM is applied to the optimization of synthetic technology and corresponding device for diamond. In this paper, the application progress of FEM in the apparatus of high pressure and the chamber of diamond synthesis are reviewed. Firstly, hinge beam and working cylinder are simulated and analyzed by considering facts such as static forces, stress strength, stress distribution, and deformation. Also, the mechanism of the action, the damage, and the new design for anvil were simulated and analyzed by FEM. Secondly, it is summarized that the application progress of diamond chamber with temperature field, pressure field, and electrical field, etc. is simulated and analyzed using FEM. Finally, the application prospect of FEM in diamond synthesis is forecasted.

A novel tangential split apparatus was designed to improve the pressure bearing capacity of the ultra-high pressure die. The tangential block structure can not only eliminate the circumferential tensile stress of the inner wall of the cylinder through mutual friction and extrusion on the split surface, but also generate a large circumferential compressive stress on the inner wall. This pressed state is very advantageous for the cemented carbide material and can significantly increase the ultimate pressure capacity of the cylinder. The numerical simulation results show that under the same load conditions, the equivalent stress of the segmented cylinder is significantly less than that of the belt cylinder. The three principal stresses on the inner wall of the block cylinder are compressive stress, and the difference is small. These stresses are close to the isostatic pressure state, so the cylinder can withstand higher sample chamber pressure. The comparative experimental results also prove that the tangential split-belt ultrahigh pressure apparatus has higher ultimate load carrying capacity.

A crystal plasticity finite element model combined with equation of state was built to simulate the dynamic elastic-plastic large deformation behavior of <100> LiF under high-rate shock loading. The characterization of the stress wave profile, the patterns of the dynamic mechanical evolution and their essential causes in view of the continuum mechanics were obtained through simulations, with the following results achieved: (1) the wave profiles of millimeter-sized specimens exhibit elastic-plastic two-wave response, elastic precursor decay and stress relaxation below 15 GPa; (2) in view of continuum mechanics, the stress relaxation is essentially due to the viscous plastic flow which accounts for the increase rate of the total strain being less than that of the plastic strain, and which further reduces the elastic strain and pressure; (3) the third derivative of pressure to time being greater than zero was proposed as a criterion for estimating the critical pressure of the two-wave and the one-wave response of the stress wave profile, and the estimation result indicated that the critical pressure increased with the increase of the doping concentration in specimen; (4) the effect of temperature rise during the high-rate shock deformation is non-negligible, and the elastic volumetric deformation contributes to most of the temperature rise.

In order to study the change law of physical parameters in the process of rock fracturing and throwing during slope bench blasting, the equation of rock damage under dynamic tension-compression effect was established and applied to numerical analysis. The results showed that the tendency of time node and step size in simulation was basically identical with the triaxial synthetic rate curve of vibration wave and particle vibration displacement, which can be used as a criterion for reducing vibration and decreasing disaster. Cracks were formed in the foot of slope at about 0.6 ms and completely extended at about 12.5 ms. The pulverizing area radius around the blast hole was 28 cm. The rock separation phenomenon was preliminarily observed at the middle part of the blast hole. The maximum throwing velocity was distributed in the vertical region between this part and the free surface of the slope. The throwing velocity at the free surface was less than that of the rocks around the blast hole, which results in the secondary crushing phenomenon during the throwing process. The large bulk rocks were mainly produced in the toe of slope, the surrounding rock on both sides of the contact surface between explosive and plug, and the free-surface at the top of the step. The range of large rock diameter in the process of blasting was 1.6–2.7 m.

A new approach is presented herein to predict the failure of metallic materials. A failure criterion that caters for the effects of stress triaxiality and Lode parameter is proposed and it is applicable not only to metals with ē_f > e_f but also to metals with ē_f ≤ e_f , here ē_f and e_f are the two parameters defined as the true strains at stress triaxiality of η = 1/3 for Lode parameters of ξ = 1 (axisymmetric stress state) and ξ = 0 (plane strain state) respectively. Furthermore, only two laboratory tests such as smooth bar tension test and pure shear test are needed to calibrate the failure criterion. The present failure criterion is proved in good agreement with the test data for various metals under different loading conditions.

The Lagrangian analysis method was employed to investigate the deformation mechanism and stress response of graded metallic foams. The mesoscopic finite element models of the graded metallic foams with five different density gradient parameters were constructed by the 3D-Voronoi technique, and the corresponding Taylor numerical tests were performed under high-speed impact, and the particle velocity distributions of different graded foams were obtained. By combining the Lagrangian analysis method with the results of Taylor numerical tests, the effects of density gradient parameters on the local strain distribution, stress distribution, shock wave propagation and attenuation of metallic foams under high-speed impact were investigated. The results show that the metallic foams with negative density gradient have better resistance to vertical deformation than those with positive density gradient, and the deformation degree decreases with the decrease of the density gradient parameter. The local densification stress distribution of the metallic foams with negative density gradient decreases linearly, and the maximum local densification stress increases with the decrease of the density gradient parameter. The metallic foams with negative density gradient have high load bearing capability near the impact end. The local densification stress distribution of the metallic foams with positive density gradient has a plateau stage, and the maximum local densification stress is less than metallic foams with negative density gradient.

In this work we investigated the quasi-static and dynamic compression of spherical cell aluminum foam with homogeneous pore morphology and size. We identified the deformation mechanisms of the aluminum foam in the quasi-static compression at both macroscopic and mesoscopic levels using digital image correlation. The results showed that the compressive strength, plateau stress and energy absorption were significantly improved by increasing the loading strain rate, that is, the spherical cell aluminum foam exhibited obvious strain rate sensitivity. Because of the inhomogeneous cell wall thickness and the random distribution of cell wall defects, the deformation bands dominated the compressive behavior during the compression process, and the strain concentration zones were observed on the single cell hole where the cell wall defects were identified. Meanwhile we examined the implications of compressive behaviors operating on the mesoscopic cell walls and the formation of macroscopic deformation bands. The deformation modes of cells mainly fell into 3 types, i.e. axial compression, shear, torsion and shear combined deformation. The failure mode of the cell walls throughout the deformation zone was mostly determined by shear deformation, which was obviously related with the cell wall thickness and the loading direction.

In this work we performed blast loading tests on basalt fiber-aluminum alloy laminates and carbon fiber-aluminum alloy laminate using an explosion impact pendulum system and obtained different loading impulses by changing the quality of the explosive, thereby analyzing the influences of load impulse, structure combination and fiber type on the deformation/failure mode of fiber metal laminates and revealing the laminates’ typical failure modes such as delamination, matrix failure, metal tear and plastic deformation. The experimental results showed that the plastic deformations of the aluminum alloy layer in the fiber metal laminate and the damage area of the fiber layer increase with the increase of the impulse, and the fiber metal laminates have better impact resistance than that of the single metal laminate.

In this study we analyzed the shock initiation process of covered TNT using experiments and LS-DYNA3D to study the damage effect of the near-field strong shock wave on the covered charge. We obtained the critical thickness of the covered plate for detonating TNT during contact explosion and the sympathetic detonation distance of the covered TNT during non-contact explosion and the relation between the covered plate thickness and the distance of the explosion using the non-linear least square method. The results show that the numerical simulation results accord well with the experimental results. The sympathetic detonation distance of the covered-pressed TNT in non-contact explosion ranges from 12-15 mm when the thickness of the 45 steel covered plate is 3 mm. The critical thickness of the covered plate is between 20 and 23 mm for the pressed TNT ignited by contact explosion. The sympathetic detonation distance of the non-contact explosion decreases as the covered plate thickness increases. Without a covered plate, the sympathetic detonation distance is 79 mm. When the thickness of the covered plate increases from 1 mm to 5 mm, the sympathetic detonation distance reduces from 51 mm to 1.5 mm. The thickness of the covered plate is of great importance for the protection against shock waves.

Two charge samples of same composite and shape, but one with and the other without an aluminum interlayer, were prepared following the designated inner/outer composite charge. The expansion process of the aluminum interlayer was determined by X-ray technology, and the difference in the driving capability between the two charges were compared using the high speed scanning and the cylinder test. The results show that the detonation wave does not change obviously due to the similar impedance. The detonation products of the inner and outer charges can be divided by the interlayer when the relative specific volume is below 3.0. However, the driving ability is not affected and the ratio of the specific kinetic energy of the two charges is gradually close to the ratio of the two effective charging masses.

In this study we investigated the residual characteristics of the high velocity fragments penetrating the protective liquid cabin using finite element analysis by ANSYS/LS-DYNA, found out about the variation of the penetration depth and the velocity of the fragment after the fragments’ penetration into the vertical and inclined liquid cabins, and discussed the optimal inclination angle of the liquid tank in a ship. The results indicated that the presence of the inclination feature of the liquid cabin helps to reduce the instantaneous velocity of the fragments entering the water, and the velocity dropped faster in water with the increase of the instantaneous velocity of the fragments. In the stage of impact and cavitation, the penetration depth of the fragments rose immediately, and the larger the instantaneous velocity, the faster the increase of the penetration depth. The penetration depth in the two phases was about 10% of the final penetration. Judging by the rate of the decrease of the projectile’s velocity and that of increase of the fragments’ penetration depth, we conclude that the tank with a tilt of 60° can achieve better protection.

In this work we improved the explosion shock wave mitigation capability of the interruption structure in the tandem cutting warhead and matched the front shaped charge with the post-stage projectile and the explosive interruption by installing the explosive interruption structure between the front cutter and the rear following projectile, and established the simulation model using ANSYS/LS-DYNA, a finite element analysis software. We also analyzed the mitigation capabilities of the structures in different combinations and compared their explosive interruption capabilities using numerical simulation. The results showed that the explosion shock wave first converged to the inner region of the projectile, rather than to the tip of the warhead, so that the tip area of the outer metal flameproof medium was thinned properly. When the outer metal turned from hard steel to aluminum, little change was observed in the stress peak value of the rear end shell, suggesting that the outer metal medium was aluminum. Judging by the comparative study, the aluminum polyurea flameproof capability was superior to the aluminum foam-aluminum structure. Finally, the "soft" explosive interruption medium was determined to be polyurea, and the best explosion proof parameters were determined by adjusting the thickness of the aluminum and polyurea layer, which serves the needs of practical applications.

To investigate the penetration of steel plates by fragment simulated projectiles (FSP), we carried out a theoretical analysis of the steel plate’s penetration process, dividing it into 4 stages, sequentially of initial contact, penetration, plugging and perforation and successfully obtaining the formula that calculate the penetration remaining velocity and energy transformation. The calculation result is in good agreement with theresults from experiment and finite element observation. The formula is applicable to practical steel plate design.

In this study we aimed to study the effects of high hydrostatic pressure (HHP) with bamboo vinegar (BV) on enhancing the quality and improving the protein properties of perch (Lateolabrax japonicus) fillets over refrigerated storage. We treated fillet samples stored under refrigerated conditions at 4 °C using HHP (250 MPa, 9 min) along with 0, 1%, 2%, 3% BV respectively. We calibrated the physicochemical qualities (color difference, pH value, electrical conductivity and total volatile basic nitrogen (TVB-N) value) and examined the changes that occurred in terms of the sensory impressions and protein properties (actin globulin content, total sulfhydryl content, TCA soluble oligopeptide elution) of the samples on the 1^st, 4^th, 8^th, 12^th, 14^th, 16^th, and 18^th day respectively during the storage time. The results showed that the samples exhibited obvious quality improvement: the TVB-N value of the samples treated by HHP with 3% BV was (31.88±1.33) mgN/100 g on 18^th day, significantly lower than that of CK group ((44.77±1.89) mgN/100 g). In addition, the treatment also reduced the increase of the pH value and electrical conductivity, thereby significantly slowing down the protein degradation and maintaining its good characteristics. Finally, the shelf life of the perch fillets thus treated in cold storage was prolonged by four days.