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2018, 38(S2): .

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2018, 38(S2): .

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Experimental Study on Mechanical Properties of Red Sandstone Under Low Temperatures and Impact

YANG Yang, YANG Ren-shu, WANG Jian-guo, FANG Shi-zheng, DAI Qi-liang, ZHANG Nian-nian

2018, 38(S2): 1-5. doi:10.15918/j.tbit1001-0645.2018.s2.001

Abstract(552) PDF(131)

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The dynamic mechanical properties of red sandstone at negative temperature were studied by the dynamic impact test of Hopkinson pressure bar (SHPB), and the effects of different degrees of negative temperature on strength, damage variables and energy dissipation of rock were analyzed. Based on the microscopic fracture morphology obtained by SEM scanning, the reasons for the deterioration of dynamic mechanical properties of rock under low negative temperature were revealed. The study shows that low negative temperature will lead to frostbite of red sandstone, which will lose bearing capacity rapidly under high strain rate loading, and the dynamic mechanical strength will drop sharply; The negative temperature is equivalent to applying precompressive stress to the red sandstone, the whole rock tends to be brittle, but the ability to resist tensile stress is enhanced. According to the fracture morphology analysis, red sandstone appears strength degradation after -30℃.

A Method for Evaluating Velocity of Flyer Driven by Metal Electric Exploding

GUO Jun-feng, ZENG Qing-xuan, LI Ming-yu, WANG Tao

2018, 38(S2): 6-8. doi:10.15918/j.tbit1001-0645.2018.s2.002

Abstract(522) PDF(123)

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For exploding foil initiation system (EFIs), an experimental method based on the piezoelectric film (PVDF) was established to estimate the instantaneous velocity of a flyer. The average velocity of a flyer was measured using a PVDF and compared with the theoretical results of the one-dimensional flyer velocity model. The errors of flyer average velocities are within 10%, indicating that the one-dimensional velocity model meets the calculation accuracy requirements. Meanwhile, relationship between average velocity and instantaneous velocity of flyer was analyzed based on theoretical calculations, indicating that instantaneous velocity of flyer is nearly in proportion to average velocity (v=Δv/0.86). Thus, PVDF film method can be utilized to evaluate instantaneous velocity of flyer.

Numerical Simulation of Dynamic Response Law of Bedding Slope Blasting Based on Goodman Element

CAO Xiao-li, GAO Wen-xue, LIU Jiang-chao

2018, 38(S2): 9-13. doi:10.15918/j.tbit1001-0645.2018.s2.003

Abstract(478) PDF(131)

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To study the dynamic response of bedding slope rock under blasting load, numerical simulation method is used to analyze the propagation law of velocity and stress field of the slope. Goodman unit is used to simulate the relative slip of rock masses on both sides of the structural plane. The results show that the change of the slope shape at the step of the slope will cause the vibration velocity and stress value of the particle to fluctuate significantly, and the "whiplash effect" of the protruding part of the slope step is obvious, but the vibration velocity and stress do not reach the peak at the same part of the slope. Therefore, it is unreasonable to use the peak vibration velocity or stress value as the single index to evaluate the stability of the slope. The dynamic response of the internal mass of the rock mass is mainly related to the factors such as medium damping, structural plane and slope shape. The existence of the internal structural plane will cause the reflection of the explosion stress wave to be superimposed, and the vibration velocity and stress value of the particle point will also be enlarged to some extent before the structural surface. The reflection superposition effect of stress wave on the free surface should not be ignored

Surface Vibration Test and HHT Signal Analysis of Explosion in Subway Shallow Buried Tunnel

LIU Dong, GAO Wen-xue, SHI Lian-song, WANG Lin-tai, CAO Xiao-li

2018, 38(S2): 14-17. doi:10.15918/j.tbit1001-0645.2018.s2.004

Abstract(545) PDF(129)

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To eliminate the effect of blasting vibration on subway construction and the surrounding structures in shallow buried tunnel, several vibration monitoring tests were conducted on the Zhongyinggong-Xiaoxigou segment of Xinjiang Urumqi Line 1 subway tunnel surface. The vibration velocity decreases gradually. By HHT transform analysis of blasting vibration signal, it is concluded that the vibration energy generated by blasting is mainly distributed in the time period of 0~1.5 s and low frequency band of 0~50 Hz. Dividing cut holes into several segments can significantly reduce the surface vertical vibration velocity, and it effectively control the impact of the tunnel blasting construction on the surrounding structures.

Differential Sensitivity of Engineering Vibration Signal and its Application

WANG Lin-tai, GAO Wen-xue, CAO Xiao-li, ZHANG Fa-cai

2018, 38(S2): 18-21. doi:10.15918/j.tbit1001-0645.2018.s2.005

Abstract(504) PDF(144)

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In engineering construction monitoring, it is often necessary to monitor the vibration velocity signal or vibration acceleration signal. The spectrum characteristics of vibration velocity signal and vibration acceleration signal are very different, which will affect the subsequent analysis. In this paper, the time-domain calculus of Fourier transform is adopted to analyze the sensitivity of the spectrum of engineering vibration signal. The Fourier spectrum, self-power spectrum and frequency response function of structural vibration are obtained by Laplace transform, and their sensitivity is analyzed. The physical significance of its differential sensitivity is analyzed by frequency response function. The vibration signal of measured natural excitation in middle and high buildings in the background engineering is verified, and the influence of the sensitivity of spectrum calculus on the vibration signal analysis is analyzed. The results show that:In terms of mathematics, the frequency distribution of the peak of Fourier spectrum is sensitive to calculus due to the time-domain calculus nature of Fourier transform. With the increase of the differential order of vibration signal, the high-frequency component increases gradually and the low-frequency component decreases gradually;The frequency distribution of dynamic stiffness, impedance and dynamic mass of the structure is described by the frequency response function expression of different signals;Different monitoring signals have different recognition accuracy for high and low frequency components, as well as high order modal recognition accuracy for structures. Vibration acceleration signal monitoring is recommended for identification of high order frequency components, and vibration velocity signal monitoring is recommended for identification of low order frequency.

Numerical Modelling of High Pressure Natural Gas Jet Fires

HU Mei-juan, MA Xiao-he, Wu Yi, ZHANG Qing-ming, YANG Ming, ZHANG Xiao-wei, SHANG Chen

2018, 38(S2): 22-24. doi:10.15918/j.tbit1001-0645.2018.s2.006

Abstract(537) PDF(200)

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Natural gas jet fire can cause destructive damages by the heat it radiates to the surrounding space. With CFD code, numerical simulations were carried to analyze geometry and heat flux properties of natural gas jet fires. Six cases with mass flow rate up to 163 kg/s, pressure up to 12 MPa, and with outlet diameter up to 100 mm were conducted, and compared with Thornton model results. Flame sizes are obtained to show a linear relationship between outlet diameter and both flame length and width. The calculated results are in a nice fit with the Thornton model results, while heat flux distributions differ when concerning areas are near the outlet. The far field heat flux distributions perform generally the same with engineeringly acceptable tolerance, confirming both methods can be considered in natural gas facility safety designs.

Numerical Simulation on High Pressure Overhead Gas Pipeline Leakage and Diffusion

ZHANG Zhe-ju, CHEN Li, ZHANG Qing-ming, MA Xiao-he

2018, 38(S2): 25-28. doi:10.15918/j.tbit1001-0645.2018.s2.007

Abstract(526) PDF(139)

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Based on commercial CFD software FLUENT, the component transport model andk-εturbulence model were selected, and the PISO solution method was used to simulate the leakage and diffusion process of natural gas with methane as the main gas in air. The numerical simulation results of different pipe pressures and different leakage ports are obtained. The numerical simulated results of natural gas leakage are basically consistent with the calculated results based on the small hole leakage theoretical model. The results show that the pressure and leakage in the pipe are linear, and the diameter and leakage of the leakage are quadratic. The height of the jet generated by the leakage increases with the change of the pressure inside the pipe and does not change with the diameter of the leakage.

Effect of Quenching Temperature on the Microstructure and Compression Behavior of U-2.5Nb Alloy

XIAO Da-wu, LU Chao, MENG Xian-dong, WANG Qin-guo

2018, 38(S2): 29-32. doi:10.15918/j.tbit1001-0645.2018.s2.008

Abstract(442) PDF(168)

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The compression behavior of U-2.5wt%Nb (U-2.5Nb) alloy with different heat treatment condition was investigated. The microstructure and phase composition were analyzed by OM, XRD and SEM. Results show that the microstructure and phase composition are closely related to the quenching temperature. With the quenching temperature decreased from 800℃ to 620℃, the nb-containing supersaturation monoclinic evolved into α+γ₂two-phase. The yield strength decreased with decreasing quenching temperature, while the ductility increased significantly. The 655℃ quenched specimen exhibited the lowest yield strength, which may be related to the considerable content of α″ phase obtained by quenching of γ₁phase.

Preliminary Analysis on the Influence of Lode Parameter on the Failure Strain

WU Xing-xing, LIU Jian-hu, MENG Li-ping, WANG Hai-kun, ZHANG Lun-ping

2018, 38(S2): 33-36. doi:10.15918/j.tbit1001-0645.2018.s2.009

Abstract(433) PDF(189)

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Lode parameter is important to describe the material stress status. To reveal the influence of Lode parameter on the failure strain, several kinds of tensile specimen were carried out. Meanwhile, the Lode parameter of specimen broken location were achieved by using numerical simulation method. The results indicated that Lode parameter could separately influenced the failure strain by contrasting the several specimen results under the same value of stress triaxiality.

Numerical Simulation of Influence of Detonation Distance on Deflection of Bulkhead Deformation in In-Cabin Explosion

HUANG Song, ZHAO Peng-duo, YIN Jian-ping, LI Xu-dong, XU Yu-xin

2018, 38(S2): 37-40. doi:10.15918/j.tbit1001-0645.2018.s2.010

Abstract(484) PDF(170)

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In order to study the damage effect of the change of explosion distance on in-cabin explosion, the simulation model of cabin explosion was established by using the finite element analysis software. The deformation of the bulkhead and the pressure of shock wave were analyzed. The results show that when the blasting distance ratio isL₁/L₂>1, the deflection of the far bulkhead is always greater than that of the near bulkhead. When the detonation distanceL₁increases, the deflection of the far bulkhead increases linearly, and the deflection increment is about 11% of the explosion distance increment, but the deflection of the near bulkhead does not change significantly. The shock wave that reaches the far bulkhead for the first time after the explosion in the cabin is the superimposed wave formed by the interaction of the initial shock wave and the reflection shock wave from the near bulkhead and the rigid bulkhead.

Study on Petalling Model for Oblique Penetration of Thin Metallic Plates by Ogive-Nose Projectiles

WU Hai-jun, ZHANG Qing-ming, CHU Zhe, WANG Ke-hui, GONG Bo-lin, ZHOU Gang

2018, 38(S2): 41-45. doi:10.15918/j.tbit1001-0645.2018.s2.011

Abstract(631) PDF(137)

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By using the analytical method of conical projectile, a modified petalling perforation model of the ogive-nose projectile oblique penetrating thin metallic plate was established according to the energy conservation principle. The formulas for the energy of the propagation of radial cracks, petal dynamic power and petal bending were deduced on the basis of the ogive-nose projectile's characteristic. The application range of the model was discussed as well. The model provided in this paper could give satisfied predictions of the projectiles' residual velocity of the projectile for both vertical and oblique penetration which is precise than the results of empirical formula if the deformation of the projectile can be neglected.

Characteristic Research of the Impact Crushing Load on Aluminum Alloy Profiles

GUO Chao, WEN Li-jing, ZHANG Chun-ming, XIA Yu-qi, SONG Li, ZHANG Qing-hui, DUAN Zhuo-ping

2018, 38(S2): 46-49. doi:10.15918/j.tbit1001-0645.2018.s2.012

Abstract(578) PDF(137)

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In order to determine the crushing load in the Riera formula, based on the material testing machine and the Hopkinson pressure bar experimental system, the static and dynamic crushing behaviors of aluminum alloy under axial quasi-static and different velocity impact loading were studied. The load-time curves of various sizes and shapes of aluminum alloy in static and dynamic crushing process, as well as the variation of peak crushing load and average crushing load with impact velocity were obtained. The results show that the average crushing force is a good choice for the crushing load in the Riera formula, and the difference between the dynamic and static crushing forces of the aluminum alloy comes from the lateral inertial effect of the structure. Based on the dimensional analysis and further analysis of experimental data, the unified average crushing force empirical formula for the aluminum alloy suitable for quasi-static and impact loading was obtained.

Study on Shock Wave Characteristics of Different Charges by Underwater Explosion

CHENG Su-qiu, GHENG Xin, QIN Jian

2018, 38(S2): 50-53. doi:10.15918/j.tbit1001-0645.2018.s2.013

Abstract(573) PDF(144)

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Characteristic parameters, such as impact wave pressure, time reduces constant, etc, of complex-PBX, fusing THL, thermoplastic THL and TNT are analyzed utilizing tested data in underwater explosion. Underwater explosion power of different charges is compared. The result indicates that the peak pressure of four charges are, from high to low, thermoplastic THL, fusing THL, TNT, complex-PBX; Decay constant are, from high to low, complex-PBX, thermoplastic THL, fusing THL, TNT; Contrast shock wave pressure impulse are, from high to low, complex-PBX, fusing THL, thermoplastic THL, TNT. Therefore, complex-PBX is the best performance of charges by multi-parameter comprehensive evaluation.

Simulation on Impact Initiation of Underwater Covered Composite B by Shaped Charge Jet

WEI Ji-feng, ZHANG Liang, XIE Xin, JIN Zi-yan, DU Zhi-xin

2018, 38(S2): 54-58. doi:10.15918/j.tbit1001-0645.2018.s2.014

Abstract(602) PDF(243)

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In order to obtain the capability of jet impacting and initiating underwater covered composite B, the effect of water layer thickness is studied. Based on quasi-steady penetration theory, the velocity expression of copper jet penetrating into aqueous medium is obtained. A penetrate-blast simulation model is established, and the movement, penetration and initiation of jet to different mediums are analyzed in detail. The velocity and diameter of jet before and after penetrating cover board are calculated. The simulation results show that the critical water layer thickness to initiate Composite B by jet is 261 mm, and the initiation threshold value of composite B is determined by Held to be 18.598 mm³·μs^-2. The results may provide useful reference for underwater damage technology of shaped charge jet.

Study on the Feasibility of Low-Density Material Used in Tandem Warhead

LIANG Zeng-you, LIANG Fu-di, MIAO Chun-zhuang, WANG Ming-guang

2018, 38(S2): 59-62. doi:10.15918/j.tbit1001-0645.2018.s2.015

Abstract(449) PDF(129)

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In order to study the feasibility of three low-density materials, floatglass, lucite and plexiglas, applied in the forward shaped charge liner of tandem warhead. The formation of three low density jets and the detonation process of explosive reactive armor were numerically simulated by Autodyn-2D. The result shows that low-density jets have higher jet tip velocity, larger jet diameter and better ductility compared with the copper shaped jet under the same condition. The low-density jets initiated the charge of ERA more effectively and rapidly. The feasibility of using three kinds of low density materials as forward shaped charge liner of tandem warhead is verified primitively.

Safety Study on Drop Impact of Cluster Warhead

MA Ai-e, WANG Jun-lin, ZHAI Yong-bing, ZOU Ren-qiu, LIU Zhi-lin

2018, 38(S2): 63-66. doi:10.15918/j.tbit1001-0645.2018.s2.016

Abstract(533) PDF(170)

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The 3 m drop impact of semi-armor-piercing cluster warhead is simulated by nonlinear finite element software ANSYS/LS-DYNA and a verification test is conducted. The structural distortion and the acceleration of explosive are obtained under different conditions. The results show that the acceleration of projectile explosive is the largest when the large end of the warhead falls vertically downward, which provides guidance for the following experiment. The simulated results agree well with the experiment data.

Study on Performances of Graded-Impedance Materials under Front/Back Side Hypervelocity Impact

SONG Guang-ming, LI Ming, GONG Zi-zheng, WU Qiang, ZHANG Qing-ming

2018, 38(S2): 67-70. doi:10.15918/j.tbit1001-0645.2018.s2.017

Abstract(533) PDF(166)

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In order to analyse the effect of gradient distribution on the performances of graded-impedance materials against hypervelocity impact, experiments and numerical simulations with titanium alloy as the impact face (front impact) and magnesium alloy as the impact face (back impact) were designed and carried out for the graded-impedance materials with graded-impedance distribution of titanium alloy/aluminium alloy/magnesium alloy. The characteristics of debris cloud and rear wall damage were obtained. The impact pressure and internal energy conversion characteristics of projectiles and targets under different conditions were analyzed. The results show that front impact is beneficial to increase the impact pressure, promote the transformation of kinetic energy to internal energy, and thus improve the protection ability.

The Damage of Composite Cylindrical Explosion Vessel Under Internal Explosion

GAN Yun-dan, ZHANG Qing-ming, LONG Ren-rong, ZHAI Hong-bo, DING Gang, LIANG Hao-zhe

2018, 38(S2): 71-74. doi:10.15918/j.tbit1001-0645.2018.s2.018

Abstract(522) PDF(168)

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In this paper, a fiber composite reinforced metal liner with a length to diameter ratio of 2.5:1 is used instead of the barrel of the composite cylindrical explosive container. The failure characteristics of the barrel under different charge masses were studied. The maximum circumferential deformation is obtained by theoretical analysis, which has a good agreement with the experimental results. The failure of composite cylindrical explosion container under certain charge mass can be predicted. This work provides important insights for the design of fiber composite cylindrical explosion containers and scientific experiments.

Experimental Investigation on Indoor Gas Blast Loading with Vent Glass Window

LIU Jin-chun, RONG Chao, BAO Qi, GAN Jia-pin, YANG Shi-gang

2018, 38(S2): 75-80. doi:10.15918/j.tbit1001-0645.2018.s2.019

Abstract(475) PDF(156)

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A gas blast experiment system is established in this paper. The regularity and characteristics of gas blast loading is investigated by 19 tests with respect to gas concentration, vent glass failure strength and vent area. The analysis results show that when the gas concentration of methane is 7.5%~10.5%, there are two pressure peaks produced by indoor methane gas explosion, the combustion is acoustically unstable, and the second peak is larger than the first one. When the gas concentration of methane is larger than 10.5%, there is no acoustic phenomenon with only one pressure peak, and the peak is mainly affected by the cover of the vent window. When the gas concentration of methane reaches 9.5%, the internal gas blast pressure is the maximum because of vigorous reaction. Increasing vent glass failure pressure gives rise to the first pressure peak, and increasing vent area results in the slight drop of the first pressure and the drastically decrease of the second peak. The results may be helpful for knowing the regularity and characteristics of internal gas blast loading and investigating the response and failure patterns of structure under gas blast loading.

Kinetics Model and Effecting Factors Research of Piston Dispersing

GONG Ping, ZOU Ren-qiu, GAO Xin-hao, QU Hong-yi, XUE Zai-qing

2018, 38(S2): 81-85. doi:10.15918/j.tbit1001-0645.2018.s2.020

Abstract(482) PDF(140)

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Base on classical interior ballistics theory, kinetics model of piston dispersing for high-low pressure combustion chamber was established. Numerical calculation code was compiled by four-order Runge-Kutta method. A cluster warhead was calculated to obtain the pressure of high-low pressure combustion chamber, the velocity and acceleration of bullet. Changing rules of pressure,velocity and acceleration were acquired by analyzing the effect of fumarole area, powder mass and volume of combustion chamber for dispersing process. The calculated results are in agreement with actual changing rule, which has reference and guidance on the piston constructional design for cluster munitions.

Research on ‘Acoustic-Electricity’ Composite Detection Method for Combustible Dust Concentration

ZHANY Yan, LOU Wen-zhong, LIAO Mao-hao, FU Sheng-hua

2018, 38(S2): 86-89. doi:10.15918/j.tbit1001-0645.2018.s2.021

Abstract(471) PDF(141)

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The concentration limit of combustible dust is one of the sufficient conditions for dust explosion. The monitoring of dust concentration is an effective method to prevent disaster, but there is no practical technology to detect the concentration of combustible dust up to now. To solve this problem, an ultrasound-electricity comprehensive measurement scheme is presented, and the mixed structure system is designed. The relation of comprehensive measurement data is analyzed and a two-level data fusion model is proposed. The data fusion algorithm based on the optimal weighting method is studied, and ultimately a rapid fuel concentration detection model is given. The results show that the multi-mode fuel concentration detection method is able to realize the rapid and accurate concentration detection.

Analysis on Quasi-Static Pressure and Ground Motion Under Enclosure Space after Explosion

SONG Shi-qian, CUI Yun-xiao, ZHOU You, LI Xiao-mao, GUO Xian

2018, 38(S2): 90-94. doi:10.15918/j.tbit1001-0645.2018.s2.022

Abstract(442) PDF(131)

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The parameters of quasi-static pressure and ground motion velocity are important references to ensure the safety of explosion operation in closed space. The analysis on time-frequency domain characteristics of the measured ground motion velocity data and quasi-static pressure data is carried out. The results show that the particle velocity time-history curves and frequency-domain curves are consistent under different proportions of explosive charge. With the increase of detonation center distance, the particle velocity amplitude decreases, and the main frequency band approaches the low frequency band. The proportional charge only affects the amplitude of ground velocity, and it has little effect on the frequency-domain distribution and the main frequency. The quasi-static pressure peak value and attenuation velocity are affected by different mass of sand wall. The smaller the mass of sand wall, the larger the quasi-static pressure peak value after blasting, and the faster the attenuation.

Influence of Charge Shapes on Deformation Law of Open-End Steel Cylinder Under Internal Blast Loading

CUI Yun-xiao, GUO Qing-wei, SUN Zhen-yu, WANG Lei-yuan, ZHANG Guo-dong

2018, 38(S2): 95-99. doi:10.15918/j.tbit1001-0645.2018.s2.023

Abstract(566) PDF(148)

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The influence of charge shape on the deformation law of open-end steel cylinder under internal blast loading was studied by means of numerical simulation and experiment. The dynamic explicit code LS-DYNA and the Johnson Cook model were used to simulate dynamic response of open-end steel cylinder. The numerical model and parameters were verified by comparison with experimental results of residual hoop strain of steel cylinder without concrete reinforcement under different charge mass. The influence of different shapes of charge, such as cuboid, sphere and cylinder, on the plastic deformation of open-end steel cylinder without concrete reinforcement were studied by numerical simulation at charge mass of 200 g. The aspect ratio of charge was changed from 0.25 to 4. The variation laws of overpressure, impulse and hoop strain of outer wall of steel cylinder were obtained. Based on this, the dynamic response of concrete reinforced steel cylinder under different aspect ratio was simulated. Compared with the experimental results, the deformation law was validated. The results show that the deformation of structure is closely related to the shape of charge. The hoop deformation of steel cylinder is larger when the aspect ratio is larger under the explosion of same charge mass. But the deformation will decrease when the aspect ratio is larger than a certain value. The influence of shape of the charge on the deformation of structure should be emphasized in the design process of protective structures.

Numerical Simulation of the Effect of Nose Shape on Dynamic Damage of PBX Charge During the Penetration Process

DAI Kai-da, CHEN Peng-wan, SHI Xiao-hai

2018, 38(S2): 100-104. doi:10.15918/j.tbit1001-0645.2018.s2.024

Abstract(445) PDF(151)

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Nose shape has significant influence on dynamic mechanical response of charge during penetration. An user defined material model based on cohesive crack model is constructed to directly simulate the penetration of concrete with LS-DYNA. The damage evolution process of charge is calculated. The influence of caliber-radius-head of ogival nose warhead is analyzed by element crack width and volume fraction of visible crack. The results show that the variation of nose shape for ogival nose warhead has significant influence on dynamic damage, and controlling caliber-radius-head of warhead is beneficial to reduce charge damage.

Analysis of Influence of Strain Rate Effects on Similarity Law of Structural Response

XU Kun, PI Ai-guo, LIU Jian-cheng, LIU Yuan, LIU Zhi-lin, HUANG Feng-lei

2018, 38(S2): 105-108. doi:10.15918/j.tbit1001-0645.2018.s2.025

Abstract(483) PDF(163)

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Based on the dimensional analysis method, the influence of strain rate effects on the similarity law of structural response under impact load is analyzed. A velocity correction method is provided to decrease the deformation difference due to strain rate effects. The reverse ballistic Taylor impact prototype experiment and model experiment are performed. The velocity correction method is used to guide the reverse ballistic Taylor impact correction model experiment, and the results are compared with the results of prototype experiment and model experiment. The result shows that the velocity correction method can effectively decrease the structure response between prototype and model due to strain rate effects.

Research on Thermal Protection Efficiency of Insensitive Ammunition Fuze for Slow Cook-Off Environment

HAN Yan-hui, LOU Wen-zhong, FENG Yue

2018, 38(S2): 109-112. doi:10.15918/j.tbit1001-0645.2018.s2.026

Abstract(760) PDF(166)

Abstract:
In order to meet the operational efficiency requirements of ammunition, many countries attach great importance to avoid the serial explosion of ammunition caused by accidental thermal stimulation. Usually, the thermal conductivity of metal fuze shell is large, and the heat conduction speed is fast after being stimulated by ambient heat, which seriously endangers the safety of subsequent detonators and explosives. In order to study the heat barrier ability of fuze protective shell material and further enhance the thermal protection effect of fuze, a controllable burning system based on quartz lamp array is developed for simulating thermal environment stimulation, and a multi-channel temperature measurement micro-system embedded in fuze is designed and implemented, which is proved to have high reliability and multi-channel embedding testing ablity. The advantages of synchronous test are analyzed. By using the finite element thermal simulation technology, the influence of thermal protection layer on the thermal response of the booster under slow cookoff condition is analyzed. The protective shell material can effectively reduce the heat transfer. In addition, numerical comparisons of four kinds of protective materials (PTFE, Al-Mg fiber, ceramic insulating tile material (FRCI-12) and aerogel felt) under slow cook-off conditions show that the thermal protection effect of aerogel felt is the best.

Optimization and Characterization of Ultrafine RDX Preparation Process by Response Surface Methodology

JI Wen-su

2018, 38(S2): 113-117. doi:10.15918/j.tbit1001-0645.2018.s2.027

Abstract(536) PDF(155)

Abstract:
Submicron particle morphology spherical precipitation RDX was successfully prepared by supercritical rapid expansion (RESS) with liquid dimethyl ether (DME) as solvent. The effects of extraction temperature, extraction pressure and nozzle inner diameter on the RESS process were discussed. The process was optimized based on the Box-Behnken response surface methodology and the product performance was characterized in the end. Results show that the influence of all three factors is significant, and the inner diameter of the nozzle has the greatest influence, followed by the extraction pressure. The optimization parameters are extraction temperature 293 K, extraction pressure 15 MPa, and nozzle inner diameter 50 μm. RDX products show particle and spherical morphology, with sub-micron size and average particle size of 0.183 μm. The crystal enthalpy change (ΔH=714.4 J/g) is higher than that of the original RDX (ΔH=381.5 J/g), and the estimated explosion probability decreases from 76% to 55%. On the whole, the explosion performance of the newly prepared RDX is obviously improved, the violence increases and the sensitivity decreases.

Algorithm Research on Damage Assessment of Typical Buildings

WANG Hong-yu, LIU Yan, XU Yu-xin, HUANG Feng-lei

2018, 38(S2): 118-122. doi:10.15918/j.tbit1001-0645.2018.s2.028

Abstract(544) PDF(182)

Abstract:
A damage assessment system was developed, which can be applied to damage assessment of penetration projectiles attacking concrete buildings. That includes a data format to describe the internal logic of concrete buildings, and a.XML file format for associating the data format with the building model; a projectile modeling system and a power analysis system based on material database and research results on detonation physics, etc; a vulnerability analysis system based on AHP and Function Damage Tree; algorithms for simulating explosion process and penetration process. At last, we analyzed the effect of aiming position, penetration depth and CEP radius on the damage result, which could be a reference for related research.

Numerical Simulation on Armor Penetration of Double-layer Shaped Charge

LI Shou-cang, WANG wei-Zhan, CHEN Zhi-gang, XU Qiang

2018, 38(S2): 123-127. doi:10.15918/j.tbit1001-0645.2018.s2.029

Abstract(654) PDF(193)

Abstract:
In order to increase the stability and armor penetration of shaped charge jets,numerical simulation and the effect of varying thickness on armor penetration is analyzed by using LS-DYNA software. Results show that the armor penetration of the shaped charge with the outer shaped charge with thick edge and thin top increased 10% than the shaped charge with equal thickness. The armor penetration of the shaped charge with the outer shaped charge with thick top and thin edge is basically unchanged,but the jets velocity gradient decreased obviously and the stability of shaped charge jets increased with higher explode height. The warhead with the outer shaped charge with different thickness increased the stability and armor penetration of shaped charge jets.

Electromagnetic Damage of Logic Chip Module by Plasma Generated by Strong Impact 2A12 Aluminum Plate

TANG En-ling, ZHAO Guan-jie, HAN Ya-fei, HE Li-ping, GUO Kai

2018, 38(S2): 128-133. doi:10.15918/j.tbit1001-0645.2018.s2.030

Abstract(665) PDF(168)

Abstract:
To investigate the electromagnetic damage of plasma induced by 2A12 aluminum alloy subjected to strong shock loading to the logic chip modules, CD54ACT32 and CD74HC4075 logic chip modules which are commonly used in the aerospace control system were studied by applying two-stage light gas gun, a triple Langmuir probe and logic state test system of logic chip modules, 6 sets of experiments on the damage of the plasma induced by the 2A12 aluminum subjected to strong shock loading on the logic chip modules under the given experimental conditions have been implemented, and the variation of plasma electron temperature and density against time was obtained. Moreover, the function of electron temperature and density with time was obtained by fitting the experimental data. The results reveals that transient and perpetual damage to TTL level signal CD54ACT32 logic chip modules were detected by the plasma induced by 2A12 aluminum alloy subjected to strong shock loading under the given incidence angle of the projectile and similar impact velocities. However, only transient damage to CMOS level signal CD74HC4075 was observed, verifying that CMOS logic chip modules is superior to TTL logic chip modules in terms of anti-damage of plasma under the given experimental conditions.

Design of the FAE Solid Fuel Cloud Concentration Fast Measurement System

ZHANY Yan, LOU Wen-zhong, LIAO Mao-hao, FU Sheng-hua

2018, 38(S2): 134-138. doi:10.15918/j.tbit1001-0645.2018.s2.031

Abstract(537) PDF(149)

Abstract:
The solid fuel cloud concentration measurement technology is the key factor for the FAE to realize the best fuse-warhead coordination and enhance the damage power, but the existing multiphase concentration testing methods cannot meet the demand of in-situ measurements. The general model of ultrasonic attenuation in solid-gas mixture is investigated and simplified by numerical analyses,and the fast calculating algorithm of mixture concentration of air and metal particles is established. Assembly method with dual core is adopted to design the concentration measurement system, in which the signal sampling function and concentration calculating function can be achieved independently. An experiment is conducted with a high-precision concentration measurement device to testify the characters of the concentration measurement system. The results show that the concentration measurement system performs very well in both accuracy and speed,so it can be used to test the concentration of FAE fuel cloud.

Effect of Material Characteristics of Charge on Formation of Integral Multiple Explosively Formed Projectiles

ZHAO Chang-xiao, JI Chong, GAO Fu-yin, ZHANG Jun-nan, RAN Dong-yue, LI Hui-ming

2018, 38(S2): 139-142. doi:10.15918/j.tbit1001-0645.2018.s2.032

Abstract(630) PDF(164)

Abstract:
To improve the damage ability of integral multiple explosively formed projectiles(MEFP), the formation process of integral MEFP formation with different materials of charge was studied using LS-DYNA code,and the feasibility of the warhead with B explosive is verified in static blast experiment. The simulated results coincide well with the experimented data. The results indicate that with the increase of density, detonation velocity, pressure of charge, and the velocity and length-diameter ratio of the central projectile increases significantly and the penetration performance enhances. The shape of surrounding projectile changes from ball to rod gradually,and the flight stability of projectile decreases. Therefore, selecting suitable explosive charge could improve the damage effect based on particular aim.

Design and Simulation of Longitudinal Maneuvering Motion Prediction for the Underwater Smart Ammunition

NIE Wei-biao, FENG Shun-shan

2018, 38(S2): 143-146. doi:10.15918/j.tbit1001-0645.2018.s2.033

Abstract(379) PDF(107)

Abstract:
The design and simulation of the longitudinal maneuvering motion prediction for the underwater smart ammunition were studied.The dynamic model of the underwater smart ammunition in the longitudinal plane were established.The standard and index evaluation methods of Z-shaped, trapezoidal and sinusoidal steering maneuverability of the underwater smart ammunition in the longitudinal plane were established and designed. At the same time, the matlab simulation examples were presented for each maneuvering motion prediction. The typical characteristic parameters of the maneuvering motion and their motion laws were analyzed and expounded. The simulation results show that the underwater smart ammunition has good rudder responsiveness and maneuverability, and the response time is fast, which can accurately predict the maneuverability of the underwater smart ammunition. The process and results of the maneuverability motion prediction analysis can also provide certain technical guidance and theoretical support for improving the structure and hydrodynamic design of the underwater smart ammunition.

Non-Linear Saturated Material Model for Rock and Its Application in Calculations of Underground Explosions

ZHANG Hai-bo, WANG Hai-bing, TIAN Zhou, PU Xi-feng, WANG Tie-liang, BAI Chun-hua, ZHANG Qing-ming, OU Zhuo-cheng

2018, 38(S2): 147-150. doi:10.15918/j.tbit1001-0645.2018.s2.034

Abstract(405) PDF(132)

Abstract:
A material model which is suitable for both dry and saturated rocks under explosion loading, has been built. The plastic flow rule and the damage rate evolution equation were modified, for the purpose of numerical continuity and computational stability. Furthermore, the equation of state for saturated rock has been modified, thus the calculation agrees with experimental phenomena. Moreover, these modifications have been added into our SinoDyn dynamic code. With this code, the underground explosion effects in both dry and wet granites were numerically studied for many aspects. The calculated results agree well with the experimental data.

Fragments Regularity Research on the Shock Wave Damage Effect Experiments of the Tempered Glass

ZHONG Wei, SHOU Lie-feng, TIAN Zhou, PU Xi-feng, HE Zeng, LI Wei-chang, LIU Jun, WANG Zhong-qi

2018, 38(S2): 151-155. doi:10.15918/j.tbit1001-0645.2018.s2.035

Abstract(641) PDF(169)

Abstract:
In order to investigate the secondary damage of the glass fragments of the tempered glass subjected to blast shock waves, several explosion experiments were performed on the tempered glass with the thickness of 6 mm, 10 mm and 15 mm, respectively. In the experiments, data collections and statistical work of the size distribution, the splash distance distribution and the maximum splash velocity have been done. According to the experimental results, the size and the splash distance distribution of the glass fragments were analyzed, and the regularity and characteristics of the distribution were proposed. Meanwhile, with the fragment maximum splash distance recorded in experiments and the equation of the flat parabolic motion, the maximum splash velocity of the fragments was estimated, which agrees well with the results of the reference. Experimental results show that the maximum splash velocities of the tempered glass subjected to blast wave in all experiments were larger than 11 m/s, in which the largest one was above 25 m/s.

Quasi-Static Pressure Analysis in Tunnels Under Strong Blast Impact

WU Wen-yi, XIONG Yi-bo, LI Xiao-mao, CUN Yun-xiao, HUANG Xiao-fei

2018, 38(S2): 156-160. doi:10.15918/j.tbit1001-0645.2018.s2.036

Abstract(437) PDF(173)

Abstract:
Aiming at the quasi-static pressure characteristics of TNT explosion in closed tunnel under strong explosion, a quasi-static pressure calculation model based on energy conservation and ideal gas state equation is established in this paper, and a series of TNT internal explosion tests are carried out in the test tunnel. The results show that the quasi-static pressure of confined explosion is obviously affected by the chemical reaction of secondary combustion of explosive products. When Q/V is small, the theoretical calculation model could better estimate the quasi-static pressure after tunnel implosion. When Q/V is 0.234 k g·m^-3and 0.463 k g·m^-3, the relative error between the theoretical calculated value and the measured value is only 4.6% and 1.4%. With the increase of Q/V, the proportion of explosive products participating in secondary combustion in the atmosphere of the tunnel decreases, and the proportion of quasi-static pressure increases decreases.

Numerical Simulation of Deformation of Polyurea Steel Composite Structure Based on CONWEP Algorithm

LIU Qiang, CHENG Peng-wan, SU Jian-jun, LI Zhi-rong, HAN Lu

2018, 38(S2): 161-165. doi:10.15918/j.tbit1001-0645.2018.s2.037

Abstract(601) PDF(163)

Abstract:
Based on the nonlinear finite element software LS-DYNA, the deformation of polyurea steel plate composite structure under explosive loading was simulated by using CONWEP algorithm. The simulated results were compared with the experimental results. The results show that the CONWEP algorithm can well simulate the deformation of polyurea steel plate composite structure under explosive loading. With the same steel plate thickness, the maximum deformation deflection of polyurea steel plate composite structure is smaller than that of bare steel plate. From the results of energy-absorbing, polyurea elastomer has good energy-absorbing characteristics, and the energy-absorbing of steel plate in composite structure is lower than bare steel plate, which makes the deformation of steel plate in composite structure is also lower than that of bare steel plate.

Study on Jet Forming Cohesiveness of the PTFE-Based Energetic Liner

LI Yan, ZHANG Han-yu, WANG Zai-cheng, JIANG Chun-lan

2018, 38(S2): 166-172. doi:10.15918/j.tbit1001-0645.2018.s2.038

Abstract(553) PDF(151)

Abstract:
Metal/fluoropolymer composites represent a new category of efficient damage element that releases energy through exothermic chemical reactions initiated under shock loading conditions. This paper describes an experiment designed to study the reaction characteristics of PTFE(polytetrafluoroethylene)/Ti/W energetic materials with different W mass fractions under explosive loading. An inert PTFE/W mixture without reactive Ti particles is also prepared to serve as a reference. Shock-induced chemical reactions are recorded by high-speed video through a narrow observation window. Related shock parameters are calculated based on experimental data, and differences in energy release are discussed. The results show that the reaction propagation of PTFE/Ti/W energetic materials under explosive loading is not self-sustained. Propagation distance, W mass fractions and porosity have significant influences on the energy release.

Optimization of Multi-Layer Component Armor

WU Hai-ling, ZHONG Tao, MIAO Cheng, BAI Li-hong, CUI Xin-zhong, WANG Yan-li, LI Hui, Dong Yuan-yuan

2018, 38(S2): 173-177. doi:10.15918/j.tbit1001-0645.2018.s2.039

Abstract(498) PDF(127)

Abstract:
Based on research of Florence model which incorporates coefficients reflecting surface dwell effect and Demar formula of ultimate penetration, an optimized method of multi-layer ceramic component armor taking basic armor into account was advanced. With the 14.5mm Armor Piercing (AP) ammunition penetrating component armor, defending armor was designed and validated by tests. It was found that the newly-designed armors have 9.8% lighter weight compared with traditional ones, which helps to optimize structure matching of face-plate, backboard and basic armor.

Fragment Velocity Distribution of Elliptical Cross-Section Killing Warhead Along Circumference

YANG Xiang, WU Hai-jun, PI Ai-guo, LI Jin-zhu, HUANG Feng-lei

2018, 38(S2): 178-183. doi:10.15918/j.tbit1001-0645.2018.s2.040

Abstract(729) PDF(221)

Abstract:
In order to study the fragments speed and its distribution law of the special-shaped warhead, the elliptical-section warhead structure was selected as the research object. Firstly, the finite element numerical method was used to obtain the acceleration law of warhead with different ratio of short and long axes, different ratio of charge qualityCand shell qualityM. The initial velocity of the fragmentation of the cylindrical warhead with the sameC/Mas the warhead of each elliptical section is simulated, and the initial velocity of the fragmentation of the circular section warhead, the azimuth angleδwhen the velocity of elliptical warhead is the same as that of cylindrical warhead, the variations ofδof the elliptical section warhead with the axial ratio and theC/Mchange are obtained. Based on the Gurney formula, the initial velocity and the formula for calculating the initial velocity of the fragment of the elliptical section warhead shell is obtained along the circumferential direction by correcting theβand energy loss. The calculated results show that the initial velocity of the fragment is the largest in the circumferential direction along the short axis and the smallest along the long axis.

Simulate of Laser Ignition B/KNO₃Based on Super Capacitor

WANG Hao-yu, Hong jin, CHU En-yi, Zhang Rui, HE Ai-feng, CAO Chun-qiang, JING Bo

2018, 38(S2): 184-189. doi:10.15918/j.tbit1001-0645.2018.s2.041

Abstract(565) PDF(127)

Abstract:
Aiming at the laser ignition of B/KNO₃pyrotechnic mixtures based on super-capacitor driven laser, a laser ignition model from super capacitor driven laser diode to laser irradiation heating agent is established. The influence of discharge voltage, super capacitor capacitance and equivalent resistance on laser ignition delay is analyzed. The simulation results show that with the increase of the discharge voltage and capacitance of super capacitor and the decrease of the equivalent resistance of super capacitor, the laser output power and energy are significantly increased, the delay time of laser ignition is shortened and the ignition energy decreases significantly. The simulation results can provide the basis and technical support for the laser rapid ignition design based on super capacitor.

Macro-Parameters Numerical Simulation of Ultra-Low Concentration Methane High Temperature Oxidation

NIE Bai-sheng, GONG Jie, GE Bo-qing, GE Ze, ZHU Qi-meng

2018, 38(S2): 190-192. doi:10.15918/j.tbit1001-0645.2018.s2.042

Abstract(511) PDF(136)

Abstract:
In order to study the high temperature oxidation characteristics of ultra-low concentration methane, the high temperature oxidation of five ultra-low concentration methane gases with concentration of 0.5%, 1%, 2%, 3%, 4% was simulated by CHEMKIN software. The variation of pressure, temperature, reactants and resultants after high temperature oxidation was analyzed. The simulation results show that the volume fraction of methane drops sharply with the increase of time. The volume fraction of carbon monoxide produced rises sharply and then drops rapidly to zero. Carbon dioxide volume fraction, temperature and pressure rise sharply and then tend to stabilize. Moreover, temperature, pressure, the final value of carbon dioxide volume fraction and the maximum volume fraction value of carbon monoxide increase with the increase of methane volume fraction.

Inhibitory Characteristics of Foam Ceramics in Circular Tube on Gas Explosion

NIE Bai-sheng, WANG Ye, WANG Jing-wei

2018, 38(S2): 193-197. doi:10.15918/j.tbit1001-0645.2018.s2.043

Abstract(541) PDF(153)

Abstract:
To restrain the shock wave and flame propagation of gas explosion effectively, a large scale circular pipeline experimental system for gas explosion was constructed, and the inhibitory characteristics of foam ceramics on shock wave and flame propagation during gas pre-mixed explosion were studied. The results show that foam ceramics can absorb gas premixed explosion shock wave energy, the inhibition effect of flame and shock wave propagation is obvious. The number, thickness and location of foam ceramic baffles are the key factors. The distance between the baffle position and the ignition end is very important, and its critical value should be within the maximum position of the flame propagation velocity during the detonation period to realize the effective suppression of the gas explosion propagation and development. Compared with single-layer baffle mode, the maximum overpressure of shock wave decreases faster when double-layer baffle is installed. The influence of baffle thickness is not obvious, when the baffle with a thickness of 50 mm or 30 mm is set, the attenuation trend of the maximum overpressure is consistent and the magnitude is very similar.

Study on Separation of TNT From Waste or Obsolete TNT/ RDX/Al Explosive by Melting Centrifugal Method

WANG Yuan-fang, ZHANG Shi-xiao, TONG Yi

2018, 38(S2): 198-204. doi:10.15918/j.tbit1001-0645.2018.s2.044

Abstract(633) PDF(169)

Abstract:
In order to recycle the valuable ingredients in the waste or obsolete TNT/RDX/Al explosive by low-cost method and simple operation, according to the difference of melting point among TNT, RDX and aluminum powder, a method for separating TNT from molten TNT/RDX/Al explosive by centrifugal field is designed. The results show that the optimal conditions for separation are:temperature 85℃~90℃, rotation speed 2 500~3 000 r/min, duration 30~40 min; The TNT recovery by centrifugation is 79% to 82%, and the purity is 95% to 98%.

Study on Penetrating-but-non-Initiating of Nonmetal Jet Against ERA

DONG Fang-dong, WANG Shu, Jin Yong-xi, WANG Zhi-jun

2018, 38(S2): 205-208. doi:10.15918/j.tbit1001-0645.2018.s2.045

Abstract(620) PDF(116)

Abstract:
To compare the superiority of nylon jet and teflon jet penetrating without initiating the explosive reactive armor, numerical and experimental study have been carried out. The results showed that it was the dynamic pressure that initiates the sandwich explosive during the penetrating process. The reflection of stress wave between front panel and rear panel aggravates the reaction of sandwich explosive. In addition to the low density, the penetration performance should also be taken into account to choose an appropriate material for liner. Teflon, by contrast, has shown better advantages.

The Research on Projectile with Ribbed Head Penetrating in to Concrete Target

LI Wei, ZHANG Xue-yan, ZHANG Shuang, WU Hai-jun

2018, 38(S2): 209-214. doi:10.15918/j.tbit1001-0645.2018.s2.046

Abstract(574) PDF(161)

Abstract:
A penetration model for projectile with ribbed head penetrating into concrete target is established, based on dynamic spherical cavity-expansion theory of the concrete material and three-staged theory composed of crater, tunnel and plug. Compared with the oval-shaped projectile, the projectile with ribbed head has characteristics of lower residual velocity, larger axial overload and less inadequate penetration capacity. Finally, the influences of structural parameters are analyzed, including the number,width and height of ribs.

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