Study On Solidification And Performance Of Thermobaric Explosive

For the design of solid Thermobaric Explosive (TBE), the solidification techniques of thermobric explosive was investigated by theoretical, numerical and experimental methods, including formulation design, the bonding and insensitive mechanism, manufacture techniques, solidification performances and the after-burnning energy output structure.Based on existing research results, the principles and methods of formulation design were proposed. According to the blast field test results of lkg thermobaric explosive, the method of Grey Correlation Analysis was used to investigate the influence rule of5raw materials and their contents on blast performances. The results show that the decreasing order of the factors investigated for the overpressure at a distance of3m from the explosion center is:high explosive RDX, fine particles of AP; and for the overpressure at9m the decreasing order is:fine particles of aluminum powder Al(Ⅱ), coarse particles of aluminum powder Al(Ⅰ) and coarse particles of AP. It indicates that high explosive RDX and fine particles of AP are in favor of the overpressure at3m, but weaken the overpressure at9m. Whereas the aluminum powders both fine and coarse, and the coarse particles of AP have the inverse influence on overpressure at both distances.The explosion parameters of TBE were investigated by combining the experimental results and neural network predictions. To overcome the problems of that experimental data exist error, and the training of Artificial Neural Network largely depends on initial sample data for prediction, the smooth thoughts of Whittaker were applied to improve the initial data. A new Artificial Neural Network model based on Genetic Algorithm was established and used to predict the overpressures of TBE in field tests. And the optimal formulations of TBE were predicted with the method according to certain peak overpressure or impulse.The results show that with the new prediction method the stability and accuracy of the predicted results were improved and the error was less than5%, also the convergence rate of Network was improved.The optimal binder and desensitizer were selected according to the solidification technology of pressed type TBE. The surface tension of binder containing different additives and the contact angle with RDX were measured by a contact angle meter. The coating quality was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and the impact sensitivity was tested. The spreading coefficient (S) and adhesive work (W12) were calculated, and then the dependence of the coverage degree (R) and characteristic fall distance (H5o) on S and W12were analyzed. The results show that R and H50increase with the increase of S, and reduce with the increase of W12. It indicates that the bigger S and the smaller W12, the better the coating quality. The results of SEM show that a thin layer of film was formed on the surface of RDX. The results of XPS show that the additives can extend the coverage degree from16.85%to95.41%. The results of impact sensitivity show that the additives can prolong the characteristic fall distance from11.47cm to25.12cm, and significantly reduce friction sensitivity. The mechanism of bonding and desensitization was further discussed.The coverage degrees of HTPB binder on RDX particles were studied by SEM and XPS, and a low molecular weight resin (surfactant J) was chosen as surfactant. The optimal parameters of preparation process were determined by orthogonal experiments, that is the mixing temperature50℃, the stirring rate25r/min, the mixing time45min and the maintenance temperature50℃.The cast loading theory of TBE was expounded and the main components and sensitizer were selected. The samples of casting TBE were produced in lab, and their combustion heat and hardness were measured. The explosion peak overpressure of the samples before and after curing were compared by field test, the result shows that the overpressure of casting TBE is no less than that of liquid-solid composite TBE, and the casting scheme is feasible.The application properties of solid TBE were tested, especially the formabilty and mechanical performance. The results show that the mechanical strength of resin P is twice as rubber D, and the1#tackifier and6#surfactant are in favour of improving the mechanical strength.The explosion power of solid TBE and liquid-solid composite TBE were compared and the TNT equivalents were1.71and1.70respectively. It indicates that the casting scheme is practicable.The influence rule of bursting height on blast pressure was studied both theoretically and experimentally. Based on the theory analysis, a formula was proposed to describe the variation of overpressure with specific bursting height and distance to explosion center. From the partial derivatives with specific bursting height, the optimal specific bursting height varying with distance was obtained. Variation of the peak overpressure with scaled distance to explosion center was deduced under the condition of optimal specific bursting height consequently, and it can be approximated as a straight line, under which the pressure is not less than other conditions. It can be used to guide the warhead performance design of TBE. In order to investigate the influence of after-burning on the strength of shock waves produced by the thermobaric explosive explosion in air, experiments and numerical simulations were performed to study the energy output structure. The results show that the pressure histories have two peaks in the near field and a long period in the far field. The impulse is1.6～1.8times of the same quality of TNT. Based on the analysis of JWL-Miller model parameters, the energy of after-burning is about1/3of the total energy. Furthermore, the curve of reaction degree(λ) versus time was obtained. In the case of complete reaction, the after-burning time can reach at400ms. It indicates that the after-burning of high energy additive is important to enhance the power of thermobaric explosive.