Table of Content

30 April 2021, Volume 42 Issue 4

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Contents

Contents

2021, 42(4):  0. 

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Paper

Dynamic Property of the Initial Disturbance of Projectile for the Long-range Artillery Howitzer

DING Shukui， WANG Liangming， YANG Zhiwei, DING Xuran

2021, 42(4):  673-683.  doi:10.3969/j.issn.1000-1093.2021.04.001

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A projectile dynamic model under artillery dynamic coordinate system was established to study the formation mechanism of initial disturbance of projectile during long-range artillery firing based on KANE dynamics method. Based on this model, a description method of projectile motion in the artillery movement environment is proposed, and the expressions of the interaction force and moment between the projectile and the gun are given. Combined with the engineering practice, the projectile movement laws during projectile launching are investigated. Then the effects of projectile-barrel gap, projectile mass eccentricity, leakage of gunpowder gas in the bore, bounce of gun mount and elastic vibration of the barrel on the initial disturbance of projectile were verified by simulations. The results show that the leakage of gunpowder gas in the bore may cause the abnormal movement of projectile in the bore, resulting in severe initial disturbance; the bending and elastic vibration of barrel have significant effect on the initial disturbance, and the bounce of gun mount has little effect on the movement and initial disturbance of projectile. The results can provide some important theoretical basis for improving the design of long-range artillery and the shooting accuracy.

Design of Shifting Rules of Automatic Transmission Based on Genetic Algorithm Optimization and Fuzzy Control DynamicOptimization

GAO Ziyin， DU Minggang， LI Shenlong， LI Jin

2021, 42(4):  684-696.  doi:10.3969/j.issn.1000-1093.2021.04.002

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The design of shifting rules of vehicle automatic transmission is optimized to improve the overall dynamics of light military wheeled vehicles. According to the simulation environment of MATLAB/Simulink, a vehicle dynamic model based on the two-parameter shifting rule of vehicle speed and throttle opening is constructed. Taking the shift point of the two-parameter shifting rule as the optimization object, the genetic algorithm is used to optimize the shift point. According to the characteristics of that the acceleration parameters can reflect the longitudinal dynamics of vehicle, the acceleration is introduced, and the fuzzy control algorithm is used to dynamically optimize the design of shifting rule, and a three-parameter fuzzy controller is constructed. The simulation model and real vehicle test were used to verify the influence of the shifting rule on vehicle dynamics before and after optimization. The results show that the optimized control strategy can effectively improve the vehicle's dynamic performance, more reasonably allocate the operating conditions of the engine and gear under the power demand, and effectively meet the power demand of military wheeled vehicles under complex road conditions.

Feedback Linearization Decoupling and Predictive Driving Control for Dual Independent Electric Drive Tracked Vehicle

ZHANG Jie, MA Xiaojun, LIU Chunguang, YUAN Dong, ZHANG Yunyin

2021, 42(4):  697-705.  doi:10.3969/j.issn.1000-1093.2021.04.003

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A decoupling and predictive control method is proposed for the control problem of driving dynamic coupling and tracking optimization of dual independent electric drive tracked vehicle. Based on the vehicle affine nonlinear model, the decoupling control of longitudinal speed and yaw rate is realized by feedback linearization to eliminate the coupling factors of the system dynamics. On this basis, the adaptive generalized predictive control (GPC) algorithms are designed for the longitudinal speed subsystem and yaw rate subsystem after decoupling, respectively. In the GPC algorithm, the recursive least squares method is used to identify the parameters of the controlled autoregressive integrated moving average model to correct the control law, and constrain the system control and output to achieve the tracking optimization of target speed and yaw rate based on the motor output capability. A series of experiments were conducted for an electric drive tracked vehicle prototype. The experimental results show that the designed algorithm can be used to track the target speed and yaw rate quickly and accurately, the output of the control variable is smooth, and the anti-interference performance is strong, which realizes stable driving of vehicle under various working conditions.

Effect of Inlet Bend Pipe on the Centrifugal Compressor Performance and Its Optimization Design

TONG Ding, TIAN Hongyan, LIU Xinyuan, LIU Ye, GAO Chao, LI Xin

2021, 42(4):  706-714.  doi:10.3969/j.issn.1000-1093.2021.04.004

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Bend pipe is often used for air guidance at centrifugal compressor inlet, in which the distortion of inlet flow may be caused by secondary flow. For this problem, the influence law and mechanism of bend pipe on centrifugal compressor performance were studied through numerical simulation and bench test. On that basis，an optimization design method of adding the guide fins into the bend pipe was put forward and verified through simulation and bench test. The simulated and test results show that the pressure ratio and efficiency are deteriorated to a certain extent by adding the guide fins into the inlet bend pipe, which is more obvious at the chock point of compressor. The new bend pipe with guide fins can regulate the characteristics of the inner flow in the pipe. The improved flow state makes the flow at the compressor inlet become relatively uniform, thus improving the performance of compressor.

The Effect of Metal Doping on the Friction Performance of DLC Coating for Piston Pins of Highly-strengthened Diesel Engine

GUO Shenggang, WANG Jianping, ZHAO Zhongcheng, CHENG Jingjing, TIAN Xinwei

2021, 42(4):  715-722.  doi:10.3969/j.issn.1000-1093.2021.04.005

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The piston pins of diesel engine are subjected to periodically the alternating mechanical and thermal loads, and the abnormal wear and tear often occur due to adhesion. In order to improve the friction and wear performances of piston pin of diesel engine, the diamond-like carbon (DLC) coating of three doped metals (Cr, W, Cr+Ti) was deposited on the surface of piston pin by magnetron sputtering method, the scanning electron microscope (SEM), X-ray diffractometer (XRD) and energy disperse spectroscopy (EDS) were used to analyze the micro-morphologies and structures of different DLC coating surfaces, and the friction and wear properties and film-based bonding strength were tested. The results show that the surface micro-morphologies of the three coatings are similar, their surfaces are dense without obvious defects and holes, but a small amount of particles are formed on the surfaces. Compared with Cr-doped DLC coating, the surface is smoother. For Cr-doped DLC coating, Cr exists as Cr element and Cr C compound, which greatly improves the mechanical properties of Cr; DLC coating doped with Cr has higher film-based bonding strength and better friction performance. The performance of DLC coating doped with C_r and T_i is similar to that of Cr-doped DLC coating. Cr and Ti exist in the form of element and CrC and TiC compounds. W-doped DLC coating has high brittleness and poor toughness due to the formation of WC compound.

The Strategy and Method of Intelligent Computer-aided Design for Modular Gun Family

ZHAO Shubin， XU Cheng， JIANG Hongyi， BU Chunchen

2021, 42(4):  723-733.  doi:10.3969/j.issn.1000-1093.2021.04.006

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The modular and intelligent design of gun family is the state of the art. Based on the design characteristics of gun family,a knowledge-based computer-aided design process is established, and a modularization-based intelligent design method is proposed. An unified object-oriented knowledge representation is adopted for different types of knowledge in the gun family design, and the strategies based on knowledge template, machine learning, and mixed reasoning are used in the solution of the gun family definition stage and the module design stage. Specifically, the knowledge template of module division is used to guide the modular design of the gun family, and the Random-Forest-based regression algorithm is used to estimate the main parameters of the gun family. A question-answering system based on the bidirectional encoder representation from transformers (BERT) model and a mixed reasoning mode based on case-based reasoning and cross reasoning of design rules and calculation are used to assist in completing the detailed design of each module. Accordingly, a software prototype system is constructed, and 5.8 mm/7.62 mm modular gun family is designed. The results have proved the effectiveness of the proposed methods.

Thermal Effect of Small Caliber Rifle Barrel under Continuous Single Shot Firing

GU Zucheng, WANG Guanghua, LU Haitao, YAN Wenmin

2021, 42(4):  734-742.  doi:10.3969/j.issn.1000-1093.2021.04.007

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In order to study the influence of thermal effect of small caliber rifle barrel on barrel performance under the action of thermal load and surrounding parts, the difference between the temperature field and thermal deformation field of barrel with or without surrounding parts on the barrel surface is studied. Based on the initial conditions and thermal boundary conditions, a three-dimensional thermal-structure coupling model of gun barrel and surrounding parts under the thermal action of high-temperature gunpowder gas is established using finite element analysis software ANSYS. The thermocouple was fixed on the surface of barrel, and the temperatures at 10 positions on the barrel surface were measured. The simulated results are basically consistent with the experimental results. The simulated results of temperature field and thermal deformation field show that there is obvious heat absorption phenomenon in the direct contact area between the surrounding parts and the barrel surface, and the temperature field of barrel is asymmetric due to the structure of the surrounding parts; the radial inner diameter of barrel increases, and expands unevenly along the axial direction; the radial axis of barrel deviates and shows an uneven deviation along the axial direction. The research and analysis of barrel thermal effect under the action of thermal load and surrounding parts can lay a foundation for the later optimization of gun temperature field and the improvement of firing accuracy.

The Method for Determining the Threaded Connection Parameters of Projectile-fuze System Based on Thin-layer Element Model

YAN Amin， PI Aiguo， WANG Jian， HUANG Fenglei， WANG Xiaofeng

2021, 42(4):  743-754.  doi:10.3969/j.issn.1000-1093.2021.04.008

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Threaded connection is one of the main connection modes of projectile body and fuze body, which affects the vibration response characteristics of projectile-fuze system directly. For the problem that the existing numerical simulation methods are difficult to characterize the threaded connection accurately, a thin-layer element method is peoposed to simulate the threaded connection, and a determination method for the material parameters of thin-layer element is established through theoretical and experimental research. The material parameters of thin-layer element are determined based on the elastic model of threaded connection and thin-layer element theory.The determined material parameters of thin-layer element are applied to the finite element model. The calculation accuracy of thin-layer element model is verified by the modal test of threaded tube and projectile-fuze system. Compared with the modal test results of threaded pipes with different pitch and thread length, the maximum calculated error of the thin-layer element model is 5.11%. Moreover, compared with the nodes fusion method, the maximum error of the first third-order modal frequency decreases from 17.72% to 2.54% after using thin-layer element method for the projectile-fuze system.

Interior Ballistic Characteristics of Combustion and Propulsion Process of Bulk-loaded Liquid Propellant

JIANG Dongdong， XUE Xiaochun

2021, 42(4):  755-763.  doi:10.3969/j.issn.1000-1093.2021.04.009

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A gas-liquid two-phase flow and reaction mathematical model for the 12.7 mm small caliber launch device was established by ANSYS 2020. The proposed model is used to study the influences of pressure wave and Taylor Helmholtz instability effect on the internal ballistic performance during the combustion process of liquid propellants. The evolution characteristics of Taylor cavity gas-liquid interface during the combustion process of liquid propellant were obtained through simulation, and the mass fraction of components, evaporation rate of liquid propellant, chemical reaction rate and temperature contours were obtained as well. The simulated results show that the evaporation and combustion reactions mainly occur on the surface of Taylor cavity, and the reaction products diffuse to the whole cavity. At the same time, some wrinkles are found on the cavity surface because of Helmholtz instability effect. In the whole process of expansion, the axial expansion speed of the cavity is far greater than the radial expansion speed, and there are still many liquid propellants around the chamber. As a result, the stability of interior ballistics becomes worse and the pressure oscillation intensifies.

Damage Effect of Composite Structural Reactive Fragments on Double-layer Targets

LI Xin, WANG Weili, LIANG Zhengfeng, CHEN Jin, CHEN Yuanjian

2021, 42(4):  764-772.  doi:10.3969/j.issn.1000-1093.2021.04.010

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It is of great significance to study the damage power of reactive fragments which can withstand the loading of explosive. The damage effect of Al/PTFE composite structural reactive fragments on the different types of double-layer targets is studied through the loading experiment with 14.5 mm ballistic gun. The empiricial formulas of penetration diameter in front layer plate and expanding perforation area on rear layer plate were established using multiple regression analysis. The results show that the penetration diameter in front layer steel or aluminum plate increases with the rising of impact velocity and target thickness in the range of 800-1 400 m/s. The penetration diameters in the steel, aluminum and carbon fiber composite plates are 1.25-1.62 times, 1.08-1.42 times and 1.13 times of fragment diameter, respectively. Expanding and tearing damages are caused to the rear layer aluminum plate or the carbon fiber composite plate by the ractive fragments. The expanding perforation area increases with the increase in front layer target strength and impact velocity, and the delamination of carbon fiber and resin matrix for the back of carbon fiber composite plate should be considered in damage assessment. The empiricial formulas were proved to be accurate and reliable, and the relative error was controlled within 5% through experiment.

Phase Transition Characteristics of Debris Cloud of Ti/Al/Mg Wave Impedance Gradient Material Subjected to HypervelocityImpact

ZHENG Keqin, ZHANG Qingming, LONG Renrong, XUE Yijiang, GONG Zizheng, WU Qiang, ZHANG Pinliang, SONG Guangming

2021, 42(4):  773-780.  doi:10.3969/j.issn.1000-1093.2021.04.011

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In hypervelocity impact, the wave impedance gradient material helps to transfer the kinetic energy into more internal energy, which causes the melting and vapor phase transition of debris cloud, and disperses and dissipates the kinetic energy of projectile, thus protecting the spacecraft from debris cloud. The wave impedance gradient material studied in this paper is made of titanium, aluminium and magnesium alloy（TAM）. The smoothed particle hydrodynamics (SPH) method is used to simulate hypervelocity impact. Impact-induced phase transition criteria of various materials are given by using Tilloston equation of state and Steinberg-Guinan constitutive model. The simulated results were compared with the experimental results with impact velocity of 7.9 km/s. The results show that the impact-generated debris cloud is melted and vaporized to some extent when TAM wave impedance gradient material is impacted by the velocity more than 4 km/s. For Ti, Al and Mg, the debris cloud is melted at the impact velocities of 6 km/s, 5 km/s and 4 km/s, respectively, and it is vaporized at the impact velocities of 8 km/s, 9 km/s and 6 km/s.

Flight Performance Aptimization of Glide Vehicles under Multiple Launch Conditions

SUN Yibo， MENG Xiuyun

2021, 42(4):  781-797.  doi:10.3969/j.issn.1000-1093.2021.04.012

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Glide vehicles can generally be launched in a wide airspace and speed range. A multidisciplinary analysis model, including geometric modeling, aerodynamics, structural mass, and flight performance disciplines, is established to extend the flight range of glide vehicles under multiple launch conditions. In the proposed model, the maximum flight range analysis in flight performance is taken as the core, and the analysis results is achieved by designing the flight guidance control system. The first three disciplines mainly provide the necessary data for the flight performance analysis. The flight performance discipline consists of four parts: flight control system design, optimal trajectory design, guidance law design, and trajectory simulation for maximum range analysis. To give an initial feasible design for the extended range problem of glide vehicle, an initial glide vehicle that meets the design constraints is designed by using U.S. Joint Standoff Weapon (JSOW) glide vehicle as a baseline. On this basis, the flight performance of the initial glide vehicle was analyzed under multiple launch conditions, which is close to the reported capability of JSOW. The multidisciplinary analysis model is used for the performance evaluation during the multidisciplinary design optimization of glide vehicles, and the range performance of optimized glide vehicle is increased to some extent.

Model and Characteristics of Jet Flow Erosion Damage to Silencer Layer in Silo Launching Process of Rocket

LI Liang， FENG Yongbao, MA Changlin, XIA Wenlong

2021, 42(4):  798-807.  doi:10.3969/j.issn.1000-1093.2021.04.013

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The silencer layer is corrosively damaged by high temperature and high speed jet flow of rocket engine in the launching process. This affects the launching safety.The analysis of jet flow erosion damage is important to the late repair of silencer layer and the optimization of silo structure. The jet flow erosion damage to the silo silencer layer is a complicated thermal-hydro-mechanical coupling problem. The typical glass wool silencer layer is researched to build the phase change heat transfer and jet flow erosion damage mathematic models. A simulation platform of jet flow erosion damage is established by extracting and pretreating the jet flow field data, writing an interpolation program and developing Abaqus user subroutine. And a sub-model method is introduced to build a glass wool numerical simulation model. The ablation process of glass wool was simulated, the ablation damage was analyzed under the effects of silo diameter, initial height of jet flow and engine pressure build-up speed, and the simulation and ablation damage principle experiment for silo silencer layer were performed. The simulated results show that the glass wool silencer layer of the silo is generally damaged during jet flow ablation, which mainly occurs in the reverse flow and destabilizing stage. And the ablation damage is similar in the circumferential direction of the silo, but different in the axial direction. In addition, the damage is more serious closer to the bottom of silo, and the decreased diameter of silo or the increased pressure build-up speed of engine would aggravate ablation. But the increased initial height of jet flow will weaken ablation. The experimental results show that the glass wools are all damaged to a certain extent.

Location Algorithm of Airborne External Transmitter Based on DP-BVCKF

LU Yu, YI Xiao

2021, 42(4):  808-816.  doi:10.3969/j.issn.1000-1093.2021.04.014

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An location algorithm based on dynamic programming and bivariate cubature Kalman filter (DP-BVCKF) was proposed for the target state estimation of airborne external transmitter location system in clutter environment. The state transition range of target is determined based on the error propagation theory. The amplitude of echo signal is selected as the value function of dynamic programming for recursive accumulation. Based on the statistical characteristics of clutter and the extreme value theory, the extraction threshold of target measurement of dynamic programming is determined, and the measurement sequence from target is extracted reversely. The states of target and external transmitter are estimated simultaneously by using the bivariate cubature Kalman filter algorithm. Simulated results show that the proposed algorithm can be used to extract the measurement sequence of target from clutter effectively, and the state estimation uncertainty is also reduced. The proposed algorithm has lower calculation burden and better state estimation effect.

Horizontal-longitudinal Correlations of Sound Field at Large Depth in the Direct Zone of Deep Water

WANG Mengyuan, LI Zhenglin, QIN Jixing, WU Shuanglin, WANG Guangxu

2021, 42(4):  817-826.  doi:10.3969/j.issn.1000-1093.2021.04.015

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The horizontal-longitudinal correlations of sound field at large depth in the direct zone of deep water have important reference significance for the design of horizontal array and the signal processing of array. The characteristics of deep water sound transmission loss and horizontal-longitudinal correlations are analyzed based on a deep water incomplete channel sound transmission experiment in the South China Sea in the winter of 2016. The horizontal-longitudinal correlations in deep water of the direct zone are analyzed through theory and simulation. The results show that the horizontal and longitudinal correlation radii of sound field at large depth are independent to the sound energy. The interference characteristics of sound field at large depth in deep water of the direct zone lead to the existence of oscillation structure of horizontal-longitudinal correlation coefficient. The horizontal-longitudinal correlation radius of sound field is consistent with the oscillation period of sound transmission losses. The longer the oscillation period is, the larger the horizontal-longitudinal correlation radius is. The horizontal-longitudinal correlation radius decreases with the increase in the frequency and depth of sound source in the direct zone. The horizontal-longitudinal correlation radius of sound field at the near distance from direct zone is less affected by the change of receiver depth, but it increases with the receiver depth at a far distance.

Ship Shaft-rate Electric Field Sliding Threshold Detection Method Based on Rao Detector

YU Peng， CHENG Jinfang， ZHANG Jiawei， JIANG Runxiang

2021, 42(4):  827-834.  doi:10.3969/j.issn.1000-1093.2021.04.016

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A sliding threshold detection method based on Rao detector is proposed to detect the ship's shaft-rate electric field at a low SNR in non-Gaussian noise environment. A signal model is established based on the characteristics of signal source, and a noise model is established based on Gaussian mixture model (GMM) after analyzing its non-Gaussian characteristics measured by a floating platform. In the detection process, the parameters of GMM and the Rao detection value are computed in real time; the mean value of previous Rao detection values is regarded as the sliding threshold. The simulation method is first used to verify the proposed method. The results show that the detection performance of Rao detector is better than that of energy detector. Then the measured ship data is used to compare the Rao sliding threshold method and the sliding power spectrum method. The results show that the proposed method is better in decreasing the non-Gaussian environment noise and has a better detection performance than the sliding power spectrum method.

Open-water Characteristics of Shaftless Pump-jet Thruster

ZHU Hao, JIN Shuanbao, WANG Dong, WANG Gongbao, WEI Yingsan, HU Pengfei, WU Xingyu, HE Shengyang, HU Fengge

2021, 42(4):  835-841.  doi:10.3969/j.issn.1000-1093.2021.04.017

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The shaftless pump-jet thruster (SPT) is a new type of integrated motor propulsion (IMP) device, which combines both the characteristics of shaftless propulsion and pump-jet propulsion technologies. In order to study the difference of hydrodynamic performance between SPT and conventional thruster, the computational fluid dynamics (CFD) approach is used to analyze and compare the hydrodynamic performances of SPT, traditional mechanical pump-jet thruster and E779A propeller. The definition of hydrodynamic efficiency of SPT is also discussed. The results show that the open-water efficiency of SPT reaches 0.662, which is lower than that of the conventional propeller. The high-efficiency working range of SPT is rather wider than that of the propeller, which means that SPT is able to work efficiently under more working conditions. Finally, a test bench is designed for the hydrodynamic test of SPT and the verification of the numerical simulation model of SPT above.

Complex Load of Torpedo Near-field Explosion and Its Damage Mode to Ships

LIU Wensi, LU Yue, ZHOU Qingfei, CHENG Suqiu

2021, 42(4):  842-850.  doi:10.3969/j.issn.1000-1093.2021.04.018

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A numerical analysis model of near-boundary underwater explosion was established based on nonlinear explicit dynamic analysis software LS-DYNA in order to evaluate the damage efficiency of torpedo underwater explosion to ships. The calculated results of explosion load under near-free liquid surface boundary conditions were compared with the calculated results of empirical formulas in Ref.［6］ and the experimental results in Ref.［17］, verifying that the proposed numerical simulation method can well reflect the shock wave pressure of the near-field underwater explosion and the multiple bubble pulsation processes. The technology is used to build a numerical simulation model close to the actual combat boundary conditions, and calculate and analyze the damage mode of the torpedo near-field explosion to the ship under multiple conditions. The results show that different boundary conditions in the near field have an important effect on the pulsating load of underwater explosion bubbles. Under different conditions, shock wave, bubble pulsation and water jet load have complex coupling effects with ship structure. The effect of torpedo on the ship in the near field under different conditions shows different energy output structures, which is closely related to the final damage mode of ship, and there is an optimal detonation distance to maximize the total energy of torpedo acting on the ship.

Representation of Motion Primitives of Intelligent Vehicle Based on Multiple Demonstrations and Generation of Their Sequences

LU Yaomin, GONG Jianwei, WANG Boyang, GUAN Haijie

2021, 42(4):  851-861.  doi:10.3969/j.issn.1000-1093.2021.04.019

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In order to solve the problem of human-like trajectory generation in different driving styles, a driving style parameter extraction-based motion primitive representation method and a corresponding motion primitive sequence generation method are proposed based on the real driving trajectory data set containing the same type of multiple demonstrations. The single motion primitive is represented by a modified dynamic motion primitive method, and the singular value decomposition is introduced to separate the main shape representation parameters and driving style parameters in the same type of trajectory set. The sequence of motion primitives is fitted with a clamped B-spline curve on the premise of correlating the parameters of the independent motion primitives. The results show that the proposed single motion primitive representation method not only guarantees the accuracy of trajectory representation, but also expands the generalized adjustment ability of primitives according to driving style. On this basis, the associated primitive sequence not only achieves the clamping of the course and position of target point, but also ensures a smooth transition between the individual primitives.

Dynamic Response Behaviors of Ti-6321 Titanium Alloys with Different Microstructures under Split Hopkinson Pressure BarLoading

NING Zixuan, WANG Lin, CHENG Xingwang, CHENG Huanwu, LIU Anjin, XU Xuefeng, ZHOU Zhe, ZHANG Binbin

2021, 42(4):  862-870.  doi:10.3969/j.issn.1000-1093.2021.04.020

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Ti-6321 titanium alloys with different microstructures were obtained through solution treatment, and the influence of microstructure on the dynamic behavior of materials was studied. An universal testing machine and a split Hopkinson pressure bar test device, combined with the characterization methods such as optical microscope and scanning electron microscope, were used to characterize the microstructure evolution of loaded titanium alloy sample. The results demonstrate that the alloys with equiaxed, bimodal and Widmanstatten microstructures have obvious strain rate strengthening effect, and the critical shear fracture strain rates are all 3 000 s^-1. The bimodal structure has good strength and plastic combination under static and dynamic compression, Widmanstatten structure is poor, and the equiaxed structure has higher critical shear strain and impact absorption energy, which are 0.252 and 307 MJ·m^-3 , respectively. At the strain rate of 3 000 s^-1, the strain rate sensitivity factor of the equiaxed microstructure increases gradually, the strain rate sensitivity factor of Widmanstatten microstructure decreases, and the strain rate sensitivity factor of bimodal microstructure is unchanged with the increase in strain. When the strain is 5%, the strain rate sensitivity factors of equiaxed and bimodal microstructures increase with the increase in the strain rate, while the strain rate sensitivity factor of Widmanstatten microstrucutre is unchanged. Adiabatic shear failure occurs in all microstructures. Equiaxed structure has a low adiabatic shear sensitivity, and Widmanstatten structure has a high adiabatic shear sensitivity.

Impact Point Positioning Method Based on the Objective Function without Velocity Parameter

LI Zhiming, FAN Jinbiao

2021, 42(4):  871-877.  doi:10.3969/j.issn.1000-1093.2021.04.021

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In most of the existing impact point positioning methods based on seismic wave, the velocity of seismic wave needs to be inversed or measured in advance, which causes a large positioning error. An impact point positioning method based on objective function is proposed. The unknown parameters of objective function are only the coordinates of the impact point, so there is no need to measure the wave velocity in advance or inverse the wave velocity. The simplex method is used to optimize the objective function, and the density-based spatial clustering of applications with noise (DBSCAN) algorithm is used to locate the impact point.The method can effectively suppress the positioning error caused by uneven wave velocity. A simulation model is esatablished to verify the feasibility of the positioning algorithm. When the positioning method is applied to the ground static explosion experiment and the data obtained by the geophone is used to locate the explosion center, the relative positioning error is 0.38%, which proves the correctness of the positioning method.

Optimization Model of Multi-type Shore-to-ship Missile Combat Unit Deployment

SONG Guibao， JIANG Zijie， LIU Zhan， LIU Zhenyu

2021, 42(4):  878-887.  doi:10.3969/j.issn.1000-1093.2021.04.022

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An optimization model for the deployment of multi-type shore-to-ship missile combat units is constructed to solve the problem of quantitative decision-making on the deployment of shore-to-ship missile combat units in the combined attack mission of multi-position shore-to-ship missiles. The proposed model is based on the generalized maximum coverage and location theory, and takes into account the actual condition of limited number of shore-to-ship missile forces. For the influencing factors such as the position of target ship and the firepower coverage of shore-to-ship missile, Monte Carlo simulation method is used to establish a target dispersion area calculation model, a shore-to-ship missile firepower coverage area calculation model and other auxiliary decision-making models, and the particle swarm optimization algorithm is used to solve the proposed optimization model. The simulated results show that the optimization model and algorithm for the deployment of multi-type shore-to-ship missile combat units can be used to provide reasonable and effective optimization scheme, which provides reference and basis for the deployment of multi-type shore-to-ship missiles in wartime.

Resistance Characteristics of Oil-gas Two-phase Flow for Mobile Pipeline Evacuation Operation

JIANG Junze, ZHANG Zhen, LI Jiang, CHEN Yan, CHEN Ming, JIANG Wei

2021, 42(4):  888-896.  doi:10.3969/j.issn.1000-1093.2021.04.023

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Mobile pipeline plays a great role in the oil supply，and the the pipe evacuation is a regular working. The length of the sections varies with the liquid expelled from the pipeline, and the liquid acceleration is variable, so the resistance of the pipiline system exhibits nonlinear characteristics, which shows more difference against the single phase flow. In order to provide the theoretical basis for the evacuation design, the resistance of pipeline must be accurately predicted. A calculation model is presented for the resistance characteristics in the process of pipeline evacuation. In the proposed model, a pipeline is divided into three sections, including a single-phase gas section, a single-phase liquid section, and a two-phase flow section. The resistance characteristics of the whole pipeline are obtained by calculating the friction resistance of each section. By comparing with the experimental data of various working conditions of mobile pipeline evacuation operation, the calculated result of the proposed model has a good agreement with the experimental data in the first 2/3 time period of evacuation process. In the later 1/3 time period, the resistance of pipeline is mainly caused by gas-liquid two-phase flow, so there are some errors among the calculated values and the experimental values, which may be caused by the estimation of slug frequency and the accelerated pressure drop. The calculation accuracy of the proposed model is analyzed by using the absolute mean value of error. The obvious influential factor is the physical properties of oil products, such as viscosity, density, surface tension, etc., while the influences of pipe diameter, pipe length and gas flow rate are small. The calculated results of the proposed model have a good agreement with the experimental results. The proposed model can be used for the analysis and prediction of the resistance characteristics during the mobile pipeline evacuation operation.