High-current pulsed electron beam (HCPEB) technique was used to irradiate the AISI 304L austenitic stainless steel. The vacancy defect clusters of the irradiated surface layer were investigated by using transmission electron microscopy. The experimental results indicated that a large number of supersaturation vacancies involving vacancy dislocation loops and stacking fault tetrahedra (SFT) were induced on the irradiated surface layer after HCPEB irradiation. Additionally, surface morphologies of the irradiated samples were characterized by optical microscope，scanning electron microscope and non-contact optical profiler in detail. It was found that high density, fine and dispersed micropores were inevitably formed. The dominating formation mechanism of surface micropores should be attributed to the migration of large number of vacancies (clusters) defect along line and (or) surface structure defects towards the irradiated near-surface layer during HCPEB bombardment and cause vacancies accumulation. The present results indicate that HCPEB technique is a new method to successfully fabricate the surface porous metallic materials by selecting appropriate materials and adjusting HCPEB process parameters.

Microorganism in food is one of the most important factors which cause food to decay. As one method of sterilization, ultra-high pressure has achieved significant effect in food manufactory. After a brief introduction to fundamental principle of ultra-high pressure sterilization technology, this review laid stress on the effects of high pressure on microbiological cellular configuration, metabolism, and hereditary mechanism. Finally, applications of ultra high pressure in food industry were prospected.

Using a cubic-anvil high pressure apparatus, Nylon 6 samples were annealed under different pressures. The crystallinity and crystal structure changes of Nylon 6 were studied by the methods of wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and infrared spectra. The results showed that the adjustment of nylon 6 molecular chains was suppressed because of the pressure loading, and the formation of the crystals was mainly realized by the reaction of transamidation.

In order to perform extensive research on the coaxial collision of elastic bar, finite element model was established based on LS-DYNA, the influences of the shape parameters of variable section bar on the stress wave were analyzed, producing mechanism of stress wave was discussed, and its application and development prospect in this field were also explored. The results show that, because of the variable section effect, the coaxial collision of variable section bar under conditions of some shape parameters can create the stress wave, which has the following characteristics: wave front rising is in the form of smooth concave curve, the rising time is longer and there is no waveform oscillations phenomenon. The characteristics are the intrinsic attributes of the coaxial collision of variable section bar, controlled mainly by minimum radius of variable section scope in bar, and length of variable section scope in bar exerts an influence on the partial difference; besides, the characteristics are not sensitive to the change of the loading speed. The laws obtained by the coaxial collision of variable section bar can be applied to many fields such as waveform shaping. Thus it can be seen, these laws extend the foundational theories, which can be of great theoretical and realistic significance, and moreover, its application prospect is wonderful.

An instrument design of a high-pressure optical cell system for in situ detection of aqueous samples was reported, including a manual pump, a pressure multiplier, and a high-pressure cell. The cell with three optical windows can be used within a pressure range of up to 600 MPa, using water as the pressure transmitting medium. When JGS1 quartz windows were employed, the safe pressure was around 300 MPa. The hermetic sealing effect of quartz was so good that the pressure was hold very well during experiments. In order to demonstrate the functioning of the system, the fluorescence spectra of tryptophane was determined at different pressures.

To investigate the large penetrated hole's performance of shaped charge against multi-layer target, a titanium alloy liner of shaped charge is proposed. Using the method of experimental and numerical simulation, the jet formation and penetration into multi-layer target are investigated. Difference among the explosion energy conversion, jet tip velocity, jet length, penetration performance, and also the shock wave propagation in the penetrating process are analyzed, for which liner materials include titanium alloy, mild steel and Cu. It is found that compared with the mild steel or Cu liner, the liner material made of titanium alloy has a larger energy of jet whose shape is podgier, the depth as well as diameter of crater is bigger. Although the penetration depth decreases slightly, the size of crater formed in concrete increases obviously and the average penetrated hole diameter on multi-layer increases by 20%.

In order to probe into the damage mode and its mechanisms, a box-like beam was designed, and numerical analysis and experimental verification were carried out. In the discussions, how vertical bending load forms was investigated, and the properties of flow-field were analyzed in details when explosion bubble oscillates, how explosion parameters affect the dynamics of beams was attained, and the basic condition for beam sagging damage was initially proposed. The results show that there exists a low-pressure zone like a “concave” in the fluid between beam and explosion bubble when the bubble contracts in the near-field, and the low-pressure field causes the sagging damage. If the parameter of λ, the ratio of stand-off to maximum bubble radius, meets 1<λ<2.5, explosion bubble will possibly cause beams damage into sagging condition. The smaller the value of parameter λ, the greater the impact damage.

Experiment and simulation of cylindrical charge underwater explosion bubble motion has been conducted to investigate the collapse mechanism of non-spherical bubble and the behavior of its jet. The experimental results were compared against the numerical results for different configurations of charge. Results show that jet generated by a non-spherical bubble behaves different from that of a spherical bubble, which could be attributed to the variance of radius of curvature on the bubble interface. The collapse time for an initial bubble surface with bigger radius of curvature is earlier than that with smaller radius of curvature. As a result, the water jet may exhibit an asymmetric form.

We studied an optional/dual-mode warhead with an ejectable cross-shaped cutting reseau fixed at a proper place before the liner to realize multi-function of ammunition based on 60 mm arc-cone liner Explosive Formed Projectile (EFP) charge configuration. The optional/dual-mode warhead can change the kill elements mode according to the target properties (heavily or lightly armored targets), and can form single EFP or MEFP (Multiple Explosively Formed Projectile) to provide the most effective attack. The whole process of formation, flying and penetration of single EFP and MEFP was simulated using LS-DYNA3D. The simulation results are in good agreement with the experimental data. This study indicates that the single EFP has a good aerodynamic stability at a velocity of 1 508 m/s and it can penetrate through the 45 steel targets with a thickness of 30 mm; While the MEFP has a velocity between 1 500 and 1 750 m/s with an even distribution and can penetrate through the 45 steel targets with a thickness of 6 mm. The obtained results provide important reference to the design of dual-mode warhead.

Based on parallel computation of explosive blasting in concrete and analysis of the numerical result as well as study on the foundational theory of explosion mechanics, a conclusion has been drawn that in the process of explosive blasting in rocks, explosive energy is released by way of shock waves' several times reciprocate reflect in blast cavity which is full of explosion product while rock mediums are damaged and moved, and the interface loses gradually its positive expansion velocity along with the rarefaction wave in blast cavity.