bob手机在线登陆学报自然版

2017, 37(s2): .

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2017, 37(s2): .

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Experimental Study on Damage Effects of the Equivalent Targets of Wings Subjected to Blast Loading

XU Zi-xi, CHEN Xin-xiang, LIU Yan, HUANG Feng-lei

2017, 37(s2): 1-4.

Abstract(695) PDF(460)

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The principles of strength and structure equivalence were used in designing the equivalent targets of wings to achieve the assessment of vulnerability. The damage of components can be analogized by the research taken on the targets. The dynamic blast loading taken on targets was conducted by detonating the TNT explosive in different stand-off distances. The dynamic responses and failure modes of two typical materials were revealed. The relation between the peak value of overpressure and the final deformation of targets was obtained after analysis. Moreover, a damage criterion on composite was established.

Dynamic Mechanical Property Study of CFRP Laminate Structure Based on Modified Bridging Model Under Compressive Impact

WU Wen-you, LIU Liu, CHU Yun-lin, PI Ai-guo

2017, 37(s2): 5-9.

Abstract(809) PDF(347)

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To investigate mechanical response of CFRP material under shock loading, a dynamic constitutive equation and yield criterion considering strain rate effects, which are based on bridging model, were used to conduct the design optimization and analyses the dynamic compressive strength of CFRP laminates. The calculated mechanical properties of some laminates under different strain rates are first compared with the experimental results, which are obtained from relevant literatures. The results calculated by improved bridging model and theoretical model are agreed well with the test results. Then, through analyzing some structure design schemes, one structure design scheme is selected and manufactured to conduct medium strain rate compressive tests. The previous theoretical results are consistent with experimental results. This work can be used for the optimization design and predict the property of CFRP laminate structure under shock loading.

Damage Study of Concrete Under Compressive Loading Based on Acoustic Emission Technique

WANG Zong-lian, REN Hui-lan, NING Jian-guo

2017, 37(s2): 10-14.

Abstract(820) PDF(241)

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The fracture process of concrete under compressive loading was represented by the mechanical parameters and acoustic emission (AE) characteristic parameters. The results could characterize the quantities of inner crack propagation and damage for concrete materials. The time-frequency characteristics of AE signals related with crack initiation, crack growth, microvoid collapse, and cracks coalescence were acquired based on the transient analysis using wavelet transform method. The rise time and frequencies of AE signals, which were associated with crack initiation, crack growth, microvoid collapse, and cracks coalescence, systematically increased and decreased, respectively. The experimental results are in a good agreement with the strain energy release theory.

Effect of Liner Material on Motion Characteristics of EFP in Water

WANG Ya-jun, LI Wei-bing, Huang Xuan-ning, LI Wen-bin, WANG Xiao-ming

2017, 37(s2): 15-20.

Abstract(974) PDF(488)

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Aimed at investigating the relation between the liner materials and flight characteristics of explosively formed projectile (EFP) in water, we studied underwater penetration capacities of EFP, which are formed by three groups of materials, namely, different density materials (10 steel, tantalum and aluminum), same density materials (pure iron, 10 steel, 20 steel), and high-density materials (tantalum and tungsten), using ANSYS/LS-DYNA software and on the basis of experimental data of copper material EFP in water. In addition, the effects of liner material on velocity decrease of EFP was presented. The results show that density plays a crucial role on the penetration capacity of EFP in water. Given the shape of EFP, the ability of keeping velocity are improved with increasing density. Correspondingly, the tendency of velocity reduction is similar for EFP with same density. Tantalum, tungsten, and other high-density metal material liners have broad prospects in the application of underwater shaped charge warhead.

Analysis and Assessment on Shock Initiation Criterion for Condensed Explosives

ZHANG Fan, ZHANG Rui, XIE Rui-zhen, FU Dong-xiao

2017, 37(s2): 21-24.

Abstract(687) PDF(363)

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Five shock initiation criterions for condensed explosives were introduced from literatures. The critical energy criterionPⁿτis more suitable topredict shock initiation of explosives undergoing one -dimensional short duration impact. James criterion and its modifications incorporate several variables, such as energy fluence, specific Kinetic energy, power flux, andJ_max-to interpret input shock energy at the microscale level. The series of James criterion could describe dynamic process of shock initiation and have broad prospects in the study of shock initiation threshold of explosives and assessment of the reliability of shock initiation.

Analysis of Border Problems and Precision Realized by Geodetic Problems Algorithm

YANG Hua-dong, QIU Qian-jun

2017, 37(s2): 25-30.

Abstract(783) PDF(297)

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This paper aims at solving the problem of failure of the earth theme algorithm in engineering realization, when the earth line crosses the ±180° longitude line and the equator, and the earth line crosses the ±90° north pole or the south pole. By introducing the discussion mechanism of boundary mutation, an engineering method was developed to solve the Bowring and Vincenty formula boundary problems. The simulation results show that this method solves the problem of calculated failure, when the earth line crosses the ±180° longitude line and the equator, and the earth line crosses the ±90° pole. The proposed method has good adaptability for the sudden change of boundary. On this basis, the calculation precision of the two algorithms for solving the above-mentioned geodesics in different distance ranges was further analyzed. The applicable ranges of two algorithms were pointed out respectively.

Research on Dynamic Response of RC Slab under Blast Impact Loading

ZHANG Qiang, LIU Yan, LI Zhen, LV Zhong-jie, HUANG Feng-lei

2017, 37(s2): 31-35.

Abstract(777) PDF(337)

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In order to study the dynamic response of reinforced concrete slab under blast loading, the method of dimension analysis was employed to obtain the relation between spherical charge's quality, distance between explosive and target plate, and the deflection of reinforced concrete target plate. A three-dimensional numerical model for air-explosive-reinforced concrete slab was developed by using the finite element software AUTODYN. Considering the fluid-solid coupling interaction among explosives, air, and components, the simulated results were consistent with the experimental results. The fixed conditions were changed from two-side to four-side. The distance between target and explosive and the charge weight were respectively controlled to investigate their effects on target deformation. The results showed that the central deflection of reinforced concrete slab increased linearly with the increase of charge quality when the scale distance was larger than 0.6m/kg^1/3(not consider the near-field explosion and contact explosion). However, the central deflection exponentially decreased with the increasing distance between explosive and target if the distance between explosive and target is alterable.

The Effects of The dopant of Lithium Amidoborane on The Initial Decomposition of RDX

WANG Kun, ZHANG Cheng-yu, LIU Qian, YANG Jun, CHENG Long-jiu, ZHANG Jian-guo

2017, 37(s2): 36-41.

Abstract(771) PDF(391)

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It is crucial to improve the detonation performance of high-energy explosives in the field of energy material. The metal amidoborane (MAB) with high content of hydrogen exhibits excellent chemical stability. Thus, the metal cations and hydrogen can be utilized to improve the thermodynamic properties of high energetic compounds if MAB is doped into the explosives. The crystalline RDX (1,3,5-cyclotrimethylenetriamine) was optimized to analysis the electronic characters. The periodic structure of LAB (Lithium Amidoborane)-doped RDX has been predicted by using Monte-Carlo method to understand the relation between LAB and RDX in solid state. On the basis of their electronic structures, possible reactions between LAB and RDX were designed and analyzed using the theoretical method of BP86/6-311+g (d,p) in Gaussian 09. The results indicated that chemical potentials of LAB doped RDX decreased while the enthalpies of continuous decompositions increased.

Mechanical-Thermal Responses of Explosive Charge Filled in Projectile During Penetrating Concrete Target

ZHANG Xin-yu, WU Yan-qing

2017, 37(s2): 42-46.

Abstract(667) PDF(314)

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This paper is devoted to developing a viscoelastic-plastic model with a pressure-hardening strength model and a crushable pressure model for explosive charge filled in projectile when the charge penetrates concrete target. The results show that the plastic strain of the center of the arc of the charge reaches 32% due to the convergence of stress wave. Moreover, the friction between the charge and the inner wall of the body makes a certain contribution to the heating of the charge, which can provide some foundations for projectile and explosive charge structure design.

Influence of Curve on Rotating Detonation Propagation

ZHANG Zhen, GUI Ming-yue, HU Shu-ying, PAN Zhen-hua

2017, 37(s2): 47-50.

Abstract(894) PDF(396)

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Based on the two-dimensional Euler equation with detailed finite-rate chemistry, detonation propagation of hydrogen/air mixture in an annular tube was studied numerically. Fifth-order weighted essentially non-oscillatory (WENO) scheme and third-order TVD Runge-Kutta were used to discretize the spatial derivatives and the time term, respectively. Moreover, parallel technology was also adopted. The numerical results show that outer wall is convergent, which makes cell sizes smaller around outer wall and more uniform due to its compression. However, inner wall is divergent, which makes cell sizes larger around outer wall due to its expansion. With variety of curve of inner and outer wall detonation cells around inner wall disappear and reproduce periodically.

Numerical Simulation of the Impact of A320 on Rigid Target and Determination of the Correction Coefficientαin the Modified Riera Model

WEN Li-Jing, ZHANG Chun-Ming, GUO Chao, GAO Yu, DUAN Pu, OU Zhuo-Cheng, DUAN Zhuo-Ping

2017, 37(s2): 51-56.

Abstract(833) PDF(353)

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The impact processes of an Airbus A320 airplane upon a rigid target under different impact velocities and different impact angles are simulated by using the general explicit dynamic analysis program LS-DYNA. Through comparing the numerical simulation results of the impact loads with the calculated results of the modified Riera impact load equation, the correction coefficientαin the modified Riera impact load equation under different impact velocities are determined. It is showed that the correction coefficientαis not a constant, moreover, there is a linear relationship betweenαand the square of the impact velocityV₀². The impact loads calculated with the modified Riera impact load equation are in good agreement with the numerical simulation results, which verifies the rationality of the modified Riera model.

Experiments and Theoretical Calculation of Double Pulse Laser Driven Flyer

GENG De-shen, CHEN Lang, WU Jun-ying, LIU Jia-xi, LU Jian-ying

2017, 37(s2): 57-61.

Abstract(857) PDF(270)

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Flyer velocity is an important index to measure the initiating ability of laser driven flyer. To improve the velocity of flyer at limited laser energy density is one of the major key issues in the pulse laser research. In this paper, a double-pulse laser driven flyer experiment was carried out by splitting one laser beam into two beams and then focusing onto the same target region The shape and position of the flyer at different times were recorded by schlieren high speed photography technique, and the flyer velocities were obtained. The theoretical formula for the calculation of the velocity of double-pulse laser driven flyer is derived, and flyer velocities are calculated at different laser energy and delay time. It is found that with the same laser energy, the application of double-pulse laser can increase the laser energy absorptivity and the velocity of the flyer.

Energy Release Characteristics of PTFE-Based Energetic Materials

CHEN Si-yuan, WANG Zai-cheng, TONG Yuan

2017, 37(s2): 62-65.

Abstract(771) PDF(369)

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The energy release characteristics of six different kinds of energetic fragments were measured based on Split Hopkinson Pressure Bar(SHPB)and Vented Chamber Calorimetry test method. The fireball change process of energetic fragments were acquired by a high-speed camera. The results show that energetic materials have greater damage effectiveness than inert materials. Al/W/PTFE energetic fragments release the maximum amounts of thermochemical energy under impact loading, and the reaction duration of Ti/W/PTFE energetic fragments is the longest.

Research on the Damage of Low-Density Jet to the Explosive Reactive Armor

DING Liang-liang, TANG Wen-hui, RAN Xian-wen, FAN Zi-jian

2017, 37(s2): 66-71,75.

Abstract(723) PDF(295)

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The shaped charge-shaped charge type tandem warhead is one of the weapons which can effectively deal with the explosive reactive armor, whether the pre-warhead can reliably initiate the sandwich charge directly determines the success of the combat mission. Most of the former shaped charge warheads are made of metal liner, while this article is to explore whether the low-density material can be used as the liner material, so as to achieve the purpose of damaging explosive reactive armor. The damage characteristics of low density jet are studied with numerical simulation and theoretical calculation, and the numerical simulation results are compared with the theoretical calculation results. The results show that the low-density jet not only can reliably initiate the interlayer charge, but also has many advantages over the existing metal jet. Therefore, this paper has the scientific research value to provide reference for the engineering design.

The Effect Study on Different Materials of PTFE/Al Bullet Head for Penetrating into Soil

CUI Hai-lin, MAI Rui-min, GONG Chao-an, LI Shuo, YUAN Rui, JIANG Peng-cheng, JIN Yong-xi

2017, 37(s2): 72-75.

Abstract(723) PDF(324)

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The material properties of bullet head have an important influence on PTFE/Al bullets penetrating into soil. To investigate the relationship between bullet head material and penetration depth, bullet heads made of nylon, aluminum, 45#steel and PTFE/Al were shot by ballistic gun and penetrated vertically into soil. By contrastively analyzing the penetration energy per unit distance, the mathematical relation between the location of the biggest cavity and penetration depth was obtained. The result shows that aluminum bullet head need minimum energy, and delay PTFE/Al active time will enhance penetrating depth.

Reliability Modeling and Analysis of Laser Ignition System Based on GO Methodology

CAO ke, YAN Nan, DONG Hai-ping, YANG Yuan-yuan

2017, 37(s2): 76-81.

Abstract(651) PDF(266)

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To enhance and evaluate the reliability of laser ignition systems,reliability model of laser ignition system was established by using GO methodology. The results of reliability analysis including minimal cutset of the system gotten by using GO methodology qualitative analysis and reliability of laser ignition system calculated by GO methodology quantitative method were carried on. Reliability parameters of various modules were predicted by using component stress method under the mission profile of non-working state for 5 y and working state with working time of 1 h. Compared with the results of FTA and Monte Carlo simulation,the applicability and the accuracy of reliability analysis of laser ignition system based on GO methodology are verified.

Experimental Studies of Shock Induced Particle Jetting

DU Kai-yuan, XUE Kun, SHI Xiao-liang

2017, 37(s2): 82-85.

Abstract(735) PDF(289)

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The dispersion of a cylindrical ring by a shock wave takes the shape of particle jets. Based on the quasi-two-dimensional experimental platform, the formation of particle jets in the inner surface of the particle ring is observed. It is found that the jets is generated by the inner surface of the particle ring and then develops to the outer surface. When the impulsive loads change, the shape and distribution of the jets change too. The number of early internal jets is basically the same. As the impulsive loads increase, the number of late internal jets decrease gradually. When the impulsive loads become greater, the distribution of particle jets will be more uneven, and the larger jets will merge the surrounding smaller ones during the dispersion of the particle ring, which leads to the decrease of the number of jets.

Research on the Contact Algorithm between the Penetrator And Steel Reinforcement in the Penetration

CHEN Xu-guang, ZHANG Duo, LU Fang-yun, YONG Dong

2017, 37(s2): 86-90.

Abstract(723) PDF(385)

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Nowadays, the law of penetration into the underground target is one of the key points in the weapon development and high value targets protection. Considering the influence of the steel reinforcement on the projectile's trajectory,a contact algorithm is put forward to describe the contact phenomenon between the penetrator and the steel in the penetration into the RC target. The contact algorithm is based on the equivalent single degree of freedom (SDOF) method, where the penetrator is simplified as a ball and the reinforcement steel is considered as the beam with a fixed-fixed boundary, and the resistance of the steel beam is considered as the contact force exerted on the penetrator. The resistance function presented here is validated by the comparison between the simulations with the code and the commercial software AUTODYN. In general, the contact algorithm is reasonable and effective in the simulation of the interaction between the penetrator and the steel.

Experiments and Simulations on Explosion Loads of Close-Proximity Underwater Explosion

AN Feng-jiang, LI Xu, DAI li-hui, ZHANG Yu-xia

2017, 37(s2): 91-94.

Abstract(815) PDF(369)

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The shock wave and detonation gas of near field underwater explosion are investigated experimentally and numerically. A spherical TNT charge of radius 35mm is detonated in a 800 mm×800 mm water tank. The framing & scanning ultra-high-speed photography system is applied to obtain the trajectories of shock wave and detonation gas in its initial 80 microseconds. The arbitrary Lagrangian-Eulerian (ALE) method using LS-DYNA software is applied to simulate the processes of close-proximity underwater explosion for varied spherical charges. Comparisons with the experimental tests verify the results of numerical solutions. The engineering formulas of velocities and pressures for shock wave and detonation gas are proposed.

Study on Uncoupled Numerical Simulations for Response of Structures to Blast Loads

BAO Ruo-fei, LIU Yan, LV Zhong-jie, HUANG Feng-lei

2017, 37(s2): 95-98.

Abstract(801) PDF(324)

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A numerical method of the uncoupled Eulerian-Lagrangian (UEL) for simulating the propagation and damage effects of blast wave in field tests was developed. The applicability and accuracy of the approach are investigated by analyzing the sensitivity of the model parameters. The results show that the shape of the pressure-time profile plays a significant role for the displacement-time curve in these simulations, where the loading should be considered as dynamic rather than impulsive. The structural responses based on the uncoupled Eulerian-Lagrangian approaches were found to be lower comparing to a pure Lagrangian simulation. It was demonstrated that structural? exibility reduces the pressure loads and thus the structural response.

Study on Mechanism of Spherical Fragments Penetrating Into Ballistic Gelatin with Soft Fiber Protection

JIN Yong-xi, MAI Rui-min, DONG Fang-dong, HAN Rui-guo, WU Cheng

2017, 37(s2): 99-102,108.

Abstract(648) PDF(358)

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To reveal the interaction process and mechanism of spherical fragment penetrating a gelatin target with soft fiber protection, the penetration process of spherical fragment to the ballistic gelatin target with soft fiber protection was simulated using an FAE method, and the feasibility of the simulation method was verified via experiment. The result shows that the velocity of gelatin sinking rises rapidly, while the velocity of steel sphere slows down quickly as the steel sphere impacts the soft fiber protection. Meanwhile the main failure mode of soft fiber is shearing mode. With the decrease of the velocity of steel sphere, the tensile deformation of soft fiber becomes more obvious, kinetic energy of steel sphere is converted to potential energy of fiber shells and the failure mode turns into tensile mode. Although the soft armor doesn't break, the back of fiber becomes protruding. With spreading of pressure wave, the gelatin depresses slightly,and the peak pressure is up to 3.53 MPa at 40 mm inside the gelatin, which still can cause certain damage to human organs.

FEA Simulation of the Dynamic Behaviorof a Scaled Aircraft Fuselage Model Impacting on a Concrete Block

DUAN Pu, DUAN Zhuo-ping, WEN Li-jing, GUO Chao, OU Zhuo-cheng, HUANG Feng-lei

2017, 37(s2): 103-108.

Abstract(561) PDF(374)

Abstract:
During the impact, the aircraft fuselage and its engine are considered soft and hard separately so that can be treated separately. The progressive crushing of an aircraft fuselage under extreme axial impact is a mixture process of highly nonlinear deformation, fracture and fragmentation, which will mainly affect the time history of the impact load. The research adopted the explicit FEA method to simulate the scaled aircraft fuselage impact test, and the Johnson Cook material model and failure model were used. The simulated result agrees well with the test result and Riera theory calculation, which indicated the computation method and material model were reasonable and could be applied to the numerical simulation of large commercial aircrafts impact load. At the same time, the practicality of Riera theory was demonstrated.

Numerical Simulation on Coupling Process of Dual Underwater Gaseous Bubbles near Water Surface

LI Zhuo-lin, LI Mei

2017, 37(s2): 109-113.

Abstract(793) PDF(317)

Abstract:
To study the coupling process of dual gaseous bubbles near water surface, a simulation research on single and dual bubbles near water surface based on LS-DYNA was conducted. Compare the experiment results obtaining from high-speed photography with computational simulation results, the simulation model validation was performed. According to further analysis to the results of the simulation model, maximum radius, expansion time and coupling process analyzed from complete bubble morphology were acquired. The results show that the coupling process of the dual bubbles near water surface was not a superposition of two single gaseous bubbles. The lateral contraction speed is slower than that of the single bubble; the time when bubbles reaches the highest point is 1ms delay compared with the single bubble; coupling bubbles during expansion process are merging, and the separate part along the top side of the shrinkage process is obliquely downward.

A Robot System for Puncture Diagnosis and Treatment of Skull Base and Lateral Facial Deep Region and Its Experimental Study

DUAN Xing-guang, GAO Liang, LI Jian-xi, LI Hao-yuan, LU Jia-feng

2017, 37(s2): 114-118,124.

Abstract(1192) PDF(440)

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In view of the diverse needs in the interventional process of biopsy, radioactive seed implantation and radiofrequency thermocoagulation for puncture diagnosis and treatment of skull base and lateral facial deep region, a multifunctional surgical robot system is developed. The system can assist surgeons to complete the operations of needle-placing, particle implantation and so on. Three end-effectors are designed for different surgical requirements. The rapid installation and disassembly between end-effectors and robot is realized by using a universal interface. The hybrid motion control method based on optical navigation was proposed to ensure the positioning accuracy of robot system. The positioning accuracy of robot was verified by experiments. The performance of robot system in three surgeries was verified by cadaver experiments. The results show that the robot system has high positioning accuracy and can be applied flexibly to many kinds of operations, which has certain feasibility.

Numerical Simulation of Initiation Effects on Small-Caliber Shaped Charge Against Explosive Reactive Armor

MI Hai-ming, YU Qing-bo, HE Lu-zhe, LI Wen-bing, WANG Hai-fu

2017, 37(s2): 119-124.

Abstract(891) PDF(433)

Abstract:
Mechanical and chemical responses of small-caliber shaped charge initiating a typical explosive reactive armor were simulated by using AUTODYN-2D software. Influences of charge diameter, liner angle, liner wall thickness and standoff on jet tip velocity and initiation parameter were obtained. By analyzing the initiating phenomenon of jets against ERA and the pressure change of the explosives that are set between ERA, effective methods of comprehensively judging whether the explosives explode or not are proposed. The results would provide a useful guide for the antitank front tandem warhead charging designing.

Numerical Simulation of Flyer Driven by Electric Explosion of Bridge Foil

QIAN Shi-chuan, GAN Qiang, REN Zhi-wei, CHENG Nian-shou, FENG Chang-gen

2017, 37(s2): 125-127,136.

Abstract(661) PDF(379)

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To explore the influence of bridge area width and the material of acceleration chamber on flyer speed, AUTODYN was used to simulate the process of flyer driven by electric explosion of bridge foil. The results show that, compared with bridge width of 0.27 mm, 0.30 mm, 0.33 mm, 0.36 mm and 0.42 mm, the speed of the flyer driven by the bridge width of 0.24 mm is the largest. Compared with aluminum, nickel and copper, Al₂O₃ceramic accelerator improves the speed and shear effect of flyer with small deformation due to its high hardness. Al₂O₃ceramic is better than the other three kind of materials as acceleration chamber.

Simulate and Calculate of Flyer Parameters in Impact Detonation Unit

REN Zhi-wei, QIAN Shi-chuan, GAN Qiang, CHENG Nian-shou, FENG Chang-gen

2017, 37(s2): 128-131.

Abstract(682) PDF(264)

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To study the influence of flyer parameters on shock and detonation, Lee-Tarver ignition and growth model was adopted to simulate the process that flyers shock and detonate HNS-IV explosive, where the flyer was made by different materials,thickness and diameter. The influence of different flyer parameters on detonation threshold was analyzed. The results show that the shock initiation kinetic energy of polyimide was lower than those of glass and ceramic, which makes it an ideal material for lower-energy of shock initiation devices. The detonation threshold velocity decreases as the flyer thickness increases in a range from 25 to 145μm, but when the flyer thickness exceeds 145μm, the threshold velocity has no obvious change. In a diameter range from 1.02 to 1.57 mm, the threshold velocity gradually decreases with the increase of flyer diameter, the threshold velocity tends to be a constant value when the flyer diameter exceeds 1.57 mm.

Research on Water Wave Effect and Injury Mechanics for Kinetic Less-Lethal Bullet Impacting Target

QIN Bin, WANG Jian-min, XIONG Man-man, HAN Rui-guo

2017, 37(s2): 132-136.

Abstract(638) PDF(310)

Abstract:
Kinetic less-lethal weapons may be the most widely used among the anti-terrorist equipments. The research on less-lethal bullet impacting process helps to uncover the injury mechanics, which was significant in increasing the hitting efficiency and safety. This paper introduces high-speed photograph to capture the process of a rubber ball impacting on a living target and a composite surrogate target. The high-speed images showed a transient and large skin deformation, which indicates the cooperation effect of water wave effect and skin straining was the major cause of an injury character-skin damage zone, pallor zone and congestive zone. Furthermore, this paper builds an analytical model for illustrating the connection between impacting effect parameters and typical injury mechanics. The experiment result and the analytical model helps to reveal the less-lethal bullet hit-pain mechanisms and to evaluate weapon efficiencies.

Dynamic ShearProperty and Failure Analysis of 603 Steel

SUN Zhong-yue, XU Ze-jian, Liu Yu, TONG Yi, HUANG Feng-lei

2017, 37(s2): 137-141.

Abstract(811) PDF(313)

Abstract:
Dynamic shear properties of 603 steel were tested by the new Hopkinson bar loading technology, and the microscopic failure mechanism was analyzed. The shear stress-shear strain curves of the material were obtained at strain rates above 10⁴s^-1, and failure parameters of the material were determined. The results show that with the increase of strain rate, the flow stress shows an obvious strengthening effect, while the failure stress increases slightly, and the failure strain decreases gradually. With ABAQUS/Explicit finite element analysis, the calculated shear stress-shear strain curves agree well with the experimental results. Fracture analysis shows that the failure mode of the material is ductile fracture, and it is influenced by adiabatic shear bands. With the increase of strain rate, the effect of adiabatic shear band is more obvious.

Study on the Multi-Scale Simulation of the Mechanical Behavior of Concrete

WANG Ji-peng, ZHANG Xian-feng, DING Li, CHEN Dong-dong, CHEN Hai-hua, DU Ning

2017, 37(s2): 142-147.

Abstract(833) PDF(395)

Abstract:
To study dynamic mechanical properties of concrete, three-dimensional mesoscopic concrete model which consists random convex polyhedron aggregate with different shape and size, and stochastic structure and location was established. The model was verified through static uniaxial compression simulation. According to the actual structure of concrete, the dynamic SHPB of concrete was simulated, and the experimental data under different impact velocities was obtained. Results show that the simulation results are in good agreement with the experimental results and the multi-scale method can be used to link the meso-scale characteristics with the dynamic mechanical behavior of macro-scale. In terms of the concrete mechanical performance, the reduced order homogenization method improves the computational efficiency compared with the meso-scale model.

Study on the Discharge Characteristics of Copper Wires Exploding in Different Media

WU Jun-ying, WANG Long, YU Hong-xin, CHEN Lang

2017, 37(s2): 148-152.

Abstract(670) PDF(300)

Abstract:
In order to study the electrical explosion mechanism and rules of the metal conductor in different media, a series of copper wire electrical explosion experiments have been conducted in water and in air under the different initiation voltages. The burst currents were measured using a Rogowski coil and the burst voltages were measured using a high-voltage probe. And then, the property parameter of electrical explosion of the copper wires are obtained. The influence of initiation voltage and medium on the properties of electrical explosion have been analyzed. The results show that under the same initiation voltage, the burst time of the copper wires in water lags behind the burst time in the air, and the energy deposition rate in water is higher than that in air. When the initiation voltage is low, wires explosion in water is hard to occur for secondary discharge.

Numerical Simulation of Array Bridge Foil Electrical Exploding

LI Ya-se, WU Jun-ying, WANG Long, Yang Li-jun, CHEN Lang

2017, 37(s2): 153-157.

Abstract(791) PDF(377)

Abstract:
In order to improve the energy utilization efficiency of the metal bridge foil and increase the function range of plasma beam, metal array bridge foils were designed in the present paper. The processes of array bridge foil electrical exploding were simulated based on the finite element fluid dynamics method. By using the phase change fraction and the plasma state equation considering the degree of ionization, the number of particles, and the Coulomb interaction between particles, the numerical simulation of the plasma and shock wave generated by the electric explosion of a metallic conductor under the action of a pulsed large current is realized. The evolution laws and characteristics of the plasma flow field were analyzed comparatively, with considering the electrical exploding in the acceleration chamber channel and the semi-free field without acceleration chamber. The calculation results show that the pressure of plasma beam superimposed area is high. The initial shock wave velocity and the plasma jet velocity of the electric explosion without the acceleration chamber are higher than that in acceleration chamber. In the case of having acceleration chamber, there exists a high pressure and low velocity boundary layer near the pipe wall due to the viscous effect of gas. The shock wave structure in the acceleration chamber is more complicated.

Research on Damage Character of Shaped Charge Warhead in Various Attack Angles

LI Bing, CHEN Gao-jie, SONG Dan-dan, ZHANG A-man

2017, 37(s2): 158-162,172.

Abstract(697) PDF(342)

Abstract:
For shaped weapons, once the characteristics of the warhead's drug mask, charge characteristics, and explosion distance and other factors are determined, the damage of this type of weapon mainly depends on its attack angle. The paper investigated the damage process and damage effect of shaped charge warhead of various attack angles using numerical simulation and model explosion test. The damage characteristics of shaped charge warhead subjecting to double-layer columniform shell were discussed. It can be concluded that, the smaller the attack angle, the larger the perforation diameter of shaped charge jet;The smaller the damage area, the stronger the load intension of unit area.

Numerical Modeling and Calculation of Typical Large Commercial Aircraft Impact Problem

GUO Chao, WEN Li-jing, ZHANG Chun-ming, GAO Yu, DUAN Pu, DUAN Zhuo-ping

2017, 37(s2): 163-167.

Abstract(666) PDF(385)

Abstract:
Based on the analysis of the Airbus A320 aircraft structure, the study on the simplification and modeling method of large commercial aircraft has been carried out. The finite element calculation model of large commercial aircraft is established and the appropriate mesh size is chosen. By comparing the numerical simulation and the theoretical calculation results, the rationality of the finite element model of the commercial aircraft and the reliability of the calculation method are verified. The finite element calculation model of the large commercial aircraft can be used for analyzing the impact loading characteristics of the aircraft. Numerical simulation of the structural response safety evaluation under the impact of aircraft can be directly performed.

Analysison Human Cardiac Electric Field Applied in Passive Non-Contact Detection

HAN Lei, LANG Ping, LI Yan

2017, 37(s2): 168-172.

Abstract(594) PDF(234)

Abstract:
Passive non-contact detection technique based on human heart electric field has many merits, i.e., high anti-interference, no radiation, well-concealment, operation easily and so on. Firstly, we deduced the cardiac source potential from single myocardial cell by the traditional heart dipole model; Secondly, we established the simulations of heart-torso and equivalent impedance coupling circuit to obtain the transfer function and attenuation gain of the cardiac electric field from intra-body to body surface; What is more, we acquired the detection formula of human heart electric field taken from simulation analysis of the electric field detection function for point charge model of torso, respectively. The results indicats that individual cardiac electric field can be equal to the electric field produced by the point charge within the error range. Finally, we obtained the theory detection distance based on the passive non-contact detection of individual cardiac electric field.

Verification and Validationfor Numerical Simulation Rules of the Shaped Charge Based on LS-DYNA 3D

LIU Han, MEN Jian-bing, JIANG Jian-wei, WANG Shu-you

2017, 37(s2): 173-177,182.

Abstract(741) PDF(617)

Abstract:
Using commercial software LS-DYNA 3D, credibility investigations of the jet formation and penetration simulation rules were carried out to verify BRL-82 standard charge from the conventional shaped charge structure. The result shows that the number of the liner thickness direction is meshed byδ=4, with the key areas mesh size as 0.25 mm, which is occupied by the charge, jet formation and penetration passage. The jet formation and penetration are simulated by multi-material Euler and multi-material fluid-structure interaction analysis, respectively. The simulated results could be of high reliability. The copper liner material constitutive models, i.e., Steinberg or Johnson-Cook, have less impact on the credibility of simulation result. A 56 mm shaped charge apparatus is designed. The result's credibility of jet formation and penetration is well validated by the flash X-ray radiography and static penetration experiments.

Research of Slope Bulge Movement Rule in Bench Blasting Based on High-Speed Photography

LI Xiang-long, WANG Hui-fen, HUQi-wen, HU Hui, LI Ke-gang

2017, 37(s2): 178-182.

Abstract(764) PDF(292)

Abstract:
To study the distribution rule of bench slope velocity field in high bench cast blast and to predict the maximum casting velocity and the largest casting distance on the foundation of similarity theory of bench model test, we established five bench models with similar material mix ratio at trial field based on Heidaigou open-pit coal mine to performed single-row core bench model blast test. In addition, through high speed photography, we observed that the velocity in bulge center of bench slope displayed characteristics of "acceleration-uniform velocity-second acceleration-deceleration". Moreover, the predicted largest cast distance as 108.11m and the maximum cast velocity 24.01 m/s were gained based on similarity theory.

Numerical Simulation on Explosion Dynamic Response of Blast-Resistant Door

XU Bin, WANG Cheng, WEI Jian-shu, XU Shi-lin

2017, 37(s2): 183-186,192.

Abstract(686) PDF(364)

Abstract:
Blast resistant door is used for oil and gas, unclear power station and army. The numerical simulation has been done in this paper to study the dynamic response of the blast resistant door under blast loading. The blast resistant class of the door DBD-AD150*240 has been analysed by the simulation. The strain, stress and the deformation of the door under the different blast loading has been studied to to examine whether the door can meet the blast resistant requirement or not to determine the anti-explosion grade of the door. In the present research, a type of sandwich panels was used to absorb the blast energy. The deformation of the energy absorbed structure was studied. Through the numerical simulation study, the anti-explosion grade of the studied antiknock door is determined, and the blast resistant ability of the door was obviously improved when employing the sandwich panels on the blast resistant door.

The Roles of Double-Layer Foam Ceramics in Suppression of Gas Explosion

NIE Bai-sheng, PENG Chao, WANG Cheng, WEI Jian-shu, HE Jin-tao

2017, 37(s2): 187-192.

Abstract(825) PDF(351)

Abstract:
In order to effectively suppress the shock waves generated by gas explosion in coal mine, a circular large-scale pipeline experiment system of gas explosion was designed and constructed. The suppression characteristics of porous ceramic foam on shock wave in pre-mixed gas explosion of 8% concentration were studied. The results show that the porous structure of foam ceramic can absorbs the shock wave energy through elastic and plastic deformation for indicating the effects of suppressing and attenuating the shock wave. The number, thickness and location of foam ceramic have certain influences on the suppression of gas explosion propagation. When setting double layer foam ceramic, the maximum overpressure drops faster and the gradient is larger. Thus, the influence of layer number is particularly significant. Foam ceramic installation location from the ignition side to the distance 3 m to 4 m range can successfully suppress the development of the explosion. Foam ceramic thickness has no obvious effect on the explosion shock wave trend but has an impact on the maximum overpressure. Compared with 50 mm thick, 30 mm thick foam ceramic has a stronger inhibiting effect with a hgiher overpressure attenuation rate.

The Practice Research of Power System Operation Mode Calculation Based On Machine Learning

ZENG Si-cheng, CHEN Yong, GUO Zhong-hua, SONG Rong-chang

2017, 37(s2): 193-197.

Abstract(887) PDF(261)

Abstract:
The change of power system operation mode can cause the change of the power equipment parameters, operation mode of the calculation with the power grid is gradually increasing with the increase of complexity. In order to solve the heavy workload and repetitive tasks, this paper describes how to take the advantage of TensorFlow architecture and machine learning algorithm to study thegrid operation mode calculation. The linear regression algorithm, logical regression two-classification algorithm and depth neural network algorithm are analyzed comparatively. Index of performance evaluation can be provided combining with the actual requirements.

Research on Output Characteristics Calculation Method of Micro-Magnetoelectric Generator

SUI Li, BIAN Xin-yuan, ZHANG Li-dan, SU Huai-wei, SHI Geng-chen

2017, 37(s2): 198-201,206.

Abstract(733) PDF(346)

Abstract:
The small-sized magnetoelectric generator has many advantages such as high power density, small axial size,long-term storage, and good prospects for fuze power supply. The output performance of the magnetoelectric generator is influenced by the coil parameters and the magnetic circuit structure, and it is difficult to get the analytical model. In order to analyze the output performance of magnetoelectric generator theoretically, the output voltage of the generator by method of combining analytical derivation and simulation analysis can be otained. The magnetoelectric generator were designed and machined according to the calculation results. The experimental results of the output performance of the magnetoelectric generator show that the error between the theoretical analysis and experimental results is only 0.2%, which proves the rationality of the calculation method proposed in the present paper.

Analysis and Experimental Research on Magnetic Springs with Different Stable States

HONG Yang, SUI Li, ZHANG Mei-yun, SHI Geng-chen

2017, 37(s2): 202-206.

Abstract(680) PDF(315)

Abstract:
Aiming at the problem that the traditional metal springs is liable to fail in service, a new type of spring-magnetic spring based on the interaction between magnets was studied, it was found that the magnetic spring is a variable-stiffness spring via the analysis of the relationship between the amount of compression and force. The concept of "stable state" was introduced to classify different types of magnetic springs, the mechanical model of monostable, bistablestate magnetic springs were established individually. Effects of stable state of magnetic springs and magnet structure parameters on stable state wereanalyzed by simulation and experiment. The results show that the structural parameters of the magnet such as diameter difference or thickness difference between two magnets have an important impact on the stable state of the magnetic spring.

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