Table of Content

31 August 2016, Volume 37 Issue 8

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Paper

Research on Attitude Motion Law of Rockets on Plateau

ZHANG Ping, ZHAO Zhi-ming, JIA Bo, DENG Li-jie

2016, 37(8):  1345-1350.  doi:10.3969/j.issn.1000-1093.2016.08.001

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Based on the analysis of influence of plateau environment on rocket ballistics, a differential equations model is derived for the attitude motion of rockets. The law of attitude motion of rockets is analyzed. The law and causes of attitude motion of fin stabilized rocket on plateau are determined by analyzing the attitude test data on plain and plateau. The test results show that the attack angle of rocket increases rapidly after the end of the boost phase, and keeps at large angle for coning motion during firing at high altitude. In the case of low air density on plateau, the motion is caused by the effect of Magnus moment. A theoretical reference is provided for establishing the trajectory model, realizing the motion law of rocket and enhancing the firing precision of the weapons on plateau.

Stable Steer Control of Electric Drive Tracked Vehicle Based on Equivalent Sliding Mode Technique with Conditional Integrator

ZENG Qing-han, MA Xiao-jun, LIAO Zi-li, WEI Shu-guang

2016, 37(8):  1351-1358.  doi:10.3969/j.issn.1000-1093.2016.08.002

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The steer resistance of tracked vehicle has character of nonlinear and wide range change, and the drive system is very likely to be saturated dual to large vehicle inertia and constrained drive torque, while the drive motors of dual-motor tracked vehicle are independent with each other, which leads to regulate the drive torque per side to realize stable steer. In order to improve the stability of steer, the sliding mode technique with conditional integrator is applied to yaw rate control. A velocity-yaw rate steer control structure is developed through dynamics analysis. The equivalent conditional integral sliding mode control（ECISMC） algorithm is designed，which could increase the response speed through equivalent term feed-forward compensation and adopt the robust and rapid discontinuous nature of the sliding control outside boundary layer, enabling smooth transition to a PI control law with anti-windup inside boundary layer to eliminate track error by the conditional integrator approach. Co-simulation of Matlab and RecurDyn shows that the control algorithm has advantages of high precision, robust to disturbance, anti-windup and smooth control input, which could realize stable steer performance.

Research on Wear and Performance Degradation of a Large-caliber Machine Gun Automatic Mechanism in Firing Life-span

QI Yu-hui, XU Cheng

2016, 37(8):  1359-1364.  doi:10.3969/j.issn.1000-1093.2016.08.003

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The wear of key portion and performance degradation of automatic mechanism have an impact on the mechanism function and action reliability in firing life-span, which leads to an influence on the performance and operational effectiveness of the large-caliber machine gun. A large-caliber machine gun is used as the experimental object. The wear of key portion and performance degradation of automatic mechanism during firing life-span are measured in detail, and the failure statistics of automatic mechanism are completed. Experimental results show that the wear losses of bolt locking supporting surface and locking curve groove during firing are low, but the wear loss of bolt carrier guiderail is high. With the increase in fired shot quantity, the locking force decreases, the length of recoil spring is shortened, the standard deviation of recoil velocity increases, and the moving fault of automatic mechanism increases. There is a positive correlation among the moving fault and standard deviation of recoil velocity and the wear of key portion of automatic mechanism. The empirical models of locking force attenuation and the free length attenuation of recoil spring, and a wear model of bolt carrier guiderail and impact surface when bolt carrier recoils to position and returns to original position are established, respectively. The empirical models are good agreement with the experimental data. These models can be used to estimate the wear and performance degradation of automatic mechanisms.

Theoretical Modeling and Performance Research on Multi-stage Pneumatic and Hydraulic Catapult Device

REN Rui， MA Da-wei， YAO Lin， LIU Zheng, HE Qiang

2016, 37(8):  1365-1372.  doi:10.3969/j.issn.1000-1093.2016.08.004

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A novel multi-stage pneumatic and hydraulic catapult device with oil buffering structure，which utilizes compressed air as impetus and hydraulic fluid as transmission medium, is introduced and its ejection performance is researched by analyzing two typical catapult devices involving pneumatic and hydraulic catapult. According to the complex polytropic process of gas, the flow nonlinearity of hydraulic fluid in enclosed chamber, motion uncertainty of multi-stage cylinders and the self-buffering structure, a mathematical model describing multi-stage pneumatic and hydraulic catapult process is established based on real gas thermodynamic effect. Meanwhile, the dynamic variation model of oil pressure in enclosed chamber and the nonlinear dynamic model of multi-stage cylinders are constructed. The motion laws and working performance of multi-stage pneumatic and hydraulic catapult cylinder are obtained through numerical simulation. The results show that the proposed multi-stage pneumatic and hydraulic catapult device can generate the appropriate pressure quickly and accelerate the load up to 19 m/s within 0.2 s with the speed-up distance of 2.4 m, and thus the overload is less than 16 g and the relative velocity between two adjacent cylinders is less than 15 m/s.

Research on Gas-liquid Interaction Characteristics during the Gas Curtain Launching Process of Underwater Gun

ZHOU Liang-liang，YU Yong-gang，LIU Dong-yao，MANG Shan-shan

2016, 37(8):  1373-1378.  doi:10.3969/j.issn.1000-1093.2016.08.005

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A visualization simulator is designed to understand the characteristics of interaction between combustion gas jet and liquid medium during the gas-curtain launching process of underwater gun. A high speed video camera system is used to record the motion of projectile in a cylindrical liquid-filled chamber and the gas-liquid interaction process. The flying velocity of projectile and the axial expanding speed of gas curtain are acquired in experiment. Experimental results show that the projectile velocity increases with the increase in injection pressure. With the increase in sizes of oblique nozzles, the drag reduction property of gas curtain is improved, and the projectile velocity is also increased. On the base of experimental study, an unsteady three-dimensional mathematical model is developed to simulate the expansion of multi-combustion gas jets in liquid medium. And a numerical simulation is carried out. The simulated expansion process of the multi-gas jets is consistent with the experimental result, and the axial displacement of simulated gas curtain is in a good agreement with the experiment data. The proposed numerical model provides a reference for the analysis of generation mechanism of gas curtain during launching.

Analysis on Impact Point Response of a Dual-spin Projectile with Lateral Force Based on Equivalent Force Method

WANG Yu, WANG Xiao-ming, CHENG Jie, YU Ji-yan

2016, 37(8):  1379-1387.  doi:10.3969/j.issn.1000-1093.2016.08.006

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An equivalent force method is proposed to analyze the impact point response of a dual-spin projectile with lateral control force and calculate the correction of impact point conveniently. The influence of lateral force on the mass-center motion of projectile is separated into two parts: the direct influence arose from the control force and the indirect influence caused by the variation of angular motion related to the control force and moment. Based on the seven-degrees-of-freedom rigid-body flight-dynamic-model, the change of angle-of-attack caused by the lateral control force can be derived, thus calculating the equivalent force and the variation of impact point. According to the theoretical analysis, the correction distance is almost in proportion to the length between the origin of control force and the mass center under the same condition. Simulations and experiments demonstrate that the errors of correction and phase angle calculated by the proposed method are less than 10%.

Armor Penetration Aftereffect Overpressure Produced by Reactive Material Liner Shaped Charge

ZHANG Xue-peng， XIAO Jian-guang， YU Qing-bo， ZHENG Yuan-feng， WANG Hai-fu

2016, 37(8):  1388-1394.  doi:10.3969/j.issn.1000-1093.2016.08.007

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Armor penetration aftereffect overpressure produced by reactive material liner shaped charge is researched through experiments and theoretical analysis. Quasi-static explosion experiments are carried out to investigate the overpressure produced by reactive material liner shaped charge impacting the steel plates with different thicknesses. The result shows that the overpressure decays parabolically with the thickness of plate. Based on the quasi-steady incompressible Bernoulli equation, a model is developed to describe the armor penetration aftereffect overpressure by introducing the self-delay time of reactive materials. The results calculated by the proposed model show a good consistence with the experimental results. And the influence of the self-delay time of reactive materials on armor penetration aftereffect overpressure is analyzed.

Evaluation Method for Critical Ricochet of Projectile Obliquely Penetrating Hard Target

DUAN Jian, WANG Ke-hui, ZHOU Gang, LI Ming, DAI Xiang-hui, LI Hu-wei

2016, 37(8):  1395-1400.  doi:10.3969/j.issn.1000-1093.2016.08.008

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The ballistic trajectory of a projectile may deflect or it ricochets off a target when the projectile penetrates a hard target obliquely. Once the projectile ricochets off a hard target, it cannot perforate into the target, which cannot bring effective damage to the target. In order to ensure that the projectile penetrate the hard target effectively, the critical ricochet angles of projectile impacting the hard target need to be predicted，and the range of angles of that the projectile does not ricochet is given. Consequently, the ricochet of projectile penetrating a hard target obliquely is studied, and then an evaluation method of predicting the critical ricochet of projectile is proposed. The critical ricochet angles of projectiles penetrating the reinforced concretes with compressive strength of 30 MPa and 60 MPa are calculated using the proposed method, respectively, and the calculated results are compared with the experimental results. The results show that the evaluation method can be used to analyze and evaluate the ricochet of projectile precisely.

Hardener Systems of Energetic Binder PolyNIMMO

LI Ji-zhen, FAN Xue-zhong, ZHANG Guo-fang, YU Hong-jian, TANG Qiu-fan, FU Xiao-long

2016, 37(8):  1401-1408.  doi:10.3969/j.issn.1000-1093.2016.08.009

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The curing behaviors and elasticity moduli of poly(3-nitatomethyl-3-methyl oxetane) (polyNIMMO) with toluene diisocyanate (TDI), isophorone diisocyanate (IPDI) and addition product of hexamethylene diisocyanate and water (N-100) are theoretically studied by using Materials Studio. The mechanical properties of the cured systems of polyNIMMO with three curing agents are measured. The results show that the polyurethane reactions among polyNIMMO and three curing agents, TDI, IPDI and N-100, can take place, and the hardener of N-100 and the hardening catalyzer of dibutyltin dilaurate (T₁₂) are the best match with polyNIMMO, which tensile strength and extensibility can be improved to 3.83 MPa and 282%, respectively.

Dynamic Simulation and Experimental Study of Deployment Process of Missile Folding-wing

ZHEN Wen-qiang, JI Yong-qiang, SHI Yun-guo

2016, 37(8):  1409-1414.  doi:10.3969/j.issn.1000-1093.2016.08.010

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The deployment process of transverse folding-wings of missiles is studied. The mathematical model and dynamic simulation model of deployment process of folding-wing in missile launching and ground tests are both established, in which the influences of friction and aerodynamic force are considered. The folding-wing were designed and manufactured. The images of deployment process of folding-wings are obtained using the high speed photography during ground test. The research results show that the test results are in good agreement with those of mathematic and dynamic simulation models. A value range of friction moment is also provided from the test results, which can support the design and application of folding-wing.

Drag Reduction Characteristics and Design Optimization of Spikes

LI Yong-hong， GAO Chuan， TANG Xin-wu

2016, 37(8):  1415-1420.  doi:10.3969/j.issn.1000-1093.2016.08.011

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Taking into account the configuration or aerodynamic heating, most hypersonic flight vehicles have to use the blunt-nosed body. A strong bow shock forms ahead of the blunt nose to introduce a rather high shock drag in supersonic flow，especially in hypersonic flow，that affects the aerodynamic performance of the vehicles seriously. A spike mounted on a blunt-noised body pushes the strong bow shock away from the body surface, which forms recirculation flow with low pressure ahead of the body surface, and then decreases the drag. The drag reduction effects of spikes in high supersonic and hypersonic flows are validated through experimental and numerical methods. In order to analyze the influence of spike on aerodynamic characteristics of blunt-nosed body in supersonic(Ma=1.5) flow, the numerical studies are carried out. The design optimization of spike shape is carried out based on Kriging model and genetic algorithm.

Damage Criteria of Reinforced Concrete Beams under Blast Loading

WANG Wei, LIU Rui-chao, WU Biao, LI Lin, HUANG Jia-rong, WANG Xing

2016, 37(8):  1421-1429.  doi:10.3969/j.issn.1000-1093.2016.08.012

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In order to investigate the damage criteria of reinforced concrete (RC) beams under blast loading, the experimental study of two different dimensions of RC beams under different blast distances and charge masses is carried out. Two common RC beams designed for tall buildings and frame structures are taken as the research objects. The damage mode and characteristics of RC beams are got through 11 independent blast experiments. The results show that, when RC beams are subjected to close-in blast loading, the damage level increases with the increase in explosive mass at the same blast distance, the damage mode of RC beams changes from a few fall-off of concrete on the two sides of upper side and a few ruptures on the rear face to the compressed flexural damage of reverse triangle cone-shaped concrete on the upper side and triangle cone-shaped crack and a fall-off of concrete on the rear face, and finally the triangle cone-shaped damage areas on both upper side and rear face are perforated to result in a crushed and punched damage of concrete in the middle area. The damage area increases with the increase in explosive mass. Under close-in blast loading (blast distance= 0.5 m for example), the damage criteria of the RC beams used in the experiment are: the beam suffers from minor damage for scaled burst distance Z>0.4 m/kg^1/3; it suffers from moderate damage for scaled burst distance 0.3 m/kg^1/31/3; it suffers from high damage for scaled burst distance 0.28 m/kg^1/31/3; it suffers from serious damage for scaled burst distance Z<0.28 m/kg^1/3. It is also found that the damage of RC beam not only depends on the scaled burst distance under close-in blast loading, but also depends on the burst distance. At the same scaled burst distance, the more the burst distance is, the damage of RC beam is more serious. The results can be useful for engineering application and damage assessments.

An Evaluation Method for Near-field Underwater Explosion Power Based on Effect Target

ZHANG Xian-pi, LIU Jian-hu, PAN Jian-qiang， MAO Hai-bin, ZHANG Jing, CHEN Xue-bing

2016, 37(8):  1430-1435.  doi:10.3969/j.issn.1000-1093.2016.08.013

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An effect target evaluation method is proposed to evaluate the near-field underwater explosion power of charges, which considers the power evaluation and the structural damage. The calculation method of target deformation is established and validated through the experiment and theoretical study of slip boundary circular plate, and the distribution characteristics of energy in near-field explosion are obtained. The equivalent relation among different scale target plates is established by the dimensionless power damage factor. Based on these studies, the test equipment and method for evaluating near-field underwater explosion power are preliminarily established. The results show that, for the near-field underwater explosion, the deformation energy ratio firstly decreases rapidly and then tends to be gentle as the distance increases. In comparison to conventional evaluation method, the effect target evaluation method is able to represent the damage power of charges in near-field underwater explosion.

Experimental Research on Damage of Aramid Fiber Sandwich Bulkhead under Close Range Explosion and Fragment Loadings

LI Dian， ZHU Xi， HOU Hai-liang， LI Mao， CHEN Chang-hai

2016, 37(8):  1436-1442.  doi:10.3969/j.issn.1000-1093.2016.08.014

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In order to improve the protection ability and damage mechanism of aramid fiber sandwich bulkhead under close range explosion and fragment loadings, the deformation and failure tests of aramid fiber sandwich structure are performed, and TNT and prefabricated fragments are used in the test. The load characteristics of fragments are revealed, and the failure mode of each layer in sandwich structure is analyzed. The anti-damage mechanism of sandwich structure is discussed, and the protection ability of aramid fiber sandwich structure is compared with those of the typical sandwich structures in Ref.\[14\]. The results show that the core layer in the sandwich protective structure plays a role in intermediary transformation of damage load. A fragment point load with small impact area, short duration and severe damage is converted into a pressure surface load with large action area and long duration by squeezing the rear plate, which expands the action range of loads. In view of material weight and protective capability, the protective capability of high strength polyethylene sandwich structure is superior to that of aramid fiber sandwich structure.

Experimental Study of Air-gap Effect on Water Mitigation of Confined Explosion

XU Hai-bin， WANG Zhao， HU Hua-quan， SUN Zhen-yu， SHI Guo-kai， YANG Jun， SHEN Zhao-wu

2016, 37(8):  1443-1448.  doi:10.3969/j.issn.1000-1093.2016.08.015

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To investigate the mechanism of water mitigation on air shock wave due to detonation of explosive surrounded by water, several experiments with an air-gap between explosive and water are carried out in a spherical vessel using the spherical charge and water configurations ignited at the center point of the sphere. The water mitigation concept of confined explosion is studied according to the experimental data, such as travel time of shock wave, pressure, impulse and so on. The mechanism of interaction among air-gap, detonation products and water during explosion is also discussed. The results indicate that the lower air shock wave than explosion without water followed with the continual impact of water spray forms the explosion loading from detonating the charge surrounded by water. It is useful of air-gap between charge and water layer to attenuate the reflected overpressure, quasi-state pressure and impulse, which means the air-gap can be applied to enhance the mitigation effect of water on explosion loading.

An Analytical Model for Propagation and Superposition of Internal Explosion Shockwaves in Closed Cuboid Structure

YANG Ya-dong, LI Xiang-dong, WANG Xiao-ming

2016, 37(8):  1449-1455.  doi:10.3969/j.issn.1000-1093.2016.08.016

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The method of using an image blast source to establish the reflection effect from the walls of structure is combined with the nonlinear superposition principle to deal with the multi-wave coupling effect. An analytical model of shockwave propagation and superposition in closed cuboid structure is established. The proposed model can be used for the rapid calculation of internal explosion loading in engineering projects. The results show that the maximum relative errors of theoretical and experimental first peak overpressures, pulse widths and specific impulses on the wall are less than -10.5%, -19.2% and 13.2%, respectively. The theoretical characteristic parameters of internal explosion are in good agreement with the experimental ones, which verifies the validity of this analytical model.

Experimental Investigation into Deformation and Damage Patterns of Sandwich Plates with Aluminum Foam Core Subjected toBlast Loading

WANG Tao, YU Wen-li, QIN Qing-hua, WANG Jin-tao，WANG Tie-jun

2016, 37(8):  1456-1463.  doi:10.3969/j.issn.1000-1093.2016.08.017

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The deformation and damage patterns of clamped sandwich plates with aluminum foam core subjected to blast loading are investigated experimentally. The deflections of the center point on the rear face sheet of sandwich plates under five blast loadings are obtained. The deformation and damage patterns of the front face sheet, aluminum foam core and rear face sheet subjected to different blast loadings are given also. Two types of the fracture mechanism of the foam cores, which are shear fracture and tensile fracture, are analyzed. The research results show that the foam core subjected to intensive dynamic loading is deformed in a “progressive” compressive mode, and the maximum deflection of the rear face sheet quadratically increases with the blast impulse approximately.

Experimental Research on Initiation of Insensitive High Energy Plastic Bonded Explosives by Flyer Impact

BAI Zhi-ling, DUAN Zhuo-ping, JING Li, LIU Yi-ru, OU Zhuo-cheng, HUANG Feng-lei

2016, 37(8):  1464-1468.  doi:10.3969/j.issn.1000-1093.2016.08.018

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In order to study the difference between detonation processes of HMX-based and TATB-based plastic bonded explosives and know more about the detonation growth characteristics of insensitive high energy explosives, an one-dimensional Lagrangian experimental test system is built based on manganin piezoresistive pressure gauge measurement technique, in which the aluminum flyers are used for planar impact loading. The impact initiation experiments are performed for PBXC03 (mainly HMX) and PBXC10 (mainly TATB) explosives. The pressure histories at different Lagrangian locations and the time-distance curve of shock front are obtained through experiment. The results show that the detonation growth progress of PBXC10 explosives distinctly distinguishes from that of PBXC03 explosives. This indicates that the physical mechanism of the shock initiation and detonation growth of HMX-based plastic bonded explosives is different from that of TATB-based plastic bonded explosives. The experimental data can be used to calibrate the reaction rate equation of insensitive high energy explosives.

Research on Damage Criterion of Torpedo Shell Subjected to Underwater Explosive Shock Waves

LU Xi, WANG Shu-shan, WANG Xin-ying

2016, 37(8):  1469-1475.  doi:10.3969/j.issn.1000-1093.2016.08.019

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Damage criterion of torpedo shell subjected to underwater explosion is researched. A damage criterion is proposed according to the general form of the characteristic parameters of underwater explosive shock wave. A damage criterion method which is based on “0-1”probability distribution function is proposed. For 1∶2 ring stiffened cylinder scale model of heavy torpedo, the undersea explosion experiments of torpedoes with different charge masses are done. The quantitative criterion of heavy torpedo shell damage is obtained through similarity transformation of scale model. The peak overpressure and specific impulse threshold values of each damage level are analyzed based on this criterion. The results show that the threshold of peak overpressure decreases with the increase in charge mass under the same damage grade, and the threshold of specific impulse increase; and the smaller the charge is, the greater the change amplitudes of the two threshold values are.

Sonar Signal Processing Parallel Design Based on C6678 Multicore DSP

JI Xia, CONG Wei-hua, DU Shuan-ping

2016, 37(8):  1476-1481.  doi:10.3969/j.issn.1000-1093.2016.08.020

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In parallel processing system with multicore, it is hard to turn the improvement of hardware into the efficiency of software substantially for the drastic competition of shared resources on chip. To solve the problem, a multistage parallel sonar signal processing method based on C6678 multicore digital signal processor (DSP) is presented by scheduling memory access and multicore synchronization, which includes multicore pipeline design, parallel processing design of data transmission and CPU computation, and assembly code pipeline design. The multi-parallel stage method is introduced by taking two-dimension phased azimuth filter as an example. Performance of each stage above is tested, and a real-time processing software is developed. Test result shows that the proposed method can parallel memory access and CPU computation effectively, and the software developed based on the proposed method works efficiently. In a high speed sea trial, the sharp images of a suspension ball and its counterweight rectangle stone were got by the real-time processing system. The multistage parallel processing method is of great application value in engineering.

Influence of Transonic motion on Resistance and Cavitation Characteristics of Projectiles

HUANG Chuang, DANG Jian-jun, LI Dai-jin, LUO Kai

2016, 37(8):  1482-1488.  doi:10.3969/j.issn.1000-1093.2016.08.021

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In order to research the resistance characteristics and flow cavitation of supercavitation projectiles during transonic motion, a numerical model of a compressible and supercaitation flow field is established based on VOF multiphase model, Schnerr-Sauer cavitation model, realizable k-ε turbulence model, Tait liquid state equation and moving frame model.The proposed model is validated by comparing the numerical results with those in Ref.\[11\], and the external flow field of supercavitation projectile flying at Mach number between 0.202 and 1.281 is simulated. The simulated results show that, during transonic motion , the resistance coefficient of projectile is related to the peak value of density at the stationary point of flow field and increases with the increase in flying speed; and the shockwaves have significant influence on the shapes and dimensions of supercavities near projectile. Under subsonic condition, the flying speed of projectile has no significant influence on the dimensions of supercavities, and the shapes of supercavities coincide with theoretical results; under supersonic condition, the dimensions of supercavities decrease sharply with the increase in flying speed.

Research on Microstructure and Properties of Supersonic Plasma Sprayed Mo Coating based on Orthogonal Experiment

LIU Gui-min， YANG Zhong-xu， ZHANG Yi-fan， YAN Tao， WEI Min

2016, 37(8):  1489-1496.  doi:10.3969/j.issn.1000-1093.2016.08.022

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In order to explore the anti-wear reinforcement of the surface of 45CrNiMoVA which acts as rail materials for electromagnetic railgun, Mo coating on 45CrNiMoVA surface was prepared by supersonic plasma spraying technology. The spray parameters are optimized by orthogonal experiment, and the effects of spray parameters on the properties of coating and the structure and properties of the optimal coating are discussed. The research results show that the coating has the best integrative property when spray voltage is 115 V, spray current is 380 A, Ar gas flow rate is 130 L/min, and spray distance is 100 mm. The conductivity, porosity, microhardness and adhesive strength of the optimal Mo coating are 6.01%IACS, 0.12%, 482.3 HV_0.1 and 52.1 MPa , respectively. The wear rate of optimal Mo coating is slightly lower than that of substrate at 5 N load and 5 Hz frequency, while its wear rate is only around half as that of substrate at 20 N load and 20 Hz frequency, and the wear mechanism is adhesive wear and oxidative wear.

Microstructure and Tribological Properties of Laser Cladding TiB₂/Ni-based Alloy Composite Coatings

XU Ting, LI Hua-bing, HONG Xiang, ZHANG Zhong-wei, LIN Yan-yan

2016, 37(8):  1497-1505.  doi:10.3969/j.issn.1000-1093.2016.08.023

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In order to improve the wear resistance of aluminum alloy frictional parts, TiB₂ particles reinforced Ni-based alloy composite coatings are prepared by laser cladding technology. The microstructure of the composite coatings is studied. The tribological properties of the composite coatings in dry friction and seawater environment are investigated. The results show that the TiB2 reinforced phase is uniformly distributed in composite coating, and contains the reactively generated hard phases of TiB, TiC, CrB and Cr₂₃C₆ , etc. Its microhardness is 855.8HV_0.5, which is 6.7 times as high as that of the aluminum alloys. In different friction conditions, the friction coefficients and wear losses of the composite coatings are significantly lower than those of Ni-based alloy coatings and aluminum alloys. The wear mechanisms of the composite coatings in dry friction are micro-cutting wear accompanied with hard particle peeling. In seawater environment, the composite coatings suffer from micro-cutting wear and pitting corrosion wear.

Reliability Analysis for Modular Optoelectronic Pod Based on Grey Relational Decision

HU Dong-fang， JI Yuan-hao

2016, 37(8):  1506-1516.  doi:10.3969/j.issn.1000-1093.2016.08.024

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The grey system theory is adopted in the reliability analysis for modular optoelectronic pod, and a grey relational mathematical model is established. The sample modules are partitioned according to the category of index characteristics of reliability and the design requirements of optoelectronic pod, and the reliability index parameters of each sample module are evaluated. Based on the improved grey absolute relational analysis method, the resolution coefficient in the model is analyzed and calculated. Moreover, the correlation between the sample data line and the design standard line is expounded from the perspective of proximity, and finally the reliability analysis for modular optoelectronic pod is completed. The present optoelectronic pod modules are preferred based on the analyzed results of reliability to obtain the preliminary modular design scheme of optoelectronic pod. The two test prototypes are trial-manufactured according to the optimal and sub-optimal schemes. The reliability index parameters of each test prototype are tested and evaluated. It is found that the test results are consistent with the analysis results. The effectiveness and feasibility of the research method in shortening the product development cycle and studying the reliability of modular products are verified.

Gun Slaving Speed Measuring Method Based on Image Perspective Distortion Correction

WANG Yan-hai, WANG Xiao-man, LI Yu-shan, JING Wen-bo, WANG Zi-he

2016, 37(8):  1517-1523.  doi:10.3969/j.issn.1000-1093.2016.08.025

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A gun slaving speed measuring method based on image perspective distortion correction is proposed to solve the complicated operation and low measurement accuracy of traditional measuring method. In the proposed measuring method, a gun slaving speed measuring system composed of laser, target plate, CCD camera and computer is established. The CCD camera is responsible for real-time recording of positions of laser spot on the target plate. The gun slaving speed could be calculated according to the displacement and time of laser spot. Based on feature point imaging, a transformation matrix is built according to the perspective transformation principle, through which an image correction model is acquired, thus enabling to realize the perspective distortion correction of laser spot images on the target plate. Laser spot on the corrected image is extracted, and its barycenter is computed to get the displacement and time of the barycenter. The gun slaving speed is calculated. Experimental results show that the proposed measuring method has 10 times higher measuring accuracy of gun slaving speed than that of the traditional method. The method is applicable to range test and other measuring engineering of gun slaving speed.

Load Spectra-based Lifetime Prediction for Missile Components under Varying Environment

WANG Hao-wei， TENG Ke-nan， XI Wen-jun

2016, 37(8):  1524-1529.  doi:10.3969/j.issn.1000-1093.2016.08.026

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A forecasting method based on the environmental load spectra is proposed for predicting the lifetime of missile components under time-varying storage environment. Normal and Gamma distributions are used to model the load spectra for collected temperature and humidity data, respectively. A three-parameter Weibull distribution is utilized to fit the time of failure, then the parameters, which are dependent on environment, are determined using acceleration factor constant principle. Furthermore, a simplified generalized Eyring model is used to establish the relationship between the time-varying environment and the reliability model. A case study is provided to validate the effectiveness of the proposed method. The results show that the proposed method can be used to reduce the prediction error compared with the traditional prediction method that takes the average environment as varying environment.

Reliable Fatigue Life Analysis Method Based on Probabilistic Performance Measure

LIU Qin, SUN Zhi-li, QIAN Yun-peng, LIU Ying

2016, 37(8):  1530-1535.  doi:10.3969/j.issn.1000-1093.2016.08.027

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Based on the frequently-used engineering methods for fatigue life prediction and the performance measure approach, a reliable fatigue life model is built, and a set of methods for reliable life prediction and sensitivity analysis are proposed. By expressing fatigue life as the function of random variables, the reliable life prediction problem is converted into a spherical constraint optimization problem which can be solved using performance measure approach, and then the reliable life can be gotten directly. Moreover, the sensitivity factors for each random variable and deterministic variable can be calculated by using some intermediate variables in life prediction. The proposed method is demonstrated with a torsion shaft example. The results show that the proposed method has high efficiency and precision, and the different parameters have much different influences on reliable life.

A Transient Model of Gas-liquid Two-phase Flow for Mobile Pipeline Draining

JIANG Jun-ze, ZHANG Wei-ming, DUAN Ji-miao, YONG Qi-wei, JIANG Ming

2016, 37(8):  1536-1542.  doi:10.3969/j.issn.1000-1093.2016.08.028

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Draining is a routine operation of mobile pipeline. A transient model of mobile pipeline draining is established in order to improve the scientificity and efficiency of draining operation. The proposed model consists of gas kinematic equations，liquid kinematic equations and interface coupling equations. The finite volume method is adopted to solve the model, which can calculate liquid holdup, pressure and flow rate in the case of the given initial pressure and flow rate of air compressor. The accuracy of the proposed model is verified by comparing the calculated results with the experimental parameters. The result shows that the proposed model has higher calculating accuracy, and could be used to predict the parameters of pipeline operation.

Comprehensive Review

Research Progress on Photonic Crystal Infrared Stealth Materials Technology

MENG Zi-hui, ZHANG Lian-chao, QIU Li-li, XUE min, XU Zhi-bin

2016, 37(8):  1543-1552.  doi:10.3969/j.issn.1000-1093.2016.08.029

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Photonic crystals are a kind of artificial functional materials with potential and promising application in the infrared stealth technology, of which photonic band gap has high reflectivity to electromagnetic waves. The photonic crystals can alter the radiation characteristics of targets and protect the targets from being detected in infrared region. In order to clarify the problems and opportunities in the further development of photonic crystal and provide some proposals for the requirements of infrared stealth materials for wide band, multi band compatibility and reversible dynamic adjustment. The applications of photonic crystal in the regulation of infrared radiation characteristics, the broadening of photonic band gap, the multi band compatible technology and the adaptive stealth technology with variable emissivity are reviewed and summarized. Finally, the new generation of photonic crystal infrared stealth materials is prospected.