Axisymmetric unit cell model calculations are used to study void growth in a material containing a periodic array of spherical voids under different loading rate rates. Numerical results show that: (1) Micro-inertia is found to have a strong stabilizing effect on void growth process; (2) The growth rate of void increases with the square root of mean stress; (3) Accounting for micro-inertia effect on void growth and percolation stress relaxation during the void-coalescence process, a simple dynamic damage evolution model is proposed for elastic-rigid-perfectly plastic materials; (4) By using of the proposed model the spall tests on copper under different impact velocities are simulated, and the numerical predictions are in good agreement with the experimental measurements, verifying the model applicability.

The minimum ignition energy is one of the important properties to estimate the fatalness of combustible gases. To get a theoretical value of minimum ignition, a physical model of spark ignition of the combustible gases was established, and a minimum ignition energy prediction method of combustible mixtures through a numerical analysis was given. The critical temperature and minimum ignition energy of methane-air mixture during spark ignition process were obtained. The results shows that MIE of methane-air has a U-shaped relationship to concentrations, and the MIE of premixed gas under concentration of 8.5% is 0.39 mJ, which agrees well with the experimental value.

Cr or Ti is coated on diamond surface by magnetron sputtering, and diamond with active metal coating/copper composite materials is sintered under high temperature and high pressure. The experimental results show that the introduction of active metals enhances the bond strength between diamond and copper, reduces the thermal boundary resistance and improves the thermal conductivity of diamond/copper composite materials. In addition, the experiments indicate that the thermalconductivity of the composites decreases with increasing diamond content and the reducing grain size of diamond. This phenomenon is attributed to the thermal boundary-resistance. The thermal conductivity of diamond/copper composite materials can be increased by increasing the grain size of diamond and improving the interface of diamond and copper.

Concrete is a widely used composite. The study of dynamic performance and anti-penetration effects on concrete is dependent on the numerical simulation, and the HJC model is often used in numerical simulations. On the basis of introduction about HJC model, parameter sensitivity analysis on HJC model by LS-DYNA numerical simulations is studied in the paper. There are five parameters (f_c, p_lock, A, B and N) are sensitive. According to the sensitivity parameters, it can improve the accuracy and quality of numerical simulation and the reasonable test methods and arrangements for testing chosen.

Using a two-stage light gas gun and shock recovery technique, a series of experiments up to 40-65 GPa were carried out on the nitrogen-rich material of precursor g-C₃N₄. The powder X-ray diffractions (XRD) of recovered samples showed that the precursor g-C₃N₄ was stable under 51 GPa pressure, while only a new crystalline phase β-C₃N₄ was obtained during 51-65 GPa pressure. The results confirm that β-C₃N₄ can be synthesized directly from precursor g-C₃N₄. This paper is significant for the study of synthesizing pure superhard carbon nitrides.

In some types of plasma, there did not exist an electrode or reference point. The electrode or reference point was needed when applying a bias voltage to a Langmuir probe. To acquire the characteristic parameters of transient plasma generated by hypervelocity impact, diagnostic system was established. The new electrostatic probe diagnostic system utilizing the double-Langmuir probe was given, in which no voltage and frequency sweep was required. This method can measure electron temperature and electron density as a function of time. This new instrument was based on a double-channel circuit, the current and voltage spectra were obtained from the probe synchronously by a digital oscilloscope. The aim of this work was to apply the double-Langmuir probe diagnostic system to time-dependent plasmas generated by 2024-T4 aluminum projectile hypervelocity impact 2024-T4 aluminum target.

The quasi-static and dynamic compression tests for Hf_44.5Cu₂₇Ni_13.5Ti₅Al₁₀ metallic glass were done by MTS810 and split Hopkinson pressure bar (SHPB) in the range of strain rate of 10^—4-10³ s^—1. The compressive stress-strain curves were obtained under varied strain rate and the fracture morphologies were studied by scanning electron microscopy. The experimental results show that the Hf_44.5Cu₂₇Ni_13.5Ti₅Al₁₀ metallic glsaa does not have the strain rate sensitivity under quasi-static compression. The dimple structure and periodic corrugations with about 60 nm spacing can be observed at the fracture surfaces which consist of radical zone and fan-shaped zone. Under dynamic compression, the yield strength rapidly declines with rise of strain rate, the metallic glass has the strain rate sensitivity. The fracture surfaces show floccule structure with vein-like patterns. Further observation reveals that dynamic compression fracture surfaces exist three fracture morphology: branch-like patterns, vein-like patterns and molten agglomerates.

A phase transition concerning lithium aluminate oxide (LiAl₅O₈) was observed. High pressure synchrotron radiation X-ray diffraction was used to explore its structure in a diamond anvil cell up to 47.0 GPa. We found the two phases are coexisted over a very large pressure range in the experiments. According to the analysis on the dynamic change of diffraction peaks with the increasing of pressure and the data reduction using indexed program, a new high-pressure phase of LiAl₅O₈ was identified at pressure below 45.0 GPa. This new phase has potentially a orthorhombic structure with a=0.995 9 nm, b=0.644 7 nm, c=0.333 4 nm and the space group of Pmm2.

As a novel non-thermal food processing technology, high hydrostatic pressure (HHP) is showing broad application in food industry. Compared to traditional technologies, this technology exhibits significant advantages in the retention of food quality, inactivation of microorganisms and enzymes. In this review, based on the comprehensive analysis, regulation of sub-lethal cells' membrane, genetic and structural components, metabolism under HHP treatment and a majority of sub-lethal food microorganisms general responses when exposed to some stresses are reviewed, and the stress response of sub-lethal food microorganisms exposed to HHP is discussed in this paper.

Using detonation-driven flyer, the samples of C₆₀ were shock loaded. For toluene extraction, the soot was examined by high performance liquid chromatography (HPLC). The results showed that most of C₆₀ was decomposed, a small part was changed into polymer, high fullerene, endohedral and other carbon cluster under shock wave high temperature high pressure. Under the shock waves of different intensity, the influence of the temperature and pressure on the decomposition and polymerization of C₆₀ were studied. The destruction mechanism of C₆₀ and the formation of the polymer of C₆₀ were also discussed.