Exploiting the teaching and research work of explosion theory and application specialty in China

Explosion is a universal phenomenon in space. It is of great significance for the development of national defense modernization and national economic construction in China to deeply study the mechanical, physical and chemical phenomena of explosion, master the laws of its occurrence, development and external effects, study and develop the theory and application of explosion science, and prevent and control explosion disasters.

In the autumn of p>195, Ding Xian came back from abroad and was assigned to teach in the Engineering College of North China University. After the adjustment of colleges and universities nationwide in 1952, the Institute of Technology of North China University was renamed Beijing Institute of Technology, and was identified as the first national defense industrial college in China. Ding Sui devoted himself to national defense teaching and scientific research. In 1954, Beijing Institute of Technology established the first batch of 12 military specialties in China, and Ding Wei and Chen Fumei founded the ammunition charging specialty together. After offering a series of courses such as chemical engineering principle, ammunition charging technology, initiating explosive device and pyrotechnic technology, he devoted himself to the construction of explosion theory and application. In 1958, he was responsible for the construction of the first explosion tower with a diameter of 6m in Beijing area in Beijing Institute of Technology, and then successively carried out research on topics such as shaped charge armor-piercing and fragment killing. In 1959, he published "Discussion on the Jet Mechanism of пг-2 Bomb Hollow Charge" in cooperation with Yun Shourong. In 1961, he published the textbook "Explosion Action Principle" under the pseudonym Feng Ji. In 1963, Ding Nai and Yun Shourong jointly published the "Deformation of Hollow Sphere under the Action of Explosive Products" and enrolled the first batch of graduate students in explosive physics in China. In 1964, Cui Chunfang, a graduate student, carried out numerical calculation under very simple conditions and published the "Approximate Solution of Convergent Detonation Wave on Sphere (Column)". In the early 196s, Ding Xian led the teachers and students of this discipline to conduct anti-design research on the power and structure of ground-to-ground, ground-to-air and air-to-air missile warheads imported from the Soviet Union. In 1963, together with Professor Zhou Faqi, he led dozens of teachers and students to participate in the National 142 Task, and set up the 32 Research Group, which carried out a series of work such as new explosive synthesis, explosive modification, molding powder development, precision charge forming and processing technology, explosive performance test, long-term storage and so on. After two years' efforts, HBJ and HJJ, two excellent high explosives with high detonation performance and good storage stability, have been developed successively, which have been highly praised by famous scholars and leading departments such as Professor Wang Ganchang.

At the 142-2 meeting held in 1963, Ding Wei put forward important opinions on the study of detonation, and clearly pointed out that it is not appropriate to pursue only the detonation velocity of explosives and single index sudden advance, without considering the detonation pressure and the safety of explosives. It is necessary to strengthen the theoretical study of explosive detonation and standardize various performance test methods of explosives. The higher authorities adopted this suggestion and established the Detonation Physics Group in 1964, and appointed Professor Guo Yonghuai, deputy director of the Institute of Mechanics of China Academy of Sciences and a famous scientist, as the team leader and Professor Ding Wei as the deputy team leader. At the same time, a technical group for testing the performance of high-efficiency explosives was established, with Professor Ding Nai, Professor Qian Jin and Professor Xu Kang as the chief and deputy heads respectively. In 1966, a Method for Testing the Performance of High-efficiency Explosives was formulated, which was distributed to all relevant units in the country by the Scientific Research Bureau of the State Council National Defense Industry Office.

While completing the 142 National Major Scientific Research Task and a series of other scientific research tasks, a variety of large and medium-sized precision instruments, high-voltage oscilloscopes, high-speed cameras, charging processing and explosive performance testing equipment were added, which made the explosion technology laboratory reach the domestic advanced level at that time; A number of high-level technical backbones have been trained. This period also trained the first batch of graduate students in the field of explosion research in China, and they have now become the backbone of achievements.

In p>1977, the explosive technology and charging specialty of Beijing University of Technology resumed enrolling undergraduates; in 198, the master's degree program of explosive mechanics was established; in 1984, the first doctoral degree program of explosive mechanics in China was established, with Professor Ding Xian as doctoral supervisor. In 1987, the subject was renamed explosion theory and application, and was rated as a national key subject by the State Education Commission. In 1988, with the approval of the State Planning Commission, the State Key Laboratory of Explosion Disaster Prevention and Control was established on the basis of this discipline, and a number of internationally advanced instruments and equipment were purchased with loans from the World Bank, which significantly improved the teaching and scientific research conditions of this discipline. In 1991, the post-doctoral mobile station was established in this discipline. Chen Nengkuan, academician of China Academy of Sciences and deputy director of the Science and Technology Committee of the Commission of Science, Technology and Industry for National Defense, Jing Fuqian, academician of China Academy of Sciences and director of the National Defense Key Laboratory of Shock Wave Physics and Detonation Wave Physics, and Zhang Guanren, director of the Science and Technology Committee of Southwest Institute of Fluid Physics, have been hired as part-time doctoral tutors. Huang Chunping, chief expert of 863-49 high technology, and Zhang Xinwei, researcher of Beijing Institute of Applied Physics and Computational Mathematics, are part-time professors. Young people from Peking University, University of Science and Technology of China, National University of Defense Technology, China Academy of Engineering Physics, Xi 'an Institute of Modern Chemistry, Beijing University of Aeronautics and Astronautics and other schools and institutes come to study for master's and doctor's degrees, or enter postdoctoral mobile stations to engage in scientific research.

With the strong support of leaders at all levels and under the personal leadership of Professor Ding Xian, the subject of explosion theory and application has been established and is developing steadily. This discipline has trained and brought up a group of high-level scientific and technological backbones loyal to the national defense cause, and established a laboratory with good experimental conditions. From the late 197s, Ding Kui led his assistants to study the infrastructure of detonation. By the mid-198s, advanced electromagnetic and manganin piezoresistive testing systems were built successively, and a variety of Lagrangian sensors and their analysis technologies were designed and developed, which provided necessary means and methods for studying the shock wave initiation, constitutive relation, state equation of explosion products, phenomenological reaction rate and the relationship between components and technology.

the electromagnetic method test system is equipped with a large Helmholtz coil with a diameter of 1m made of stainless steel plate and its power supply system, a digital storage oscilloscope with a sampling rate of 1MS/s and a data communication interface. The maximum bandwidth of the whole system is not less than 3MHz, and the digital recording, copying, microcomputer communication and access of particle velocity or impulse analog signals on a certain section in the measured medium are realized at the earliest in China. This system configuration and testing technology has reached the first-class level at home and abroad.

In terms of manganin piezoresistive testing technology, Professor Ding's assistants have successfully solved the submicrosecond high-speed synchronous pulse power supply technology; Expand the pressure range to MPa level; Using Kangtong tensile compensation technology, the application scope was extended to non-planar symmetric stress state, and many national patents were obtained. Many domestic research institutes have applied these technical achievements successively.

In June, 1985, Ding Xian gave a speech at an academic conference held in Poland, entitled Reactive Flow Lagrangian Analysis of the Combustion Behind Shock Wave Front, and the report was also published in the journal Archivum CombuStionis jointly published by the former Soviet Academy of Sciences and the Polish Academy of Sciences in English. Ridovics (зел?дович), a famous scientist of the former Soviet Union, attended the meeting, and this article was appreciated Я·B· him. In July of the same year, Ding Wei went to the United States to attend the Eighth International Conference on Detonation, and gave a report on the conference, entitled "Hugoniots and Reaction Rates from EMV Gage Measurements and Lagrange Analysis", which was widely welcomed. Compared with the articles read by American scholars at the conference, the work of Ding Wei and others has reached the international advanced level in directly studying the detonation performance of explosives and the behavior under the action of shock waves by using electromagnetic velocimeter (EMVG) and Lagrange analysis (RFLA), which also shows that China has a magnetic field device and electromagnetic method testing system with superior performance and repeated use. The unique feature of the paper "Study on the Impact Detonation Characteristics of Explosives by Particle Velocimeter and Laplace Analysis" is that the whole particle velocimeter measurement and Laplace analysis method are applied to the study of explosive detonation performance, and two dimensionless parameters are put forward, which can be used as a criterion to evaluate the reliability and safety of explosive initiation under the same experimental conditions. Ding Wei and Huang Zhengping deeply and carefully analyzed the influence of the conductivity of detonation products on the measurement of electromagnetic velocimeter, and put forward the corresponding mathematical and physical model and experimental method, which made the research of electromagnetic method in China enter the advanced ranks at home and abroad.

since 198s, Ding Xian and Huan Shi have turned one of the research focuses to two-dimensional detonation and its measurement technology. Many practical problems in detonation research are two-dimensional axisymmetric problems, so it is obvious that one-dimensional testing and analysis technology cannot be used. In 1986, a Laplace meter for measuring two-dimensional dynamic high-pressure flow field was developed, and a two-dimensional Vera analysis method was put forward, which was published in the proceedings of the condensed impact compression conference hosted by american physical society in 1987. On October 12, 1987, Ding Wei gave a speech entitled "Sound Velocity Surface and Flow Field in Two-dimensional Detonation Reaction Zone" at the International Conference on Pyrotechnics and Explosives, and put forward the generalized C-J condition in cylindrical symmetric two-dimensional steady detonation system. In the first issue of Explosion and Shock in 1989, five reaction characteristic quantities were put forward, namely, reaction degree, reaction rate, volume energy release rate, instantaneous reaction heat and heat coefficient. These characteristics can be calculated from the P-T data measured by a Willard meter. In 199, I made a summary of my work in ActaMechanicaSinica for several years. This research, which lasted for many years, won the second prize of national defense scientific and technological progress and the third prize of national invention in 1991.

In p>1989, Ding Wei gave a report on the Response of Composite Propellant to Impact Load at the Ninth International Detonation Conference, and reported some work in the safety research of solid composite propellant. The dynamic responses of two kinds of solid composite propellants were measured by electromagnetic velocimeter and manganin pressure gauge at the same time under two kinds of shock wave pressures of 2．GPa and 1．GPa. Firstly, it was found that there was a stage of no reaction or extremely slow reaction in the reaction process of composite propellants. The response of various components including oxidant (AP), binder (HTPB, Thiokol), the mixture of AP and aluminum powder, and the mixture of AP and binder to impact load was also studied.

ding nian, Bai Chunhua and Huang fenglei have worked on the safety research of solid propellants for nearly 8 years, and published more than 2 articles in explosion and impact, journal of astronautics, journal of ordnance and other academic conferences at home and abroad. A relatively complete research system has been established, including impact failure performance research system, shock wave initiation and detonation process research system and detonation risk evaluation system. The main progress points are as follows: (1) For the first time, the dynamic fracture is divided into two stages: dynamic compression and dynamic tension, and the test method and device are successfully designed. (2) Using a special substrate material, the spallation signal is measured by Laplace piezoresistive sensor technology, which has better accuracy compared with the VISAR measurement by Weirick et al. (3) The internal failure process and spallation nucleation mechanism of solid propellant under shock wave compression were studied by soft recovery and scanning electron microscopy, which provided strong evidence for establishing theoretical model. (4) A brittle fracture model of solid propellant is proposed, which can describe the process of crack nucleation, growth and polymerization, and a numerical simulation program is compiled. (5) For the first time, Doral meter method is used to directly measure the shock-to-detonation and detonation flow field of solid propellant, and the accuracy is improved. (6) Through theoretical analysis and comparison, the Laplace analysis technique suitable for different conditions is established to describe different states and multivariable reaction processes. (7) The state equation and reaction rate equation of solid propellant are determined, and the method of calibrating the reaction rate equation of solid propellant is put forward. On this basis, the program for simulating the process of shock to detonation and detonation is compiled. (8) Considering the factors of viscoelasticity, compressibility, heat conduction and thermal decomposition, the hot spot formation and ignition model of composite propellant is established, and the corresponding numerical simulation program is compiled. (9) For the first time, the method of analyzing and evaluating the detonation risk by using the flow field behavior from shock to detonation is put forward. (1) The concept of minimum critical initiation pressure is put forward, and the quantitative method is established, which is consistent with the results of large-scale tests in the United States, saving the test cost and having good economic benefits.

four kinds of typical solid propellants in China were studied by using the above research system. The important results are as follows: (1) Under the impact load of 5MPa, the particles of energetic components (HMX and AP) in the solid propellant began to break, and the modified double-base propellant simultaneously debonded with the matrix, which could not be detected by conventional large-size grain detection methods. (2) The dynamic process of solid propellant spalling is: microcracks nucleate, grow, polymerize and form fragments, and microcracks start from the breaking of energetic components. (3) The chemical reaction process of double-base propellant under the impact load is similar to the detonation of heterogeneous explosives, and the main components react in parallel. (4) The chemical reaction process of composite propellant under the action of shock wave is obviously different from that of double-base propellant, and there are three reaction stages, and the pressure and particle velocity appear double peaks. The chemical reaction time during detonation is about 1. μ s. (5) Compressibility and viscoplasticity are the main factors affecting the formation and ignition of hot spots in composite propellant, and heat conduction can be ignored, and hot spots are formed around micro-cavities in propellant. The ignition time is less than ．15μs s. (5) Pre-shock destroyed the interior, and the process of propellant from shock to detonation changed. With the increase of damage degree, the double peaks in the initiation flow field changed to single peaks. (7) Detonation sensitivity of modified double-base propellant increases with the increase of HMX content and with the decrease of density. (8) The shock wave grows into detonation wave in double-base propellant, which is mainly the result of the reaction near the wave front; In the composite propellant, it is mainly the result of strengthening the flow field behind the wavefront. In this way, when the grain size is small and the impact time is short, the composite propellant is not easy to detonate, while the double-base propellant is less affected by these factors. (9) The critical initiation pressures of double-base propellant, modified double-base propellant and composite propellant are 6., 3. and 2GPa, respectively. (1) The minimum critical pressures of modified double-base propellant and composite propellant under one-dimensional plane continuous loading are 1. and 1．8GPa. This result can be used to analyze the detonation risk of large and medium-sized grain under long-term continuous loading, which is close to the large-scale (about 2m) test results (1. GPA and 2．5GPa) of modified double-base propellant and composite propellant in the United States, but the test cost is much saved. The research results in this field have passed the ministerial appraisal and are considered as "the first in China, but not reported abroad".

in the early 198s, Ding Wei carried out research on shock wave chemistry and dynamic response of materials to shock wave compression. In 1984, he led students to do research on shock wave polymerization of hydroquinone and impact synthesis of tungsten carbide. In 1988, he was supported by the National Natural Science Foundation project "Study on Shock Wave Solid State Chemical Reaction", and carried out shock wave compaction of powder mixture, synthesis of nickel-aluminum compound and impact response research of tungsten alloy. He instructed doctoral student Xiong Yingming to complete the dissertation "Microstructure response and macroscopic constitutive behavior of tungsten alloy materials at high strain rate", and studied the dynamic mechanical properties of 93 tungsten alloy in the strain rate range of 1.4× 14 ~ 2× 16 s-1), and found that