Table of Content

01 January 2013, Volume 34 Issue 1

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Study on Lifetime Test for Machinegun Barrel in Normal Temperature

SHAN Yong-hai1， ZHANG Jun1, WANG Quan-zheng2， YIN Chen3

2013, 34(1):  1-7.  doi:10.3969/j.issn.1000-1093.2013.01.001

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The lifetime test always adopts whole life shooting, and it takes long time and consumes many ammunitions. A comprehensive analysis for the influence of some factors on the barrel life of machineguns was done on the basis of experimental research. The accelerating life test conditions and schemes were determined preliminarily. An accelerating test scheme for machineguns was proposed to decrease the test ammunition comsumption in great scope. It provides a method for the applying research on accelerating life test of machineguns.

Prevention Method Using Jet Flow in Laser Ignition Systems

MA Chang-jun, ZHANG Xiao-bing

2013, 34(1):  8-13.  doi:10.3969/j.issn.1000-1093.2013.01.002

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A contamination prevention method using jet flow was proposed to protect the optical window in laser ignition system from attachment of combustion remains of propellants and decrease of transparence. The pressure in chamber and gas flow between the chamber and the cavity were analyzed by using interior ballistics calculation. The mathematical model of the particle movement in the chamber was established and calculated. The calculation and simulation results indicate that the new proposed method is effective to protect the optical window, the jet flow interference can reduce the particles reaching to the optical window area effectively. The structural parameters are optimized for guns with different calibers based on the simulations. A screen tube is proved to be useful to enhance the protection effect. The increases of the length of cavity or the angle of diverting orifice can lead to a better protection.

Numerical Simulation of the Penetration of Bullet on Gelatin Target

WEN Yao-ke1, XYU Cheng1, CHEN Ai-jun2, SHI Xiao-ning1

2013, 34(1):  14-19.  doi:10.3969/j.issn.1000-1093.2013.01.003

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The dynamic process of bullet-gelatin interaction was studied using an FEA method. The numerical modelling was set up, and the numerical results are in good agreement with the experimental results. The penetration resistance and stress distribution of bullet in gelatin and the effect of angle of attack on gelatin damage were analyzed. The results show that penetration resistance increases slowly at narrow channel, while it increases rapidly with the rapid rolling of bullet, which leads to the fracture of the bullet. The maximum stress distribution of bullet always appears around the temporary cavity, and with the expansion of cavity the elements are stretched to beyond its elastic limit, which results in the deformation and fragmentation of gelatin. Angle of incidence has a great effect on the overturning moment of bullet, but the effect decreases with the increase in angle of attack.

Study on the Probability of Perforation for Soft Body Armor

LI Chang-sheng1, HUANG Xian-cong2, LI Yan2, WANG Lei2, LI Mao-hui2, ZHOU Hong2

2013, 34(1):  20-24.  doi:10.3969/j.issn.1000-1093.2013.01.004

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Probability of perforation (POP) curve is a constructive method to estimate the ballistic performance. It can be used to estimate the low velocity at smaller penetration probability. POP curves have potential and promising application in body armor design. For this purpose, the performance of UHMWPE unidirectional layers (PE armor) against 7.62mm type 51 pistol bullet was investigated. POP curves was established by logistic function and binary logistic regression. v50 (velocity with 50% penetration probability) and v05 (velocity with 5% penetration probability) of PE armor were derived from POP curves. v50 was 592m/s determined by both methods, while v05 was 538m/s and 514m/s，respectively. The results indicate that the regression method is more suitable for the estimation of velocity at low penetration probability. The difference between the two POP curves was discussed.

Study of TIG Cladding Process for Bullet's Pure Iron-rotating Band

LYU Shi-xiong1, YANG Tao1, HUANG Yong-xian1, MO An-xiang1, WANG Yang1， JIANG Hua3

2013, 34(1):  25-29.  doi:10.3969/j.issn.1000-1093.2013.01.005

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When the copper-rotating band of bullet is clad by means of tungsten inert gas (TIG) welding, the infiltrated cracks are usually appeared. The pure iron (carbon content of less than 0.04%) was selected to produce rotating band as the cladding materials instead of copper. The cold-wire TIG welding, newly designed hot-wire TIG welding and vibration TIG welding were adopted to clad the pure iron to the 20# steel surface of bullet. The cladding speed of coldwire welding was 1.3m/min, while the hotwire welding was 1.8m/min, which is faster than cold-wire welding. The cladding speed of vibration welding was 1.6m/min. Besides, it can reduce the welding current by 10A. The interface and cladding layer of welding joints produced by different welding methods were analyzed. The hot-wire welding made the grains connecting the interface and the cladding layer grow up, while the vibration TIG welding made them more smaller. The vibration welding can reduce the average hardness of cladding layer to HV160, or by HV15 or so compared with the other two methods. Shearing experiments show that the value of intensity on the connecting interface is much higher than its original intensity of bullet's cladding layer. From the results of shooting experiments, it can be seen that pure iron is another kind of feasible alternatives for copper as the cladding material.

An Experimental Study on Ultrasonic Vibration Cutting for Polymer Bonded Explosive Simulants

2013, 34(1):  30-35.  doi:10.3969/j.issn.1000-1093.2013.01.006

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The polymer bonded explosive (PBX) is an important energetic material widely used in weapon warheads. It is difficult to be machined by using conventional cutting (CC) method, because its low tensile intensity causes brittle fracture. The ultrasonic vibration cutting (UVC) method is a novel technique successfully applied to almost all the difficulttomachine materials, such as optical glass, ceramics, intractable alloys, composites and so on, except the explosives. An experimental study on UVC for PBX simulants was presented to compare with CC. Firstly, the contrastive experiments were carried out to investigate the cutting forces in UVC and CC. Secondly, the microscopic morphologies of machined surface were observed on the samples prepared by both UVC and CC method. The experiment results show that the main cutting force in UVC, compared with that in CC, decreases by 61.75% to 67.98%, and the cutting depth resistance and feeding force reduced by 55.57% to 65.56% and 31.63% to 42.29%, respectively; UVC can obtain a less extrusion and lower residual stress surface, and it may reduce the cutting heat. Moreover, UVC method can improve the manufacturing capability for PBX slender rods and thin wall parts.

Synthesis and Characterization Studies on Novel Three Explosives with Low Melting Point

LI Yong-xiang, CAO Duan-lin, WANG Jian-long

2013, 34(1):  36-40.  doi:10.3969/j.issn.1000-1093.2013.01.007

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Three new explosives, such as 1-methyl-3,5-dinitro-2,4-triazole(DNMT), 1-methyl-4,5dinitro-imidazole(4,5-MDNI) and 3,4-dinitropyrazole(DNP), with low melting point were synthesized by using dicyandiamide, Nmethy limidazole and pyrazole as raw materials through nitrification reaction, thermal rearrangement and nitrification reaction etc. The technical parameters were optimized to obtain the optimal conditions. The compounds were characterized by melting point testing, IR spectrum, element analyzing and 1HNMR. Furthermore, thermal decomposition performance of these products were analyzed through DSC thermal analyzer, which melting points are MDNT 95℃,4,5-MDNI 77℃,DNP 85℃. Three explosives exhibit the lower melting points and good thermal stability.

A Study on Preparation and Properties of High Density RDX Crystal

RUI Jiu-hou, ZHAO Xue

2013, 34(1):  41-44.  doi:10.3969/j.issn.1000-1093.2013.01.008

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The preparation method of high density RDX was introduced. The influences of solution concentration, crystallization temperature, stirring speed and dilution rate on RDX crystal density were analyzed, and the high density RDX crystal was prepared. Its crystal shape, defects, density, melting point, thermal property and thermal sensitivity were tested. The results show that the high density RDX crystal density is up to 1.808g/cm3, i.e. 0.023g/cm3 higher than that of the ordinary RDX, and reaches to 99.56% of the theory density and lacks of crystal defects. Comparing with the oridinary RDX, the high density RDX's decomposition peak temperature increases by 3.66℃, and ignition point increases by 1℃. The stability of high density RDX is better than that of the ordinary RDX.

Effect of Al/O Ratio on Detonation Performance and Underwater Explosion of RDX-based Aluminized Explosive

2013, 34(1):  45-50.  doi:10.3969/j.issn.1000-1093.2013.01.009

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The detonation parameters of RDX-based aluminized explosive were measured by test, and the test result was verified by KHT code. The influence law of Al/O ratio on detonation pressure, detonation velocity and heat was analyzed. Underwater explosion experiments were carried out on shock wave propagation and bubble pulse of 1kg cylindrical RDXbased aluminized explosive under water 4.7m.The coefficients of similitude equation for peak pressure and attenuation time constant were fitted. The study indicates that the detonation pressure and velocity reduce linearly with the increasing of Al/O ratio and the detonation heat achieves a maximum value when Al/O ratio equals to 0.997. When Al/O ratio equals to 0.366, the peak pressure and shock wave energy reach the maximum value, but the shock wave impulse and flux density reach the maximum value when Al/O ratio equals to 0.633, and the first bubble pulsation period and radius reach the maximum values when Al/O ratio equals to 0.997.

A Clock Synchronization Algorithm Based on Parametric Difference for Distributed Node Clusters

LING Yun-xiang1, FAN Lin-jun1, WANG Tao2, ZHANG Guo-hua1

2013, 34(1):  51-59.  doi:10.3969/j.issn.1000-1093.2013.01.010

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By analyzing some new features of distributed systems such as multiplatform, generality, phase synchronization et al, a novel logic clock model based on parametric difference (LCPD) and its synchronization algorithm for distributed node clusters (SADNC in short) were proposed, In LCPD, the indeterminate network delay is considered into the changing parametric difference frequency (PDF) and the local clock value is not modified. By converging on the dynamic PDF and calculating the counting values of LCPD recursively, all distributed nodes are synchronized in the whole network once each node’s counting value is equivalent and stable. The steps of SADNC algorithm consist of zeropoint time calibration and synchronization of LCPD, in which some ideas of methods such as parametric difference broadcast, phaselocked loop and cooperative time synchronization are adopted. The simulation experimental results show that the stability and convergence of SADNC are excellent and all nodes hardly can be out of synchronization once they have been synchronized, which can meet the time synchronization requirement of large-scale, heterogeneous distributed simulation systems.

Truing Error Analysis of Arc Wheel in Optical Aspheric Grinding

LIN Xiao-hui， WANG Zhen-zhong， GUO Yin-biao， JIANG Tao， ZHANG Dong-xu

2013, 34(1):  60-65.  doi:10.3969/j.issn.1000-1093.2013.01.011

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Aimed at high accurate truing of arc wheel in optical aspheric grinding, a GC cup truer was adopted for the arc wheel truing, and the truer’s geometric error and principle error were analyzed. The effects of all errors on the arc wheel truing and optical aspheric grinding were discussed. It was found that the positioning tilt error was the main error in the arc wheel truing. Truing experiment results show that the residual error of fitting radius is bigger and its distribution coincides with theoretical analysis. The optical workpiece surface error distribution is also similar to theoretical analysis in the aspheric grinding. After antitilting, the experiment results show that the surface error distribution is changed and the surface accuracy is improved.

Experimental Study on Failure Behavior of HTPB Propellant and Liner Interface

QIU Xin1, LI Gao-chun2, XING Yao-guo2

2013, 34(1):  66-71.  doi:10.3969/j.issn.1000-1093.2013.01.012

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In order to study the failure behavior of HTPB propellant/liner interface, a kind of small specimen was designed and its fracture behavior under axial tensile was observed by using a CCD microscope. The relations of the average crack width and dewet length with the clamping fixture displacement were determined by using image measurement method, and the bonding quality of the interface was analyzed from the macroscopic and microscopic views. The experiment results show that the dewet of interface between the granulated AP close to liner and the liner is the main cause of the performance degradation, and the interface energy between AP and propellant binder is greater than that between AP and liner. It can be a supplement to the traditional way to assess the bonding quality of solid propellant and liner.

Information Fusion Algorithm for Integrated Navigation System with Suppressing Interference of Particle Filters Fading Factors

SHAN Yong-zhi1,2，YIN Jian3， LIU Shao-kun4, SUN Li-wei2， XU He-chuan2

2013, 34(1):  72-75.  doi:10.3969/j.issn.1000-1093.2013.01.013

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To revise the interference statistics of an integrated navigation system, a particle filtering algorithm was adopted to discriminate the systematic error of the statistics. And the modified particle filtering algorithm changes the weights of particles to suppress the interference when a single channel subjects to interference and tends to divergence. The simulation results show that the modified particle filtering algorithm is able to keep the system even for the divergence of a superior function by reducing the error efficiently and increasing the accuracy.

Reconstruction and Extraction Methods for Micro-Doppler Feature of Ballistic Missile Precession with Sparse Frequency-stepped Chirp Signal

ZHU Feng1,2，ZHANG Qun1，LI Song3，FENG You-qian4，ZHANG Wei-qiang5

2013, 34(1):  76-81.  doi:10.3969/j.issn.1000-1093.2013.01.014

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Some microDoppler features of ballistic missile precession with frequencystepped chirp signal (FSCS) were analyzed theoretically. Combined with compressed sensing (CS) theory, a new method of microDoppler spectrum reconstruction method based on sparse FSCS was proposed. The spectrum information can be reconstructed exactly, in obviously reduced subpulses of FSCS, and the sidelobes of spectrum can be effectively suppressed. Furthermore, aimed at the reconstructed spectrum, a new extraction method for microDoppler features of ballistic missile precession was proposed on the basis of dynamic planning, by using the smooth character of microDoppler curves. The effectiveness and robustness of the method was validated numerically.

Mean-Shift Tracking Algorithm Based on Distance Information

RAN Huan-huan, HUANG Zi-li

2013, 34(1):  82-86.  doi:10.3969/j.issn.1000-1093.2013.01.015

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Aimed at the tracking drift bought by imaging perspective and distance changes in the tracking process of image-guided target tracking system, a tracking algorithm using the distance information to dynamically change the scale of tracking window of the Mean-Shift algorithm was proposed. Firstly, the targets gray feature model was established according to the selected initial tracking template, and the initial scale of tracking window of Mean-Shift was determined. Then, the window’s scale was updated according to the distance information to ensure the tracking window contain the target completely or partially while the tracking system gradually closed to the target. Finally, Bhattacharyya correlation coefficient was used to update the target template nonlinearly after the tracking convergence of each frame. This paper uses the flight video data generated by Vega to simulate the algorithm, and the result shows that it can adapt to the expanding of the goal, and reduce the tracking drift in a large extent.

A Tracking Method of Multi-sensor to Track the Multiple Targets Under the Condition of Low Detection Probability

NI Long-qiang1,2，GAO She-sheng1，XUE Li1

2013, 34(1):  87-92.  doi:10.3969/j.issn.1000-1093.2013.01.016

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A new algorithm was presented to deal with the multi-target tracking problem. Firstly the target number in an interest region was modeled as a stochastic process; secondly the state vector was augmented with target number; and finally the state estimation was carried using the multi-model particle filter (MMPF), and the numerical simulation was proposed to identify the efficiency of this method in multisensor/multitarget tracking application. The simulation results show that the improved method can be applied to track the maneuvering targets effectively by using the non-linear dynamic model.

Molecular Dynamics Simulation of NC/NG Blends

QI Xiao-fei1, ZHANG Xiao-hong1, LI Ji-zhen1, LIU Fang-li1, SONG Zhen-wei1, ZHANG Jun-ping2

2013, 34(1):  93-99.  doi:10.3969/j.issn.1000-1093.2013.01.017

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In order to explore the interaction between nitrocellulose (NC) and nitroglycerine (NG) of composite modified doublebase (CMDB) propellants, the radius of gyration of NC molecules and radial distribution function for different atoms of NC and NC/NG blends were calculated by using molecular dynamics simulation(MD). It was found that the radius of gyration of NC molecules was independent on the temperature, while the number of NG molecules increased greatly with temperature. Besides, according to the radial distribution function of the models, it was revealed that the Hbond could be formed between NG and NC molecules instead of Hbond in the individual NC molecule, which could decrease the interaction force inside NC molecules, thus increase the radius of gyration of NC.

Research on Shock Wave Propagation of Underwater Explosion of Bottom Charge

YANG Li， WANG Yu， DU Zhi-peng， SHI Shao-hua

2013, 34(1):  100-104.  doi:10.3969/j.issn.1000-1093.2013.01.018

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A numerical model for simulating the underwater explosion of bottom charge was established using the hydrodynamics analysis software, and the underwater explosion process was numerically simulated to obtain the law of its shock wave propagation. For the underwater explosion of a bottom charge, the shock wave propagation complies with the law of exponential decay. The bottom affected the shock wave propagation. Mach wave was formed due to the reflective wave catching up with the incident wave at the gauge points which were close to the explosion point on the bottom. For the points near the bottom their incident wave was strengthened or weakened by the shock wave or the rarefaction wave reflected from the bottom.

Investigation on Bullet Proof Mechanism of Light Ceramic/Steel Composite Armor

HOU Hai-liang, ZHU Xi, LI Wei

2013, 34(1):  105-114.  doi:10.3969/j.issn.1000-1093.2013.01.019

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In order to explore the bullet proof mechanism of ceramic/steel composite armor, the ballistic impact experiment was carried out to study the dynamic response of ceramic/steel composite armor subjected to the impact of high speed fragments. The damages of projectile, ceramic and steel back plate were described physically and analyzed phenomenologically. The damage modes of ceramic and steel back plate were determined. The energy transformation during the ballistic penetration and the bullet proof performance of the ceramic/ship steel composite armor were analyzed. The results show that the conical crash is a main damage mode of ceramic under the impact of high speed fragments. And the main macro cracks are radial, ring and conical cracks which extend outward at about 65° angle included between the conical crack and the initial surface normal. Besides there are the inverse conical cracks extended outward at angle of 65° to the back surface normal. The deformation range, destructiveness and damage mode of the back plate have great different from those of ship steel target. The deformation mode of the backing plate is bulgingdishing when the impact velocity is below the ballistic limit. When the impact velocity exceeds the ballistic limit, the back plate has 3 damage modes, i.e. shearing damage, dishing-shearing-petaloid damage and dishingpetaloid damage, as the relative thickness of ceramic increases. In the penetration process of light ceramic/metal composite armor, the kinetic energy of projectile is mainly dissipated in the deformation and damage of projectile and back plate. When the velocity of the penetrator is about ballistic limit, the energy dissipated in projectile and back plate damages varies with the relative thickness of ceramic. But the total energy dissipated in these facets occupies more than 90% of initial kinetic energy of the projectile, and the energy dissipated in the fragmentation of ceramic and the ejecting kinetic energy of ceramic fragments occupies less than 10% of its initial kinetic energy.

Research on Welding Processes of Armor Steels

TAN Jun1, ZHANG Yong2

2013, 34(1):  115-124.  doi:10.3969/j.issn.1000-1093.2013.01.020

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The armor steel is a kind of protective alloy material which is used in a variety of combat equipment. The welding is a main joining method of armor steel structure. On the base of crack category, characteristics and formation causes of armor steel, the welding materials and welding processes of armor steel, and the measures taken to improve the properties of welded joint were introduced. Those include austenite welding electrode, ferrite and austenite/ferrite dual phase welding electrodes, the processes of arc welding, CO2 gas protection welding and thermit welding of armor steel crack repairing, and the measures taken to improve the properties of the welded joint of heat treatment after welding, ultrasonic impact, toe grinding and tungsten arc welding. The improving measures and development direction of armor steel welding were put forward by analyzing the armor steel welding processes.

Study on Projectile Muzzle Velocity Measurement Based on Rotational Speed

PEI Dong-xing, WANG Wen-wu, CUI Chun-sheng

2013, 34(1):  125-128.  doi:10.3969/j.issn.1000-1093.2013.01.021

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A method for the muzzle velocity measurement utilizing the rotational speed was put forward. The earth magnetic field sensor and test circuit were installed in bullet or fuse. When the projectile rotates, the coil in the sensor would cut the earth magnetic line and periodically produce inductive electromotive force. Then, the test circuit acquired the signal and saved it in the memory device. After reclaiming the circuit, the data could be obtained from the memory and the muzzle rotational speed could be known. According to the twist pitch of rifling, the projectile’s muzzle velocity could be found out. The method was verified by using live ammunition test.