Cyclic loading and unloading experiments and the uniaxial compressive experiment of plastic-bonded explosives (PBX) under different strain rate were performed by a universal material testing machine. The stress-strain curves of plastic-bonded explosives were obtained in different operating conditions. Based on the idea of combining phenomenological analysis and micro-statistical analysis, a damage evolution equation with damage internal variable and rate-dependent constitutive relations with damage for plastic-bonded explosives were given. The model was checked with the experimental data, and the relevant parameters of rate-dependent constitutive relations with damage were obtained. Experimental results indicate that the constitutive equation can describe mechanical properties of the PBX explosives at the linear elastic stage, strengthen stage, and strain softening stage. The constitutive relation is simple and requires less parameters to be determined. The damage variable defined by micro-crack density can be easily determined by mechanical testing.

High pressure can effectively modify the inter-atomic interaction of materials (i. e., the electron orbital overlap, chemical bonding, and electron charge distribution of materials), and further the crystal structures, mechanical, thermal, optical and electrical properties of materials. For more than one century, the progress in experimental generation of highest pressure and the development of advanced theoretical method have significantly moved forward the high pressure science. One of the most challenging research topics under high pressure is targeted to the investigation of pressure-induced diatomic molecular dissociation. This article reviewed the high pressure dissociation of typical diatomic molecular solids of H₂, O₂ and N₂ and their atomic phases reported in the literature, and the dissociation mechanisms were also discussed.

To evaluate the hazard of gaseous epoxypropane-air explosions, characteristic parameters of gaseous epoxypropane explosion inside 5 L-sphere closed vessel with 40% and 88% relative humidity were measured. The obtained results show that: Maximum overpressures reduce slightly at near optimum explosion concentration, the others make no difference; a major influence of the initial humidity on maximum rates of pressure rise is observed only at 7.0% in the examined ranges of the gaseous epoxypropane concentrations; and the maximum temperature and the maximum rates of temperature rise are slightly influenced by the initial humidity.

Through the application of Lambourn's CIM model, a simplified analytic method was proposed to study the post-shock reactive flow in the case of unknowing the real formula of reaction rate. Based on this method, a more reasonable empirical reaction rate can be extracted to better understand the initial hydrodynamic phenomenon during shock to detonation transition. The method assumes that reaction rate is a function of time. The history and relationship of particle velocity, pressure, extent of reaction and reaction rate can be obtained by combining with experimental particle velocity. The results show that the decrease of particle velocity on impact interface relates with extent of reaction, and peak reaction rate after shock wave appears within the peaks of particle velocity and pressure.

According to the forming process of internal thread, the microstructure, microhardness and mechanical properties of internal thread surface layer were investigated. The microstructure change and deformation mechanism, harden ability and depth of hardening layers on the crest, the flank and the root of the thread along the layer depth direction were obtained. The results showed that the grains on the surface layers of the thread were refined after the cold extrusion. Fibrous structure of the metal surfaces on the root of thread was pressed to distinguish the grains difficultly, and formed a layer of flown line and smoothly rounded the root to flow from the flank to the crest. The grains on the root were the smallest, followed by the flank and the crest. In the extrusion processes, the microhardness and the tensile strength of the material were increased significantly, and the plasticity and the toughness were decreased. The work-hardening phenomenon greatly increased the surface texture and the mechanical strength of internal thread with cold extrusion.

The flow field evolvements inside the explosion vessel volume and the dynamic response of the vessel shell are basic data in designing of the vessel shape, structure and material selection. But for some reason of the vessel large scale, multi-component, high-density ratio and complex structure, and thus the numerical simulation of explosion flow field inside the vessel is very difficult. In this study, we ultilized the level set method differentiate the large deformation of the flow field from the small deformation of the vessel, and the Euler MVPPM method and Lagrange were respectively used in numerical calculations. The ghost fluid technology was employed to deal with the fluid and solid at the interface of the physical information. We successfully applied the present method to the ellipsoidal head and the similar spherical explosion vessel simulations.

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.