An investigation on the structural stabilities and electronic properties of CaF₂ under high pressure was conducted using first-principle calculation based on density functional theory (DFT) with the plane wave basis set as implemented in the CASTEP code. Our results demonstrate that the sequence of the pressure-induced phase transition of CaF₂ is the fluorite structure (Fm3m) to the PbCl₂-type structure (Pnma), and to the Ni₂In-type phase (P6₃/mmc). The energy gap increases with pressure in the Fm3m and Pnma phases, then begins to decrease in the P6₃/mmc phase. The band gap overlap metallization does not occur up to 210 GPa. It is predicted that the metallization pressure of CaF₂ should be over 300 GPa. The pressure effect on the optical properties is discussed.

Using hBN-LiH or hBN-Li₃N-B as starting materials, we synthesied black cBN crystals under high pressure and high temperature. The results of Raman spectrum show that the reason why cBN crystals become black is that the redundant B atoms get into them. The cBN crystal is synthesized in hBN-Li₃N-B system, and then we observe a trigonal shadow is formed clearly. This phenomenon indicates that there are more B atoms from center to apex in cBN crystal, and the B atoms content gradually decrease from center to edge. However, the color of cBN crystal which is synthesized in hBN-LiH system was from transparent black to opaque black directly, and the trigonal shadow does not be formed. This phenomenon indicates that the B atoms as impurity diffuse equably in cBN crystals. The two circumstances illustrate that as an impurity atom, B has two kinds of distributions when it enter into cBN crystal: one is centeral symmetric distribution, the other is uniform distribution. In this paper, we analyze the reason why cBN crystals have different phenomenon above according to its growth environment and its ability of excluding impurity.

By high pressure and high temperature (HPHT) method, we used hexagonal boron nitride (hBN) as raw materials, Li₃N, Li₃N+LiH, LiH, LiH+LiNH₂, Li₃N+LiNH₂ as catalyst, and successfully prepared thick plate, spherical, octahedron or hex-octahedron, flat cone and flaky hexagon morphology cubic boron nitride (cBN) crystals with relevant growth conditions. It was summarized that various Li-based catalysts/additives had distinct effects on the cBN crystal morphologies synthesized.

The multi-material arbitrary lagrangian-eulerian (ALE) formulation and the penalty-based coupling approach were applied to simulate the air explosion and the interaction between explosive blast and curtain wall in resistance test of curtain wall by using LS-DYNA software. The dynamic behavior of glass curtain wall under blast loading was analyzed. Including the brittle failure of glass material in the model, the damage regions of inner and outer glass were reappeared in the numerical simulation. The numerical results are in agreement with the experimental observations, which will provide an important reference for the blast resistance design and improvement of glass curtain wall.

In order to understand the energy output characteristics for underwater explosion of explosive, especially the decay law of shock wave energy along with the distance, the efficient shock wave energy per unit mass was researched. In traditional empirical formulas, it satisfies the similarity law. The underwater explosion experimental results show that the shock wave energy, bubble energy and total energy per unit mass of TNT explosive are all in agreement with the empirical results. By analyzing the experimental results, the trend line of the efficient shock wave energy per unit mass decayed with the scale distance was obtained. Compared with the empirical results, it is found that the efficient shock wave energy decays more rapidly in small charge experiment.

Simple analytical equations are given to predict the perforation of fully-clamped thick metallic plates struck normally by rigid conical-nosed projectiles over a wide range of velocities based on the assumption that the deformation is localized and that the impact energy is dissipated only by penetration. It is further assumed that the mean pressure offered by the target materials to resist the projectiles consists of two parts: a quasi-static part due to the elastic-plastic deformation of the laminate materials and a dynamic part due to penetration velocity. Equations are obtained for the residual velocity and ballistic limit. It transpires that the present model predictions are in good agreement with available experimental data for thick metallic plates struck normally by conical-nosed projectiles.

Basing on the detonation theory, the structure of the deformable warhead was simplified to be double layer cylindrical shells under the detonation. Plastic hinges were introduced into the loading section of the shell, which contacted with the deforming charge, and the deforming charge was divided into small segments accordingly. Loading and movement of these segments were analyzed. Deforming shape of the cylindrical shell under the loading with equal distribution was bulgy, and the displacement of shell segments was obtained. Deforming charge with different thickness, according to the displacement of the segment, was set up to realize the same displacement of the shell segments on the loading direction. The D-shape was achieved theoretically, and the shape of deforming charge was designed accordingly. Numerical simulation validated the feasibility of the designed plan. The results indicate that the deformable warhead with the new-designed deforming charge can realize the D-shape.

By means of velocity interferometer system for any reflector (VISAR), X-ray diffraction (XRD) and scanning electron microscope (SEM), phase transition and spalling behavior of the FeMnNi alloy were studied through symmetric impact and reverse impact experiments. The FeMnNi alloy experiences a α→ε phase transformation when shocked to the pressure above 6.5 GPa. The FeMnNi alloy produces ε→α reverse phase transition and rarefaction shock wave when the pressure reduce to 4~5 GPa due to the rarefaction wave. By analyzing the interaction among plastic wave, phase transition wave, rarefaction wave and rarefaction shock wave, it was found that the FeMnNi alloy has a physical mechanism inducing the formation of spall behavior in symmetric impact experiments as the impact stress exceeds α→ε transition threshold.

An investigation on the structural stabilities and optical properties of BaX (X=S, Se and Te) under high pressure was conducted using first-principles calculations based on density functional theory. The results show that the sequence of the pressure-induced phase transition of these compounds is from the NaCl-type (B1) to the CsCl-type (B2) structure. The structural transition pressure and the metallization pressure are 8.57 and 45.4 GPa for BaS, 7.44 and 36.5 GPa for BaSe, 5.67 and 16.7 GPa for BaTe, respectively. The calculation of the optical properties showed that almost all peaks of the imaginary part of dielectric constant (ε₂) in the B1 and B2 structures shift towards high-energy region with increasing pressure (blue shift), and the static dielectric constant increases as the pressure increases.

Based on the pore collapse energy model, a new thermodynamic equation of state was derived to predict and describe the Hugoniot behavior of the silicon rubbers foam with different initial states. The model was tested on the silicon rubbers foam with initial densities of 0.52 g/cm³ and 0.92 g/cm³, respectively. Compared with the corresponding experimental data published previously, the results showed that this Hugoniot model can satisfactorily predict the Hugoniot behavior of silicon rubber foam.