Table of Content

22 February 2020, Volume 41 Issue 2

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Contents

2020, 41(2):  0. 

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Paper

Test Study of Viscoelastic Elastomer Damper for Remote Weapon Station

WANG Zhiqian, MAO Baoquan, ZHU Rui, YANG Yuying, HAN Xiaoping

2020, 41(2):  209-221.  doi:10.3969/j.issn.1000-1093.2020.02.001

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The spring dampers for remote weapon station have large stiffness and small damping that leads to low firing dispersion and poor reliability. A viscoelastic elastomer damper suitable for remote weapon station was developed. A viscoelastic elastomer material with good viscosity-temperature characteristic was prepareded based on the existing viscoelastic elastomer material. A viscoelastic elastomer damper prototype was designed on the basis of the property and structure parameters of spring damper for remote weapon station. The mechanical properties of the viscoelastic elastomer damper prototype and the spring damper were compared and studied through the static pressure test and the drop weight test. In order to reduce recoil stroke, a new viscoelastic elastomer damper was designed without changing the external dimensions and structure. The mechanical properties and the firing frequency adaptabilities of the new viscoelastic elastomer damper were studied through the static pressure test and the firing frequency simulation test. The test results indicate that the compounded viscoelastic elastomer material has a strong viscosity-temperature characteristic; the energy absorptivity of the viscoelastic elastomer damper prototype is 1.47 times more than that of spring damper, and there is no secondary impact effect; the energy absorptivity of the new viscoelastic elastomer damper is 77.28%, and its maximum stroke is 7 mm, which has good firing frequency adaptability. The viscoelastic elastomer damper is able to effectively reduce the recoil stroke and increase the energy absorptivity, thus improving the firing dispersion and reliability of remote weapon station. Key

Experimental Research on Effect of Return Water Temperature on the Combustion Progress in a Diesel Engine

QIANG Yongping， LI Haiying， ZHANG Xiaoqin， CAI Zhongzhou， ZHU Weiqing， LI Yufeng, GONG Yongxing

2020, 41(2):  222-230.  doi:10.3969/j.issn.1000-1093.2020.02.002

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The effects of return water temperature on the piston erosion, in-cylinder pressure and heat release rate are studied to solve the ablation problem of piston in a diesel engine in low temperature environment. Typical characteristics of in-cylinder combustion process for ablation of piston are determined through the experiment. Results show that the average maximum pressure rise rate reaches 25- 40 MPa/ms under the condition of 70% load at 1 500 rpm at the return water temperatures of 15 ℃, 25 ℃ and 40 ℃, which exceed the limit of pressure oscillation in a common diesel engine. Under this condition, the average maximum combustion pressure reaches the allowable pressure of 13 MPa during 120 cycles. The results indicate that the strong combustion pressure oscillation exists at this operating point. Especially in the case of return water temperatures of 15 ℃ and 25 ℃, the number of cycles is up to 33% when the maximum cylinder pressure is over 13 MPa. Moreover, the maximum pressure rise rate in a single cycle is over 100 MPa/ms in these two cases. Above all, with the decrease in return water temperature, the number of cycles exceeding the limits of maximum pressure and pressure rise rate increases sharply. This is the main reason of piston ablation for this series of diesel engines under the condition of low temperature. Key

Vehicle Integrated Navigation Based on Velocity Constraint and Fuzzy Adaptive Filtering

HU Jie， YAN Yongjie， WANG Zihui

2020, 41(2):  231-238.  doi:10.3969/j.issn.1000-1093.2020.02.003

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The satellite signal is easily obstructed to reduce the positioning precision of the integrated navigation system for the vehicle integrated navigation system. An integrated navigation scheme is proposed, which is assisted by the vehicle velocity constraints. The Kalman filter measurement equation is deduced by taking the side and up velocities of normal running vehicle be zero. A new adaptive Kalman filtering (ADKF) algorithm is deduced in consideration that it is difficult to determine the statistical characteristics of integrated navigation measurement noise. After calculating the ratio of actual covariance to theoretical covariance of innovation sequence, the fuzzy inference system (FIS) is used to adjust the Kalman's measurement noise covariance matrix adaptively. The verification experiments were carried out by using fiber optic strapdown inertial navigation system (SINS). The experimental results show that, when the satellite signal is invalid, the integration of virtual velocities can improve the positioning accuracy of SINS, and the maximum latitude error is reduced from 41.33 m to 8.61 m. The positioning accuracies of the vehicle's three directions calculated by the proposed FIS-ADKF integrated navigation algorithm are more than 60 percent higher than those calculated by the standard Kalman filtering algorithm, which verifies the effectiveness of the proposed algorithm. Key

Research on Evaluation Index of Military Vehicle Crew's Information Operation Aptitude under Different Task Demands

FU Binhe, LIU Xixia, LIU Weiping, ZHANG Chuanqing, SONG Haijun

2020, 41(2):  239-245.  doi:10.3969/j.issn.1000-1093.2020.02.004

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For the different demands on military vehicle crew's capability posed by different tasks, the evaluation index of crew's information operation aptitude under different task demands is studied. The influences of cognitive ability and psychomotor ability on information imputing and in-situ target shooting task performance are analyzed through simulated experiments. Performance predictors of two tasks are analyzed comparatively by multiple regression modeling. Evaluation indexes of crew's operation aptitude are built under different task demands. The results show that reaction ability, memory ability and attention ability should be selected as evaluation indexes of operation speed aptitude for communication task, while memory ability and attention ability should be selected as evaluation indexes of operation accuracy aptitude. Hand-eye coordination ability and attention ability should be selected as evaluation indexes of operation speed aptitude for shooting task, while bimanual control ability and attention ability should be selected as evaluation indexes of operation accuracy aptitude. The results provide references for identifying evaluation index of military vehicle crew's operation capability adapted to task demands. Key

ZHANG ChuanqingSONG Haijun（239）Simulation Analysis of Influencing Factors of Flyer Driven by Small-size JO-9C Booster Explosive

LIU Rongqiang， NIE Jianxin， JIAO Qingjie， XU Xinchun

2020, 41(2):  246-253.  doi:10.3969/j.issn.1000-1093.2020.02.005

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A simulation model of the flyer driven by a small size booster explosive is established to optimize the performance of flyer driven by booster explosive in an explosive train. A calculating method of the JWL equation of state (EOS) parameters for booster explosive is proposed. A typical booster explosive JO-9C is chosen to drive metallic flyer in experiment, verifying the accuracy of the proposed simulation model. The velocity and kinetic energy of flyer are chosen as the parameters to evaluate the perfor- mance of flyer. The influences of the charge structure, the diameter of accelerating chamber and the thickness of flyer on the performance of flyer are analyzed. The results show that both the flyer velocity and the charge quantity should be taken into account when the length-to-diameter ratio of charge is 1.5. The diameter of the accelerating chamber should not be greater than that of the charge, so that good flyer morphology and high flying speed would be achieved. If the flyer is too thin, it may easily break. Taking a 5 mm-diameter JO-9C charge as an example, the optimal design is as follows: the length-to-diameter ratio of charge is 1.5, meaning that the charge height is 7.5 mm, the diameter of accelerating chamber is 5 mm, and the thickness of flyer is 0.3 mm. In this case, the velocity and kinetic energy of flyer are 1 663 m/s and 51.79 J, respectively. This work has certain theoretical and practical value for the reliable design of explosive train. Key

The Influence of Ambient Temperature after Gun Firing on Thermal Safety of Modular Charge in the Chamber

QIAN Huanyu， YU Yonggang， LIU Jing

2020, 41(2):  254-261.  doi:10.3969/j.issn.1000-1093.2020.02.006

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To analyze the thermal safety of modular charge retaining in the chamber after continuous firing of gun until the temperature in inner chamber reaches the possible temperature value of cook-off response, a 2D unsteady state cook-off model of the modular charge is established. Cook-off process of the combustible module filled with single-base propellant is simulated by Fluent. Cook-off characteristics of modular charge during retaining in the chamber after a number of rounds were fired at 1 round/min under different ambient temperatures of 50 ℃,20 ℃,0 ℃,-20 ℃ and -40 ℃ were analyzed numerically. Results show that the lower the ambient temperature during firing is, the longer the cook-off response time of modular charge is. The cook-off response times are 136.0 s,176.4 s,205.7 s,237.4 s and 278.5 s, respectively, under five ambient temperatures. The initial ignition position is near the right end inner surface of module box, where the single-base propellant ignites first and forms an annular firing response zone under all ambient temperatures. The ignition response temperatures of single-base propellant are 454.2-462.6 K under different firing conditions. Key

Experimental Study of Biological Injury Effect Caused by Blunt Impacting of Rubber Bullet

XIONG Manman, QIN Bin, WANG Shu, HAN Ruiguo

2020, 41(2):  262-269.  doi:10.3969/j.issn.1000-1093.2020.02.007

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The ballistic experiment of rubber bullets impacting the pigs was carried out to study the biological injury mechanism. The influences of velocity, hardness, and caliber of rubber bullet on creature injury effect are analyzed and characterized by trauma and behavior response. The experimental results indicate that trauma is mainly dominated by skin peeling, pale and blush. The visible discontinuity of skin injury exists between peeling zone and pale zone. The shear action of rubber bullet gives rise to peeling and pale, and synergistic effects of tensile and contraction of skin give rise to blush. Trauma degree is increasingly severe with the increase in impacting velocity of the same kind of rubber bullets impacting on creature thorax and abdomen, but the diameter of peeling is almost unchanged at different impact velocities. The single variable method is used to analyze the experimental results of rubber bullet impacting on creature thorax. It is indicated that the specific kinetic energy needing to cause visible trauma (skin peeling, pale or blush) follows as 70 HA Shore bullet＜45 HA Shore bullet＜20 HA Shore bullet, 32 calibre bullet ＜16 calibre bullet＜8 calibre bullet, which means that if Shore hardness and caliber are larger, the less specific kinetic energy needs in visible trauma inducement. And if the caliber is larger, the less specific kinetic energy needs in obvious abnormal behavior response (continuous scream, sudden jump or trying to escape) inducement. Moreover, the specific kinetic energy leading to 50% abnormal behavior risk is higher than that leading to 50% visible trauma risk. Key

Optimization Design of Modular Tactical Missile under Uncertainty

LIU Junsheng， WANG Gang， WANG Kun， SHI Hongbo， GUO Bin

2020, 41(2):  270-279.  doi:10.3969/j.issn.1000-1093.2020.02.008

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The designed missile can not meet the requirements due to the influence of uncertainty on the overall parameters of modular tactical missile. An optimization design of modular tactical missile is made in consideration of uncertainty. A 38 kg helicopter-borne air-to-ground missile (HBAGM) is taken as a case study in the present paper. The robust design optimization (RDO) theory is applied to solve the problem of insensitive HBAGM weight under both design variable and design parameter uncertainties. A missile RDO model is established, including missile conceptual design, surrogate model and robust optimization. Three uncertain problems which exist in modular HBAGM conceptual design, namely, payload weight and center-of-mass location, velocity characteristic, and flight trajectory, are taken into account in a probabilistic setting. The RDO results show that the HBAGM weight is much less insensitive to the uncertainties with a slight weight penalty, and the constraints are also satisfied with much higher probabilities. Comparison of various schemes suggests that the increases in flight height and terminal cruise velocity reduce the effects of uncertain parameters on HBAGM weight. The constraint probabilities can be significantly improved by increasing the terminal cruise velocity as well as tail fin span, and decreasing the wingspan. Key

Research on Adaptability of a Cold Launching System of Missile to Launching Site

ZHANG Zhendong， MA Dawei， ZHONG Jianlin， GAO Yuan， WANG Xi

2020, 41(2):  280-290.  doi:10.3969/j.issn.1000-1093.2020.02.009

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In order to study the adaptability of a cold launching system, the influencing factors and evaluation indexes of adaptability of cold launching system to launching site are found, and the calculation methods of vertical stiffness and wind load are derived. According to the range of influencing factors and evaluation indexes, the test sample points are generated by use of Latin hypercube design method. The angular displacement and angular velocity of sample space are obtained from dynamic response analysis of large sample simulation based on the equipment FEM model. An approximate model of missile attitude is established, and the sensitivity of missile attitude is analyzed by using the radial basis neural network method. On the basis of sensitivity analysis, a synthesis criterion considering multiple factors of adaptability is given, which provides a reference for evaluating the adaptability of launching system. It is shown through the analysis that the four-stage asphalt pavement can meet the missile launch requirements when the wind speed is not more than 2.5 m/s and the longitudinal slope of road is less than 1.2°. Key

Experiment of Slow Cook-off Response Characteristics of Penetrator

DAI Xianghui, DUAN Jian, SHEN Zikai, WANG Kehui, LI Mingrui, LI Pengjie, ZHENG Yafeng, ZHOU Gang

2020, 41(2):  291-297.  doi:10.3969/j.issn.1000-1093.2020.02.010

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An experimental device was designed for evaluating the slow cook-off response characteristic of full-scale penetrator. The penetrator with a mass of 290 kg was placed in the slow cook-off oven and slowly heated at a heating rate of 3.3 ℃/h. The surface temperature of penetrator was collected in real time, and the whole experimental process was recorded. The peak value of reflected shock wave overpressure at a distance of 7 m from the mass center of penetrator was measured. The full-scale penetrator burns when it is heated for 42 hours, 45 minutes and 23 seconds and the temperature reaches 190 ℃, a more intense reaction occurs after 41 seconds, and the slow cook-off oven and the penetrator are exploded to form large fragments. The exposed explosive equivalent is deduced to be 4.153 kg from peak value of the reflected shock wave overpressure, which is far less than the actual charge equivalent and the exposed explosive equivalent during full detonation. Based on the analysis of the heating time, the surface temperature of penetrator, the damage on experimental site, the fragments of penetrator, the peak value of reflected shock wave overpressure and the reaction mechanism, the slow cook-off response type of penetrator is judged to be combustion-to-explosion transition.Key

Experimental Research on the Influence of Ablation Product of Carbon Fiber Reinforced Composite Material on the PlasmaFlow Field Characteristics

YUAN Ye, WANG Liyan, CAO Zhanwei, NIE Chunsheng, NIE Liang, MA Haojun

2020, 41(2):  298-304.  doi:10.3969/j.issn.1000-1093.2020.02.011

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The thermal protection material of high speed flight vehicle would be ablated and release the plasma under the high temperature induced by aerodynamic heating. In order to study the influence of ablation products of carbon fiber reinforced composite material on the flow field characteristics in different conditions of ablation, the high speed plasma jets were established through the ablation of two kinds of carbon fiber reinforced composite thermal protection materials (C/C and C/ZrC) in high frequency plasma wind tunnel. The number density of electrons and the stagnation point heat flux downstream were acquired using Langmuir probe and calorimeter in different conditions of ablation. The results show that the number density of electrons and the stagnation point heat flux in the flow field decrease with the increase in the ablation rate, relieving the “black-out” and aerothermal heating. C/ZrC is superior to C/C in weakening the ionization and the enthalpy of the flow field. With the increase in the enthalpy of the incoming flow, the differences in the ionization and enthalpies of the flow fields induced by the ablation of C/C and C/ZrC decrease to some extent.Key

Optimal Control of Improved MAC Protocol for Tactical Data Link Networks and Its Performance Analysis

YANG Zhijun， LIU Zheng， DING Hongwei， LIU Qianlin

2020, 41(2):  305-314.  doi:10.3969/j.issn.1000-1093.2020.02.012

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In order to solve the priority problem of tactical data link，a prioritized two-level polling control strategy based on exhaustive access strategy and asymmetric gated access strategy is proposed for media access control in tactical data link.In the polling control strategy，an asymmetric gated access strategy is adopted for the low priority outposts in tactical data link，and the exhaustive access strategy is adopted for the high priority outposts.When the network control site is transferred from the high priority outpost to the low priority outpost，the transmission service and the transfer query are processed in parallel to reduce the time cost during the query conversion，and the operating efficiency of the polling system is improved. The Markov chain and probabilistic generating function are used to establish the mathematical model of the polling system，which accurately resolves the expression of the average number of information packets waiting to be sent in each outpost. The approximate expression of the average waiting time for the information packets in the outpost is resolved by using the second-order characteristic quantity approximation method of the cyclic period. The simulated results of the proposed model show that the experimental value is approximately equal to the theoretical value，and the service quality of the high-priority outpost is better than those of other outposts，indicating that the theoretical analysis is correct，and the proposed model achieves the purpose of prioritizing. Key

Comprehensive Priority-based Task Scheduling Algorithm for Anti-missile Early Warning Phased Array Radar

YANG Shanchao， TIAN Kangsheng， LI Hongquan， ZHOU Guangtao， LIANG Futai

2020, 41(2):  315-323.  doi:10.3969/j.issn.1000-1093.2020.02.013

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A comprehensive priority-based task scheduling algorithm is proposed for the resource allocation problem about anti-missile early warning phased array radar tracking multiple ballistic missile targets. A target threat level model is established for ballistic missile targets. Target threat level and task deadline are combined together to calculate the comprehensive priority by designing a two-dimensional priority table. A dynamic value function of tasks is established based on the comprehensive priority. A value optimization model for task scheduling is constructed according to the principle of scheduling timeliness. The genetic algorithm is improved by setting adaptive selection, crossover and mutation operators, and then the modified algorithm is used to solve the scheduling model. The performance of the proposed algorithm is compared with the traditional scheduling algorithms by simulation experiments, and the impacts of task value function parameters on scheduling performance are analyzed. Simulated results show that, compared to the traditional scheduling algorithm, the proposed algorithm reduces the average time shift ratio by 46%, and improves the hit value ratio by 12%. Key

Detection of Similar Duplicate Records Based on OCSVM and Multi-objective Ant Colony Optimization

L Guojun， CAO Jianjun， ZHENG Qibin， CHANG Chen， WENG Nianfeng， PENG Cong

2020, 41(2):  324-331.  doi:10.3969/j.issn.1000-1093.2020.02.014

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A classification method based on one-class support vector machine (OCSVM) and multi-objective ant colony optimization is proposed for solving the problem of a small number of similar duplicately recorded samples. Based on whether the two records are similar, the detection of similar duplicate records is modeled as a two-class classification problem, the classification is performed by OCSVM, and the classifier is trained by only using the dissimilar duplicately recorded sample pairs. Appropriate attribute similarity function is selected to calculate the similar feature vectors of two records which are taken as the OCSVM's input. A multi-object model for feature selection based on the integrated optimization of recall ratio, precision ratio and feature set's size is set up. According to the characteristic of the single class training samples, a multi-object ant colony algorithm is designed to solve the model, in which the heuristic factor is defined as the minimization constraint of intra-class divergence. The proposed method is validated by comparing OCSVM with other algorithms, such as support vector domain description algorithm and traditional two-class support vector machine. Key

Experimental Investigation on Shallow-angle Oblique Water-entry of a High-speed Supercavitating Projectile

HOU Yu， HUANG Zhengui， GUO Zeqing， CHEN Zhihua， LIU Rushi， LUO Yuchuan

2020, 41(2):  332-341.  doi:10.3969/j.issn.1000-1093.2020.02.015

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The shallow-angle oblique water-entry of a high-speed supercavitating projectile is studied by using the high-speed photography technology. The characteristics of the ballistic trajectory, splash formation and underwater pressure wave propagation during the initial water-entry impact at different sideslip angles are observed and analyzed from the underwater pressure signal monitored along the left side of the trajectory. The results show that the small sideslip angle of the projectile has few effect on the smooth cavity formation and the enter trajectory stability during the high-speed oblique water-entry at small entry angle. The larger sideslip angle is able to lead to the severe water atomization in the cavity, the ballistic deflection and the projectile damage. The increase in the sideslip angle can exacerbate this instability. The impacts of the cavitator and the warhead conical section on the free surface at a small entry angle make the splash be an approximate symmetrical “butterfly shape” in birds-eye view. The sideslip angle has inverse influence on the symmetry of the front half of splash comparing with the rear half of splash. Large changes are presented in the splash range with the increase in sideslip angle. The symmetry axis of the front half of splash is deflected with the increase in sideslip angle. The changing process of underwater pressure wave induced by the water-entry impact is divided into two stages: the initial pressure fluctuation stage induced by the initial impact of the projectile on the water and the fluctuation stage of high frequency induced by the superposition of the pressure waves from various directions. The two pressure fluctuation stages show different variation characteristics with the corresponding water entry state due to the increased sideslip angle.Key

Calibration Algorithm for Underwater Navigation System Based on Rodrigues Matrix Transformation

ZHANG Sen， GUO Jinbiao， WU Yuanyuan

2020, 41(2):  342-349.  doi:10.3969/j.issn.1000-1093.2020.02.016

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In order to solve the problem that multi-orthogonal signal underwater navigation system has no prior knowledge of attitude in system calibration, a system calibration algorithm based on Rodriguez matrix transformation is proposed to estimate the attitude angle of transmitter. The proposed method is used to solve the problem that the initial error of the traditional non-linear least squares method is too large to lead to the convergence of the algorithm. In the proposed method, the non-linear approximation is not required to avoid the error caused by linearization, and the calculation is simple and efficient. It has no limitation on angle size and has a wide range of applications. The lake trial results show that the estimation accuracy of the proposed method is higher than that of the least square estimation method without prior information. Key

CalculationTest and Degaussing Optimization of Magnetic Field in Diesel Engine

ZHAO Jianhua， YING Yuchen， GUO Chengbao

2020, 41(2):  350-355.  doi:10.3969/j.issn.1000-1093.2020.02.017

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The magnetism and demagnetization of diesel engine of low magnetic ship are studied from the finite element simulation results of magnetic field of diesel engine. A finite element simulation model of a diesel engine is established by using the magnetic analysis COMSOL software, and the strength of induced magnetic field and its spatial distribution are calculated. The degaussing method is used to find the optimal degaussing parameters through the integrated simulation of the diesel engine and degaussing array. The results show that, on a plane at 9 m below the diesel engine, the magnetic flux density at the positive center is the largest, the magnetic field is elliptically distributed, and the calculated value of the magnetic field strength relative to the maximum distortion of the geomagnetic field is as high as 224.35 NT. The error between the measured result and the simulated result is less than 5%, within the allowable error range; the optimal degaussing parameters can be used to reduce the intensity distortion variable of magnetic field on the plane at 9 m below the diesel engine to 8.33 nT, about 95%. Key

H_∞ Consensus Control of Multi-agent Systems with Transient Response under Directed Switching Topology

ZHOU Shaolei, ZHAO Xueyuan, QI Yahui, WANG Shuailei

2020, 41(2):  356-365.  doi:10.3969/j.issn.1000-1093.2020.02.018

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The H_∞ consensus control method is studied for consensus tracking of leader in multi-agent system under directed switching topology. The consensus tracking problem of leader is transformed into the stability problem of low-dimensional system by using Laplacian matrix with leader. The sufficient conditions satisfying the transient response index are given. Lyapunov function and linear matrix inequality are used to analyze the stability of the system, and the design method of distributed controller and the average dwell time condition are obtained. The proposed method can be used to make the states of the system tend to be identical rapidly with smaller oscillation when the system is affected by random external disturbance. The multi-UAV system was simulated with considering the transient response, and without considering the transient response and external disturbance. The results show that the H_∞ consensus controller considering the transient response can attain the consensus faster and more smoothly than the controller without considering the transient response, which meets the transient response performance index.Key

Research on Dynamic Mechanical Properties of TC4 ELI Titanium Alloy and Its Sensitivity to Adiabatic Shear Banding

XU Xuefeng， WANG Lin， SHA Yangang， YANG Siqi， LIU Anjin，TAYYEB Ali， ZHANG Binbin， ZHAO Denghui

2020, 41(2):  366-373.  doi:10.3969/j.issn.1000-1093.2020.02.019

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The α lamellar microstructures with different thicknesses were obtained by proper heat treatments of TC4 ELI alloy. The influence of α lamellar thickness on the dynamic mechanical properties of the material and its sensitivity to adiabatic shear banding was investigated. The split Hopkinson pressure bar and the stop ring technique are used to test the samples under strain controlled loading. The microstructure evolution is analyzed by microscope and quantitative metallography method. The experimental results demonstrate that the thickness of titanium alloy with lamellar structure decreases from 3.1 μm to 1.0 μm with the increase in solid solution temperature. Under the quasi-static compression and dynamic compression conditions, the material strength decreases as the thickness of lamellar α increases, while its plasticity exhibits a declining trend. In the adiabatic shear sensitivity experiment, the adiabatic shear bands are more likely to nucleate and propagate in the alloy with smaller lamellar thickness, that is, as the thickness of the lamella decreases, the adiabatic shear sensitivity of the material increases. Key

Study of Electrochemical Property of FeS₂-CoS₂ Multiphase Sulfide Cathode Materials

GENG Jia， ZHU Yanli， WU Qibing

2020, 41(2):  374-380.  doi:10.3969/j.issn.1000-1093.2020.02.020

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FeS₂-CoS₂ multiphase cathode materials for thermal battery were prepared by physical-mechanical mixing method, and the effects of iron and cobalt contents on the electrochemical property of the thermal battery were discussed. The component content, microstructure and surface morphology of mixed disulfide are analyzed by using X-ray diffraction (XRD) and scanning electron microscopy(SEM). Compared with the single-phase sulfide material, the iron-cobalt composite material not only maintains its high voltage, but also prolongs the discharge duration. SEM experimental result shows that the morphology of cathode material is changed after discharging. Since the lithium-ion channels are covered with the products during the reaction process, the channels are decreased. When the ratios of iron to cobalt are 1∶4 and 1∶0.25, the maximum discharge voltages of a single battery are 1.67 V and 1.72 V, respectively. Meanwhile, the specific capacity of the single battery is 250.7 mA·h/g and 167.1 mA·h/g when the cut-off voltage is 1.25 V, which is higher than that of other multiphase sulfide materials.Key

Research on Process Parameters of Laser Solid-formed 30CrNi2MoVA Steel Based on the Size Prediction

ZHANG Zhen， WANG Min， FAN Huaxian， LIU Guangzhi

2020, 41(2):  381-387.  doi:10.3969/j.issn.1000-1093.2020.02.021

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30CrNi2MoVA steel is widely used in the ordnance equipment manufacturing industry, we have researched the laser solid forming (LSF) technology with this material. The influence of main process parameters on the sizes of deposed layers is analyzed by using regression orthogonal design method through the real-time monitoring of molten bath. The main influence factors and size values of deposed layers, and the regression equation are achieved. Spot diameter, laser power and scanning velocity have obvious effects on the deposed layer width. The width of deposed layer is positively correlated with spot diameter and laser power, but it's negatively correlated with scanning velocity. The height of deposed layer is obviously affected by scanning velocity and powder feed rate. The height of deposed layer is positively correlated with powder feed rate, but it's negatively correlated with scanning velocity. Experimental results show that the forming dimension prediction model is used to accurately predict the forming size value. The select range of process parameters range of LSF 30CrNi2MoVA steel is determined from the aspect ratio of deposed layer. When the spot diameter is 3.5 mm, the laser power should be 1 300-3 000 W, the powder feed rate should be 0.7- 2.5 r/min, and the scanning velocity should be 5-12 mm/s. Key

Research on the Failure of Bolted Flange Connection Structure between Stages of the Missiles (Rockets) under the AbnormalLoad

TIAN Tonghui, YUAN Jiehong, WANG Qingwen, GUAN Zhenqun, CHEN Baisheng

2020, 41(2):  388-397.  doi:10.3969/j.issn.1000-1093.2020.02.022

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According to the structural characteristics of the bolted flange connection structure between stages of the missiles (rockets), two sets of simplified principle test specimens were manufactured, and the failure experiments of connection structure under impact and quasi-static loads were designed and carried out. The response data of bolts and the slotted displacement of connecting interface are analyzed by comparing the failure results under the action of impact force and quasi-static loading force, and the failure mechanism of connection structure is summarized. A finite element model is established to stimulate the failure process of connection structure, which is verified by the measured data. The research results indicate that the connection structure shows a sequential failure mode under the transverse abnormal load, and the actual failure mode of single bolt is “stretching-bending coupling” failure due to the obvious bending deformation caused by the “leverage effect” of flange. The “strain rate effect” of bolt material under impact loading is not significant, and the “strain rate effect” of dynamic loading can be temporarily ignored in the choice of constitutive model in simulation. It can be seen from the comparison with the measured data that the simulation model based on the explicit algorithm of Abaqus has the simulation error of failure process of connection structure within 15%, and the conclusion obtained by the numerical simulation can be considered to be reliable in the engineering. Key

UGF-SORA Method for Reliability Optimization of Structure

ZHU Dawei， ZHOU Jinyu， ZHUANG Bailiang

2020, 41(2):  398-405.  doi:10.3969/j.issn.1000-1093.2020.02.023

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Universal generating function (UGF) method has great advantages in dealing with probabilistic analysis problems with non-normal random variables and highly non-linear performance functions.A method of sequential optimization and reliability assessment based on universal generating function (UGF-SORA) is proposed to improve the optimization accuracy of structural reliability. In the porposed method, the high precision reliability analysis method and the offset vector solving strategy are introduced for optimization, and the iteration process is divided into three parts. In the first step, the least square method is used to fit the response surface regression model of migration function, and the offset vectors are solved according to the model and the permissible reliability index. In the second step, according to the offset vector, the deterministic optimization is completed and the current design points are obtained. In the third step, the reliability analysis and evaluation are carried out by UGF method. Furthermore, the migration function is reconstructed according to the relevant constraints. It is shown through the example analysis that the proposed method is used to ensure the efficiency of solution, but also improve the accuracy of optimization. It also solves the problem that the optimization results can't converge when the performance function is highly non-linear. Key

Emergence Measurement Model of Armament Systems Based on SEM

QI Xiaogang， LIU Xuexing， ZHANG Bozi， ZHAI Doudou

2020, 41(2):  406-416.  doi:10.3969/j.issn.1000-1093.2020.02.024

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A measurement model for the emergence of the combat capability in armament systems is established for assessing and measuring the emergence of the combat capability of armament systems. Firstly, in view of a complex adaptive system (CAS), a conceptual model of the emergence of combat capability is constructed, and the internal factors of each subsystem in the system are analyzed, thus establishing the index system to evaluate the combat capability of measurement model. And then the linear and nonlinear emerging structural equation modeling (SEM) models are established according to the index system. Finally, the structural equations of model parameters are built based on two SEM measurement models. In order to verify the performance of the proposed model, the model parameters are verified using structural equation modeling software LISREL8.70 by taking an aircraft carrier formation anti-ship warfare as an example, and then the two SEM structural equations are determined. The structural equations are used to evaluate the combat capability. The results show that the nonlinear model is closer to the actual combat capability than the linear emergent SEM model. Key