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    31 December 2024, Volume 45 Issue 12
    Scientific and Technical Issues in Cross-terrain Process and Driving Device Design
    MAO Ming, CHEN Yijie
    2024, 45(12):  4191-4204.  doi:10.12382/bgxb.2024.0977
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    Cross-terrain scenarios are common in human activities and production. The ongoing development of cross-terrain equipment characterized by high mobility, low power consumption, and safety is crucial. Such equipment enables human to access inaccessible areas, particularly in emergency rescue and military operations. This paper aims to establish a new technical scientific discipline. It introduces cross-terrain science and defines it. The paper methodically addresses major scientific and technological challenges in four areas of cross-terrain science: surface soil mechanics and adhesion, driving device design theory and method, cross-terrain driving dynamics and control, and ergonomics and biomimetics of cross-terrain machines. Additionally, it recommends priorities for future research and development in cross-terrain technologies and equipment.

    Research Progress on Target Detection Technology of Magnetic Gradient Tensor System
    LI Qingzhu, LI Jing, LI Zhining, SHI Zhiyong, WEN Xuezhong
    2024, 45(12):  4205-4230.  doi:10.12382/bgxb.2023.0964
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    The magnetic gradient tensor system (MGTS) is the application basis for detecting the full tensor gradient field of magnetic target. Regional magnetic anomalies leads to a magnetic gradient tensor field, which MGTS uses as an information source to achieve the magnetic gradient tensor measurement through the differential calculation between vector magnetic sensors. Compared to the magnetic total field and vector field detection equipment, MGTS has high resolution, large information content, and strong anti-interference ability, which can obtain more potential physical property information of targets. The progress of target detection technology based on MGTSs worldwide is studied to provide theoretical reference and technical support for the modernization and informatization construction of magnetic detection equipment in China. The development process and stages of modern magnetic detection technology are elaborated, and then the two types of MGTSs based on superconducting technology and flux gate method, as well as their applications areintroduced and summarized. The calibration, compensation, noise reduction, magnetic target positioning and recognition technologies of MGTSs are reviewed. Finally, the design ideas for future high-precision magnetic gradient tensor detection instruments are prospected, and the current problems and development trends of various key technologies for magnetic gradient tensor detection are summarized.

    End-to-end Intelligent Construction Algorithm of Air-defense Firepower Network for OODA Operation Process
    LUO Yuyu, DING Wei, MING Zhenjun, LI Chuanhao, WANG Guoxin, YAN Yan, WANG Yuqian
    2024, 45(12):  4231-4245.  doi:10.12382/bgxb.2023.1010
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    Aiming at the problems of a large number of targets, difficult equipment coordination, and poor system response in an air-defense battlefield environment, an end-to-end intelligent construction algorithm of air-defense firepower network for the observe-orient-decide-act (OODA) operation process is proposed. An air-defense system-of-systems framework composed of an intelligence network, command network, and firepower network is constructed for the OODA operation process. Based on this framework, the intelligent construction of firepower network, which is the key to the success or failure on a battlefield, is solved. The process of intercepting the weapon attacking a target is modeled as a Markov decision process, and the corresponding state space, action space, and reward strategy are given. On this basis, the standard end-to-end proximal policy optimization (PPO) algorithm is optimized to improve the model accuracy and reduce the training time. The proposed algorithm is evaluated and verified by taking a joint regional operation scenario of air-defense and antimissile missiles as an example. The results show that the proposed algorithm can quickly and accurately generate the design scheme of air-defense firepower network compared with the rule-based and heuristic algorithm. Especially in terms of computational efficiency and operational cost in the same large-scale combat scenario, it provides the basis for the construction of a kill network in the whole process of the operation system-of-systems.

    Study and Analysis on Numerical Simulation of Empty Hole Effect Induced by Cutting Blasting
    TAO Zihao, LI Xianglong, HU Qiwen, WANG Jianguo
    2024, 45(12):  4246-4258.  doi:10.12382/bgxb.2024.0250
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    Cutting blasting plays a crucial role in achieving single-free-surface blasting during roadway excavation. To investigate the impact of empty holes on cutting blasting, the finite element method-smoothed particle hydrodynamics (FEM-SPH) coupling approach is used to establish a three-dimensional model of single empty hole cutting blasting based on the theory of empty hole action. The distribution characteristics of stress near the empty hole in multi-stage cutting blasting is analyzed, and the response laws of rock breaking, throwing, and cavity formation with respect to empty hole are studied. It is found that an empty hole guides the distribution of stress fields in the nearby rocks, the significant concentration effects of stress are generated around the empty hole. and the peak value area of stress is expanded, thereby providing the favorable conditions for subsequent blasting operations. there exists a strong correlation among rock throwing efficiency, empty hole and cavity size. Compared to the cases without an empty hole, the single empty hole cutting blasting exhibites a 34.7% increase in throwing speed and a 10.2% improvement in throwing efficiency. In field tests, cavity volume is increased by 17.1%, and the cutting depth is increased by 16.3%. However, there are no significant changes observed in overall cavity shape. These research findings provide partial theoretical support for designing and optimizing the actual cutting blasting parameters.

    Research on the Identification of Spherical Explosive Fragmentation Damage Effect Based on Siamese Networks and Regional Attention Mechanisms
    LI Haotian, CUI Xinyu, LIU Mengzhen, HUANG Guangyan, LÜ Zhongjie, ZHANG hong
    2024, 45(12):  4259-4271.  doi:10.12382/bgxb.2023.1215
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    In the information warfare, the damage assessment of explosive fragments is of great significance to achieve accurate strike. However, the manual acquisition of distribution and geometric information of damage areas are inefficient in the damage experiment. To this end, a lightweight image segmentation model based on siamese networks and regional attention mechanisms is proposed, which achieves the efficient and accurate recognition of small-targeted spherical explosive fragmentation damage area under small samples. The model’s ability to perceive the explosion holes is improved by introducing the siamese structure, regional attention module and multi-scale convolution module. A loss function with multiple constraints is added and the best optimizer is screened so that the model optimization is more focused on the effective information for accelerating the model convergence. A quantitative detection method for the damaged area based on the connected-domain fusion watershed algorithm is proposed to achieve the accurate identification of the overlapping case of explosion broken holes. Experimental results show that the proposed method achieves higher efficiency and accuracy compared with the current mainstream models, and the average errors in predicting the area and diameter of damage region are 4.78% and 3.79%, respectively. The research work provides a reference for realizing the intelligent damage assessment of explosives containing fragments.

    Model Predictive Control for Wheeled L-quadruped Robots Based on Hierarchical Decoupling
    XING Boyang, XU Wei, LI Yufeng, ZHAO Haoyu, WANG Kang, YAN Tong
    2024, 45(12):  4272-4282.  doi:10.12382/bgxb.2023.0984
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    The wheeled-quadruped hybrid robot is an innovative composite robot platform that combines the features of legged and wheeled robots, enabling three modes of movement: fast wheel motion, legged obstacle-crossing, and wheel-leg combination. A control method for wheeled-quadruped robot based on linear model predictive control (MPC) is proposed to achieve the above three maneuvering modes. The MPC-based control method employs a hierarchical framework to separate the wheel speed control from the quadruped stability control. It independently controls the wheel speeds and estimates the torques while compensating for wheel-ground disturbances in real-time. For body stability control with MPC, the control model is converted into Ax+Bu standard form using state augmentation. Gravity acceleration is used to equivalently transform the end-effector force disturbances, allowing the external force disturbances to be integrated into the dynamic model without increasing the system’s state space dimension. In the simulation and practical test on Panda-W wheeled-quadruped robot, the proposed algorithm effectively mitigates the wheel-ground disturbances during wheel-leg acceleration and deceleration, achieving stable body control and successful Trot gait locomotion on various terrains.

    Detonation Diameter Effect of CL-20-based Pressed Explosives
    HE Chao, LIU Yan, BAI Fan, LIU Moyan, WANG Hongfu, HUANG Fenglei
    2024, 45(12):  4283-4294.  doi:10.12382/bgxb.2023.0980
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    The detonation propagation characteristics of hexanitrohexaazaisowurtzitane (CL-20)-based pressed explosives are studied to promote the application of CL-20 mixed explosives in micro-detonation sequences. For a typical pressed CL-20 mixed explosive (C-1, CL-20/binder=95/5), the reaction rate equation parameters of Lee-Tarver shock initiation model for this explosive are calibrated through the shock initiation experiments, providing the model parameters for simulation studies of diameter effect. Based on this, the detonation diameter effect of cylindrical step charges is verified through numerical simulation and experiment, and the relationship between charge diameter and detonation velocity is established. The detonation diameter effects of C-1, PBX9404 and PBX9502 explosives are compared through the numerical simulation of conical charge detonation propagation. The critical diameters of the three explosives are obtained by fitting the relationship between detonation velocity and charge diameter, and the influence rules of different constraint conditions on the critical detonation diameter of C-1 explosive are mastered. The study shows that the critical detonation diameter of C-1 explosive (1.34mm) is between those of PBX9404 (1.27mm) and PBX9502 (2.3mm). This is because the detonation velocity decay caused by the detonation diameter effect of explosive is related to its shock initiation characteristics, and the different stages of detonation velocity decay are controlled by different reaction rate terms (ignition, low-pressure slow reaction, and high-pressure fast reaction). In addition, with the strengthening of constraint conditions, the critical diameter of C-1 explosive decreases. the influence of lateral rarefaction wave can be greatly weakened by using radial full constraint, and its critical diameter is decreased by 51.5% compared with that of unconstrained charge.

    Armored Vehicle Cluster Trajectory Prediction Method Based on DBSCAN Clustering Algorithm and LSTM Network
    CHEN Gang, WANG Guoxin, MING Zhenjun, CHEN Wang, SHANG Xiwen, YAN Yan
    2024, 45(12):  4295-4310.  doi:10.12382/bgxb.2023.1064
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    It is difficult to accurately predict the movement trajectory of armored vehicle cluster due to the complexity of armored vehicle motion states, the uncertainty of battlefield situations, and the tactical confusion and deception. This paper proposes a trajectory prediction method for armored vehicle cluster based on density-based spatial clustering of applications with noise (DBSCAN) clustering algorithm and long short-term memory (LSTM) network. Firstly, a kinematic model of armored vehicles is established based on the states of armored vehicles driving on slopes, turning and interacting with other vehicles. And then the trajectory characteristics such as maneuver features, environmental features and vehicle-to-vehicle interaction features are selected, and the trajectory of an individual armored vehicle is predicted using a dual-layer LSTM network. Finally, the DBSCAN algorithm is utilized to segment the multiple single-vehicle predicted trajectories, calculate the similarities among them, and cluster them to obtain a representative trajectory for the cluster, as the predicted trajectory for the armored vehicle cluster. Simulated results demonstrate that the proposed method can effectively predict the trajectories of armored vehicle clusters.

    LTV-MPC-based Real-time and Anti-noise Motion Control for High-speed Vehicle
    REN Hongbin, SUN Jiyu, Chih-Keng CHEN, ZHAO Yuzhuang, YANG Lin
    2024, 45(12):  4311-4322.  doi:10.12382/bgxb.2023.0979
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    A two-layer control architecture is proposed for the real-time high-precision motion control of high-speed autonomous vehicles, in which an upper layer consists of a path point filter based on a path point Cost function and a velocity planner based on tire force analysis in both lateral and longitudinal directions, and a lower layer consists of a path tracking controller predicted by a linear time-varying dynamic model and a velocity controller. A least mean square (LMS) adaptive state estimator is introduced to enhance the system’s noise immunity. The path point filter improves the operation speed and reduces the loss of crucial information during selection, and the velocity planner generates the optimal speed curve under the premise of safe driving. The path tracking controller considers the tracking deviation soft constraint to improve the tracking effect. The LMS state estimator estimates the lateral velocity and yaw rate online based on an online-corrected dynamic model. A dSPACE-TX2 hardware-in-the-loop simulation environment is constructed, and the proposed path tracking architecture is compared with traditional motion tracking control under high-speed and double lane change scenarios. The hardware-in-the-loop simulation results demonstrate that the proposed motion controlling architecture improves the noise immunity and the tracking accuracy of 21% while meeting the 50Hz high-frequency control requirement.

    Rock Blasting Crack Propagation and Dynamic Response of Adjacent Roadway Structure under Active Confining Pressure
    MAO Xiang, HE Chenglong, CHEN Dayong, YANG Kexu, HUO Ziyi
    2024, 45(12):  4323-4338.  doi:10.12382/bgxb.2023.1089
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    In order to study the failure process of rock blasting and adjacent roadway under confining pressure, the rock rectangular plate specimen with blast hole and roadway structure is tested, and the dynamic damage process of rock is obtained by using dynamic testing technology and high-speed camera method. A rock model containing roadway and single blasting hole is established based on Holmquist-Johnson-Cook (HJC) constitutive model. The simulated results without confining pressure are compared with the test results, and the feasibility of the numerical simulation method is verified. The stress initialization method is introduced into a finite element simulation platform to simulate the rock failure process under confining pressure, and the influences of different confining pressure environments on the rock blasting crack growth and the influence of partial confining pressure coefficient (k) on the failure process of roadway structure are analyzed. The results show that, under the condition of bidirectional constant confining pressure, the inhibition effect on crack is more significant and the protection effect on roadway is better with the increase in confining pressure level. Under the condition of unidirectional confining pressure, the roadway is damaged more seriously with the increase in horizontal confining pressure, and the roadway is less prone to failure with the increase in vertical confining pressure. Under the condition of partial confining pressure, the confining pressure has obvious guiding effect on the propagation of explosive crack, and the crack will expand in the direction of the principal stress. With the increase in confining pressure, the conductivity of crack is more significant. For partial confining pressure coefficient k<1, the cracks mainly spread in the vertical direction, and the roadway does not fail. For k>1, the greater the damage degree of the left spandrel of blasting face of roadway is with the increase in k, the worse the stability of the roadway is.

    Research on Constitutive Model of Low-temperature Concrete Subjected to Impact Load
    NING Jianguo, LI Yuhui, YANG Shuai, XU Xiangzhao
    2024, 45(12):  4339-4349.  doi:10.12382/bgxb.2023.1090
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    The mechanical properties of concrete in a cold environment are different from those in normal temperature state. The impact loading test of concrete is made to study the dynamic mechanical properties of concrete under low temperature environment. In consideration of the influence of temperature and strain rate, the impact damage law of low-temperature concrete is analyzed by introducing the temperature effect based on damage theory of thermal activation energy. The moduli of all components of low-temperature concrete are associated with each other to obtain the equivalent modulus of concrete by using the principle of mixing law, the spherical model of two-phase material and the strain rate effect. Damage evolution function is introduced into Drucker-Prager yield criterion, which is established with temperature and strain rate as parameters, and a dynamic constitutive model of low temperature service concrete is proposed. The results show that the size of concrete fragments increases significantly and the damage situation decreases with the decrease in service temperature, which shows that the free water condenses into ice in concrete pore cracks at low temperature, and ice has a certain bonding effect on pore cracks. With the decrease in temperature, this bonding effect is strengthened, thus inhibiting the development of damage during impact loading. With the decrease in service temperature, the content and modulus of ice in pores increase, and the strength of concrete is significantly enhanced.

    Detection Method for Field-of-view Defect of Ultraviolet Image Intensifier Based on Improved SSD Algorithm
    DING Xiwen, CHENG Hongchang, YUAN Yuan, SU Yue
    2024, 45(12):  4350-4363.  doi:10.12382/bgxb.2023.1091
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    The field-of-view defect of UV image intensifier is acknowledged as a crucial element impacting the imaging performance of such device. The data enhancement procedures are used to address the issues of few field-of-view defect samples and the significant variances of images in field-of-view. A feature pyramid network (FPN) is added to the single shot multibox detector (SSD) algorithm for the successful detection and fusion of multiscale features. A convolutional block attention module (CBAM) is also introduced to improve the network’s focus on small defect targets and minimize noise interference. The experimental results show that, on the self-constructed dataset, the feature pyramid network-convolutional block attention module-single shot multibox detector (FPN-CBAM-SSD) algorithm outperforms the SSD algorithm significantly in the actual detection of field-of-view defects. For 5 categories of defects including bright spots, dark patches, striped defects, bright patches, and dark spots, the average detection accuracy is improved by 19.76%, 22.84%, 29.56%, 34.55%, and 38.14%, respectively. FPN-CBAM-SSD algorithm is capable of meeting the practical application requirements and adapting to more complex field-of-view conditions, making it an effective method for detecting field-of-view defects in ultraviolet image intensifiers.

    Reliability Analysisfor Anti-oil Hammer of Hydraulic Pipe Based on Kriging Model
    ZHA Congyi, SUN Zhili, LIU Qin, DONG Pengfei
    2024, 45(12):  4364-4371.  doi:10.12382/bgxb.2023.1025
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    The oil hammer can easily lead to the adverse effects such as pipeline damage and leakage. The current analysis for the hydraulic pipe is based on its deterministic parameters, whereas the parameters generally exhibit random uncertainties in actual working conditions due to the manufacturing errors, material dispersion, and environmental changes. To address this issue, a reliability model with anti-oil hammer is developed for the pipe in considering the parameter uncertainties. Based on the four-equation model with fluid-structure interaction, the method of characteristics (MOC) is used for the dynamic characteristic analysis on the pipe subjected to oil hammer. Then a limit state function with anti-oil hammer for the pipe is established based on the criterion whether the oil hammer-induced peak pressure exceedes the yield strength or not. As the limit state function is implicit, a reliability analysis method with anti-oil hammer for the hydraulic pipe is established based on an adaptive Kriging model. Subsequently, the failure probability of the hydraulic pipe under oil hammer is calculated. The results indicate that the reliability analysis method based on the adaptive Kriging model can significantly improve the computational efficiency while meeting the accuracy requirements.

    Research on Robot Navigation Method Integrating Safe Convex Space and Deep Reinforcement Learning
    DONG Mingze, WEN Zhuanglei, CHEN Xiai, YANG Jiongkun, ZENG Tao
    2024, 45(12):  4372-4382.  doi:10.12382/bgxb.2023.0982
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    A robot navigation method based on deep reinforcement learning (DRL) is proposed for navigating the a robot in the scenario where the global map is unknown and there are dynamic and static obstacles in the environment. Compared to other DRL-based navigation methods applied in complex dynamic environment, the improvements in the designs of action space, state space, and reward function are introduced into the proposed method. Additionally, the proposed method separates the control process from neural network, thus facilitating the simulation research to be effectively implemented in practice. Specifically, the action space is defined by intersecting the safe convex space, calculated from 2D Lidar data, with the kinematic limits of robot. This intersection narrows down the feasible trajectory search space while meeting both short-term dynamic obstacle avoidance and long-term global navigation needs. Reference points are sampled from this action space to form a reference trajectory that the robot follows using a model predictive control (MPC) algorithm. The method also incorporates additional elements such as safe convex space and reference points in the design of state space and reward function. Ablation studies demonstrate the superior navigation success rate, reduced time consumption, and robust generalization capabilities of the proposed method in various static and dynamic environments.

    Numerical Analysis of Muzzle Flow Field Characteristics of Underwater Gun Using Gas Curtain Launch
    BAI Wenbin, YU Yonggang, ZHANG Xinwei
    2024, 45(12):  4383-4394.  doi:10.12382/bgxb.2023.1041
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    A two-dimensional unsteady numerical model for the muzzle two-phase flow field is established to study the muzzle flow field characteristics of underwater gun using gas curtain launch. The accuracy of the numerical model is verified, and the initial jet flow field and gunpowder gas jet flow field at the muzzle of 30mm smoothbore gun using gas curtain launch are simulated. The numerically simulated results indicate that the gas curtain in front of the projectile expands out of the muzzle to form an initial jet under the propulsion of projectile, and two oblique incident shock waves generated by initial jet near the muzzle normally reflect at the central axis. As the ambient pressure within the gas curtain decays, two incident shock waves undergo Mach reflection at the central axis, resulting in the formation of a bottle-shaped shock wave structure then. The displacement of Mach disk of initial jet remains relatively constant, but it’s diameter linearly increases over time. Once the tail of projectile exits the muzzle, the gunpowder gas rapidly expands towards the front of projectile side, engulfing the Mach disk of initial jet. The incident shock waves of gunpowder gas jet undergo Mach reflection on the bottom wall of projectile at 210μs, followed by Mach reflection occurring twice near the central axis, leading to the formation of a bottle-shaped shock wave structure with double three-wave points. The displacement of Mach disk in the gunpowder gas jet demonstrates an exponential attenuation pattern over time, while the diameter exhibits a trend of “growth-sudden increase-stability”.

    A Trajectory Planning Method Based on DQN Variable Dynamic Intelligent Decision
    MEI Zewei, LI Tianren, ZHU Jialin, SHAO Xingling, DING Tianyun, LIU Jun
    2024, 45(12):  4395-4406.  doi:10.12382/bgxb.2023.1009
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    The aerospace craft faces difficulty in maintaining emergency lateral maneuver to avoid obstacle due to aerodynamic deficiency. Therefore, a trajectory planning method based on DQN variable dynamic intelligent decision is proposed. According to the kinematics equations for variable dynamic aerospace craft, the longitudinal guidance law based on range error and the lateral guidance law based on line-of-sight angle deviation are designed to respectively correct the heeling angle amplitude and symbol in real time, which ensures the terminal guidance accuracy and safety. In consideration of variable dynamic intelligent decision, the dynamic gear switching problem of aerospace craft is transformed into a Markov decision process. Then, the angle of attack, Mach, and relative distance from the aerospace craft to obstacle are taken as the state space, and the power gear position of aerospace craft is used as the action space. A reward function, considering the lowest collision probability and the smallest terminal error, is designed. and a DQN network is constructed to train the agent to obtain the best power gear. The simulated results show that the proposed algorithm can enable the aerospace craft to improve the lateral maneuverability during moving under the terminal constraints.

    Mechanical Properties and Damage Performance of Zr-based BMG-W Energetic Fragments
    HU Aobo, ZHAO Chaoyue, CHEN Jin, CHEN Peng, LI Peng, SUN Xingyun, CAI Shuizhou
    2024, 45(12):  4407-4422.  doi:10.12382/bgxb.2023.0989
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    To reveal the synergistic enhancement mechanism of strength and plasticity of Zr-based BMG-W energetic fragments and elucidate their impact damage process, a series of Zr-based BMG-W energetic fragments with different spherical W particle contents are prepared by the spark plasma sintering method. The mechanical properties and damage performance of Zr-based BMG-W energetic fragments are thoroughly studied through quasi-static compression experiments and ballistic gun loading penetration experiments on double-layer targets. The research results show that the addition of W particles significantly improves the mechanical properties of Zr-based BMG-W energetic fragments. The Zr-based BMG-W energetic fragments with sintering temperature ranging from 370℃ to 385℃ and W particle content ranging from 20 vol.% to 40 vol.% have better strength and plasticity than pure BMG energetic fragments. Among them, the Zr-based BMG-40W energetic fragment prepared at 380℃ has the highest fracture strength and plastic strain, which are 2047.0MPa and 16.6%, respectively. The synergistic enhancement mechanism of strength and plasticity of Zr-based BMG-W energetic fragments includes two aspects: W particles hinder the rapid expansion of shear bands, promote their turning and proliferation, and delay the fracture failure of energetic fragment; the initiation and propagation of shear bands caused by modulus mismatch result in the formation of local plastic deformation zones in the BMG matrix near the W particles, reducing the spatial constraint of BMG matrix on the W particles. The W particles themselves undergo plastic deformation, delaying the fracture failure of energetic fragments. With the increase in W particle content, the damage performance of the Zr-based BMG-W energetic fragments increases first and then decreases, but all are better than pure BMG energetic fragments. Among them, the Zr-based BMG-40W energetic fragment has the strongest damage performance with an expansion ratio of 27.9. The impact damage process of Zr-based BMG-W energetic fragments mainly includes primary detonation, kinetic energy perforation, secondary detonation, and aftereffect damage.

    Collaborative Regional Information Collection Strategy Based on MLAT-DRL Algorithm
    LOU Shuhan, WANG Chongchong, GONG Wei, DENG Liyuan, LI Li
    2024, 45(12):  4423-4434.  doi:10.12382/bgxb.2023.1081
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    Aiming at the difficulties faced by UAV swarm collaborative regional information collection in adversarial environment (e.g., complex environment structure and blocked swarm communication), a multi-level hybrid observation space with attention-deep reinforcement learning (MLAT-DRL) is proposed for decision making of UAV in information collection task. The proposed algorithm adopts a centralized training with decentralized execution paradigm, which realizes the efficient collaboration of UAV swarm in the absence of communications. In addition, a multi-level hybrid observation space method is proposed to develop the multi-scale representations of environmental features and realize the efficient use of global information and local observation. Moreover, the algorithm introduces a recurrent neural network incorporating an attention mechanism in the network, which improves the risk perception ability of UAV swarm. A prioritized experience replay strategy is employed to improve the utilization rate of samples and reduces the difficulty of training. It is verified from simulations that the proposed MLAT-DRL algorithm outperforms baseline algorithms in terms of data collection and risk aversion.

    Autonomous Attack Decision-making of Missile Swarm on Ground Targets Based on Visual Damage Assessment without Communication
    XU Yibo, YAN Jiarun, ZENG Zhiwen, LÜ Yunxiao, FENG Shiru, LU Huimin
    2024, 45(12):  4435-4450.  doi:10.12382/bgxb.2023.1078
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    For the mission scenario of using a cluster of patrol missiles to fight against the ground high-defense mobile targets, an attack decision-making process method based on the height division of patrol missiles with different operational functions is proposed. By deploying the YOLO X and VGG-16 integrated online target recognition and damage assessment network (YOLO-VGGNet) on any patrol missile, the patrol missile can autonomously strike a target based on visual sensing information only under no communication conditions. At the same time, a method for terminal reassessment and target attack point selection is proposed so that the patrol missile can not only reassess the ground target at the terminal of attack when flying to the target, but also locate the feature parts that have not been struck. The nodes of missile swarm can autonomously decide whether to continuely attack and prioritize the attack on the feature parts of target. Simulated results show that under no communication conditions, the proposed YOLO-VGGNet online damage assessment network can not only destroy the targets in the mission area completely, but also reduce the unnecessary ammunition loss and prioritize the attack on the functional parts of the target, which is expected to improve the overall combat effectiveness of missile swarm.

    Combustion Characteristics of a Solid Fuel Ramjet with Secondary Air Intake in Combustion Chamber
    CHANG Ya, WU Zhiwen, WANG Rui, GAO Kunpeng, ZHANG Zhe, WANG Ningfei
    2024, 45(12):  4451-4461.  doi:10.12382/bgxb.2023.0905
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    In response to the low combustion rate and efficiency caused by diffusion combustion in solid fuel ramjet, a solution involving a solid fuel ramjet withdual-side secondary air intake is proposed to improve combustion performance. A combustion model for the ramjet is established based on Standard k-ε turbulence model and vortex dissipation equations. Simulation calculations are conducted to analyze the internal flow field, burning surface recession rate, and combustion efficiency for both the basic ramjet model (without side air intakes) and the dual-side secondary air intake ramjet model. And the influence of bypass ratio on the performance of dual-side secondary air intake ramjet is investigated. The results indicate that the internal flow field of dual-side secondary air intake ramjet exhibits new flow field characteristics such as secondary recirculation zone and swirling zone, which contribute to enhanced mixing and combustion. Combustion efficiency and specific impulse (Isp) increase first and then decrease with the increase in bypass ratio, reaching their highest values when the bypass ratio achieves 60%. Compared to the basic ramjet model, the combustion efficiency of dual-side secondary air intake ramjet is increased by nearly 40%, and its specific impulse is increased by 12.09% at a bypass ratio of 60%. Overall, the thrust increases with the increase in bypass ratio, with the maximum thrust being observed at a bypass ratio of 60%. However, the thrust increment diminishes gradually as the bypass ratio continues to increase.

    Effect of Vertically-arranged Strut on the Mixing and Initiation Characteristics of Oblique Detonation Engine
    LIU Yidong, QIN Qiongyao, LI Jianzhong, YUAN Mingze, LI Longgang, LI Xiafei
    2024, 45(12):  4462-4474.  doi:10.12382/bgxb.2023.1076
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    The oblique-detonation engine is a new type of air-breathing engine that has great advantages in hypersonic flight above Mach 9. The oblique detonation engine with inner-jet configuration faces the problem of inhomogeneous fuel mixing due to the short mixing distance, and the inhomogeneous fuel distribution affects the stable and reliable detonation of detonation wave. A vertically-arranged strut is proposed for the efficient and low-resistance mixing of fuel. The superiority of vertically-arranged strut in achieving the stable detonation of oblique detonation waves is studied through numerical simulation, and the influence of the injection angle of vertically-arranged strut on the fuel mixing and detonation is analyzed. The results show that the hydrogen mass fraction at the outlet of the mixing section reduces with the increase in the injection angle of vertically-arranged strut, leading to the bending of hydrogen distribution structure. At the same time, the detonation area is tilted, and the detonation distance increases slightly and then gradually decreases. It can be seen that the increase in the injection angle of vertically-arranged strut strengthens the hydrogen doping and reduces the detonation distance, thus achieving stable and reliable detonation of oblique detonation waves.

    Research on Automatic Optimization of Oil Pressure Curve during Shift Process of Integrated Transmission Device in Service
    REN Xiaochen, PENG Jianxin, WANG Cheng, GONG Ran, HU Yuhui
    2024, 45(12):  4475-4487.  doi:10.12382/bgxb.2023.1028
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    Tracked vehicles face complex and harsh driving environments in service. The key performance parameters of hydraulic control system, as an important component of the integrated transmission device, will undergo degradation, leading to a significant deterioration in shifting quality. In order to improve the shifting quality of the integrated transmission device under different service conditions, the degradation mechanism of the hydraulic control system under service conditions is studied. Then, a shifting process model including power source model, planetary transmission unified dynamic model, and load model is established. According to the shift quality evaluation function, the genetic algorithm and global optimization algorithm are used to optimize the oil pressure curve during the shift process of the integrated transmission device. A simulation experimental platform is established for optimizing and testing the shift oil pressure curves of vehicles under different service conditions. The results indicate that the optimization method for shifting oil pressure curve can effectively improve the shifting quality of vehicles under different service conditions.

    Effect of Cutting Edge Angle of PCD Tool with Chip Breaker on Chip Flow
    WANG Jiawei, YU Aibing, LI Yi, YE Jiawang, ZHAO Jiazhen, QI Shaochun
    2024, 45(12):  4488-4499.  doi:10.12382/bgxb.2023.1051
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    A tool angle can be reasonably selected to improve the chip control effect of polycrystalline diamond (PCD) tools with chip breakers. The cutting process is observed by finite element simulation and high-speed photography, and the influence of cutting edge angle on chip flow direction is analyzed. A concept of chip contact rate is put forward to measure the influence of chip breaker on chip flow direction, the types of chip are collected and counted, the relation curve between cutting edge angle and chip contact rate is established, and the reasonable value range of cutting edge angle is determined. The deflection angle parameters of chip breaker are presented, and the relation curve between the deflection angle and the chip contact rate is established. The results show that the increase in the cutting edge angle will weaken the control effect of chip breaker on the chip flow direction. When the cutting edge angle is in the range of 75°- 95°, the chip can flow to the workpiece surface and break to form C-shaped, 6-shaped and compact short spiral chips. and the chip breaking effect under the condition of unreasonable cutting edge angle can be improved by adjusting the chip deflection angle. Selecting the reasonable cutting edge angle and chip breaker deflection angle can improve the chip contact rate of PCD tool with chip breaker, realize the effective chip breaking and improve the excellent chip ratio.

    Preparation and Combustion Performance of a Ti/Fe(NCN) Thermite
    WAN Lixiang, ZHU Lixiang, LI Xiaopeng, LANG Maoyun, CAI Changwu, YIN Yanjun
    2024, 45(12):  4500-4507.  doi:10.12382/bgxb.2024.0006
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    As a type of high-energy, insensitive and safe energetic material, the thermites have been applied in solid propellants, metal welding, new material manufacturing and other fields. In recent years, a type of metal carbodiimide Mx(NCN)y (where M is an alkali metal, alkali earth metal, transition metal or non-metallic element) has gradually become a research hotspot due to its unique electronic structure and novel physicochemical properties. This study utilizes the high nitrogen content and metastable properties of metal carbodiimides, represented by Fe(NCN), to assemble a new type of thermite system with nano Ti-Ti/Fe(NCN). And the composition, structure, morphology, combustion characteristics and reaction process of Ti/Fe(NCN) are explorated. The results show that the combustion process of Ti/Fe(NCN) is outstanding with a heat release of 605J/g and a pressure release of 319kPa, and Fe, TiC0.2N0.8 and gas product N2 are detected in the reaction products when the mass ratio of Ti-Fe(NCN) is 5∶1. The study of new thermite Ti/Fe(NCN) would enrich the research system of energetic materials and provide new ideas for the development of new energetic devices.

    Design of UWB Vivaldi Antenna for Through-wall Radar
    ZHEN Fajian, LIU Yunqing, LI Xingguang, TONG Yongcai
    2024, 45(12):  4508-4516.  doi:10.12382/bgxb.2023.1052
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    In order to meet the needs of ultra-wideband (UWB), high-gain, and miniaturized antenna for through-wall radar, a new ultra-wideband Vivaldi antenna for through-wall radar is proposed. The antenna surface current is optimized and the antenna gain is improved by designing a chute with gradient distribution. An asymmetric elliptical curvature director is loaded to couple the high-frequency energy and improve the high-frequency gain of antenna. The working frequency band of the antenna is 1-3GHz, and its gain reaches 7dBi. The antenna has the directional symmetrical radiation characteristics and good time-domain response characteristics. The antenna size is 160mm×150mm×1.5mm. The through-wall scene is simulated by using the full-wave simulation software to verify the antenna’s through-wall radiation capability and target detection capability behind the wall. The transmission signal and target echo signal indicate that the Vivaldi antenna has the performance of a through-wall radar antenna.

    Mechanical Properties and Model Parameter Calibration of a Novel GAP/RDX/TEGDN Propellant at Wide Range of Strain Rate
    DONG Liying, TAN Xianglong, WU Yanqing, YANG Kun
    2024, 45(12):  4517-4529.  doi:10.12382/bgxb.2023.1001
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    The accuracy of mechanical model parameters of high-energy and low-vulnerability solid propellant is of great significance to the prediction of its macroscopic mechanical response. In order to decouple the parameters of the viscoelastoplastic damage model of solid propellant, a model parameter calibration method based on experiment is proposed. The viscoelastoplastic damage parameters of GAP/RDX/TEGDN (GRT) solid propellant are calibrated by the quasi-static and dynamic tests using a universal testing machine and a split Hopkinson pressure bar device. The mechanical properties and damage mechanism of GRT at a wide range of strain rate are analyzed. The experimental results show that the mechanical behavior of GRT propellants is obviously strain rate-dependent, and the tensile strength and elongation are increased by 75% and 43.33%, respectively, with the increase in the tensile rate (1-1000mm/min). With the increase in quasi-static compressive strain rate (0.001-1s-1), the yield strength is increased by 16.67%. With the increase in dynamic compressive strain rate (2100-4100s-1), the yield strength is increased by 72.98%. The fracture strain of the material is related to the stress state. The fracture strain is decreased by 36.36% with the increase in stress triaxial degree (η=0.33 to η=0.74). In addition, according to the microscopic characterization of GRT propellants, the main failure mechanism is interface debonding under quasi-static stretching, and the main failure mechanism is particle breakage under quasi-static and dynamic compressions. On this basis, the parameters of Plastic-Kinematic constitutive model are calibrated by quasi-static and dynamic compression tests, the parameters of Prony series are calibrated by stress relaxation test, and the parameters of fracture damage model are calibrated by notch test and quasi-static tensile test. Therefore, the model parameters could be calibrated more accurately by the proposed method. It provides support for the prediction and analysis of macroscopic mechanical properties of propellants.

    Reliability-based Optimization of Selective Laser Melting Process Parameters for Co-Cr Alloy
    ZHOU Jinyu, WANG Xinyuan, CHENG Jinxiang, WANG Lin
    2024, 45(12):  4530-4538.  doi:10.12382/bgxb.2023.0923
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    Selective laser melting (SLM) is one of the most common additive manufacturing technologies at present. The process parameters, material properties and atmosphere stability have important impacts on the forming quality. A multi-factor and multi-level experiment is designed by taking the nominal value of laser power, scanning speed and scanning pitch as design variables, and the laser power, local distribution mean value of Co-Cr alloy powder diameters, and wind speed fluctuation strength as random parameters. Based on the principle of rank correlation, the probabilistic augmentation of incomplete data is achieved to obtain the response surface among design variables, random parameters and properties of samples. The reliability-based design optimization (RBDO) model for SLM process parameters of Co-Cr alloy is established with the optimization goal of maximizing forming efficiency under the probability constraint of meeting the allowable tensile strength. Aiming at non-normal random parameters and non-linear performance function in the Co-Cr alloy SLM process, the universal generation function is introduced, discrete enumeration and random sampling are integrated, and an innovative RBDO algorithm based on adaptive subdivision-importance sampling strategy is proposed to obtain the optimal solution of SLM process parameters for achieving the highest forming efficiency under reliability constraints.

    Numerical Simulation on Cavity Evolution and Flow Field Characteristics of Cylinder Obliquely Entering Water under Ice Hole Constraint
    YANG Zhe, LU Lin, LI Qiang, SUN Zhiqun, HOU Yu
    2024, 45(12):  4539-4553.  doi:10.12382/bgxb.2023.0969
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    In order to study the influence of ice hole constraint on the inclined water entry process of a cylinder, a numerical method for a cylinder entering water entry under ice hole constraint is established based on a volume-of-fluid multiphase flow model. The accuracy of the numerical method is verified by experimental tests. On this basis, the process of the cylinder entering water under the condition of different ice hole diameters is simulation, and the cavitaty evolution and motion characteristics of the cylinder entering water under the constraint of ice hole are analyzed. The results show that the ice hole constraint changes the flow of free liquid surface, thus affecting the direction and shape of surface splash. In addition, because the liquid hits the wall of ice hole, it consumes part of the energy of cavity for expansion, which leads to the obstruction of cavity expansion. A reflected flow is formed after impact, and the reflected flow is opposite to the expansion direction of cavity, which further hinders the cavity expansion and causes the cavity wall of the water-away side to be curved. The cavity wall is in direct contact with the ice hole under the condition of small ice hole diameter, which makes the cavity deform locally and hinders its expansion. Under the condition of larger ice hole diameter, the cavity wall does not contact with the ice hole, and the reflected flow becomes the main reason for inhibiting the cavity shape. In addition, under the constraint of ice holes, a wider shear deformation area appears on the free liquid surface, and there are more large-scale vortices in the cavity. The vortices lead to the increase of pressure gradient in the cavity to make the cavity subject to pressure in different directions, thus inhibiting the cavity shape at the free liquid surface. Ice hole constraint causes the increase in the peak value of water-entry load of cylinder, and the faster velocity decay of cylinder.

    An Equivalent Simulation Test System for Complex Terminal Ballistics of Fuze Based on Counter Target Method
    LOU Wenzhong, HE Bo, YUAN Yong, LI Zhipeng, SHAN Liang, FENG Hengzhen, ZHANG Mingrong, ZHU Haokun
    2024, 45(12):  4554-4564.  doi:10.12382/bgxb.2023.0985
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    In response to the increasing demand for high initiation reliability of fuze under complex terminal ballistic in mobile warfare, an equivalent simulation test system for complex terminal ballistic of fuze based on the counter target method is studied to address the issues of limited incident angle, non-real-time acquisition of initiation signals, and high testing cycle/cost in current forward shooting tests. The similarities of axial impact characteristics of key modules in 30 mm small caliber projectile fuze are compared through finite element simulation. A theoretical model of the impact characteristics of a cylindrical target plate reverse impact fuze is established based on elastic-plastic mechanics. The theoretical model is numerically solved using a micro surface force method and verified through comparison of simulated results. An equivalent simulation test system model is built based on a 20mm light gas gun, and the response characteristics of two trigger switches are collected in real-time and studied. The experimental results show that the response time of a trigger switch for small caliber projectile fuze when forwardly impacting on a 2mm aluminum alloy target plate is approximately 58.2μs. The feasibility of the equivalent simulation test system based on the counter target method is verified by comparing the calculated results of the forward shooting test fuze hitting a 2mm aluminum alloy target plate and causing a “surface explosion”.

    Performance Optimization and Serrated Design of Trailing Edge on Compressor Blade under the Effect of Rotor-stator Interaction
    YANG Wenjun, SUI Dongdong, WANG Xupeng, PAN Wujiu, WANG Lei
    2024, 45(12):  4565-4577.  doi:10.12382/bgxb.2023.0981
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    Complex excitation of compressor blade wakes is induced by the effect of rotor-stator interaction. The trailing-edge serrations are used as an effective means for controlling the excitation of blade wakes. Considering the interaction of rotor-stator blades, the serrations at stator trailing edge are designed to improve the wake turbulence of blades and the performance of compressor. Additionally, the experimental design of Latin square is applied to optimize the profile of rotor blades. This method is used to control the wake disturbance of compressor blades and optimize their performance under the effect of rotor-stator interaction. The results indicate that the wake patterns of stator blades are effectively improved by the distribution of non-homogeneous serrations, the mixing effects between blade mainstream and wake regions are enhanced, and the velocity loss at blade trailing edge is reduced. Consequently, the efficiency of transonic compressor is improved by 2.70%, and the stable operating range is increased by 12.31%. The efficiency of compressor is increased to 91.42% by optimizing the profile of rotor blade, and its performance margin is further expanded. This research not only has an important theoretical significance for the wake control, but also has a great engineering significance in the design of high-performance blade-disk system.

    Power Coordinated Predictive Control of Hybrid Amphibious Vehicle with Model Mismatch
    WANG Xu, GAO Xiaoyu, HUANG Ying, CUI Tao, LUO Chengliang
    2024, 45(12):  4578-4588.  doi:10.12382/bgxb.2023.0919
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    To achieve the optimal comprehensive efficiency of hybrid amphibious vehicle, a power coordinated predictive control strategy is proposed. This strategy deals with the coupling relationship between energy management strategy and longitudinal control strategy through collaborative optimization. Aiming at the mismatch of prediction model, an extreme learning machine (ELM) is used for real-time error prediction, and the prediction model is corrected through the predicted value. A model predictive controller (MPC) is designed for the real-time optimal control of energy management and longitudinal control, and it is verified by simulation. The results show that, compared with the traditional energy management strategy based on MPC, the proposed strategy can be used to reduce the equivalent fuel consumption, state-of-charge (SOC) standard deviation, bus voltage standard deviation and battery capacity fading by 9.35%, 59.63%, 15.79% and 45.33%, respectively. By comparing the power coordinated predictive control with and without model correction, it shows that the equivalent fuel consumption, SOC standard deviation, bus voltage standard deviation and battery capacity fading can be reduced by 6.95%, 25.91%, 13.46% and 24.07%, respectively, through model correction, which reflects the superiority of the power coordinated predictive control based on ELM model correction in improving the fuel economy, maintaining the stability of electrical system and reducing the battery consumption.

    Interference Suppression Approach for FMCW Radar Based on Complex Iterative Filtering
    CHEN Qile, YANG Jin, QAO Caixia, ZHANG Ruiheng
    2024, 45(12):  4589-4596.  doi:10.12382/bgxb.2023.0996
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    An interference suppression approach based on complex iterative filtering (CIF) is designed to address the issue of frequency modulation continuous wave (FMCW) radar being susceptible to FM interference which has the same bandwidth with the radar. Based on the fact that the beat signal of target echo is a superposition of multiple single tone signal but the beat signal of interference is an FM signal covering the bandwidth of radar receiver, the CIF algorithm proposed in this paper is used to decompose the beat signal of radar into the intrinsic mode functions (IMFs) domain, and the energy distribution position of interference signal is obtained by the constant false alarm detection of each IMF. Furthermore, a method for eliminating the interference energy and reconstructing the amplitude and phase of target echo is designed. The proposed interference suppression approach is verified by the simulation and measured data. The results show that the proposed approach has a suppression effect of the signals with co-frequency and noncoherent frequency modulation at signal-to-interference-plus-noise-ratio of less than 20dB.

    Simulation on Transmission Characteristics of Laser in Chaff Cloud Environment
    TAN Yuran, ZHA Bingting, ZHENG Zhen, ZHANG He, HE Rui
    2024, 45(12):  4597-4611.  doi:10.12382/bgxb.2023.1002
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    The laser fuzes are easily affected by chaff clouds, but the interference characteristics of chaff clouds on laser have not been sufficiently studied, Therefore,a laser transmission characteristic model in the chaff cloud environment is established. The diffusion models of chaff clouds under no wind/wind conditions are developed, and the diffusion models of chaff clouds at stability stage under different environments are obtained. The similarity of the interference effects of main disturbing clouds of chaff cloud in the absence/possession of wind is determined based on the laser transmission characteristic models. The scattering characteristics of single chaff under different morphologies are studied based on Fresnel principle. The chaff cloud is segmented, and a propagation model of laser in chaff cloud environment is established by using the continuous field Monte Carlo radiation transfer model. In this propagation model, a laser echo model with or without target in the chaff cloud environment with different central concentrations can be obtained. The laser echo model is verified by comparing the simulated data with the measured data. It is concluded that the chaff cloud interference echo has the characteristics of narrow pulse width and high peak value, and the continuous frequency of chaff cloud interference echo is positively correlated with the concentration of chaff cloud. The laser echo model can provide support for research on anti-chaff cloud interference of laser fuze.

    Power Generation Characteristics of DSMR-PMG
    CHEN Yang, LIU Xin
    2024, 45(12):  4612-4622.  doi:10.12382/bgxb.2023.0902
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    Aiming at the problem of inconvenient charging for military outdoor activities, a double-stator disc motion rectifier permanent magnet generator (DSMR-PMG)that can be carried in military backpacks is proposed, which is small in axial size and easy to carry, and can realize the collection of human movement energy. A multi-ring equivalent analytical model is established based on the structural characteristics and working principle of the generator, The no-load air-gap magnetic density, back electromotive force (EMF), load output voltage and output power of the generator are analytically calculated by integral method, and the calculated results are compared with the simulated results. Through the analysis of the output powers and efficiencies of the generators with different structural parameters and feed speeds, it is concluded that the output power of the generator is not obviously affected by the polar arc coefficient, is less affected by the thickness of permanent magnet and the length of air gap, and is greatly affected by the number of teeth of disc outer rotor and the gear transmission coefficient. The output power and efficiency of the generator can be effectively improved by increasing the modulus, feed speed and effective armature length.