Table of Content

28 March 2023, Volume 44 Issue 3

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Electronic edition of this issue

2023, 44(3):  0. 

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In-plane Compressive Mechanical Behavior of SLM Titanium Alloy Honeycomb Structure

QIAO Yang, ZHAO Zhicheng, XIE Jing, CHEN Pengwan

2023, 44(3):  629-637.  doi:10.12382/bgxb.2022.0585

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In order to explore the potential application of additively manufactured metal honeycomb structures in the field of protection, titanium alloy honeycomb samples were prepared by selective laser melting (SLM), and uniaxial in-plane compressive mechanical experiments were carried out. Periodic crushing and unloading phenomena appeared in the platform section, which was different from the features of the platform section of traditional plastic/brittle materials honeycomb. Using the digital camera and scanning electron microscope, the structural deformation modes and fracture failure mechanism were analyzed. Based on the parametric finite element analysis, the influence of wall thickness on the crushing and unloading of honeycomb structures was studied. The results showed that: the titanium alloy honeycomb samples prepared by SLM had high printing accuracy and small difference in mechanical properties; when the titanium alloy honeycomb structure was compressed in the plane, the fracture of the honeycomb edge connection in the structural shear zone results in the periodic crushing and unloading in the stress-strain curve of the structure; obvious dimples could be observed on the fracture surface at the failure site, showing an obvious plastic failure morphology; the wall thickness thinning can effectively increase the rotation angle of the short side of the honeycomb during failure and reduce the minimum bending radius, thus significantly improving the crushing and unloading phenomena and enhancing the bearing stability of the structure.

Review and Prospect of Life Extension Technology for Gun Barrels

MAO Baoquan, ZHAO Qijin, BAI Xianghua, WANG Zhiqian, ZHU Rui, CHEN Chunlin

2023, 44(3):  638-654.  doi:10.12382/bgxb.2021.0787

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The challenge of extending barrel life has restricted the improvement of the performance and combat effectiveness of guns for a long time. Therefore, extending the service life of gun barrels has become the urgent need for modernization and future battlefields. First, the main factors affecting gun barrel life are summarized. Then the domestic and foreign technical methods for barrel service life extension are introduced, including propellant improvement, surface treatment of the barrel bore, optimization of projectile and rifling design, gun steel improvement, and anti-ablation technology based on magnetron plasma. Moreover, research progress of relevant technologies at home and abroad is summarized, and the shortcomings in these technical fields in China are analyzed. Finally, this study gives the prospects of the future development direction in the field of barrel life extension from the aspects of clarifying the ablation and wear laws of the barrel bore, selecting feasible life extension methods, and taking multiple measures to conduct key research, and exploring and developing the anti-ablation technology based on magnetron plasma. This study provides ideas for the development of conventional barrel life extension technology and insights into new life extension technologies, thus improving the combat effectiveness of weapons.

High-Speed Impact Engraving Characteristics of Cased Telescoped Ammunition

SHI Junfei, QIAN Linfang, CHEN Hongbin, FU Jiawei

2023, 44(3):  656-669.  doi:10.2382/bgxb.2022.0834

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To study the mechanical mechanism and motion law of the high speed impact engraving process of cased telescoped ammunition, the physical and mathematical interior ballistic models were analyzed and established with a 40mm caliber CTA gun as the research object, and the interior ballistic model was verified by live fire experiments. Considering the friction and contact characteristics between the interfaces, a high-speed impact engraving model was built by the FEM-SPH coupling algorithm, and the numerical solution of the interior ballistics was used as the boundary condition to obtain the change laws of the deformation of the rotating band, projectile motion, projectile attitude and engraving resistance by numerical calculations. The results showed that: the established ballistic model is accurate and reasonable; the initial velocity of the projectile at the bore was 78.2m/s; the entire engraving process can be divided into the decelerating and accelerating phases, and the projectile was in the quasi-static state between the two phases; during the decelerating engraving process, the projectile attitude changed periodically, and the amplitude of the oscillation angle decreased continuously; the oscillation angle increased rapidly during the accelerating engraving process; as the engraving was completed, the oscillation angle showed a decreasing trend; the engraving time was 2.65 ms and the projectile velocity was 73.92 m/s at the completion of engraving; the surface temperature of the rotating band during the engraving process was close to the melting point of the material; there were two "rise - fall" processes in the dynamic engraving resistance with the maximum engraving resistance of 95.288 kN, and the resistance decreased and stabilized at 10 kN at the moment of fully engraving.

Damage Characteristics of Ship’s Double Bottom Structure Subjected to Underwater Explosion

CHEN Yanwu, SUN Yuanxiang, WANG Cheng

2023, 44(3):  670-681.  doi:10.12382/bgxb.2022.0390

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To study the damage characteristics of a ship’s double bottom structure subjected to underwater explosion. Experiments on the interaction between the electric spark bubble and the ship’s double bottom structure with a hole are carried out. The pulsation characteristics of the bubble are captured by a high-speed camera, and the experiment is simulated by LS-DYNA to verify the effectiveness of the numerical model. Then, the finite element model of the full-scale cabin is established. By changing the explosion distance and water level between the double bottoms and designing 15 simulation scenarios, the damage characteristics of the double bottom structure subjected to shock wave and bubble loads are analyzed. The results show that: when the explosion distance is small, the outer bottom is broken, and the expansion of the "inner bubble" intensifies the tearing of the outer bottom and causes the plastic deformation of the inner bottom; when the explosion distance is large, the outer bottom only deforms and contacts with the inner bottom, driving the deformation of the inner bottom at the same time; when the water level between the two bottoms is low, the shock wave load attenuation is large with a small damage to the inner bottom, and the expansion of the "inner bubble" plays a major role in the deformation of the inner bottom; when the water level between the two bottoms is high, the shock wave load attenuation is small, the shock wave and bubble pulsation loads propagate through the water medium and act on the inner bottom, whose combined action causes its deformation.

Experimental Study of Impact Energy Absorption of Aerogel Sandwich Structures

LI Zehao, XU Wenlong, WANG Cheng, JIA Shiyu, XUE Shengpeng, MA Dong

2023, 44(3):  682-690.  doi:10.12382/bgxb.2022.1009

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To meet the impact and collision protection needs of armored vehicles, ships and other weapons and equipment, an impact energy absorption structure with an aerogel core is proposed. Using a one-stage light air gun system, combined with the force sensors, a high-speed camera and digital image related technologies, the impact energy absorption characteristics of seven aerogel sandwich structures at three impact velocities of 10.4 m/s, 15.4 m/s and 19.0 m/s are studied. The results show that: the peak impact force, collapse distance, specific energy absorption and mean impact force of the seven aerogel sandwich structures increase gradually with the increase of impact velocity; under the same impact velocity, with the increasing aerogel layer thickness, the specific energy absorption of the sandwich structures gradually increases, the peak impact force decreases, and the overall change of the impact force efficiency is small. Therefore, within the research scope, a larger aerogel layer thickness is beneficial to the improvement of impact energy absorption of the aerogel sandwich structures, and can avoid the damage of excessive peak force to the protection personnel or equipment.

Preparation and Thermal Decomposition Properties of Multi-scale Interface-Tunable Al/RDX Energetic Composites

XU Ruixuan, XU Jiaxing, XUE Zhihua, LÜ Jieyao, YAN Qilong

2023, 44(3):  691-701.  doi:10.12382/bgxb.2022.0618

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Based on the integrated design concept of oxidant/metal fuel (Al) in propellants and the surface modification of aluminum particles, the multi-scale interface-tunable semi-embedded Al/RDX and fully-embedded Al@RDX composites were prepared by resonant acoustic mixing and spray drying. The morphology, true density and heat of combustion of the composites were characterized by scanning electron microscopy (SEM) and other techniques, and the thermal decomposition process and its gas products were studied by simultaneous thermal analyzer (DSC-TG-FT-IR). The results showed that compared with the mechanical mixture, the true density of the composites remained basically unchanged, but the heat of combustion of these two composites was higher, which were 17.31 kJ/g and 18.82 kJ/g. The DSC results showed that the heat of thermal decomposition of RDX can be increased by these two ways. Although the embedding of aluminum particles does not change the types of gas-phase products of RDX decomposition, it is more conducive to generate more HCHO. After the embedding of aluminum particles, the first decomposition stage of RDX changed from the random nucleation model (A2) to the random chain scission model (L2), while the second decomposition stage of the fully-embedded Al@RDX composites was transformed into the autocatalytic model (AC).

RVE Size Εffect and Homogenizing Response of Directional Modulus in Stochastic Multi-scale Chopped Carbon Fiber Composite Structure Model

QIU Yijian, ZHENG Ping, CHENG Xiangping, GUO Yusong

2023, 44(3):  702-717.  doi:10.12382/bgxb.2021.0835

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A new homogenization method of multi-scale chopped fiber filling resin matrix was adopted with the purpose of exploring the effect of the discrete angle of stochastic chopped fiber on the homogenizing response of directional modulus of the composite structure. We also studied the changes of composite structure performance caused by the random distribution of the crimp chopped carbon fiber (CCF) unit in the representative volume element (RVE) structure. In the homogenization method, a RVE subdomain post-processing scheme based on Gauss theorem was used to extract the average strain and stress of the three-dimensional structure. In addition, X-ray computed tomography (CT) was employed to determine the second-order tensor orientation angle and the probability distribution information of chopped fiber length in the test sample. The RVE models of three dimensions were designed and compared. The influencing factors of attenuation length in stress-affected zone of multi-scale CCF composite model and the homogenizing response of RVE directional modulus with rotation angle caused by this homogenization method were studied by experiments and calculations. The results showed that the shear modulus of the composite structure is more sensitive to rotation angle than the positive axial modulus, and that the attenuation length is related to RVE size, unit cell (UC) structure and fiber tortuosity. Therefore, it is of practical significane to study the discreteness of stochastic chopped carbon fiber for the design of directional modulus of macroscopic composite structures and the optimization of layering angle.

Parafoil-based UAV Recovery System Under Random Initial Conditions

SUN Hao, SUN Qinglin, SUN Mingwei, CHEN Zengqiang

2023, 44(3):  718-727.  doi:10.12382/bgxb.2021.0450

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A parafoil recovery system consists of a flexible parafoil wing and a payload. It has unique advantages such as low requirements for landing ground, flight stability, and flared landing. As a result, this system is indispensable for airdrop supplies and recovery of unmanned aerial vehicles (UAVs). Considering that the parafoil system relies on a flexible wing for lift, it exhibits complicated dynamic characteristics. Tracking the trajectory of such a flexible aircraft is much more challenging than tracking a traditional rigid one. For solving this problem, this study first analyzes the forces between the flexible wing and the payload, and builds an accurate dynamic model of the parafoil recovery system. Then, based on the active disturbance rejection control theory, the horizontal controller and homing strategy are designed to realize the homing control under random initial condition. The UAV will be transported to the target position from a random initial yaw angle. Lastly, the results of the flight tests indicate that the simplified model can provide the simulation environment for the actual flight test, and realize the adjustment of the controller parameters. The average landing error of the parafoil system is 21.9 m in fifteen homing control tests.

Dynamic Compressive Properties of Graphene/Ceramic Particle Reinforced Polyurethane-Based Composites

ZOU Guangping, WU Songyang, XU Shubo, CHANG Zhongliang, WANG Xuan

2023, 44(3):  728-735.  doi:10.12382/bgxb.2021.0777

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The good mechanical properties of polyurethane make it widely used in various fields. By introducing graphene reinforcement into the polyurethane matrix, it can greatly enhance the properties of the polyurethane-based composites. To obtain the polyurethane-based composites with high impact resistance, graphene oxide reinforced polyurethane was prepared by in-situ polymerization, and dynamic compression tests at different strain rates were carried out with the Hopkinson bar device. On this basis, 3.3 mm diameter Al₂O₃ granular ceramics was added as a new reinforcing phase by the pressureless infiltration method. The dynamic confining pressure experiment of graphene / granular ceramic reinforced polyurethane-based composites is performed, and the stress-strain curve of the sample is obtained. The finite element simulation model of the composite is established by using LS-DYNA. Combined with the experimental data, the reliability of the simulation is verified, the deformation process and damage mechanism of the composite under dynamic confining pressure are analyzed, the simulation analysis of the samples with different particle sizes under dynamic confining pressure is carried out, and the influence of ceramic particles with different particle sizes on the dynamic compression mechanical properties of the composite is discussed. The results show that: the particle size of ceramic particles is closely related to the compressive strength of the composites; with the decrease of ceramic particle size, i.e., the number of ceramic particles increases and the particle gap decreases, the compressive properties of the composite are improved.

A Marching Stable Control Method for a New Vehicle-Mounted Multi-Tube Load

GAO Qiang, HOU Yuanlong, LÜ Mingming, MAO Bin, HOU Runmin, YANG Shuyi, WU Bin

2023, 44(3):  736-747.  doi:10.12382/bgxb.2021.0782

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A novel vehicle multi-tube load faces internal and external disturbances, as well as instability on the move in travelling. In order to solve these problems, a stable controller with adaptive compensation of disturbance velocity is designed based on neural network. The load structure is optimized to balance the loads at both ends of the trunnion and reduce energy consumption and nonlinear interference caused by the unbalanced torque. The main control quantity is calculated by PI controller, and the velocity and acceleration of disturbance are obtained by the extended state observer and the hybrid differentiator, respectively. The single neuron controller is adopted to calculate the compensation control quantity, of which the inputs are disturbance velocity and acceleration. Gradient information is employed by the RBF neural network for online learning of the compensation coefficients of velocity and acceleration. Numerical simulation and bench test results show that the proposed stability controller has strong self-learning and adaptation ability, and it is robust to disturbances of different frequencies and amplitudes. The time for parameter learning is less than 3.7 seconds, and the mean square deviation of integral position errors is less than 0.33 mil. The results verify the feasibility and effectiveness of the proposed controller for vehicle multi-tube loads.

Magnetic Scattering-Based Detection Technology for Inner Surface Wear of Rifled Gun

LI Kai, ZHOU Shichao, WEN Peng, SUN Jiangang, GONG Qingqing, LI Yuan, HAN Yan

2023, 44(3):  748-756.  doi:10.12382/bgxb.2022.0346

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To meet the requirement of wear detection of the inner surface of the barrel during the use of the rifled gun, a magnetic scattering model of the inner surface wear of the rifled gun was established, and a detection method for the inner surface wear of the rifled gun was studied. In the geomagnetic environment, based on the magnetic dipole model, the two-dimensional magnetic dipole model of the rifling wall on both sides of the land was analyzed, and the scattered magnetic field distribution models of the bore, the guide side, the ablation groove, the coating and other wear is deduced. The variation law of the magnetic field distribution of the barrel’s inner surface wear was obtained by simulation. A hardware-in-the-loop simulation test was carried out for the wear detection of the rifling. The experimental results showed that when the land was not worn, the difference between the magnetic field strength of the land and the groove was 17.6 A/m; when the land wear was 56.15%, the magnetic field strength difference was reduced to 1.78 A /m. The proposed method provides a rifling wear inspection theory and method for the delivery and use of barrels.

Self-Destruction Time Distribution of Fuze Based on Functional Analysis

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

2023, 44(3):  757-762.  doi:10.12382/bgxb.2021.0838

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To deal with the problem that the fuze’s self-destruction time test cannot reflect the self-destruction time distribution when the sample size is small, the initial velocity, self-destruction rotating velocity and time relationship are analyzed. The functional analysis method is used to establish the relationship between the initial velocity and the self-destruction rotating velocity of the ballistic model. The Euler-Lagrange equation is employed to solve the parameters related to the normal distribution of the initial velocity and the self-destruction rotating velocity, and thus obtain the time distribution. The simulation results show that the proposed method can determine the relationship between initial velocity and self-destruction rotating velocity, and verify the effectiveness of the method through hypothesis testing. The joint distribution of initial velocity and self-destruction rotating velocity is used to solve the self-destruction time distribution, so as to obtain the satisfaction of tactical technical indicators. This study provides a more effective method for the performance appraisal test of the firing range, and serves as a theoretical support in terms of self-destruction time for the safety of military training.

Evaluation Method of Fault Diagnosability Based on Recursive Plot and Tensor Decomposition

LÜ Jiapeng, SHI Xianjun, NIE Xinhua, QIN Yufeng, LONG Yufeng

2023, 44(3):  763-772.  doi:10.12382/bgxb.2021.0790

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Diagnosability reflects the difficulty of diagnosing system faults, so diagnosability evaluation of the system is a prerequisite for fault diagnosis. Taking the signals of test points into consideration, a fault diagnosability evaluation method based on a recurrence plot and tensor decomposition is proposed. The phase space reconstruction technique is used to graphically represent the signals of measured points in different states to form a recurrence plot. Features are extracted through analyzing the recurrence plot, which are then regarded as the original signal features. Through tensor decomposition, the similarity between signal features in different states is calculated as a basic measure of fault diagnosis difficulty. Simulation experiments show that, compared with the previous D-matrix diagnosability evaluation method that only considers the system model, the newly proposed method has effectiveness and objectivity.

Study of the Hard Turning Processability of Hardened Ultra-high Strength Steel 45CrNiMoVA

DU Kai, JIAO Li, YAN Pei, YU Jianhang, WANG Yubin, QIU Tianyang, WANG Xibin

2023, 44(3):  773-782.  doi:10.12382/bgxb.2021.0757

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In order to avoid tensile residual stress and heavy use of highly-polluting cutting fluid, in the grinding process of hardened steel, a hard turning process is proposed. The turning process is carried out for the quenched-tempered 45CrNiMoVA steel. The cutting forces during the process are recorded, and the surface morphology, residual principal stress, and microhardness of the machined surfaces are analyzed. The results show that the cutting forces increase with the cutting depth and feed rate. However, the change in cutting speed has little effect on the cutting force. The surface roughness Ra of the workpiece after hard turning can reach 0.64 μm. The consistency of surface morphologies is also satisfying. The residual principal stress decreases with the increase of the feed rate and the cutting depth. By comparison, the residual principal stress first decreases and then increases with the increase of the cutting speed. The direction angle of the maximum residual principal stress changes steadily within the range of 37°~45° with the increase of cutting speed and cutting depth. It first increases and then maintains stable within the range of 22°~45° with the increase of feed. The surface microhardness decreases with the increase of cutting speed, and the depth of hardened layer is about 200 μm.

Underwater Vehicle Control Based on Linear Active Disturbance Rejection

GAO Quanxi, KE Wei, QIAO Haiyan

2023, 44(3):  783-791.  doi:10.12382/bgxb.2021.0769

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To deal with the influence of strong nonlinearity, strong coupling, external disturbance and uncertain parameters of underwater vehicle, an attitude decoupling control method based on linear active disturbance rejection control is proposed. The mutual coupling of each control channel of the underwater vehicle and the internal and external disturbances are regarded as the total disturbance, which is estimated by the extended state observer and introduced into the feedback controller for compensation. The original nonlinear system is transformed into a linear system to realize decoupling control. The virtual control quantity is introduced to decouple the coupling caused by the rudder. Based on the control system and the nonlinear dynamic model of the underwater vehicle, the stability analysis is given. The simulation results show that the controller based on linear active disturbance rejection has the characteristics of fast response, small overshoot and steady-state error, and strong robustness. Compared with PID control, the dynamic performance and anti-disturbance ability are greatly improved.

Effect of Welding Wire Composition on Welding Usability of High Nitrogen Steel Using Cold Metal Transfer Plus Pulse Welding Method

ZHANG Jian, LI Tao, LIN Hongxia, YANG Dongqing, FANG Hui, FAN Jikang, WANG Kehong

2023, 44(3):  792-798.  doi:10.12382/bgxb.2021.0799

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To improve the welding quality of high nitrogen steel and optimize the welding process, the welding stability caused by nitrogen and manganese content was studied. Welding experiments were performed using five different welding wires made of high nitrogen steel by the Cold Metal Transfer plus Pulse welding method to investigate the effect of welding wire composition on electrical signal, droplet transfer, spatter rate. The results showed that: the increase of nitrogen content caused the fluctuation and discrete distribution of electrical signals, while the change in manganese content had less effect on electrical signals: the effect of nitrogen content in welding wire on welding stability using the CMT+P welding method was greater than that of manganese content; the mode of droplet transfer changed from one droplet per pulse to one droplet per multiple pulses as the nitrogen content increased, and the melting droplets becames irregular in shape and larger, meaning the welding usability of wires was worse; when the nitrogen and manganese contents in the welding wire was small, namely 0.42% and 7.19%, respectively, the welding process stability was better; the rapid escape of nitrogen and the evaporation of manganese caused high-nitrogen steel droplets to explode violently, producing a large amount of spatter; the welding spatter rate increased with the increasing nitrogen and manganese contents.

Study of the Guidance Law for Super-Twisting Sliding-Mode Guided Projectiles with Multiple Constraints

ZHOU Meng, QIAN Weixian, REN Kan

2023, 44(3):  799-805.  doi:10.12382/bgxb.2021.0776

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Regarding the terminal guidance with accelerated speed, impact point and impact angle constraints, an multiple-constraint super-twisting guidance law for guided projectiles is proposed. First, to simplify the design process, the relative motion model of the missile and the target is converted into a standard second-order form. By applying the Super-Twisting (ST) algorithm, the guidance system can realize convergence faster. By replacing the sign function with saturation function, vibration is decreased. Moreover, an auxiliary guidance scheme is designed by adopting the auxiliary system (AS) theory to solve the problem of accelerated speed constraints. The simulation results indicate that suggested super-twisting sliding-mode guidance law is highly precise and can realize anti-windup control.

Fatigue Life Prediction Model with Back Stress Energy Method Based on the Machined Surface Layer of High Strength Steel

WANG Yong, WANG Xibin, WANG Zhibin, LIU Zhibing, LIU Shuyao, CHEN Hongtao, WANG Pai

2023, 44(3):  806-815.  doi:10.12382/bgxb.2021.0828

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The cyclic strain energy method has been widely used because it can predict fatigue life from the perspective of fatigue damage mechanism and explain many fatigue phenomena which cannot be explained by other methods. However, in the large amount of empirical study of the overall properties of materials, the machined surface layer is often not considered, which affects the prediction accuracy of the energy method. Based on the energy method, a new fatigue life prediction model with back stress energy based on the machined surface layer of high strength steel was proposed. The effect of surface mechanical characteristics on total back stress energy was considered by introducing the area of residual stress with depth as the influence factor, while the effect of surface layer geometry and metallurgy on strain energy was considered by taking the non-propagation threshold of microcrack as the influence factor. The results showed that: the dispersion band of fatigue life prediction error for the modified model considering surface integrity was reduced by 38% and the prediction accuracy improved by 25%; it had the same error dispersion band (1.25 times) as the model for the real-time statistical single cycle energy density after fatigue fracture, which overcomes the disadvantage that the fatigue life can be predicted only after the fatigue test of the traditional energy method; for quenched and tempered high strength steel, the average accuracy of fatigue life prediction of the modified model considering surface integrity was improved from 72.7% to 90.6%; compared with the real-time statistics after fatigue fracture, the error dispersion band of the single cycle energy density prediction model was reduced from 3.30 times to 1.41 times. This model provides a method to assess the fatigue service performance of the machined surface layer, and improves the applicability of strain energy in different machined surface layer characteristics.

Multi-Objective Spare Parts Scheduling Method in Wartime Considering Lateral Transshipment and Emergency Distribution

LI Jingfeng, CHEN Yunxiang, XIANG Huachun, GAO Yangjun, ZHAO Jing

2023, 44(3):  816-830.  doi:10.12382/bgxb.2021.0809

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To deal with the fact that the existing wartime spare parts scheduling model is not flexible enough, ignores the priority sequencing of demand points, only handles a single type of spare parts, and has a low algorithm operation efficiency, a multi-objective spare parts scheduling method in wartime considering lateral transshipment and emergency distribution is proposed. On the basis of the traditional forward scheduling model, lateral transshipment and emergency distribution strategies are added, and a wartime spare parts scheduling model that simultaneously handles multiple types of spare parts is established with the objectives of the smallest number of missing parts and the shortest transportation time. A priority sequencing method for demand points based on the technique for order of preference by similarity to ideal solution (TOPSIS) is formulated, and the multi-objective evolutionary algorithm based on decomposition considering priority sequencing (MOEA/D-PS) is designed to solve the model using the framework of the multi-objective evolutionary algorithm based on decomposition (MOEA/D). The results show that: the scheduling model considering lateral transshipment and emergency distribution has the best support effect; the MOEA/D-PS algorithm can satisfy both the solution quality and the computational efficiency, and the average CPU running time is 62.86% shorter than the non-dominated sorting genetic algorithm II (NSGA-II); in addition, the priority sequencing and the required time limit significantly affect the effectiveness of spare parts supply support.

Strength Calculation Method of Double-Pin Track Shoes Under Tensile Load

ZENG Zihao, ZHANG Jingdong, GONG Xuelian, LIU Kunming, GUI Xuewen, LIAO Ridong

2023, 44(3):  831-840.  doi:10.12382/bgxb.2021.0771

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Tensile load is one of the main loads on the track of armored vehicles and also an important working condition for strength calculation, but the distribution of tensile load at the connecting parts of the track is not clear. To figure out the load distribution ratio of double-pin track shoes under tensile load, single and double-shoe track tensile experiments and simulations of a certain type of armored vehicle track shoes were carried out, the difference in load distribution and stress when different numbers of track shoes were subjected to tensile load were discussed. The iterative calculation of the finite element method was used to figure out the results of stable load distribution when the track was stretched, and a two-step method to quickly calculate the stable load distribution of the track shoes was proposed. The results showed that: the tensile load distribution of the track shoes changes with the increase of the number of the track shoes; when the number of the track shoes is large enough, the load distribution of the end coupling and the guide tooth tends to have the distribution ratio of 1:2:1; the change of the number of tracks in the tensile test has some influence on the maximum stress on the track shoe and the deflection of the track pin, which should be considered in the tensile strength test of the track.

A Motion Planner for Unmanned Tracked Vehicles in Multi-storey Buildings Considering the Characteristics of Vehicles

XIONG Guangming, YU Quanfu, HU Xiuzhong, ZHOU Zijie, XU Jiahui

2023, 44(3):  841-850.  doi:10.12382/bgxb.2021.0800

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To solve the navigation problem of the unmanned vehicles in multi-storey buildings, a motion planning framework considering the characteristics of vehicles is proposed. Based on the characteristics of tracked vehicles, the primitive scheme of zero-radius steering is adopted and the Voronoi Path is introduced, which improves the flexibility and safety of the global planner in a narrow environment. Then, the smooth global path is obtained through piecewise cubic Hermite interpolation. Based on model prediction with respecting to the kinematic model of tracked vehicles, the Wavefront Value is introduced to improve the robustness of the local planning algorithm in the case of inaccurate obstacle positioning, and combined with the Finite State Machine to implement the autonomous navigation task between multiple floors. Finally, the simulation and real vehicle experiment are performed. The results show that the proposed algorithm can better adapt to the characteristics of narrow indoor space and also prove its feasibility in the actual environment.

Flexible Body Simulation Technology for Replenishment Equipment Based on PBD Algorithm

LI Nan, REN Hongxiang

2023, 44(3):  851-856.  doi:10.12382/bgxb.2021.0807

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To address the problem that the 3D movement of flexible bodies such as the rigging and oil hose cannot be simulated in the Replenishment Simulation Training System, which leads to the lack of immersion of the system, the PBD algorithm was adopted for the simulation study of flexible bodies such as the rigging and oil hose in the replenishment equipment. Firstly, the flexible body particle model of the replenishment equipment was established based on the multi-body dynamic model. Then, the PBD algorithm was improved, and the dynamic deformation of the flexible body was simulated by adding tensile constraints, bending constraints and long distance constraints. Finally, the Gauss-Seidel iteration method was compared with the Newton iteration method, and the results showed that the former met the requirements of the simulation system in a relatively low number of iterations. So the 3D motion of the flexible bodies such as the rigging and oil hose in replenishment equipment was simulated.

Analysis of Electric Field Interference Characteristics and Signal Detection Method Based on Ocean Buoys

SUN Qiang, ZHANG Jiawei, YU Peng

2023, 44(3):  857-864.  doi:10.12382/bgxb.2021.0671

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To solve the problems of electric field acquisition and target detection in the deep ocean environment, the interference characteristics of an electric field measured by a deep sea electric field detection buoy are analyzed. It has been confirmed that the energy of buoy shaking interference is primarily below 0.5 Hz and decreases with depth increases. The interference of the electric field can be reduced to 0.1μV/m. Then, to detect the electric field signals of the buoy platform, an improved detection method based on adaptive threshold line spectrum energy sum is proposed, based on the analysis of interference characteristics. Simulation and experimental results show that the proposed improved algorithm can effectively detect the target electric field signals and reduce the false alarm probability while ensuring target detection probability.

Fast Deorbit Guidance Method Based on Virtual Reentry Angle

QUAN Shenming, WANG Zhu, CHAO Tao, YANG Ming

2023, 44(3):  865-875.  doi:10.12382/bgxb/2021.0710

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To meet the requirement of rapid deorbit of reentry vehicles, an online guidance algorithm for rapid deorbit based on virtual reentry angle is proposed. On the basis of analyzing the guidance mechanism of the pulse deorbit, the finite thrust method is used to gradually approach the terminal state so as to meet the shift requirements of the reentry angle and reentry speed. The convex optimization method is used to calculate the time-optimal trajectory that meets the multi-terminal constraints. Combined with the simulation results of the finite thrust guidance algorithm, the trajectory characteristics are analyzed, the concept of virtual reentry angle is proposed, and an online guidance algorithm for fast deorbit considering multi-terminal constraints is designed. The proposed method is compared with the existing methods from the aspects of computational efficiency and guidance accuracy, Monte-Carlo simulations are carried out under the condition of deviation of the thrust magnitude and direction of the engine. The simulation results show that compared to the existing algorithms, the proposed algorithm achieves the goal of rapidity in the deorbit stage and can meet the needs of online computing while ensuring the same control accuracy.

Cushioning Energy Absorption of Four-layered Composite Tubes with Regular Pentagon and Hexagon Cross-sections under Axial Drop Impact

CHEN Shenghui, GUO Yanfeng, FU Yungang, MA Xiaojiao, QIN Fang

2023, 44(3):  876-885.  doi:10.12382/bgxb.2021.0732

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The paper corrugation sandwich tube provides an innovative solution to deal with impact. For the polyethylene foam double-filled configuration of paper corrugation sandwich tube, the energy absorption of the four-layered tube and the influence of geometrical and loading parameters are investigated through comparison tests of axial drop impact and parametric analysis. According to the results, the length of plastic plateau of the X-direction corrugation sandwich double-tube with double-filling is much longer than that of the Y-direction double-tube, and the energy absorption of the former is better than that of the latter. The specific energy absorption, unit volume energy absorption, specific total efficiency, and average crushing stress of the double-tube with double-filling decrease as a whole with the increase of the edge number of the tube. Whereas, as the mass of the drop hamper increases, the energy absorption of the tube increases. For the tube length ratio of 3.0, the total energy absorption and specific energy absorption of the X-direction regular pentagonal double-tube increase by 15.6% and 48.8%, respectively, compared with those of the hexagonal tube; the numbers for Y-direction double-tube are 14.4% and 47.9%. The double-tube with a tube length ratio of 2.2 has better higher impact resistance and initial peak stress than those with tube length ratios of 1.4 and 3.0.

Analysis of Petri Net Model and Index Demonstration for Torpedo Equipment Testing and Maintenance

ZHANG Ning, LIN Haihua, SUN Yaping, LI Zongji, WANG Shizhe

2023, 44(3):  886-894.  doi:10.12382/bgxb.2021.0768

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To meet the needs of testing and maintenance of torpedo equipment, the generalized stochastic Petri net model is used to the testing and maintenance modelling of the torpedo equipment, and the testability indices are analyzed. Firstly, the GSPN models of the system layer and the structure layer of the torpedo equipment are established respectively, and the failure modes of the torpedo equipment are classified according to the failure mode, effects and criticality analysis (FMECA). Then the non-basic transition of the GSPN model of the torpedo structure layer is expanded. Second, the isomorphism method is adopted to solve the maintenance sub-network GSPN model, and the steady-state availability analytical formula is employed to analyze the influence relationship between the testability parameters and the use availability (A₀). Finally, taking a certain type of torpedo as an example, the testability index solution and model simulation verification are carried out. The model simulation availability is A’=0.999 8, and the error with the system requirement value is less than 1%, which verifies the feasibility and effectiveness of the constructed model.

Gait Control Algorithm and Simulation of New Parallel Quadruped Military Robot

LI Shanshan, WANG Hongbo, CHEN Jianyu, ZHANG Xingchao, TIAN Junjie, NIU Jianye

2023, 44(3):  895-909.  doi:10.12382/bgxb.2021.0796

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In the multi-joint walking robot control strategy, when only the CPG network control is used, there will be problems of various parameter and complex network structure. In addition, the robot’s work environment is usually varied and complex, requiring higher flexibility of robots and stronger anti-interference ability. So using a single control mode is difficult to meet the above requirements. To address these problems, by combining the CPG control method and the control method based on the virtual model, a new gait control algorithm is designed for parallel quadruped military robots whose each leg is a 3-UPS mechanism. CPG is used to complete the basic walking gait and the construction of the nonlinear oscillator network model between input and output, and then the output is mapped to the driving moment of the joint motor. The foot virtual force required to maintain the robot’s stable posture during walking is generated by the virtual model, and the foot virtual force is mapped to the joint’s driving moment. Finally, V-REP and MATLAB are used to simulate the proposed gait control algorithm, and the simulation results verify its effectiveness. The advantage of the proposed gait control algorithm is that it can simplify the control network and ensure the robot’s strong flexibility and anti-interference ability during walking, thus providing new insights into the gait control of parallel quadruped military robots.

Structural Design and Shielding Performance of Multi-spectral Interfering Smoke Module

LI Xiaonan, LI Tianpeng, ZHANG Kaichuang, CHEN Hao, GUO Aiqiang, GAO Xinbao

2023, 44(3):  910-918.  doi:10.12382/bgxb/2021.0818

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The survivability of battlefield targets has been greatly threatened due to the employment of a series of advanced precision-guided munitions. To meet the performance requirements of multi-band interference, the multi-spectral interfering agent and smoke module were prepared through in-situ synthesis reaction, compound dispensing technique and numerical calculation, respectively. The infrared transmittance, mm-Wave attenuation and visible transmittance spectra of the multi-spectral interfering agent were characterized by a smoke screen test system. Mass extinction coefficients at infrared and visible bands were measured using the Beer-Lambert law. The matching performance of smoke module and multi-spectral interfering agent was examined by using an explosion experiment. The smoke screen production process, effective smoke screen width and smoke duration were obtained. The transmittance of the multi-spectral interfering agent was 1.98% at 1-3 μm, 3.04% at 3-5 μm, 8.11% at 8-14 μm and 6.96% at 0.4-0.8 μm. α_e was 1.28 m²/g at 1-3 μm, 1.14 m²/g at 3-5 μm, 0.82 m²/g at 8-14 μm and 0.87 m²/g at 0.4-0.8 μm. The attenuation values of 3 mm and 8 mm waves were -14.52 dB and -11.76 dB. The duration of smoke screen was greater than 60 s, and the effective smoke screen width exceeded 60 m. This study demonstrates that the smoke module equipped with multi-spectral interfering agent is an efficient strategy to jam advanced precision-guided munitions.