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2022, 42(6)

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2022, 42(6): 1-2.

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Anti-Explosion Analysis of Honeycomb Sandwich Panels with Three Kinds of Core Structures

ZHANG Hao, CHANG Baixue, ZHAO Kai, ZHENG Zhijun, YU Jilin

2022, 42(6): 557-566. doi:10.15918/j.tbit1001-0645.2021.225

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The anti-explosion performance of three kinds of honeycomb sandwich panels was simulated and analyzed using finite element method ABAQUS/Explicit to further understand their deformation mechanism under strong explosion load. The out-of-plane compression performances of three kinds of core layer structures, namely circular hole honeycomb, hexagonal honeycomb and hexagonal array circular tubes, were compared. The deformation process of sandwich panels under explosion load was analyzed. The results show that for the three core layers with the same relative density, the hexagonal array circular tubes are the easiest to crush and have the lowest plateau stress under quasi-static compression, and the honeycomb with circular hole has the highest plateau stress. Under the explosion load, the sandwich panel with hexagonal array circular tubes has the smallest deflection of back plate with the same structural parameters, and its anti-explosion performance is the best. The influence of parameters on the anti-explosion performance of circular tube sandwich panel was analyzed. Combined with the mechanism of load transfer and compression deformation of the core, the anti-explosion mechanism of the sandwich panel was clarified, and it is pointed out that the total energy absorption cannot directly reflect the anti-explosion performance of sandwich panels.

Dynamic Behavior of Aluminum Alloys Under High-Speed Impact of Laser Induced Micro-Particle Impact Tests

ZHANG Wei, WU Xianqian, ZHANG Ruijie, HUANG Chenguang

2022, 42(6): 567-577. doi:10.15918/j.tbit1001-0645.2021.227

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Dynamic behavior of aluminum alloy under high-speed micro-particle impact is of great importance for the structural safety design under extreme environments. The dynamic response of 2024 aluminum alloy was investigated through laser induced micro-particle impact tests and simulations. First, laser-induced particle impact tests were conducted to obtain kinetic energy dissipation of the micro-particles and the local deformation behavior of the aluminum alloy plate at room temperature, and the finite element model was validated by the experimental results. Then, phase field modeling was employed to obtain the microstructure characteristics of the solid-liquid coexisting aluminum alloy at a temperature near the melting point, from which the fluid-solid coupling simulation model was established. With this method, the characteristics of impact energy dissipation, stress distribution, deformation and failure behavior of the solid-liquid coexisting aluminum alloy were analyzed. The simulation results show that the fluid-solid interaction under dynamic loadings plays an important role in the mechanical response of the solid-liquid coexisting aluminum alloy. The energy absorption efficiency decreases at such a high temperature, and the dynamic stress transmission varies significantly due to the interaction between solid dendritic crystals.

Structural Topology Optimization Design and Dynamic Response Analysis Under Impact Loading

SHI Fengyuan, LI Shiqiang, LIU Zhifang

2022, 42(6): 578-587. doi:10.15918/j.tbit1001-0645.2021.233

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A structural topology optimization method was established to solve the problems of complicated calculation process, low calculation efficiency, and convergence difficulty of structural topology optimization under dynamic impact loading. Bi-directional evolutionary structural optimization and the equivalent static loads method structural optimization were combined, and the weight method and the material interpolation model were introduced. The topology optimization of single and double phase composite materials and structures were realized by an optimization algorithm with nested loop structure for impact loading. According to two examples, the feasibility and efficiency of the method were verified, and the dynamic response of the optimized structure was analyzed. The analysis results show that the structure optimized by the improved method could better adapt to impact loading. This method is more suitable for topology optimization design under impact load. The optimization process is simple with a higher calculation efficiency, and the optimization is stable and efficient.

Study on Dynamic Behavior of Coral-Reef Limestone Under Impact Loading with Confining Pressure

SANG Dengfeng, LIAO Qiang, LIN Yuxuan, TANG Liqun, LIU Yiping

2022, 42(6): 588-595. doi:10.15918/j.tbit1001-0645.2021.295

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The deep piling project of coral rock puts forward a new scientific demand for understanding dynamic mechanical properties of coral rocks under confining pressure. Impact tests on coral rocks were carried out through split Hopkinson pressure bar (SHPB) with confining pressure, and mechanical responses of coral rocks under different confining pressures were obtained. Studies show that: in the absence of confining pressure, the dynamic compressive strength of coral rocks is the same as that of conventional rocks, and has obvious strain rate sensitivity; as confining pressure increases, not only the dynamic compressive strength of coral rocks increases significantly, but also its strain rate sensitivity is stronger. The failure strength formula was proposed with confining pressure and strain rate effects. The proposed failure strength formula in this paper has important reference value for deep overburdened coral rock geological pile foundation engineering.

Static and Dynamic Mechanical Properties of 675 Armor Steel and Determination of J-C Model Parameters

MA Minghui, YU Yilei, JIANG Zhaoxiu, WANG Xiaodong, WANG Jiangbo, GAO Guangfa

2022, 42(6): 596-603. doi:10.15918/j.tbit1001-0645.2021.149

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In order to study the dynamic response of 675 high strength armor steel after impact by projectile, it is necessary to determine a set of material model of 675 armor steel suiTab. for penetration simulation calculation. Therefore, the dynamic and static mechanical properties test and material fracture test of 675 armor steel were carried out, and the Johnson-cook constitutive model and failure model parameters of 675 armor steel were fitted according to the experimental results. At the same time, the penetration simulation model was established according to the ballistic test, and the numerical results were compared with the test results. The results show that: when the Johnson-cook constitutive model and failure model of 675 armor steel obtained from material performance experiment are applied to the numerical simulation, the average error between the simulation results and ballistic test results is 6.5%, and the maximum error is less than 10%. The parameters of Johnson-cook constitutive model and failure model are reliable, it is of great significance to the simulation of 675 armor steel under impact load.

Crashworthiness of Protected Battery Pack

HU Lingling, CHEN Shengru, ZHANG Ziwen, ZHOU Mingzhe, ZHAO Xin

2022, 42(6): 604-611. doi:10.15918/j.tbit1001-0645.2021.270

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A new protection method was proposed to improve the crashworthiness of cylindrical battery packs. The crashworthiness of unprotected battery pack, resin protecting battery pack and metal foam protecting battery pack were studied by experiments and numerical simulations. The results show that resin protecting battery pack has higher safety under impact. This is because resin can improve the stiffness of battery pack and can make the batteries’ deformation more uniform with reasonable force conditions, thus reduce the risk of damage. Furthermore, numerical simulations were conducted to study the crashworthiness of the battery pack filled with metal foams. Simulation results show that, synthetically considering the energy absorption ability of the material and its effect on energy distribution of battery pack, the battery pack filled with metal foams with moderate hardness can present a best safety.

Effect of UHMWPE Back Plate Layering Angle on the Anti-Elasticity of Ceramic Composite Target Plate

YU Yilei, WANG Xiaodong, REN Wenke, MA Minghui, JIANG Zhaoxiu, GAO Guangfa

2022, 42(6): 612-619. doi:10.15918/j.tbit1001-0645.2021.209

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To study the influence of backplane strength on the anti-elastic properties of ceramic/fiber composite armor, a ballistic impact test of ceramic/fiber composite armor with different UHMWPE back plate angles was carried out by using 12.7 mm perforating projectiles (rigid brittle). The energy dissipation mechanism and anti-elastic energy of ceramic/fiber composite armor were analyzed by observing the macroscopic failure characteristics of the recovered projectile core, target ceramics and fiber backplane. The test results show that conical fracture is the main failure mode of ceramic panel, and the macroscopic cracks mainly include radial, annular and conical cracks. The deformation mode of the backplane is dynamic conical bulge and boundary fold, and its failure modes include shear failure and interlaminar stripping. The strength of the backplane has a great influence on the anti-elastic energy of ceramic/fiber composite target plate. With the stacking angle of UHMWPE back plate decreased, the strength of the backplane and the overall structural stiffness of ceramic/fiber target plate increase. The crushing effect of the target plate on the core becomes more obvious, and the mass of the maximum fragments in the residual core decreases after impact, while the number of small fragment increases. Penetrating the target plate, the residual penetration ability of the projectile fragments decreases, the anti-elastic energy of the target plate increases, the height of the backplane bulge decreases, and the angle formed by the conical bulge increases. The failure mode of fiber laminates changes from shear failure to interlaminar stripping.

Investigation on Bullet Proof Mechanism of YAG Transparent Ceramic Composite Targets

DENG Jiajie, ZHANG Jian, ZHANG Xianfeng, BAO Kuo

2022, 42(6): 620-628. doi:10.15918/j.tbit1001-0645.2021.230

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Transparent ceramic is a new kind of transparent material with excellent optical performance and mechanical properties for the potential application of transparent armor arranged with low areal density, high transmittance and better protection capability. In order to explore the bullet proof mechanism of YAG transparent ceramic composite target, an experiment of ceramic composite target subjected by 12.7 mm armor-piercing incendiary was conducted. Based on the ballistic testing technique and high-speed camera technology, the damage characteristics of each layer of transparent ceramic composite target and the damage form of projectile body were determined. The change of the back convex of the backplane was measured by the data in high-speed photography. On this basis, a finite element simulation method of YAG transparent ceramic composite target resistance process was established based on the AUTODYN finite element simulation software platform. The bullet proof mechanism of transparent ceramic composite target with typical structure was studied based on finite element simulation. The effect of thickness change of transparent ceramics and polycarbonate on its ballistic performance was analyzed. The results show that the transparent ceramic armor can effectively consume the impact energy of the projectile body by the high strength crushing of the transparent ceramic panel. The layer of glass consumes the impact energy of the ceramic cone, and the backplane absorbs the residual kinetic energy, so as to realize the transparent armor protection with low areal density. The increase of transparent ceramic panel destroys the projectile body more effectively so as to improve the ability of armor protection. Polycarbonate can effectively protect low areal density of composite target in a certain thickness range.

Influences of Impactor Parameters on the Impact Damage Response of Composite Laminate

LIANG Jiarui, HUANG Jinhong, HANG Yu, ZHANG Xinyue, HOU Bing, LI Yulong

2022, 42(6): 629-633. doi:10.15918/j.tbit1001-0645.2021.231

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The low-energy impact damage responses of a composite laminate prepared by prepreg forming process were studied under the impacts with various impactors. Firstly, the impactors made of steel, aluminum and polymer were applied to impact the laminates at the same energy (60 J) by using drop weight/air gun facilities. Then, the damaged structures after impact were compressed to obtain the residual strength/residual stiffness of composites under low-energy impact. From these experimental results, one can see that with the same impact energy, the damage responses of composite laminate impacted by the same material (with different mass and velocity) are almost the same, however, the results of impactors with different materials are significantly different. The Hertzian contact theory is employed to illustrate the influence of elastic parameters of impactors on the contact stiffness as well as the damage responses of composite laminate.

Attitude Control Algorithm for High Spin Projectile Based on Variable Universe Fuzzy Control

SHEN Qiang, WAN Chupeng, GAO Xiao, WANG Hanyu

2022, 42(6): 634-640. doi:10.15918/j.tbit1001-0645.2021.118

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Aiming at the problems of model uncertainty, nonlinearity and strong coupling in the attitude control system of high-speed rotating projectile, a parameter adaptive attitude control algorithm based on variable universe fuzzy control was proposed. On the basis of establishing the attitude control model and decoupling the projectile pitch and yaw channels by pre-feedback compensation method, the parameters of the feedback control system were adjusted online using the variable universe fuzzy controller. The simulation results show that the variable universe fuzzy controller can effectively improve the dynamic response characteristics of the closed-loop feedback control system, reduce the influence of time-varying missile parameters on the controller performance, and improve its adaptability.

Broadband Low-Frequency Sound Isolation and Absorption Mechanism Based on Shunting Circuit Regulation

ZHOU Xiaoming, HU Qinchun, HUANG Yu, LIAO Yunhong

2022, 42(6): 641-648. doi:10.15918/j.tbit1001-0645.2021.124

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Considering the structure of loudspeaker with shunting circuits, a new mechanism was proposed to widen the frequency bandwidth of sound absorption and isolation based on the concept of adaptive modulation. Firstly, a suitable loudspeaker structure for broadband and low-frequency sound insulation was studied. The analysis result shows that, in the two-dimensional space parameterized by sound frequency and inductance in shunting circuits, there a trajectory with high sound transmission loss exists, being of advantage to determine a specific profile of the frequency-inductance relationship. According to the analysis result, a shunting circuit was designed, making the frequency-dependent inductance adaptively trace the high sound transmission loss trajectory. The practical experiment results show that, the sound insulation bandwidth can be significantly expanded in the low frequency region, and the bandwidth can be further broadened by combining the adaptive structures with different operating frequency. And then a suitable loudspeaker structure for sound absorption was also studied. The result shows that, there is a similar high sound absorption trajectory existing in the frequency-inductance parameter space. The absorption bandwidth can be broadened by designing a control circuit to adaptively trace the high sound absorption trajectory. Finally, combining an absorptive loudspeaker with micro-perforated plates, a composite structure was studied. The Simulation results show that, the sound absorption bandwidth can be further broadened due to the action of both adaptive circuits and small holes. The study achievement provide a new mechanism for widening the sound absorption and insulation bandwidth of the loudspeaker structure, and is potentially useful in noise control engineering.

Writing Consistency Evaluation Based on Siamese Neural Network

LIU Jie, ZHANG Wenxuan, LI Yaguang, ZHANG Yichao, ZHOU Jianshe

2022, 42(6): 649-657. doi:10.15918/j.tbit1001-0645.2021.171

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For current chapter graded consistency metric model only considers the full text consistency of the tested composition, and cannot capture the implicit semantic characteristics of the text language block and the consistency between them. In view of the above problems, a composition text consistency evaluation model was proposed for general compositions. Refering to the thoughts of the twin neural network, the model was arranged to extract the character, image characteristics, and storyline characteristics of the core character simultaneously in the composition and to perform similarity metrics, so as to obtain the central idea of the text and the matching score of the text consistency. A subject model Biterm-LDA（Latent Dirichlet Allocation）was used to extract the subject character of composition to avoid the dependence of the artificial labeling. The results show that the proposed model score is consistent with the results of artificial labeling, and is superior to ordinary neural network models.

Microstructure and Mechanical Properties of B₄C-TiB₂-SiC Ceramics Fabricated by Spark Plasma Sintering

ZHAO Pengduo, WANG Qi, ZHANG Lei, LI Mao, SONG Qi, ZHANG Zhaohui, YIN Shipan, JIA Zhaohu

2022, 42(6): 658-664. doi:10.15918/j.tbit1001-0645.2021.139

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A new preparation method of B₄C-based composite ceramics was proposed to improve sintering performance and decrease preparation cost of B₄C ceramics. Taking B₄C, Ti₃SiC₂, and Si mixtures as raw powders, B₄C-TiB₂-SiC composite ceramics with 30 wt. % (TiB₂+SiC) second phase were fabricated based on spark plasma sintering (SPS) method. Taking advantage of special sintering mechanism of SPS and in situ exothermic reaction during the sintering process, the new method was arranged to improve the sintering property and reduce the preparation cost of B₄C ceramics. The results indicate that composite ceramics with high relative density (98.5%) can be obtained at 1650 °C and 50 MPa for 5 min. With the increasing of sintering pressure, hardness of B₄C-TiB₂-SiC composite ceramics gradually increases, fracture toughness decreases, while flexural strength shows a trend of rise slowly at first and then rise rapidly.

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2022 Vol. 42, No. 6

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