The dynamic mechanical behavior and rate constitutive model of reactive powder concrete (RPC) after exposure in high temperature are studied experimentally by means of split Hopkinson pressure bar system. Both the untreated specimens and those after exposure in high temperature (400, 600 and 800 ℃) are tested with lead flakes as pulse shapers. The experimental results show that both dynamic compressive strength and toughness of RPC after different high temperature treatments exhibit remarkable strain rate sensitivity while the peak strain and initial Young modulus do not. Furthermore, the dynamic uniaxial compressive mechanical properties of RPC at different strain rate debased after exposure at high temperature over 400 ℃. The scanning electron microscope (SEM) technology is also used to investigate the microstructure change of the RPC material; it proves that the deterioration of microstructure is the essential reason for the reduction of the RPC's macroscopic mechanical performance. In addition, ZWT viscoelastic constitutive model is utilized and modified, thus it can be used to analysis the rate constitutive relations of concrete after exposure in high temperature.

It is very important to develop a high time and space resolved velocity diagnostic technique for laser-driven shock wave experiments. However, it is still a difficult problem because of the limited size of laser-launched mini-flyer and ultra-short loading time in shocked sample. Thus, a micro focus Doppler pins system with time resolution of 50 ps and spatial resolution of 200 mm has been developed in our nanosecond laser-driven shock wave experiments, to perform an integrated velocity profile measurement from laser driven mini-flyer to impacted sample. The measured particle velocity of Z-cut quartz sample is 1.27 km/s while the impact velocity of 6 μm-thick Al foil flyer is 2.48 km/s, which is in agreement with the calculated Hugoniot results. This validates our technique. Using our technique, the experimental results for three different types of mini-flyers show that the “substrate/deposit layer/silicone oil/Al foil flyer” structure has higher laser energy coupling efficiency and better integrity. This is valuable for designing a laser-driven shock wave experimental assembly. These results indicate that our technique is a viable approach for studying dynamics of laser-driven shock wave in materials.

An ultra high hydrostatic pressure device with operating pressure of up to 1.6 GPa is designed and developed, and its design principle, structural characteristics and major technical difficulties are introduced. The structures and optimum parameters of high pressure processing chamber, sealing system and pressure sensor system are also studied and determined. The performance test results prove that it has the advantages of reasonable structure, easy operation, steady performance and reliable security. Furthermore, the pressure-resistant mushroom polyphenol oxidase is completely inactivated after treated at 1.6 GPa for 1 min by using this equipment.

The electrical conductivity of albite was in-situ measured at pressures of 1.0, 2.0 GPa and temperatures of 673-973 K using a.c. impedance spectroscopy method in YJ-3000t multi-anvil press. The experimental results indicate that the electrical conductivity (σ) of albite ranges from 10^-3.0 to 10^-5.5 S/m. The modulus and phase angle of complex impedance strongly depend on frequency. The electrical conductivity of samples rapidly increases with increasing temperature (T), and the relationship between lg σ and T^-1 fits Arrhenius relation. In addition, the electrical conductivity of samples decreases with increasing pressure in the investigated temperature and pressure range. The dominating conduction mechanism for albite is suggested to be the migration of sodium cations within the channels in the aluminosilicate framework.

The property variation of brittle material is closely related to its microstructure variation under shock compression. The present work is aimed to understand such a failure process by the measurement of electrical resistivity changes under weak shock compression. After improvements on the Weir's differental technique, the electrical resistivity of K9 glass has been measured under shock loading. Experimental results indicate that the electrical conductibility increases as shock wave propagating in the K9 glass. At the shock pressure of 7.6 GPa, the electrical resistivity changes gradually from the insulation state to a constant of about 420 Ω·m.

An investigation on the structure transformation, elastic and thermodynamic properties of TiN under high pressure is conducted using first-principles calculations based on density functional theory (DFT) with the plane wave basis set. At elevated pressures TiN is predicted to undergo a structural phase transition from a relatively open NaCl-type (B1) structure into a denser CsCl-type (B2) structure. The predicted transition pressure is 348 GPa. The elastic constants, Debye temperature, and heat capacity each as a function of pressure and/or temperature of TiN are presented.

An angular dispersion-type Fabry-Perot interferometer is developed to measure the velocity spectrum. Using this interferometer, the interference fringes with different Doppler shift are separated from each other in space, then the Doppler shift arise from a single moving source or multiple moving sources can be detected, and consequently the velocity spectra are obtained. The laser-driven aluminum foil experiments are conducted by the angular dispersion-type Fabry-Perot interferometer. Different kinds of velocity spectrum are obtained as the driving laser energy is changed, including velocity spectrum without velocity dispersion in space, discrete spectrum corresponding to a few pieces of broken aluminum foil with different speed, and continuous spectrum caused by fragment cloud or jet. Moreover, the fringe splitting caused by foil/glass interface separation under shock pressure loading is also observed.

Allyl Isothiocyanates (AITC) is a degradation product of thioglycoside in the red cabbage pigment extract, which limits the industrial applications of red cabbage pigment extract. In order to solve this actual production problem, the process and possible mechanism of removing AITC using high pressure carbon dioxide (HPCD) under different pressures and temperatures are analyzed with the AITC solution as experimental material. The results show that the removing process of AITC using HPCD follows the first-order kinetics model. Pressure is a non-significant factor (P>0.05) for the removing rate and half-life period, which indicates that the treatment pressure has little influence on the removing of AITC. Elevating treatment temperature can improve the removing rate of AITC nearly twice, and also shorten the half-life period, which indicates that the treatment temperature has more influence on the removing of AITC. The significant effect of the thermal degradation during the removing process of AITC by HPCD is verified by the further analysis.

Ceramics materials have been widely used in military projects, aerospace, aviation and ship structure protection, due to their good mechanical properties such as low density, high strength and high sound velocity. The destructive process of alumina ceramic impacted by a tungsten alloy projectile is simulated using smoothed particle hydrodynamics (SPH) techniques of AUTODYN. The simulation results are consistent with the experimental results, which indicate that the method is feasible and effective. The method proposed provides a convenient and economical way to study the failure behavior of alumina ceramic under strong impact loading.

The mixture of TiO₂ and dicyandiamide powder is processed by high energy milling at different milling speed and milling time. The structure and phase composition of the recovered samples are determined by X-ray diffraction (XRD). The results show that anatase transforms to rutile and srilankite appears at milling speed of 700 r/min. With milling time increasing, srilankite high-pressure phase content increases and gradually approaches a constant value. When the milling speed is raised to 1 000 r/min, the transformation of anatase to srilankite is dominant, and the mass fraction of srilankite high-pressure phase is increased greatly to 47.8%.

Motivated by the current interest in the mechanism of the deflagration to detonation transition (DDT), the DDT process and detonation wave structure of aluminum-air mixture are investigated experimentally by a large scale tube with length of 32.4 m and inner diameter of 0.199 m. The overall DDT process can be divided into slow reaction compression stage, pressure wave speed-up and shock wave formation stage, transfer from shock reaction to critical shock reaction, transfer from critical shock to overdriven detonation, and detonation stage. The optimal concentrations of mixtures in this experimental tube are obtained, and the critical concentration of DDT is also studied. Eight pressure gauges are well-distributed at each periphery of four certain sections in the 1.4 m long detonation testing tube for detonation wave testing. According to the test results, the detonation wave structure of aluminum-air mixture is analyzed, which shows single head mode.

To study magnetic field of the high field magnet powered by flux compression generator (FCG), a theoretical model is established by analysis of loading process. According to this model, a comparative study on magnetic fields of six high field magnets with different structures is carried out, and the variation laws of the magnetic fields are also acquired. The results show that the parameters of FCG are the main factor in the initial stage, which cause small differences of peak strength and range of magnetic field between six magnets; but in the flux compression stage, the influence of the magnetic structure is more and more important with the variation of circuit process, and the peak strength and range of magnetic field for different magnets are changed significantly. Furthermore, the structure of magnet plays the decisive role in the spatial distribution of magnetic field, which is not affected by the loading process.

Using AUTODYN-3D and the Stochastic random fragmentation model which based on the Mott's fragment distribution law, the scattering properties of the warhead fragments are numerically simulated and analyzed under three different ways of initiation including center point initiation, asymmetrical single point initiation and asymmetrical multi-point initiation. The results show that compared with center point initiation, the numbers of random fragments in the target area produced under asymmetrical single point initiation and asymmetrical multi-point initiation are increased by 37.12% and 62.86%, the availabilities of the fragments are improved by 4.01%-6.08%, and the average velocity gains are 25.95% and 28.37% respectively. Furthermore, the effects of the initiation radius on the scattering properties of the random fragments are obtained under asymmetrical initiation. It is shown that the numbers of fragments in the target area, the axial velocity and radial velocity are all reduced with the initiation radius increasing.

This study is aimed at the relation between maximal penetration depth and impact velocity for a long-rod penetrator vertically penetrating a semi-infinite target. The effects of impact velocity on the maximal penetration depth are obtained by numerical simulation. The results show that the threshold velocity exists in the process of penetrating due to the target strength and the interfacial effect, and the penetration enters into the quasi-steady stage from the dwelling stage only as the impact velocity of the penetrator is beyond this value, which is the key reason why the penetration depth does not change or increases extremely slowly with increasing impact velocity when the impact velocity is small compared with the threshold velocity. The penetrator velocity and penetrating velocity are close to a constant in the quasi-steady stage, and the positive linear relation between them is only related to the strength properties of the penetrator and the target, which is the main reason why the penetration depth linearly increases quickly with the impact velocity increasing when the impact velocity is beyond this threshold velocity.

Combustion and explosion experiments are carried out in an explosion tank of 10 m³ for the mixture of 8% methane-75 g/m³ coal dust-air. Optical method and pressure method are adopted to obtain the laminar burning velocity, flame speed, flame thickness, Markstein length as well as the explosibility index of the mixture when the flame spread. The results show that the burning velocity of the mixture of methane-coal dust-air is 0.437 m/s, while the value is 0.459 m/s according to the relationship between pressure and time, and the results from the two methods are coincide. The flames trends determined by flame thickness and Markstein length are the same, and both tend towards stability. The maximum of explosibility index occurs at 0.5 m, and the explosibility index at the wall of explosion chamber is a bit small.

On the basis of explosion gas dynamics, the movement of flyer plate is studied using characteristic curve difference method in this paper. In the process of difference, the basic assumption of steady detonation is used to study the law of flyer plate movement. According to the theory of two-dimensional steady flow, the compatibility relationship of characteristic curves is derived which belongs to general equation of state, with Mach number taking the place of the density of detonation gas. The movement parameters of flyer plate accelerated by TNT and emulsion explosives are calculated by the difference programs of characteristic curve. In addition, the flying postures of flyer plates driven by the two kinds of explosives at different mass ratio are also analyzed and compared with the calculated results by Ritchter's formula in terms of its accuracy.

In order to study the influence of lead powder on the properties of the copper-tungsten shaped charge liner, the experiments are carried out by adding 5%-20% of the lead powder to the original copper-tungsten liner. The results show that the addition of lead can reduce the porosity of liner; and with the increase of the amount of lead powder, both the penetration depth and the entrance aperture increase firstly and then decrease after reaching the maximum values when the lead content is 10%-15%. The reasons for this phenomenon are analyzed in detail from the liner molding, jet formation, stretching and penetration. Consequently, a reasonable explanation for the influence of lead powder on the properties of the copper-tungsten powder shaped charge liner is presented. The results provide a theoretical basis for making use of lead powder instead of bismuth powder to improve the penetration performance of copper-tungsten powder liner.

Detonation shock dynamics (DSD) method is an effective way to study the non-ideal propagation of detonation waves. Using the generalized geometrical optics model of DSD, the non-ideal propagation of detonation waves is studied for explosive grain with high slenderness ratio. A computer code is developed to calibrate the DSD parameters for JB-9014 insensitive high explosive by genetic algorithm. Calibration data are obtained from measurements of the detonation velocities and detonation wave fronts in JB-9014 explosive at low temperature of -30 ℃, with diameters of 10-30 mm. The steady-state detonation velocities and detonation wave fronts predicted by these DSD parameters can fit the experimental data within the experimental uncertainty.