A cell-centered arbitrary Lagrangian-Eulerian method based on a global grid generation technology was developed to simulate compressible multimaterial flows with large deformation. The method adapts well to subdomain grid generation and global grid generation. The static and dynamic numerical examples demonstrated the efficiency of the global grid generation. For the examples with complex regions, the calculated results show the efficiency of the global grid generation.

Weapons have to face some extremely abominable situations, such as high temperature, high pressure, shock loadings, etc. In such situations, the mechanical properties of the high explosive filled in weapons will decide the level of security of the whole system, making it necessary to get a deep understanding on the mechanical properties of these explosives. In this work, we tested the dynamic compressive properties of an aluminized polymer bonded explosive (PBX) at four temperatures (12, 29, 45 and 62 ℃) by using split Hopkinson pressure bars. Specimens were heated individually before fixed to the bars to get the target temperature. The strain rate was ranged from 250 s^-1 to 1 200 s^-1. The results show the failure compressive stress is strongly dependent on strain rates and temperatures, while the failure strain almost keeps constant. The failure stress increases obviously with the rise of strain rates and the decrease of temperatures. And a double-linear function is used to fit the compressive failure stress-strain rate-temperature relationship. However, this relationship for dynamic compression may become invalid when the temperature is lower than the glass transition temperature.

Based on gas-phase reaction mechanism, a fast cook-off model was established to study the process of RDX in a confined vessel irradiated by laser. The model considers steel vessel, air gap and condensed explosives. The heat conduction in air gap was used to describe the nonideal thermal contact. The process of decomposition, melting and evaporation in condensed RDX, and the reaction of multi-species and multi-steps in air gap were considered in model calculation by use of finite difference. Results show that the fast cook-off process of RDX can be approximately divided into three stages: inert heating, accumulation of reactants and increase of temperature, and ignition caused by rapid chemical reaction.

An analytical investigation into the penetration and perforation of thick metal targets struck normally by rigid ogival-nosed projectiles over a wide range of velocities was conducted. Based on the assumption that the deformation is localized and that the mean pressure offered by the target materials to resist the projectiles is no longer a constant but a linear function of penetration velocity, equations are derived for predicting the depth of penetration in the targets and the ballistic limits or residual velocity in the case of perforation. Furthermore, the range of applicability of the perforation model is discussed. It transpires that the present model predictions are in good agreement with the test data for thick metallic targets in terms of penetration depth, residual velocity and ballistic limits.

The small spinning solid rocket motor was employed to perform as the power of the radial twice throwing system. Interior ballistic model of spinning solid rocket motor, in which eroding burn effect was considered, was established. The calculated pressure-time curve was set as initial pressure value for subsequent simulations. Fluid field of nozzle with straight segment was simulatated by software of Fluent, whether fluid field was supersonic or not can be identified. Finally static and dynamic tests of spinning solid rocket motor were performed. The tested results of spinning solid rocket motor indicate that spinning solid rocket motor works well at 19 000 r/min and meets the working need.

For comparison with several methods used to define the location of the onset of detonation, several of experiments were performed to study on the deflagration to detonation transition (DDT) for premixed C₂H₂+2.5O₂ mixture in a shock tube. A high-speed digital camera was used to track the velocities of flame, shock, or detonation wave. In this work, six methods were used to define the location of the onset of detonation, and six different results of the DDT run-up distance (L_DDT) and the time of the detonation onset (t_DDT) were obtained. It is found that the methods based on the flame emission radiation and the growth trajectory of flame, shock, or detonation wave can accurately define t_DDT and L_DDT. The onset of detonation defined by the other methods based on the speed of detonation wave might result in some error or underestimated values due to the localized explosion taking place just prior to the generation of detonation.

The hypervelocity impact interaction of the sphere projectile with continuous shield and mesh shield, which were of the same thickness or area density, was investigated numerically. The study was aimed at mastering the hypervelocity impact characteristics of the mesh shield and applying effectively it in development of lightweight shields. The study involved the differences in the morphology and the distribution of momentum, velocity and mass of the debris clouds generated by impacting two kinds of shields. The calculations show that the morphologies of the debris cloud vary with the impact locations when a projectile impact the mesh shield, and there is the linear distribution of debris in the front of debris cloud. Comparison between the continuous shield and the mesh shield with the same thickness, the maximum of momentum density in the mesh shield is higher than that in the continuous shield, while the maximums of momentum density are almost near in the two kinds of shields with the same area density. The mesh shield does not effectively slow the penetration velocity of projectile, but can break it up. The dynamical response of the projectile varies with the shields. Impacting the mesh shield, the main part of debris is at the rear end of the debris cloud, which is different from the case of continuous shield.

The flash X-ray radiography is an important diagnostic tool for the ejecta from shocked metal surface. The influence of metal surface characteristics on the ejecta is a main aspect of numerical simulations and experiments on ejecta phenomena from shocked metal surface. A commercial flash X-ray tube, a X-ray camera and high accuracy synchronization timing system were used to establish a system of ejecta diagnosis. The radiographs of ejecta from the tin targets with different depths of grooves were captured and analyzed. The experimental results showed that (1) the mass ejection of tin targets with grooves presented the quasi-multilayer in vacuum; (2) the zone width and ejecta mass increased with the depth of target grooves in vacuum; (3) the region width and ejecta mass decreased as in gas pressure of 0.1 MPa.

In order to investigate on cracks propagation of the coal under column charge blasting subjected to geostatic stress, the damage constitutive model was established by considering tension and compression. The improved damage constitutive model was embedded in the FEM software to study the mechanics of cracks propagation coupled by blasting loads and geostatic stress. The precision of simulation is proved because the numerical results are in good with model experiments. The results show that the interaction of the compression wave and unloading wave yield cracks in the coal. The cracks are somewhat inhibited by geostatic stress. The direction of cracks is in accordance with the major principal stress.

The compression experiment of molybdenum foil combined with finite element modeling calculation reveals the history of elastic deformation of diamond and elastic-plastic deformation of sample in the pressure gradient method used for measurement of yield strength at high pressures. The influence from elastic compression and cupping of diamond on the in situ thickness measurement and pressure profiles of molybdenum foil is analyzed. The results show that the elastic compression of diamond is very small and reasonable to ignore at least below 31 GPa which is the highest experimental pressure. The cupping of diamond is somewhat notable. But the agreement of pressure profiles and their pressure gradients between calculation and experiment indicate no evident change due to the influence of cupping of diamond below 31 GPa. The cupping finally leads to the contact of corners of culets at 60 GPa. The proposals of experimental design are also given to reduce the influence from cupping deformation of diamond at high pressure.