Table of Content

31 December 1991, Volume 12 Issue 4

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Paper

A Study on Projectile Motion in Bore

Rui Xiaoting、Liu Zhengfu、Lu Yuqi

1991, 12(4):  1-6.  doi:10.3969/j.issn.1000-1093.1991.04.001

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A dynamic model for a projectileˊs motion with the bourrelet touching the bore wall is proposed in this paper. The model reflects projectile spin, mass eccentricity, dynamic unbalance, clearance between projectile and bore, forces acting on the projectileˊs rotating band and bo?urrelet by the wall，gas pressure, deformation and vibration of gun tube. With this model analytical solutions for differential equations of the pro?jectileˊs motion within an ideal bore can be obtained. Comptations for some projectile-gun systems have been done and some useful conclusions reached at.

Aerodynamic Coefficient Fitting Methods and Their Errors

Zhao Yanan、Qian Xingfang

1991, 12(4):  7-15.  doi:10.3969/j.issn.1000-1093.1991.04.002

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Multivariate regression analysis and parameter optimization method (conjugate gradient method and variable metric method) are em?ployed in the fitting of aerodynamic coefficients. A comparison and ana?lysis of the said methods is carried out in this paper. The results can be used to calculate trajectories of flight and simulate control systems.

Enginnering Design for Drop Safety of Set-Back Mechanisms

Tan Huimin、Liu Xinyu

1991, 12(4):  16-21.  doi:10.3969/j.issn.1000-1093.1991.04.003

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It has been recognized that equations presently in use for the calculation of safe drop height involve large errors which come about not in the assumptions concerning instataneousness of action but in the enormous amount of distortion given to the base excitation during its transmission through the shell-fuze system. This paper proposes an engi?neering design method of set-back devices in fuzes.The method, based on the theory of response functions, is easy to use and its design accuracy can be controlled within ± 5 %.

Molecular Diagrams of Nitrourea and Its Intermediates Calculated Using CNDO/ 2 and some of Its Applications in Organic Reactions

Zhang Xihe、 Liu Xiongmin

1991, 12(4):  22-26.  doi:10.3969/j.issn.1000-1093.1991.04.004

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The molecular diagrams of nitrourea and its dearranged intermediates in aqueous solution have been calculated using the CNDO/ 2 method.The results can clarify some new phenomena during synthesis and may explain the dearrangement mechanism of nitrourea in aqueous solution as that of a 1， 5 -sigmatropic shift.

Banding and Electronic Structure of Cellulose Trinitrate

Xiao Heming、Li Yongfu、 Zhou Kouhong、 Fan Jianfen

1991, 12(4):  27-33.  doi:10.3969/j.issn.1000-1093.1991.04.005

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The crystal orbitals and band structures of the long一chain macromolecule of cellulose trinitrate (or trinitrocellulose) have been calcula?ted at the gg configuration by the Extended Huckel tight binding (i.e. Crystal EH) method. The average Fermi energy limit for 6 k points is 一 12.45eV, The band gap at the edge of the first Brillouin Zone is 2.31eV. It shows that cellulose trinitrate has an electric conductivity similar to a se?miconductor. The electronic structures of its partial structural units (i.e.the systems having single-rings and double-rings) have been calculated by the SCF一CNDO/2 method at the gg, gt and tg configurations, respectively. Some of the structure—property relationships have also been discussed.

Global Calibration Method of the Constitutive Relationship in an Explosive Reaction Zone

Huan shi、Dingjing

1991, 12(4):  34-39.  doi:10.3969/j.issn.1000-1093.1991.04.006

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The constitutive relationship for describing the properties ini an explosive reaction zone consists of the chemical reaction rate equation， equations of state of the explosive and products, and laws governing their mixing. In this paper, a global calibration method is proposed, that is，us?ing the results of Lagrange tests and Lagrange analysis to calibrate the con?stitutive relationship of an explosive. In order to show the effectiveness of this method, we have calibrated five constitutive relationships of TNT and TATB at different physical-mechanical conditions. These relationships have directly been used in 1 HD and 2 -D numerical simulations. They simulated fairly well the records of tests，and no coefficients of constitutive relatioia- ship were adjusted. This method is a quick and economical way for the ca-libration of the constitutive relationship of explosives. The calibration pro?cess depicts a clear physical picture and its errors can be estimated. During, the calibration，not only the coefficients of the rate equation are determin?ed, but the consistency among these equations,which constitutes tlie con?stitutive relationship of explosives，is established at the same time.

Statistical Data Analysis and Study for Closed Bomb Testing of Gun Propellants

He Zhenbang、 Hu Guosheng、 Liu Xiangsun

1991, 12(4):  40-45.  doi:10.3969/j.issn.1000-1093.1991.04.007

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Closed bomb test is a standardized method in the tests for the quality and homogeneity of gun propellants. In this article，based on mathematical statistics, data on closed bomb experiments are analysed，their distribution regularities studied，and a new method of analysis for assessing the quality or estimating the properties of gun propellants is put forward. Besides, a method of determining the standard value or calculating the con?fidence for the given standard value is discussed.

concurrent Optimization in the Automatic Correctioa of Optical Systems

Wang Yongzhong

1991, 12(4):  46-51.  doi:10.3969/j.issn.1000-1093.1991.04.008

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Prevalent programs for the automatic correction in optical designs adopt either the adaptive method or follow the damped least square approach. Theory and practice have proved that both approaches in optimi?zation have their defects. The paper advances a new approach of optimization， combining the two in concurrence? and points to a simple and practi?cal way of its realization.

Application of the Instantaneous Detection Method CIDM) In the Suppression of Band Limited Interference

Zhao Ziyao、 Xu Hui 、 Guan Hong

1991, 12(4):  52-57.  doi:10.3969/j.issn.1000-1093.1991.04.009

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This paper introduces a digital communication system based upon the Instantaneous Detection Method(IDM). Under the condition： bandwidth(BW)3000Hz, data rate 2400bps and input SNR at least-10 dB, the bit error rate (BER) achieved is less than 10E- 4. The experimental data has shown that IDM is effective for suppression of both band limited noise and intersymbol inetrference，and has superiority over conventional detec?tion method. Using IDM, we can realize high-speed digital communication on the voice band or improve the capability of a system to suppress noise.

A Study on the Formula for the Strain Controlled Fatigue at Elevated Temperatures

Liu Jiangnan、 Tian Changsheng、 Zheng Xiulin

1991, 12(4):  58-63.  doi:10.3969/j.issn.1000-1093.1991.04.010

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Based on recent researches on fatigue under cyclic strains at room temperature and considering the fatigue characteristics of metals at elevated temperatures，in particular the interaction between fatigue and creep， a new formula for the strain-controlled fatigue at elevated tem?perature is developed, as has been substantiated in the present study. The newly developed fatigue formual reveals the correlation between the fatigue life and the tensile properties，theoretical endurance limit，as well as the cyclic loading frequency (or load time) at high temperature. It shows in particu?lar the existence of the theoretical endurance limit. This new fatigue formula can also be used in cases when interaction between fatigue and creep occurs，making it possible to predict the higk temperature fatigue life of metals from the tensile properties and the conventional endurance limit. Validity of the fatigue formula newly developed, has been verified through a series of experimental results.

Experimental Techniques and Analysis

Potentiometric Titration of Perchlorate Ammonium in Composite Propellants with Fluoroborate ISE

Gu Junling、 Yang Jiayu

1991, 12(4):  64-70.  doi:10.3969/j.issn.1000-1093.1991.04.011

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The method presented here for the potentiometric titration of ammonium perchlorate in composite propellants uses cetyltrimethylam- monium chloride (CETAC) or cetylpyridinium chloride (CPC) as the ti— trant. The titration is performed with a fluoroborate ion-selective electrode as the indicator electrode and a double—junction calomel electrode as the re?ference electrode. This new method is suitable for the determination of NH4CIO4 in a variety of propellants, with this method the mean recovery and σ attain values better than 99.74% and 0.24 respectively.

Research Notes

Measurement of the Engraying Process of Projectiles

Zeng Simin、 Tong Weimin、 Jiao Huanan

1991, 12(4):  71-74.  doi:10.3969/j.issn.1000-1093.1991.04.012

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This paper introduces a system for the measurement of th engraving process of projectiles. The system makes use of measurement of bottom pressure on the projectile by leading a wire directly to the pres sure gauge fixed on the projectile. The bottom pressure is successfully mea?sured with the system within a short—barrelied gun. The engraving pressur is obtained through the engraving touch signal method and the pressure mea suring method.

A Method for the Aerodynamic Engineering Calculation of Ribbon Stabilized Grenades

Zhang Weiquan

1991, 12(4):  75-82.  doi:10.3969/j.issn.1000-1093.1991.04.013

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On the basis of experimental and theoretical analyses the present paper gives a mathematical model for the aerodynamic calculations of a ribbon-body complex，and a method for its aerodynamic engineering calculations. The computed results as shown in the examples， agree well with the experimental values, and show the parcticability of the present method.

A Programmable, Realtime Projectile-Borne Waveform Recorder

Zu Jing、 Zhang Wendong

1991, 12(4):  83-86.  doi:10.3969/j.issn.1000-1093.1991.04.014

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The recorder is a programmable and miniaturized integrated measuring device that can be housed in a shell or rocket having a ca?liber larger than 57mm，capable of collecting ballistic data under exacting ambient circumstances viz. peak axial acceleration up to 50000g，high tem?perature, high pressure and violent vibration. In this paper，the working principle and ways of operation are given in some detail. As an example of measurement results, the axial accelera- tion of a shell during the whole ballistic process is presented.

Experimental Research ot Dense form Boron Nitride by Explosion Synthesis

Yun Shourong、 Sun Yanfeng 、Wu Fengyuan、 Zhang Jinyun

1991, 12(4):  87-91.  doi:10.3969/j.issn.1000-1093.1991.04.015

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The conditions of synthesis of dense form BN by dynamic high pressure is analysed.A series of experiments were done on graphitic BN with cylindrical explosion device. Results of X-ray diffraction and SEM on the recovered sample show that dense form BN exists in the black part of the sample, Increasing the density of the original sample，weight of explosi- ve used and use of confined tube will tend to favor the formation of dense form BN.