Zhuo-Cheng Ou

A Pore Collapse Model for Hot-spot Ignition in Shocked Multi-component Explosives

A new pore collapse model, in which the effect of the binder in Plastic Bonded Explosives (PBX) is taken into account, is developed and integrated into the so-called hot-spot ignition model of shocked explosives. A two-dimensional hydrocode DYNA2D is used to simulate the shock initiation of PBX, with a reaction rate model consisting of a hot-spot ignition term, a slow-burning term at low pressure and a high-pressure reaction term. The numerical results show that the model can successfully describe the effects of the strength and the content of the binder, particle size and porosity of explosives on the shock initiation.

Effects of the aluminum content on the shock wave pressure and the acceleration ability of RDX-based aluminized explosives

To better understand the influence of the aluminum content on the performance of aluminized explosives, experiments in concrete and cylinder tests were performed. Three types of RDX-based aluminized explosives, in which the mass ratio of aluminum content was 0%, 15%, and 30% were considered in this paper. The shock wave pressures of the aluminized explosives in the affected concrete bodies were measured using manganin pressure sensors. The acceleration ability was obtained using a high-speed camera and a rotating mirror streak camera. The peak pressure attenuation characteristics of the explosives with various aluminum contents indicated that a higher aluminum content is associated with a slower peak pressure attenuation of the shock wave. In addition, the results of the cylinder tests and the metal-rod acceleration tests revealed the influence of the aluminum content on the acceleration ability of explosives in three different time periods. The test data presented in this paper verified the relationship ...

Effects of HMX Particle Size on the Shock Initiation of PBXC03 Explosive

Abstract A series of shock initiation experiments are performed on the PBXC03 explosives in different formulations to understand the influence of the explosive particle size on the shock initiation, and the in-situ pressure gauge data are obtained which show that shock sensitivity decreases with the explosive particle size under the test condition used in this paper. Moreover, a mesoscopic reaction rate model which is calibrated by the experimental data on a medium formulation PBXC03 explosive is adopted and then applied to predict numerically the shock initiation of other PBXC03 explosives in different formulations. The numerical results are in good agreement with the experimental data.

Prediction of Initial Temperature Effects on Shock Initiation of Solid Explosives by Using Mesoscopic Reaction Rate Model

Abstract A kind of mesoscopic reaction rate model is reexamined in this paper with the aim of getting rid of the temperature dependence of its experiential parameters and making it available to predict the shock initiation of solid explosives under different initial temperatures. It is found that the initial temperature effect is induced mainly by the temperature dependence of the local chemical reaction rate and the initial density of the explosives, and, via the introduction of such temperature dependence, the reaction rate model can predict well the shock initiation processes under different initial temperatures, in which just the experiential parameters under a certain temperature (e.g. the normal temperature) are needed. Moreover, for verification, the shock initiation processes of PBX-9501 under different initial temperatures were simulated numerically by using the DYNA2D software. The numerical results on the run distance to detonation are found to be in good agreement with previous experimental data.

Theoretical Prediction of Expansion History of Metal Cylinder for Multicomponent Explosives

As a traditional experimental approach, the cylinder test has been widely applied to evaluate the ability to accelerate metal, acquire the specific dynamic energy, and calibrate the equation of state of the detonation product for an explosive. In this article, based on the constant metal-density Gurney formula, a theoretical approach to predicting the expansion history of a metal cylinder shell driven by the detonation product of a multicomponent explosive under any explosive mixture ratio is proposed, providing that the corresponding theoretical density and the initial internal energy and the Jones-Wilkins-Lee parameters of each explosive component in the multicomponent explosive are known. Based on this predicted expansion history, the ability to accelerate metal, the specific dynamic energy, and the equation of state of a multicomponent explosive under any explosive mixture can all be acquired without an extra cylinder test for the multicomponent explosive itself. For verification, numerical results for the expansion histories of a copper cylinder driven by the detonation products of a PBX-C03 and a Comp-B multicomponent explosive were calculated and found to be in reasonably good agreement with previous cylinder test data.

Mesoscopic effects on shock initiation of multi-component plastic bonded explosives

A series of one-dimensional Lagrangian tests have been performed to examine model parameters in the mesoscopic reaction rate model for shock initiation of multi-component plastic bonded explosives (PBXs) for two multi-component plastic bonded explosives PBXC03 (87% HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazoncine), 7% TATB (triaminotrinitrobenzene), and 6% binder by weight) and PBXC10 (25% HMX, 70% TATB, and 5% binder by weight). As the numerical results are in good agreement with experimental data, the model parameters have been used to predict the effects of variations in mesoscopic properties (the particle size, initial density, binder strength, and content) on the shock initiation characteristics of PBXC03 and PBXC10. It is found that the time to detonation for PBXC03 increases with all these mesoscopic properties, while the time to detonation for PBXC10 is basically independent of its mesoscopic properties. Thus, PBXC03 is sensitive to mesoscopic properties, but PBXC10 is not. Moreover, it is also found that the pressure-history curves behind the initial shock wave in PBXC03 have different trends from PBXC10, which implies different chemical reaction mechanisms. Further analysis reveals that it arises from the different hot spot ignition processes due to their different threshold initiation pressures. The hot spots are ignited gradually and almost simultaneously in PBXC03 and PBXC10, respectively.A series of one-dimensional Lagrangian tests have been performed to examine model parameters in the mesoscopic reaction rate model for shock initiation of multi-component plastic bonded explosives (PBXs) for two multi-component plastic bonded explosives PBXC03 (87% HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazoncine), 7% TATB (triaminotrinitrobenzene), and 6% binder by weight) and PBXC10 (25% HMX, 70% TATB, and 5% binder by weight). As the numerical results are in good agreement with experimental data, the model parameters have been used to predict the effects of variations in mesoscopic properties (the particle size, initial density, binder strength, and content) on the shock initiation characteristics of PBXC03 and PBXC10. It is found that the time to detonation for PBXC03 increases with all these mesoscopic properties, while the time to detonation for PBXC10 is basically independent of its mesoscopic properties. Thus, PBXC03 is sensitive to mesoscopic properties, but PBXC10 is not. Moreover, it is a...

Research on Equation of State For Detonation Products of Aluminized Explosive

ABSTRACT The secondary reaction of the aluminum powder contained in an aluminized explosive is investigated, from which the energy loss resulted from the quantity reduce of the gaseous products is demonstrated. Moreover, taking the energy loss into account, the existing improved Jones-Wilkins-Lee (JWL) equation of state for detonation products of aluminized explosive is modified. Furthermore, the new modified JWL equation of state is implemented into the dynamic analysis software (DYNA)-2D hydro-code to simulate numerically the metal plate acceleration tests of the Hexogen (RDX)-based aluminized explosives. It is found that the numerical results are in good agreement with previous experimental data. In addition, it is also demonstrated that the reaction rate of explosive before the Chapman-Jouget (CJ) state has little influence on the motion of the metal plate, based on which a simple approach is proposed to simulate numerically the products expansion process after the CJ state.

The Dynamic Response of Brittle Materials under Impact Loading

Abstract In order to make sense of the dynamic response of brittle materials under the certain range of impact strength, the numerical simulation for two kinds of representative ones glass and ceramic are conducted, in which the elastic micro-crack damage model is used. The plane impact experiments of ceramic and glass are summarized, which are used to compare with the simulation results. The simulation results show that the dynamic responses of brittle materials, failure wave and the plastic-like response appeared in glass and ceramic respectively are depended on their micro-cracks distribution in meso-scale. And moreover, both of failure wave and the plastic-like response are controlled by the same mechanism, and the different phenomena are just influenced by the size and distribution of the micro-cracks.

Strain Rate Effects on the Interaction between an Eccentric Matrix Crack and a Circular Inclusion in Composites under Dynamic Loadings

Abstract The interaction between an eccentric matrix crack and a circular inclusion in composites was investigated numerically to explore the strain rate effects on the crack deflection/penetration behavior at the matrix-inclusion interface. It is found, with the increase of strain rate, that there will occur in turn the crack deflection, the double-crack fracture and the crack penetration processes for a certain material. Moreover, both higher relative interfacial strength and smaller eccentric angles can redound to the crack penetration. Additionally, it is demonstrated that the strain rate effect on the composite strength is a local structural response characteristic rather than an intrinsic material property, which sounds in agreement with that proposed by previous authors.

Multi-Thickness Target Plate Impact Experimental Approach to Failure Waves in Soda-lime Glass and Its Numerical Simulation

Abstract A multi-thickness target plate impact experimental technique is proposed in this paper and adopted in the research on the so-called failure wave phenomenon in soda-lime glasses, in which, four sub-targets in different thicknesses embedded in the target ring are impacted simultaneously and the longitudinal stress temporal curves at the backing surface of each of the sub-targets are measured by four manganin piezo-resistive stress sensors. Hence, the failure wave trajectory under a certain dynamic loading can be obtained by only one test, which can reduce considerably the experimental expense as well as the experimental period, and, more importantly, the measurement uncertainty resulted from different loading conditions in repetitious impact experiments is avoided. It is found that the propagating velocity of failure wave is approximate to a constant and increases with the magnitude of the impact loading, and there always exists an initial delay time for the initiation of failure wave behind the precursory shock wave, which decreases with the magnitude of impact loads. Moreover, a numerical simulation for the failure wave propagation is carried out by using the LS-DYNA applied software, together with a statistical isotropic elastic microcrack model to describe the dynamic damage evolvement of soda-lime glasses. It is demonstrated that both the critical damage value distributions and the free surface particle velocity temporal curves can be used to determine the failure wave trajectory, and the numerical results are consistent substantially with the experimental data.