Table of Content

31 May 2021, Volume 42 Issue 5

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Contents

2021, 42(5):  0. 

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Paper

On Concentration Detection of FAE Cloud at High-speed Intersection between FAE Cloud and Sub-fuze

FU Shenghua， LOU Wenzhong， LI Chubao, PAN Xiaojian, WANG Jingkui, JI Tongan, LIU Weitong

2021, 42(5):  897-902.  doi:10.3969/j.issn.1000-1093.2021.05.001

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The large-area detonation of the second-detonation fuel-air-explosive (FAE) warhead is related to the initiation control under the condition of optimal fuel cloud concentration when FAE cloud intersects with fuze at high speed. Based on the attenuation characteristics of the reflection coefficient of pulsed ultrasound in the cloud, a prototype of a FAE sub-fuze was developed, and a rocket sled test platform was built for detecting the intersection concentration of FAE cloud with the sub-fuze with rocket sled speeds of 75 m/s and 100 m/s. The curve of the sub-fuze dynamic recognition cloud concentration under high-speed environment and the gradient characteristics of pulse ultrasonic attenuation at different concentrations were obtained through test. The test results show that the proposed method can be used to obtain the high-speed intersection concentration identification of FAE cloud at the different speeds. The calculated error is not more than 15% at the nominal concentrations of 75 g/m³, 150 g/m³ and 225 g/m³.

PID Parameter Tuning of Self-propelled Antiaircraft Gun Servo System Based on Differential Evolution Algorithm

SUN Guoxuan， GONG Xinyu， SHI Yan， XIE Jipeng， LU Bin

2021, 42(5):  903-912.  doi:10.3969/j.issn.1000-1093.2021.05.002

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The traditional PID parameter tuning efficiency is low and the influence of factors such as force elements among components on the parameter tuning can not be considered. An electromechanical co-simulation model of servo system is established, and the PID parameters are tuned using intelligent optimization algorithm. A servo control system model considering the attitude disturbance of moving body is established, and an electromechanical joint simulation model of servo system is established by combining with the upper mounting virtual prototype. The method of real vehicle test is used to verify the correctness of the joint simulation model. On this basis, the integral of time multiplied by the absolute value of error is used as the optimization objective function, and the PID parameters are tuned using the differential evolution algorithm (DE), and compared with the original model control parameters and the genetic algorithm (GA) tuning parameters. The joint simulation results show that,compared with the original model control parameters, the RMS value and standard deviation of the axis of firepower control error are reduced by 24.06% and 25.20%, respectively, by using the PID parameters tuned by the differential evolution algorithm for simulation, and the convergence speed is faster than that of genetic algorithm. The modeling method and parameter tuning method are effective and feasible, and have theoretical reference value for the optimization of the control accuracy axis of firepower.

Finite Element Simulation Model for Electromagnetic Buffer under Intensive Impact Load

LI Zixuan， YANG Guolai， LIU Ning

2021, 42(5):  913-923.  doi:10.3969/j.issn.1000-1093.2021.05.003

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In order to obtain the electromagnetic and damping characteristics of the electromagnetic buffer under intensive impact load, an improved exponential demagnetization model is proposed to simulate the demagnetization process of NdFeB permanent magnets. An improved vector hysteresis model is adopted to consider the hysteresis effect of soft magnetic materials. And a primary-secondary eddy current coupled time-step finite element model is established, in which demagnetization and hysteresis are considered. The accuracy of the finite element model is verified through the laboratory impact load test. The damping and electromagnetic characteristics were obtained and analyzed through the magnetic field test. The intensive impact test was carried out to obtain the damping characteristics of electromagnetic buffer under high buffering velocity conditions. The results show that the finite element model has high reliability. The demagnetization effect increases with the increase in buffering velocity, which leads to the decreased damping coefficient. Hysteresis effect can disturb the magnetic field distribution and affect the damping force.

Computation Method for the Optimal Burst Height of Proximity Fuze Based on Improved Particle Swarm Optimization Algorithm

ZHAO Xin, JI Yongxiang, LUO Xibin, LIU Shefeng, NING Xiaolei

2021, 42(5):  924-929.  doi:10.3969/j.issn.1000-1093.2021.05.004

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The timely detonation of warhead with proximity fuze is related to whether it can effectively attack and destroy a target. The optimal coordination relationship of fuze and warhead is proposed. A mathematical model of warhead power is established. The relationship between related parameters is analyzed using the particle swarm optimization algorithm, and the inertia weight is dynamically updated using the Euler distance method. An improved particle swarm optimization algorithm was presented and applied to the mathematical model to obtain the calculation model of warhead power in fuze-warhead coordination. Through simulation experiments, the relationship among lethal area, burst height and falling angle was obtained, the best power conditions for fuze-warfare coordination were determined, and the maximum lethal area, the corresponding interval of 90% lethal area and the corresponding burst height were calculated. The results show that the proposed method has higher calculation accuracy of the maximum lethal area than the traditional method, and has faster convergence speed than the particle swarm optimization algorithm, which can better meet the speed calculation requirements for the range test and tactical fied firing.

The Influence of Inhibiter Ring on Thermoacoustic Oscillations in Solid Rocket Motor

MA Baoyin, LI Junwei, ZHANG Hailong, ZHAO Guiqi, ZHANG Zhihui, XI Yunzhi, WANG Ningfei

2021, 42(5):  930-943.  doi:10.3969/j.issn.1000-1093.2021.05.005

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The suppression characteristics of thermoacoustic pressure oscillation is systematically investigated to effectively solve the thermoacoustic pressure oscillation in a propulsion system. For solid rocket motors (SRM), an experimental system with a flat flame cylindrical combustion chamber was designed. According to the experimental system, the influences of the inhibiter ring and its installation position in combustion chamber on thermoacoustic pressure oscillation were experimentally studied, and the influence characteristics were verified through theoretical calculation. The results show that a first-order pressure oscillation with a frequency of 115 Hz and an amplitude of 119 dB is excited in the combustion chamber without inhibiter ring. After the inhibiter ring is installed, the amplitude of the first-order pressure oscillation is reduced to 81 dB, which is reduced by about 32%, but at the same time, a weaker high-order pressure oscillation is also excited. As the inhibiter ring moves towards the outlet boundary of combustion chamber, the amplitude of the first-order pressure oscillation is further decreased by 13%, while the amplitude of the high-order pressure oscillation increases slightly. The theoretically calculated results are in good agreement with the experimental results, indicating that the inhibiter ring increases the damping of the system, thereby effectively suppressing the thermoacoustic pressure oscillation. And the inhibiter ring near the outlet boundary has greater damping, and the suppression effect is more obvious.

Self-ejection Interior Ballistic Characteristics of Rocket Projectiles

SONG Jian， SONG Xianghua， CAI Qian， SHE Huqing

2021, 42(5):  944-954.  doi:10.3969/j.issn.1000-1093.2021.05.006

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A self-ejection launcher is proposed to solve the negative influence of exhaust plume on the surrounding equipment and perssonel. The exhaust plume generated by self-ejection launcher is sealed in a low pressure chamber until the tail leaves the launcher barrel. In order to study the characteristic and rules of interior ballistic of self-ejecting rocket projectile, a solution model of internal ballistic of self-ejecting rocket projectile was developed based on the classical interior ballistic. Physical tests of 5 rocket projectiles were carried out under three working conditions, i.e., low pressure chamber with initial length of 300 mm, low pressure chamber with initial length of 300 mm and two holes with pore diameter of 15 mm on it, and low pressure chamber with initial length of 150 mm. Compared with the experimental data and simulated data,the curves of the pressure in low pressure chamber have good consistency. The maximum relative error of the peak of pressure in low pressure chamber and the instantaneous velocity of the missile leaving the launcher are 9.29% and 5.24%, respectively, and the validity of interior ballistic model is verified. The influences of the trepanning on low pressure chamber, the length of low pressure chamber, the length of launcher ,the mass flow rate of motor on the interior ballistic of self-ejecting rocket projectile are ananlyzed based on the interior ballistic model.

Preparation of Nanocellulose and Its Application in Nitrocellulose-based Gun Propellant

YU Qingyuan, WANG Wenjun, SUN Meiling, TANG Fangyuan, ZHAO Jing, SHAO Ziqiang

2021, 42(5):  955-960.  doi:10.3969/j.issn.1000-1093.2021.05.007

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Nanocelluloses were prepared via a process of dissolution in phosphoric acid followed by regeneration in water. To facilitate the dissolution, the cellulose was pre-treated with aqueous urea solution. The composition, structure, and morphology of the materials in different preparation stages were studied by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The nanocelluloses were added into the nitrocellulose-based gun propellant as the reinforcement, and the physicochemical properties, low temperature drop hammer crushing and impact strength were tested. The results show that the physicochemical properties of the propellant are not changed after nanocelluloses with mass fraction of 1.68% are added. However, the low temperature drop hammer crushing ratio is reduced from 70% to 20%, and the low temperature impact strength is increased by 30%.

Component Analysis of Industrial Grade Catocene and Preparation of Binuclear Ferrocene

FENG Haitao， SUO Qi， ZHANG Chi， LIU Xiaoju， MA Xiaoyan

2021, 42(5):  961-967.  doi:10.3969/j.issn.1000-1093.2021.05.008

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2,2-bis (ethylferrocenyl) propane (catocene) has become one of the main burning rate catalysts in composite solid propellant because of its excellent catalytic activity and pharmaceutical technology. The composition of industrial grade products is also very complicated due to the complex synthesis process of catocene, which makes the performance of related products difficult to be guaranteed. The composition of industrial grade catocene is analyzed by using gas chromatography-mass spectrometry and high performance liquid chromatography. According to the structural characteristics of the components and the differences in their polarities and solubilities, the components of catocene were separated and purified by using column chromatography and dissolution-precipitation method, and the binuclear ferrocene containing two ferrocene units in the molecular structure with high content was obtained. It is found that the total contents of binuclear ferrocene and mononuclear ferrocene in the industrial grade catocene are 84.82% and 15.18%, respectively. The results show that column chromatography can be used to obtain binuclear ferrocene with a content greater than 99.0%; the dissolution-precipitation method can be used to obtain binuclear ferrocene with a content greater than 96.5%, and the proposed method has the characteristics of large-scale preparation, simple operation and low cost, etc.

Numerical Calculation of Thermodynamic Response of Shocked HMX Single Crystal at Elevated Temperatures

DING Kai, WANG Xinjie, HUANG Hengjian, WU Yanqing, HUANG Fenglei

2021, 42(5):  968-978.  doi:10.3969/j.issn.1000-1093.2021.05.009

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A nonlinear thermoelastic-viscoplastic model is developed for studying the thermodynamic response of octogen (HMX) single crystal at elevated temperatures, in which the thermal activation and phonon drag dislocation glide regime are considered. The proposed model can reproduce the thermal hardening behavior of Hugoniot elastic limit (HEL) of HMX single crystal in plate impact experiment. The effects of phonon scattering and radiation damping on the thermal hardening behavior are quantitatively analyzed to investigate the evolution of dislocation glide regime and the thermodynamic response at 373 K and 423 K. It is found that the thermal hardening behavior of HEL of HMX single crystal is due to the increase in phonon scattering and radiation damping with the initial temperature from 300 K to 423 K. The phonon drag coefficient is increased to strengthen the viscous friction of mobile dislocation. Therefore, the average dislocation velocity decreases from 2 237 m/s to 1 537m/s, which leads to slower plastic shear strain rate and higher flow stress. The shear modulus changes slightly with the increase in temperature (about 1.0 GPa), thus the contribution of radiation damping to thermal hardening is less than that of phonon scattering.

Effect of Dispersity on Explosion Sensitivity of Aluminum Powder

ZHANG Jiangshi， LIU Jianhua

2021, 42(5):  979-986.  doi:10.3969/j.issn.1000-1093.2021.05.010

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In order to select the particle size parameters which can characterize the explosion characteristics of aluminum powder and improve the accuracy of aluminum powder explosion risk assessment, the influence of particle size distribution on the explosion characteristic parameters of aluminum powder under the span of large particle size distribution was analyzed, and the explosion sensitivity of aluminum powder was studied. The influence of dispersity on the minimum explosive concentration (MEC) and minimum ignition energy (MIE) of micron-sized aluminum powder was investigated by using Siwek 20 L vessel apparatus and Hartmann tube. The results show that the explosion sensitivity parameter of aluminum powder accelerates with the increase in particle size. When the particle size of aluminum powder is small, the influence of particle size change on MEC and MIE is relatively small; for the mixed aluminum powder sample with larger particle size span, the small particle size dust component acts as a potential ignition source, which reduces the MEC and MIE measurements and greatly increases the aluminum powder explosion risk. It can be seen from Pearson correlation analysis that the particle size parameters D_3,2 (Saucter mean diameter) and D₄₀ (40th percentile of particle size) have the highest correlation with MEC and MIE. The correlation coefficients of D_3,2 with MEC and MIE are 0.962 7 and 0.746 0, and the correlation coefficients of D₄₀ with MEC and MIE are 0.947 9 and 0.741 1. In contrast, the size polydispersity (σ_D) and particle size span (PSS) have weak correlation with MEC and MIE. Therefore, it is more appropriate to choose D_3,2 and D₄₀ as the main expression of particle size distribution in the study of aluminum powder explosion sensitivity.

Failure Modes of Ring-stiffened Convex Cone-cylinder in Deep Underwater Explosion

LIANG Haozhe, ZHANG Qingming, LONG Renrong, REN Siyuan

2021, 42(5):  987-996.  doi:10.3969/j.issn.1000-1093.2021.05.011

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The dynamic response of submarine structure at underwater explosion (UNDEX), which is significantly affected by the depth of water, is the basis of submarine safety design. Based on the protection of typical submarine structure in deep underwater explosion (D-UNDEX), the failure modes of the ring-stiffened convex cone-cylinder in D-UNDEX are studied. The D-UNDEX experiment with the maximum water depth of 500m was completed. The dynamic response process of convex cone-cylinder under various conditions was obtained by ABAQUS numerical simulation method. Based on the deformation and failure degree of the structure, three failure modes of ring-stiffened convex cone-cylinder were obtained, and the evolution and transformation processes of different failure modes were revealed. The results show that, with the increase in water depth and shock factor, the deformation and failure results of ring-stiffened convex cone-cylinder are more serious, and the evolution and transformation processes of failure mode are more complex.

Knapsack Problem-based Algorithm for Time Resource Management of Multiple Phased Array Radars for Multiple Targets Tracking

DING Haiting, ZHOU Lin, DIAO Weifeng

2021, 42(5):  997-1003.  doi:10.3969/j.issn.1000-1093.2021.05.012

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A knapsack problem-based algorithm for time resource management of multiple phased array radars for multiple targets tracking is proposed for target grouping and time planning. When the time resource is limited, the target grouping and time planning can be realized jointly. The segmented pulse repetition period and fuzzy logic priority method are used to obtain the time resource and priority used for tracking the target from the priori information of target, and construct the time resource management model. The time planning and target grouping are considered jointly based on the knapsack problems, the sum of the tracking target priorities is used as the objective function of the algorithm, and the time resource model is solved through the idea of dynamic planning. Simulated results show that the knapsack problem-based algorithm effectively improve its hit value ratios. The problem of multiple phased array radars tracking multiple targets is solved from the perspective of the knapsack problems, which can track more targets in limited time and ensure the tracking of important targets at the same time.

A Calculation Method for Key Data of Data Stream Based on ρ-dominant and n-of-Nρ-dominant Skylines

BA Jianmin, GUO Yonghong, PENG Long, ZHAO Dongyang, SHAO Pengzhi, DU Hongbo

2021, 42(5):  1004-1015.  doi:10.3969/j.issn.1000-1093.2021.05.013

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The data collection method has constantly been enriched and developed, but the network in the data collection area is often limited, such as intermittent network and small network bandwidth, so the collected data is difficult to be accurately transmitted to the application side in real time. It is very important to ensure how to calculate the key data to reduce the network usage during data transmission. Based on the state data transmission of armored vehicles,the nature of the ρ-dominant relationship in the data stream is reanalyzed,and the query algorithm of ρ-dominant skyline in the data stream is changed and expanded. On this basis, a query algorithm of n-of-Nρ-dominant skyline in the data stream is proposed to further meet the requirements of the selection and transmission of key data in the network-restricted environment. Through the experiment, it is found that the improved ρ-dominant skyline query algorithm and the n-of-Nρ-dominant skyline query algorithm can calculate the relatively critical data, thereby reducing the network cost of data transmission,and n-of-Nρ-dominant skyline query has wider application than ρ-dominant skyline query in the data stream.

Control of Wake Flow of a Circular Cylinder by Continuous Blow and Suction

REN Liuzhen， LI Lin， ZHANG Mengzhuo， FENG Jiaxing， HU Haibao

2021, 42(5):  1016-1022.  doi:10.3969/j.issn.1000-1093.2021.05.014

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The flow separation behind a bluff body causes adverse effects such as increased resistance and fluctuation of lift force. Therefore, it is of great importance to control the flow separation on the bluff bodies so as to improve their mechanical properties. An active control method, which combines continuous blow and suction, is employed to circular cylinders,and the wake characteristics of cylinders are researched systematically using an IFA300 constant-temperature anemometer in a small low speed wind tunnel. Test results show that the combination of front suction and rear blow can significantly weaken the flow separation of cylinders, reduce the range of wake region, and greatly suppress the turbulence of this region.The increase in blow-suction velocity and angle can both promote the effectiveness of flow control in the test range, especially for cases with angle of 50° or 70° and a velocity which is three times the inflow velocity. In this instance, the low velocity zone behind the cylinder is almost disappeared, and the turbulence decreases greatly, which is even less than 5% of turbulence when the cylinder is not controlled.By comparing the control effects of a circular cylinder with single front continuous suction or single rear continuous blow, it is found that the contribution of rear blow is much greater than that of the front suction in the continuous blow-suction control method, which indicates that the former plays a key role to efficiently control the cylinder wake flow.

Growth Behaviors and Resident Stability of Electrolyzed Microbubble

ZHU Rui， ZHUANG Qibin， LI Shang， ZHANG Zijie， ZHANG Huanbin， WEN Weiqi, LIU Zhirong， WU Dezhi

2021, 42(5):  1023-1031.  doi:10.3969/j.issn.1000-1093.2021.05.015

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The influences of micro-pits, hydrophobic coating and electrolysis specifications on the growth behaviors and resident stability of the electrolyzed microbubbles are analyzed to achieve the adaptive start-stop control and stable residence of electrolyzed microbubble. The electrolytic test pieces with polyimide insulation surface and Pt bottom electrode were manufactured, and the observational experiments of electrolyzed microbubbles with normal and hydrophobic wall surfaces in the static water were made. The research results show that the adaptive start-stop control and stable residence of electrolyzed microbubbles in the micro-pits on electrolytic test piece can be achieved. The electrolyzed microbubbles start generating at the nucleation points, and more nucleation points are formed on the hydrophobic surface to accelerate the microbubble growth. The increased NaCl concentration from 0.5 % to 3.5 % would reduce the voltages of starting microbubble electrolysis on normal and hydrophobic wall surfaces by 4.43% and 2.31%, respectively. The increased NaCl concentration from 0.5 % to 2.5 % would also reduce the voltages of filling micro-pits on normal and hydrophobic wall surfaces, but the voltages of filling micro-pits turn to be constant as the NaCl concentration is greater than 2.5 %. The electrolytic voltage is increased to directly stimulate the combinations of H ions and electrons, thus significantly accelerating the electrolyzed microbubbles to inflate to the stable diameter. Under the same experimental conditions, the hydrophobic surface would lead to the greater stable diameter of microbubble to shorten the time to reach the stable diameter, and the resident stability of microbubble is improved using a greater contact angle θ.

Wave Components and Energy Ratio Characteristics of Seismic Wave Field Motivated by Airgun Source in Shallow Water

CHENG Guangli, LIU Bao, WANG Zeming, YANG Zhehui

2021, 42(5):  1032-1040.  doi:10.3969/j.issn.1000-1093.2021.05.016

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The fluctuation components and their energy ratio characteristics of seismic wave field motivated by airgun source in shallow water are analyzed through theoretical derivation, numerical simulation and experiment.The layered model of shallow water is simulated using high-order staggered-grid finite difference method, and the wave systems and components of seabed seismic wave field are given. Wave components of the simulated seabed seismic wave field are separated using τ-p method, and the fluctuation components and their energy ratios of seismic wave field are simulated and analyzed. A lake trial and two sea trials were made to validate the theoretical and simulated results. The results demonstrate that the seabed seismic wave motivated by airgun source in water is divided into longitudinal wave, transversl wave, underwater acoustic wave, and surface wave, τ-p method can be used to separate the wave components of seismic wave field, and the sea bottom characteristics can be obtained from the signals received by the seismic array. The seabed seismic wave, interface wave and transversal wave are easily motivated on hard seabed, the longitudinal wave is easily motivated on soft seabed, and the interface wave is difficultly motivated on very soft seabed.

Protective Properties of Porous Foam Aluminum Sandwich Composite Plate under the Combined Action of Fragment and ShockWave

WANG Mengxin， CHEN Ruiying， WANG Jinxiang

2021, 42(5):  1041-1052.  doi:10.3969/j.issn.1000-1093.2021.05.017

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The porous foam aluminum alloy plate not only overcomes the shortcomings of the traditional protective structure such as heavy weight and inconvenient transportation, but also has the advantages of fatigue resistance and high specific strength. The lightweight and efficient anti-explosion protection materials are of great significance. The finite element analysis software LS-DYNA is used to numerically simulate the failure mode and protection performance of the sandwich composite plate under the combined action of shock wave and fragment, and analyze the effect of the foam aluminum sandwich structure on the deformation of the backboard under different arrangements. The results show that, at a detonation distance of 40 cm, the fragments will act on the target plate before the shock wave, and the fragment load strength is far greater than the shock wave load strength. When the arrangement of foam aluminum and fiber is “1 mm-thick aluminum alloy panel +10 mm-thick foam aluminum +10 mm-thick foam aluminum +10 mm-thick fiber +1 mm-thick aluminum alloy backplane”, the deformation displacement of the backboard is the smallest, and the total internal energy of the structure is the highest, which are 13.9 mm and 52.7 kJ, respectively. The overall deformation degree of the structure can be more effectively reduced and the energy generated by the panel deformation is absorbed under the working condition.

Stress Distribution and Influence Factors of Fiber-optic Coil for Unmanned Submersible Vehicle

TANG Weijiang, LIU Weidong, GAO Zhuo, ZHANG Kai, ZHAO Peidong

2021, 42(5):  1053-1064.  doi:10.3969/j.issn.1000-1093.2021.05.018

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Fiber-optic coil is the key component to set up a dynamic wired communication channel between two nodes, which can is deployed during the movement of unmanned submersible vehicle. The stress distribution state of the coil in winding process directly determines its wire releasing performance.The radial deformation of the fiber-optic micro-cable and the relationship between its radial and axial deformations are explained by introducing its radial elastic parameters. A stress distribution model of the coil is established on the basis of the force analysis of the cable and the end plate. The variation of the stress distribution of coil with the elastic parameters of cable and winding tension is studied through simulation. Then the effect of each parameter on the storage life of coil is analyzed, and the optimization design of cable and winding tension is further proposed. Compared with the measured data of the coils, the changes of stress distribution and bathtub feature parameter are consistent with the simulation conclusions. The results show that the smaller the axial elastic modulus of cable is, the greater the radial elastic modulus and the radial elastic coefficient of cable are, the more stable the structure of coil is, but the storage life of optical fiber will be reduced; and the greater winding tension reduces the storage life of optical fiber, but does not affect the structural stability of the coil.

Structural Design and Optimization of Space Tether-net

SI Jiyue， PANG Zhaojun， YOU Meng， FENG Guangbin， DU Zhonghua

2021, 42(5):  1065-1073.  doi:10.3969/j.issn.1000-1093.2021.05.019

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The kinetic energy exchange between the bullets and the space tether-net makes the net rebound during the deployment, which severely affects the deployment performance of tether-net. The deployment performance of the quadrilateral net is improved by optimizing the mesh structure without changing the topological structure of tether-net. Two kinds of matrices are introduced to represent the topological structure and length of net, and the mass-spring-damper method is used to model the tether-net. An optimization strategy of mesh structure based on a genetic algorithm is proposed to optimize the effective deployment displacement. Finally, the structure and deployment performances of tether-nets with and without optimization are compared by numerical simulation. The rebound of the optimized net can be restrained and its effective deployment displacement can be improved without reducing the maximum deployment rate.

A Numerical Solution of Coupler Curve and Orientation for Reconfigurable Single-driven 3-RRR Planar Parallel Mechanism

LI Xiang， LI Ruiqin， LI Hui， NING Fengping

2021, 42(5):  1074-1082.  doi:10.3969/j.issn.1000-1093.2021.05.020

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For complex driving and control and high energy consumption of 3-DOF 3-RRR planar parallel mechanism，the parallelogram kinematic chain is used to constrain the mechanism to a single-driven 3-RRR planar parallel mechanism. The coupler curve and orientation of the single-driven 3-RRR planar parallel mechanism are calculated using numerical method. The influence of reconfiguration on the coupler curve and orientation are analyzed. The input-output (IO) equation of the mechanism is derived based on Freudenstein equation. The numerical solution method of the equation is established using iterative algorithm. By changing the initial input angle of the mechanism，a reconfigurable method of mechanism configuration is proposed. A set of mechanism parameters was given as numerical example, and two kinds of configurations of the mechanism，which are called configuration I and configuration II，were obtained. The variations of coupler curve and orientation with the input angle for configuration I and reconfigured configuration I were obtained. Results show that the theoretical curves are consistent with the simulated curves, and the solution method is correct. The reconfiguration can significantly change the coupler curve and orientation of configuration I.

Effect of Laser Energy Density on Microstructure and Properties of Laser Cladding NiCoCrAlY Coating

NIE Jinhao， YANG Yixin， LI Yuxin， ZHANG Hongjian， WEI Shouzheng， CAI Jie， GUAN Qingfeng

2021, 42(5):  1083-1091.  doi:10.3969/j.issn.1000-1093.2021.05.021

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NiCoCrAlY coating was prepared on the surface of 304 stainless steel in order to study the effect of energy density on the microstructure and properties of NiCoCrAlY coating during laser cladding. The phase composition and microstructure of NiCoCrAlY coating were analyzed by X-ray diffractometer (XRD) and scanning electron microscope (SEM). The hardness and wear resistance of NiCoCrAlY coating were studied by using a micro Vickers hardness tester and reciprocating friction and wear testing machine. The results show that the number of pores in NiCoCrAlY coating decreases with the increase in laser energy density, and the penetration and melting height increase with the increase in laser energy density. When the laser energy density is 3.8 kJ/cm², the coating dilution rate is the lowest, and the number of pores is less. The NiCoCrAlY coating contains γ/γ′ phase and β phase, and its microstructure is mainly columnar crystals. As the laser energy density increases, β phase content increases and the columnar crystals become larger. The hardness of NiCoCrAlY coating is higher than that of the substrate at different laser energy densities. The coating hardness is the highest when the laser energy density is 3.8 kJ/cm², which is 301 HV_0.2. In the reciprocating friction and wear experiment, when the laser energy density is 3.8 kJ/cm², the friction coefficient is the smallest (0.46) and wear volume is the smallest (0.235 9 mm³), the wear mechanism is mainly abrasive wear, and the wear resistance is the best.

Assembly Process Parameters Optimization of Turbine Engine Rotor System Based on Non-dominated Sorting Genetic Algorithm

FENG Kuikui， ZHANG Faping， WANG Wuhong， ZHANG Wenjie， ZHANG Tianhui

2021, 42(5):  1092-1100.  doi:10.3969/j.issn.1000-1093.2021.05.022

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An optimization determination method of different matrices of assembly angle was proposed to explore the optimal method for assembly process parameters to guarantee the dynamic balance of rotor system and grasp the changing law of dynamic balance at high temperature. According to the thermal-structure dynamic balance theory model at high temperature and the nonlinear change of material characteristics with temperature, a analytical equation is established for calculating the temperature change of dynamic balance of rotor system with temperature at high temperature. Then, according to the difference between system unbalance and offset torque under the different assembly parameters, the NSGA-Ⅱbased solution is presented by converting the high temperature dynamic balance optimization into multi-objective and multivariable optimization. Taking the assembly of high-pressure rotor system of a missile turbine engine as an example, the proposed method was verified in 600 ℃ working environment, and the optimal assembly angle matrix was obtained, which minimizes the influence of high temperature on the dynamic balance of rotor system and improves the assembly quality. The results show that the assembly angles have great influence on the dynamic balance of rotor system at high temperature, and the influence of high temperature conditions on the dynamic balance of multi-part rotor system can be significantly reduced through the optimization of assembly parameters.

Loitering Munition Penetration Control Decision Based on Deep Reinforcement Learning

GAO Ang， DONG Zhiming， YE Hongbing， SONG Jinghua， GUO Qisheng

2021, 42(5):  1101-1110.  doi:10.3969/j.issn.1000-1093.2021.05.023

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Loitering munition penetration control decision (LMPCD) is an important research direction under the concept of “multi-domain war”. The research on real-time route planning of loitering munition penetration has important military significance. Traditional knowledge, reasoning, and planning methods do not have the ability to explore and discover new knowledge outside the framework. The bionic optimization method is suitable for solving the path planning problem in static environment, such as traveling salesman problem, and is difficult to be applied to the penetration problem of loitering munition with high requirement of environmental dynamics and real-time decision-making. For the limitations of the first two methods, the applicability of the deep reinforcement learning method is analyzed, and the domain knowledge of loitering munition is introduced into each element of the deep reinforcement learning algorithm. The flight motion model of loitering munition is analyzed, the state space, action space and reward function of loitering munition are designed, the algorithm framework of loitering munition penetration control decision is analyzed, and the training process of loitering munition penetration control decision algorithm is designed. Through the penetration simulation test of 1 000 rounds of loitering munition, the result shows that the penetration success rate of loitering munition is 82.1% and the average decision time is 1.48 ms, which verifies the effectiveness of the algorithm training process and the control decision model.

Game and Reconfiguration Method of Complex Combat Network System

CHEN Xiaonan， HU Jianmin， CHI Benliang， CUI Yang

2021, 42(5):  1111-1120.  doi:10.3969/j.issn.1000-1093.2021.05.024

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An improved reconfiguration method is proposed to study the game relationship between the two sides in the complex combat network system. The game methods of the two sides in the complex combat network system are described, the importance degrees of structure and value of combat nodes are defined, the income measurement method of the same camp and different camp is defined, and a new strategy updating criterion is proposed based on the traditional Fermi equation. A reconstruction model of enemy network is established, and a new update rule of the combat game strategy is proposed. Three reconstruction methods for the enemy network link, the enemy node value and the unknown area of enemy are proposed. The combat case analysis is carried out, and the effect of the game and reconstruction in the complex combat network system is demonstrated through the simulation experiment. The results show that the game model and the reconstruction methods are reasonable and effective, which are of practical significance for the study of complex combat network system operations.