Table of Content

30 August 2013, Volume 34 Issue 8

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Research on Hill-start Control Strategy for Military Heavy-duty Wheeled Vehicles with AMT

LU Jia, LIU Hai-ou, PENG Jian-xin, XI Jun-qiang

2013, 34(8):  929-934.  doi:10.3969/j.issn.1000-1093.2013.08.001

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A strategy of hill-start control is presented for military heavy-duty wheeled vehicles with automated mechanical transmission(AMT). A concept of that the opening degree of accelerator pedal, the engine speed and the decline rate of engine speed are used to estimate the clutch transmitting torque is put forward based on the dynamics analysis of hill-start process of vehicle and the engine speed characteristic curve. And also the parking brake release conditions are identified. The clutch control strategy is designed based on the existing experimental vehicle platform, and the satisfactory results are achieved when vehicle tests are carried out at the different angles of slopes. The experimental results show that the proposed theory is feasible.

Partition between Useful Jet and Liner Material

HOU Xiu-cheng, JIANG Jian-wei, CHEN Zhi-gang

2013, 34(8):  935-941.  doi:10.3969/j.issn.1000-1093.2013.08.002

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Explicit finite software LS-DYNA and tracer point method are used to study the nice partition between useful jet and liner material. The useful jet is divided into four sections in terms of velocity distribution, such as high speed(vj 逸5 km/ s), sub-high speed(4 km/ s臆vj < 5 km/ s), medium speed(3 km/ s臆vj <4 km/ s) and low speed(2 km/ s臆vj <3 km/ s). The result indicates that the useful region of liner is a thin-wall cone with variable thickness along axial direction. The highest speed section of useful jet is nearby the top of liner, and its thickness is 0. 12 thickness of liner. The lowest speed section is in the lower part of liner, and its thickness is 0. 46 thickness of liner. The material in rang of about 0. 2 height from the bottom of liner can not generate useful jet. Liner material is stripped progressively from the inner side of liner in the process of jet forming. The thickness and mass ratios of useful region to liner are of exponential distribution along axial direction of liner. It can offer a reference the design of efficient shaped charge and composite liner.

Research on Large FOV Single Transceiver Bidirectional-driving Detection Technology for Laser Fuze

GAN Lin, ZHANG He, ZHANG Xiang-jin

2013, 34(8):  942-947.  doi:10.3969/j.issn.1000-1093.2013.08.003

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Due to the limitations of system power consumption and space, the conventional ammunition laser fuze is unable to use a plurality of lasers and laser receivers for multi-transmitting and multi-receiving,and therefore the traditional large field-of-view (FOV) laser detection method can not meet the requirements of system miniaturization. A new large FOV single transceiver bidirectional-driving detection scheme is proposed,a mathematical model is established, and the target acquisition rates at the different projectile-target distances and the different projectile spin rates are analyzed. For the electromagnetic interference factors, a prototype is manufactured, and a variety of methods are used to shield the electro-magnetic signals. The anti-electromagnetic interference experiment and the detection experiment of targets at different distances are performed. The results show that the scheme can effectively shield the electro-magnetic interference; ensure that a target can be captured at the distance of 8 m when the spin rate of project tile is 50 000 r/ min; and make the application of laser fuze with large FOV detection capability in conventional ammunition possible.

Modeling and Simulation on Scanning Target Using Laser Fuze of Intelligent Mine

YU Ning, ZHANG You-long, YANG Dong-lai, YIN Dong

2013, 34(8):  948-952.  doi:10.3969/j.issn.1000-1093.2013.08.004

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In order to study the range profiles of laser fuze installed on intelligent mine,the dynamics, kinematics and analytic geometry are applied in scanning movement modeling of intelligent mine submuni tion. The mathematics models of ground, barriers, armored targets, and rendezvous of scanning line and target are established by using an analytic geometry method. At the same time, the computer numerical simulation of range profiles of laser fuze scanning the stationary and moving armored targets are carried out under the influence of different barriers. The results show that laser fuze could detect target repetitiously, the frequency and time of detecting target depend on the relative position of the mine submunition and target, and the range profiles of laser fuze has uniqueness for the target with unique figuration. The simulation model can provide references for overall design of intelligent mine, design of laser fuze and research on target recognition algorithm.

Preparation and Performances of Nano-micron Flaky Energetic Material for Integrated Device

WANG Jian-hua, LIU Yao, YAN Li-wei, LIU Yu-cun, CHANG Shuang-jun, YU Yan-wu

2013, 34(8):  953-957.  doi:10.3969/j.issn.1000-1093.2013.08.005

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Flaky RDX and HMX are prepared by using solvent/ non-solvent recrystallization and soft template method in order to meet the integration requirements of energetic material in miniature explosive element. Its surface appearance is investigated by SEM. The result shows that the thickness and length of hexagonal flaky RDX crystal are about 3 μm and 20 -50 μm, respectively; the thickness and length of quadrilateral RDX flaky crystal are approximately 1 μm and 10 -50 μm, respectively; the thickness and length of rectangle HMX flaky crystal are less than 1 μm and 3 -10 μm, respectively. The impact sensi- tivity and thermal decomposition of flaky energetic material crystal are tested. The test results show that the impact sensitivity of flaky energetic material crystal is increased, but its exothermal peak value is not changed compared with near-spherical crystal.

Study on the Electrostatic Hazards of Lead Styphnate

LI Zhi-min, ZHOU Ming-rui, ZHANG Tong-lai, ZHOU Zun-ning, YANG Li, ZHANG Jian-guo

2013, 34(8):  958-964.  doi:10.3969/j.issn.1000-1093.2013.08.006

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To characterize the electrostatic hazards of lead styphnate (LTNR), the static electricity accumulation and electrostatic spark sensitivity are tested. 5 kinds of flumes with different lengths and slanting angles made of stainless steel, aluminum, fabroil, conductive rubber and shellac painted kraft are used to test the flowing time and static electricity accumulation of LTNR. The friction coefficients between LTNR and various flumes are calculated. The quantitative relation between the static electricity accumulation and the length and slanting angle of flume is investigated, and the linear and quadratic equations are obtained. The effects of slip velocity and friction on the static electricity accumulation of LTNR are studied, and the binary linear regression equations are obtained. Furthermore, the electrostatic spark sensitivity of LTNR is tested with various capacitances, resistances and electrode gaps. The result shows that the test condition has an significant effect on electrostatic spark sensitivity which increases with the increase in electrode gap.

Experimental Research of the Effect of Ambient Humidity on the Explosion Characteristic Parameters of Aluminum Powder

TAN Ru-mei, ZHANG Qi

2013, 34(8):  965-969.  doi:10.3969/j.issn.1000-1093.2013.08.007

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In order to assess the explosion risk of aluminum powder comprehensively, the influence of humidity on aluminum powder explosion is studied in a explosion tank. The maximum explosion pressure and the maximum pressure rise rate of aluminum powder explosion were obtained at the relative humidities of 33%, 60% and 90%, respectively. It is shown that the relative humidity usually distinctively affects the probability of aluminum powder explosion, and the effect is related with dust concentration. When dust concentration is lower, with the increase in ambient humidity, the maximum explosion pressure and the maximum pressure rise rate first increase and then decrease; but when dust concentration is higher, the maximum explosion pressure and the maximum pressure rise rate are significantly increased with the increase of the ambient humidity. Meanwhile, based on the nonlinear fitting of experimental data, the DoseResp function between the maximum explosion pressure and aluminum powder concentration at different ambient humidity is obtained.

Experimental Study of Cutting PMMA Plate with Miniature Detonation Cord

LI Zhi-qiang, WANG Zhi-hua, LIU Xiao-ming, ZHAO Long-mao

2013, 34(8):  970-974.  doi:10.3969/j.issn.1000-1093.2013.08.008

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Miniature detonation cord (MDC) with HNSII is used to cut aerial PMMA plate. 45 experiments of MDC cutting PMMA plates with three different lengths are performed at three different temperatures on a modified test apparatus. The effect of temperature, size and boundary condition on cutting results is investigated. Experimental results indicate that these factors, such as temperature, size and boundary condition of PMMA plate studied in the paper, have a slight effect on the cutting results, which can almost be neglected. Consequently, the cutting canopy experiment is directly guided by component experimental parameters and results, which provides science foundation for the design and improvement of ejection-lifesaving-system.

Numerical Research on Aerodynamic Characteristics of Cavity with Store at Supersonic Speeds

Aeronautics and Astronautics Engineering College, Air Force Engineering University, Xi'an 710038, Shaanxi, China

2013, 34(8):  975-980.  doi:10.3969/j.issn.1000-1093.2013.08.009

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The aerodynamic characteristics of cavity with store at supersonic speeds are researched using large eddy simulation (LES) method and FW-H equations. A computational model is established, and the grid reliability is proved. The results show that the flow field is separated into three independent vortices because of the existence of missile, and the fluctuation of static pressure coefficient is enhanced. The sound pressure level (SPL) of cavity with store is 5 ~6 dB lower than that of empty cavity. The max SPLs are on both the sides of the cavity aft-wall, and the peak frequency is below 200 Hz. Flow field sound is generated from the self-sustained oscillation of shear layer. The sound generation cycle is “shed vortices sound wave-reflection sound wave-new shed vortices", which exists in the area between the head of missile and the aft-wall of cavity. These results can be used to build the control method for flow field of cavity with store at supersonic speeds.

Experimental Research on Hyperivelocity Impact of Middle and Low Density Material Flyers on Aluminium Shield Structure

ZHANG Yong-qiang, TAO Yan-hui, CAI Jin-tao, SONG Zhen-fei, TAN Fu-li, ZHAO Jian-heng

2013, 34(8):  981-985.  doi:10.3969/j.issn.1000-1093.2013.08.010

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The average velocity of space debris impacting on on-orbit spacecrafts is 10 km/ s, and 90% of them in low earth orbit are the middle and low density materials. The experiments of Mylar foil and Al flyer impacting on Al shield structure at 14 km/ s and about 9 km/ s, respectively, are done by electric gun and magnetic driving technology, and the damage results of Mylar foil and Al flyer impacting on shield structure are obtained. The results show that the debris cloud created by Al flyer impacting on Al shielding slab at about 9km/ s contains fluid state and even gas state, and the debris cloud created by Mylar foil impacting on Al shielding material at 14km/ s is solid state. For the Mylar foil flyer, the shielding effect of double shield structure is better than that of the single layer structure.

Effect of Driving Force Characteristics on the Power Flow of L-shaped Plate

ZHAO Zhi-mei, SHENG Mei-ping

2013, 34(8):  986-993.  doi:10.3969/j.issn.1000-1093.2013.08.011

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A theoretical model of L-shaped plate is established based on the waveguide method. The effect of an included angle between driving force and L-shaped plate on its power flow characteristics is analyzed. Both force and moment are applied to investigate how the moment affects the correlationship between the excitation angle and the system's power flow. The research shows that the in-plane vibrational power flows in the system increase as frequency increases and get close to the power flow of the flexural wave gradually. If the moment applied is very small, the flexural wave in the indirectly excited plate is mainly decided by the transmission of flexural wave from the adjacent plate at low frequencies and reduces with the decrease in the exciting angle of force, yet the high frequency flexural wave is mainly transited from the in-plane wave and increases when the excitation angle decreases. However, if the moment applied is large, all vibrational power flows in the L-shaped plate depend principally on the moment and increase with it.

Matching Target Spectrum Method for Artificial Synthesis of Blast-induced Ground Motion

NIAN Xin-zhe, ZHANG Yao, XU Yuan, YAN Dong-jin

2013, 34(8):  994-999.  doi:10.3969/j.issn.1000-1093.2013.08.012

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To investigate the explosion seismic and vibration isolation in underground protective engineering, a method for an artificial synthesis of blast-induced ground motion by matching the target response spectra is presented. The calculation and processes of the matching target spectrum method are described. In the process of generating non-stationary acceleration time histories in the near or far field, two types of wave functions of blast ground acceleration are adopted to deduce the envelope functions. A procedure for construction of blast-induced ground motion design response spectra is introduced, and a modified function of the design response spectrum is proposed. As an illustration, an induced ground acceleration time history for a shallowly buried engineering is artificially synthesized using the matching-target-spectrum method. The example shows that, after iterative calculation, the adjusted response spectrum can be close to the target response spectrum within the given fitting accuracy, the synthetic blast-induced ground motion time history meets the spectrum design requirements and can reflect the spectral characteristics and non-stationary characteristics of blast-induced ground motion.

Simulation and Test Research of Sea Clutter Characteristics in Different Environments

ZHAO Ya-ming, LI Jiu, MENG Lei, ZHAO Yue-chao

2013, 34(8):  1000-1006.  doi:10.3969/j.issn.1000-1093.2013.08.013

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Sea clutter is the main factor affecting the radar target detection, but the marine atmospheric environment changes the sea clutter characteristics by influencing the electromagnetic wave propagation path. The cause of sea clutter characteristic difference is analyzed in the different atmospheric environments, and the empirical model is used to establish an algorithm of sea clutter characteristic quantity based on the "opposite distance" method. The real sea clutter characteristics are simulated with the experiment data in Ref. [9]. It is found from the comparison of the datum observed in four directions that the simulation value is agreement with the measured average value. Finally, the sea clutter characteristics in standard atmosphere, evaporation duct and surface duct environment are investigated by using the simulative environment conditions and radar parameters. And the results show that, compared with the standard atmosphere environment, the sea clutter characteristics show a trend of increase in the duct environment, and the first skip zone in the surface duct environment also presents weak clutter or no clutter.

Machinability of Structural Materials of MR-compatible Robots

REN Zhao-wei, JIANG Shan, QI Hou-jun, YAN Bing

2013, 34(8):  1007-1012.  doi:10.3969/j.issn.1000-1093.2013.08.014

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Three kinds of MR-compatible non-metal materials, namely polypropylene, nylon and polyformaldehyde, are chosen for the measurement of their cutting forces and surface roughnesses. The variations of three-dimensional cutting force and roughness in the case of different cutting parameters are discussed. According to the above mentioned experimental results and the shapes of chips obtained during machining, the machinabilities of three materials are evaluated by using digraph and matrix (DAM) method. The result demonstrates that the nylon has the best machinability among the three materials, the polyformaldehyde takes the second place, and the machinability of polypropylene is the worst. Thus the nylon is selected for the main structure of the MR-compatible robot.

Experimental Research on Modulation Characteristics of Wheel Cylinder Pressure in Electro-hydraulic Braking System

XU Zhe, WEI Min-xiang, LI Yu-fang, LIU Rui, SHI Zhi-xiao

2013, 34(8):  1013-1020.  doi:10.3969/j.issn.1000-1093.2013.08.015

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The electro-hydraulic brake (EHB) system consists of mechanical, electromagnetic and hydraulic parts. The pressure characteristic of its wheel cylinder is essential to the brake force modulation. But this characteristic is hard to be expressed with theoretical models because of the heavy nonlinearity and coupling of the system's main parts. In the research, the experiments are carried out to study this characteristic. The essential affecting factors considered in the experiment design contain the initial pressure and the duty cycle of PWM signal. The stable variation MAP is got from the experimental results. The analysis shows that there are the inflection points in the stable variation value and initial pressure curves. The inflection point is defined as the piston travel end pressure. In this system, the pressure is 2. 8 MPa. The analysis also shows that the relationship between the pressure variation and duty cycle is linear. But the line does not go across the origin point. The cross point is at 3% of the duty cycle during pressurizing, while it is at - 5% of the duty cycle during depressurizing. In the research on pressure characteristics, the nonlinear characteristics of the system are expressed by MAP, and some parts with linear relation in the system are found.

Deep Hole Machining Method for NC Adjustable Diameter Ultrasonic Elliptical Vibration Boring

LI Wen, WANG Xiao-mei, XU Ming-gang, ZHANG De-yuan, CHEN Hua-wei

2013, 34(8):  1021-1027.  doi:10.3969/j.issn.1000-1093.2013.08.016

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Ultrasonic elliptical vibration deep-hole boring method is successfully applied to precision cutting due to its superior performances, such as low cutting force, chatter suppression and high machining precision. The acoustic interface transfer theory is analyzed in order to give full play to the ultrasonic elliptical vibration cutting and NC machining advantages. For the machining problem of complex inner hole with diameter-length ratio of greater than 20, a new processing method of NC adjustable diameter double-edge ultrasonic elliptical vibration boring is put forward. The cutting contrast experiment proves that the ultrasonic vibration double-edge adjustable tool boring method has the advantages of high machining precision, high surface quality and chatter suppression compared with the traditional boring method. In the case of the same machining parameters, the diameter of machined deep hole is 16 mm, the diameter-length ratio is 23: 1, the inner hole is 17 mm, and the ultrasonic boring surface roughness Ra is 0. 65 μm.The machining precision meets the design requirements, so the NC adjustable diameter ultrasonic elliptical tool boring is an effective method for deep hole machining.

Research Notes

Research on Supercritical Fluid Foaming Technology for Preparation of Microcellular Foamed Propellants

YING San-jiu, XU Fu-ming

2013, 34(8):  1028-1036.  doi:10.3969/j.issn.1000-1093.2013.08.017

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In recent years, the supercritical fluid microcellular foaming technology has gained much attention in the polymer material processing. Much research has been done on the foaming mechanism and the polymer material processing. The change of foam structure parameters, the sorption and diffusion of supercritical CO2 in propellants and the burning behavior of foamed gun propellants are studied according to the foaming mechanism. Combined with the burning behavior of foamed propellant, the application of foamed propellant in the charge technology is prospected, and the development direction of supercritical fluid foaming in the preparation of the foamed propellant is also put forward.

Research on Ultrasonic-based Detection Method for Detecting Broken and Weak Points of Lead Sheathed Detonating Cord

LI Guang-ya, WANG Ming-quan, ZHENG Jing-yi

2013, 34(8):  1037-1040.  doi:10.3969/j.issn.1000-1093.2013.08.018

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An ultrasonic-based detection system for detecting the broken and weak points of small-diameter lead sheathed detonating cord is proposed in view of the limited detection means, low detection efficiency and low accuracy of existing non-contact detection method for lead sheathed detonating cord. This system can meet the measurement requirements of broken and weak points of detonating cord. Experiments and practical use show that this method is feasible and can effectively improve the detection efficiency and precision, and the system runs reliably.

The Numerical Simulation of Metal Foam / Metal Tube Plastic Deformation Energy Absorber for Reduction in Overload of Projectile-borne Equipment

LIANG Zeng-you, GAO Wei, CHEN Zhi-gang

2013, 34(8):  1041-1045.  doi:10.3969/j.issn.1000-1093.2013.08.019

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A metal foam / metal tube plastic deformation energy absorber is designed to reduce the high overload of projectile-borne equipment when a projectile penetrates into a target at high velocity. And the efficiency of the energy absorber to reduce the overload is studied by using finite element software LS-DYNA. The overload-time curves of projectile-borne equipment are obtained during penetrating process,and compared with the curves obtained without any measures and with metal tube plastic deformation energy absorber. The results show that the metal foam/ metal tube energy absorber can drastically reduce the overload of projectile-borne equipment at high velocity, especially, the efficiency of overload reduction and the working time is better than simple metal tube energy absorber.

Study on Influence of Impacted Craters on Landing Performance of Lunar Lander

HU Jian-guo, MA Da-wei, LE Gui-gao, CAI De-yong

2013, 34(8):  1046-1050.  doi:10.3969/j.issn.1000-1093.2013.08.020

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The attitude of lunar lander after soft landing is a premise foundation of ascender's stable take-off. The study on influence of impacted craters on landing performance of lunar lander has an important significance to ascender's stable take-off. The nonlinear mechanics characteristics of GRC-1 lunar soil are simulated by the finite element method (FEM), and the effectiveness of the simulation method is verified by comparing the simulation results with the triaxial test results in Ref. [13]. A dynamics model of lunar lander landing process is established based on the lunar soil nonlinearity, residual stress of retro-rocket,attitude control forces and gravity. Finally, the influence of impacted craters on the attitude of lunar lan- der after landing is studied by taking a four-legged hanging rack lander as a research object. The results show that the landing attitude angle increases with the increase in impacted crater depth, and the impacted crater depth should not exceed 600mm in order to ensure stable take-off of ascenders on the lunar surface.

Bifurcation Analysis and Hopf Bifurcation Control of a Motor System

ZHANG Zhong-hua, YUAN Hui-qun, ZHANG Yu-bai

2013, 34(8):  1051-1056.  doi:10.3969/j.issn.1000-1093.2013.08.021

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For the equivalent nonlinear dynamic system of brushless DC motor, the center manifold theory and Hopf bifurcation theory are used to discuss the Hopf bifurcation behaviors of original system, the Hopf bifurcation control problem of original system is investigated using a state feedback controller, and the effects of control parameters on the position of bifurcation point, bifurcation type and amplitude of periodic solution are analyzed. The research results show that the positions of Hopf bifurcation points can be changed and even the Hopf bifurcation points are eliminated by the linear control, and the bifurcation type and the bifurcation amplitude of periodic solution can be changed by the nonlinear control. Finally, the numerical simulations show the effectiveness of the proposed controllers.