2018 Vol. 38, No. 1

Display Method:
Impact-induced initiation thresholds of polytetrafluoroethylene/Al composite by gas gun
GE Chao, Wubuliaisan MAIMAITITUERSUN, TIAN Chao, DONG Yongxiang, SONG Qing
2018, 38(1): 1-8. doi: 10.11883/bzycj-2017-0030
Impact experiments by a gas gun were conducted to investigate the impact-induced initiation thresholds of a PTFE (polytetrafluoroethylene)/Al composite using targets of steel, aluminum and low-density polyethylene (LDPE) materials and sample rods of four different lengths. By subjecting the samples under different loading conditions, it is shown that the impact-induced initiation of PTFE/Al is determined by both the impact pressure and the loading strain rate. The impact pressure and the strain rate thresholds for initiation were arrested by the experiments and the impacting process of the samples was modeled to compare the experimental and theoretical data. Based on all the experimental results, a theoretical curve was proposed to predict the impact-induced initiation of PTFE/Al under normal impact. The method proposed in this research can also be used in the study of other energetic materials.
Preliminary analysis of underwater detonation performance of titanium fiber explosive
CHEN Haijun, MA Honghao, SHEN Zhaowu, WANG Bo, YANG Ming, CUI Yu
2018, 38(1): 9-18. doi: 10.11883/bzycj-2017-0155
In this study we examined the changing tendency of the shock wave energy, bubble energy, total energy per unit mass and the total energy per unit volume by analysis of the pressure-time curves, and analyzed the chemical reaction process of the Ti fiber explosive through the total energy per unit mass. The results show that the peak pressure and the shock wave energy of the Ti fiber explosive per unit decreases as the Ti fiber content increases, the bubble energy per unit mass increases with the increase of the Ti fiber content, the total energy per unit mass and its energy density increase with the increase of the Ti fiber content. With the increase of the distance between the sensor and explosive, the rate of the Ti fiber explosive's peak pressure decay is slower than that of RDX, while the tendency of the shock wave energy and the bubble energy per unit mass with different contents of the Ti fiber explosive is basically in keeping with the increase of the distance. The chemical reaction process of the Ti fiber explosive was also obtained through the total energy per unit mass.
Effect of obstacles on explosion characteristics of methane/hydrogen
YU Minggao, YANG Xufeng, ZHENG Kai, WAN Shaojie
2018, 38(1): 19-27. doi: 10.11883/bzycj-2017-0172
The effects of the blocking rate and shape of obstacles on the explosion characteristics of methane/hydrogen at the stoichiometric mixture were investigated using experimental facilities fabricated by ourselves. The results demonstrate that there are similar trends in the flame evolution structure obtained from all hydrogen fractions for the same condition, i.e. the blocking rate increases as the premixed flame propagation channel become more narrow; the rate of the premixed flame propagation increases along with the blocking rate and hydrogen fraction, and changes with the obstacle shape. Increasing the blocking rate and the hydrogen fraction enhances the maximum overpressure and speeds up the time of the arrival of the maximum overpressure; both the blocking rate and the hydrogen fraction affect the explosion characteristics of methane/hydrogen, and the explosion characteristics are affected by the blocking rate and the hydrogen fraction when the hydrogen fraction comes below 50%, but by the combustion characteristics of the premixed gas when it comes above 50%. This research can provide a theoretical foundation for the safe use of methane/hydrogen fuel.
A S-wave phase picking method for blasting seismic waves and its application in engineering
YANG Zhaowei, LU Wenbo, GAO Qidong, CHEN Ming, HU Haoran, YAN Peng, WANG Gaohui
2018, 38(1): 28-36. doi: 10.11883/bzycj-2017-0178
The initial and precise identification of the S-wave phase is a crucial step in the inverse analysis of dynamical mechanical parameters of rock mass. The efficiency and precision in this identification is directly linked with those of the dynamical parameters' inversion. Currently, the S-wave identification focuses mostly on the earthquake science and it is still difficult to effectively identify the S-wave phase on an engineering scale. This paper proposes a method that can be effectively used in engineering. Here, by using the four characteristic functions including the short time average cross zero ratio, the deflection angle, the degree of polarization and the ratio of the transversal to the total energy, this method identified the S-wave phase, without having to go through the filtering processes. Combining the identification result of some data from the blasting field experiments in the Fengning hydro power station with our numerical simulation, we validated this method, showing that its relative error is below 3% and that the method is effective, simple and suitable for the S-wave phase identification on the engineering scale.
Influence of thermal shock mechanism and thermal environment on concentric canister launcher
XIA Qianqian, ZHANG Wenyi, QI Bing, YANG Fengbo, YUE Guigao
2018, 38(1): 37-49. doi: 10.11883/bzycj-2016-0141
Based on the homogeneous multiphase theory and vaporization solving program of liquid water, the three-dimensional model of the gas-liquid two-phase fluid dynamics for new concentric canister launcher (CCL) self-launching system was built using the dynamic mesh technology of spring-based smoothing method and laying-based zone moving method. The reliability and validity of the three dimensional calculation of the vaporization program were verified by the experiment of injecting liquid water into the free rocket jet. Transient numerical calculation was carried out, and the influences of the water injection angle on the thermal environment of the launching system and the load characteristics of the missile were discussed. Analysis shows that obvious vaporization reaction occurred in the launch tube, in the -30 degree water injection scheme, the gas-liquid two-phase mixing was sufficient, and the transverse cooling range of the cylinder was more uniform; the overall thermal environment of the missile and launching system was improved significantly, and the goal of continuously cooling the launching system was achieved; after the water injection at the cylinder bottom, the additional thrust and the thrust of the rocket engine increased, with the decrease of the water injection quantity, and the influence of the water injection on the missile load was increasingly weaker.
Simulation on jet formation induced by interaction of shock wave with SF6 bubble
ZHU Yuejin, YU Lei, PAN Jianfeng, PAN Zhenhua, ZHANG Penggang
2018, 38(1): 50-59. doi: 10.11883/bzycj-2016-0135
To better understand the mechanisms governing the shock focusing and jet formation, we simulated the interaction between the planar incident shock wave of the Mach number 1.23 and the SF6 heavy gas bubble using the high resolution computation schemes and grid. The numerical results are consistent with the experimental results of the reference. It was found that the incident shock wave converges along the streamwise direction inside the gas bubble, and forms a pair of longitudinally symmetrical high pressure regions, which then collide in the central symmetrical axis where the shock focusing is completed. The shock focusing forms a local region with high pressure and density, considerably larger than the initial pressure and density. Its peak pressure exceeds by far the normal atmospheric pressure, implying that the SF6 heavy gas bubble has a strong cumulative energy effect. Simultaneously, the shock focusing also induces vorticity variation near the downstream interface of the gas bubble, and the rotation of the vortex pair accelerates the jet formation and development. Hence, both the high pressure region and the vorticity distribution near the downstream gas interface promote the formation of the jet.
An isentropic equation of state of detonation product based on a Hugoniot relationship of detonation product
LIU Yiru, HU Xiaomian
2018, 38(1): 60-65. doi: 10.11883/bzycj-2016-0132
First, an empirical fit of the detonation product Hugoniot relationship through the C-J (Chapman Jouget) point was obtained by fitting 136 sets of the pressure-particle velocity experimental data of different explosives. Then, by Riemann integrating this relationship, an isentropic EOS (equation of state) of the detonation product, which describes the relationship between the pressure and the relative volume of the detonation product, was proposed. Unlike the traditional and empirical isentropic EOS, the new EOS requires no calibration by specific experiment because the parameters in it are just the initial specific volume and the C-J status variables of the explosive, thereby saving the cost of the calibration experiment and computing. For verification, the isentropic expansion curves of the detonation product of the Comp-B, HMX, PETN, ANFO, TNT and LX-14 explosives were plotted in the p-V space by adopting this new isentropic EOS and found to be in good agreement with the corresponding curves plotted by adopting the JWL isentropic EOS.
Failure mode and energy absorption mechanism of steel/aluminum composite plates impacted by spherical fragment
ZHOU Nan, WANG Jinxiang, ZHANG Yaning, GUO Haitao, JIANG Jing
2018, 38(1): 66-75. doi: 10.11883/bzycj-2016-0131
In order to investigate the influence of target structure on the protective performance, series of ballistic experiments and LS-DYNA 3D finite element code were adopted to research the failure mode and energy absorption mechanism of two-layer (steel/aluminum) and three-layer (steel/aluminum/steel) explosive welded targets, as well as a monolithic steel target, which were perforated by spherical fragments. The effects of the layer number, thickness and the combination of the interface on the failure mode were analyzed based on the experimental and numerical results obtained. The results show that the influence of the combination of the target interfaces on the failure mode is the most obvious as compared with the other influencing factors. The fracture mechanism of different plates were shearing and plugging when the interface was well bonded but, when the bonding interface failed due to tension, the thinner rear plate failed mainly due to ductile prolonging deformation. With the increase of the total thickness, the targets were more apt to suffer damage resulting from shearing and plugging. The protective performance of the three-layer composite target is superior to that of the two-layer one with the same areal density and total thickness.
Protection ability of liquid-filled structure subjected to penetration by high-velocity long-rod projectile
WU Xiaoguang, LI Dian, WU Guomin, HOU Hailiang, ZHU Xi, DAI Wenxi
2018, 38(1): 76-84. doi: 10.11883/bzycj-2016-0146
In this work we carried out ballistic impact tests on the liquid-filled structure to improve its protection capability. By adjusting the thickness match ratio to the structure's front panel to its rear ones, we studied how this ratio's influence on the structure's failure modes, pressure loading characteristics and protection capabilities. The results show that the projectile velocity is the main factor that affects the magnitude of the incident pressure peaks. With the increase of the ratio of the back panel thickness to the rear panel thickness, the front panel's failure mode changes from the shear plugging-film bulging-depressed deformation to the shear plugging-film bulging until the shear plugging is damaged, whereas the back panel's failure mode changes from the bulging-dishing damage to the film bulging-petal cracking damage. The front and back panels' failure modes affect each other, the matching relationship of the front and back panels' thicknesses determines the occurrence of the corresponding failure modes. The total thickness of the front and back panels being the same, the larger the thickness ratio, the more the impact energy is absorbed and the stronger the structure's penetration capability.
Dynamic responses of aramid honeycomb sandwich panels loaded by an electric gun
ZHAO Yayun, MO Jianjun, TAN Fuli, SUN Yuxin, ZHANG Jin
2018, 38(1): 85-91. doi: 10.11883/bzycj-2016-0267
We studied the dynamically loaded quadrate sandwich plates constructed from titanium alloy plates with an aramid honeycomb core using high-velocity Mylar flyers produced by an electric gun, and classified systematically the deformation/failure modes of the plates and the honey comb core. Applying the velocity interferometer system for any reflector (VISAR) in measuring the velocity history at the midpoint of the back plates, we analyzed the dynamic response processes of the sandwich panels and identified the influences of the impact velocity on the dynamic response and the impact resistance of the sandwich panels. The results indicate that the stress pulses were blocked by the aramid honeycombs (a low wave impedance material), which led to the deformed front plates that absorbed most of the impact energy, thereby improving effectively the impact resistance capability of the general sandwich panels owing to the high strength of the titanium alloy and the energy absorption of the aramid honeycomb.
Explosion severity parameters of hybrid mixture of methane and lycopodium dust
YU Jianliang, SUN Huili, JI Wentao, YAN Xingqing, ZHANG Xinyan, CAI Linfeng
2018, 38(1): 92-97. doi: 10.11883/bzycj-2016-0276
A modified 20 L standard spherical dust explosion vessel was used to systematically study the explosion characteristics of the methane/lycopodium hybrid mixtures. The explosion pressure (pex), the explosion pressure rise rate (dp/dt)ex and the explosive deflagration index (Kst) of the single-phase methane, the single-phase lycopodium dust, and the methane/lycopodium hybrid mixtures were measured under the same initial conditions. The results showed that methane could obviously enhance the explosion pressure pex of low-concentration lycopodium dust but reduce the pex of high-concentration lycopodium dust. It was proved that methane had no significant effects on the maximum explosion pressure pmax of lycopodium dust. But it could significantly increase the maximum explosion pressure rise rate (dp/dt)max. By evaluating the Kst, it was found that the explosive deflagration index of the methane/lycopodium hybrid mixtures was higher than that of single-phase lycopodium dust. However, the explosive deflagration indices of both methane/lycopodium hybrid mixtures and single-phase lycopodium dusts were lower than that of single-phase methane. Therefore, the coexistence of combustible gas and combustible dust in industrial production process should be avoided to reduce the risk of dust explosions.
Research and application on efficient rock blasting based on circular free surface
HONG yong, MA Honghao, SHEN Zhaowu, REN Lijie, CUI Yu, ZHAO Kai
2018, 38(1): 98-105. doi: 10.11883/bzycj-2016-0176
The present work aims to improve the speed and efficiency of rock excavation by forming a circular excavating surface with the coring technique so that the smallest possible charge of explosives would be needed. At first a numerical simulation was conducted to figure out the explosive parameters, then an experiment was carried out to verify the simulation. Two concrete models were fabricated to respectively model the coring blasting and the traditional blasting, with a vibration meter installed to measure the vibration. Comparison of the vibration data and the blasting effects between the two models show that the effect and the blasting vibration of the coring blasting are significantly superior to those of the traditional blasting. And the coring technique was successfully applied to an actual excavation project. The results show that the coring technique can be applied to blasting in circular excavating surface, thus reducing the number of shot holes, controlling the blasting vibration and improving blasting efficiency. This technique can be applied in urban engineering projects.
Overpressure-impulse damage criterion of air shock waves on biological targets
WANG Xinying, WANG Shushan, LU Xi, WANG Jianmin
2018, 38(1): 106-111. doi: 10.11883/bzycj-2017-0031
In this paper, in view of the damage criteria for air shock waves damaging biological targets, we studied the overpressure-impulse damage criterion that makes up for the deficiencies of the single damage criterion. According to the general damage parameters of air blast shock waves, a normalized formula as damage criterion was proposed, and the acquisition method of damage criteria based on the explosion similitude law was proposed. Then, the damage tests of biological targets were carried out under different explosion conditions. According to the overall damage conditions suffered by the biological targets, the damage levels were determined. The continuous overpressure-impulse curves were obtained using the discrete test data, and the expression of the overpressurevimpulse damage criterions with different damage levels were fitted. The results can be used to evaluate the damage problems of biological targets
A method for blasting vibration signal denoising based on ensemble empirical mode decomposition-wavelet threshold
FEI Honglu, LIU Meng, QU Guangjian, GAO Ying
2018, 38(1): 112-118. doi: 10.11883/bzycj-2016-0148
In this work we proposed a method based on ensemble empirical mode decomposition (EEMD) and wavelet threshold for eliminating the noise contained a in blasting signal. Following this method, the signal is firstly decomposed using the ensemble empirical mode decomposition; then, the intrinsic mode function with noise is processed by the wavelet threshold denoising; and, finally, the processed signal is superimposed on the untreated component of the signal, and the signal thus reconstructed is the denoised signal. This method can not only can effectively remove the noise, but also enable the burst wave form to retain its authenticity and integrity
Influencing factors of dynamic response of hollow laminated glass subject to blast loads
SHI Bo, ZHANG Xiaoying, LI Kuo, LI Zhiqiang
2018, 38(1): 119-123. doi: 10.11883/bzycj-2017-0018
This paper simulated the dynamic responses of hollow tempered laminated glass under the blast load based on a multi-material ALE algorithm using the software LS-DYNA, and analyzed the effect of changing the PVB interlayer property and the thickness of the hollow gas layer on the maximum deflection of the glass plate. The result shows that, with the increase of the thickness of the gas layer, the upper glass plate deflection of the hollow laminated glass decreases, while the lower glass plate deflection increases. However, the deflection of the upper and lower glass plates decreases with the increase of the Young's modulus of the interlayer. The results provide a reference for the safe and efficient design of the hollow laminated glass.
Antiknock analysis and structure optimization for coal mine cylindrical shell refuge capsule under gas explosion load
CHEN Xiaokun, LI Haitao, WANG Qiuhong, JIN Yongfei, DENG Jun, ZHANG Yanni
2018, 38(1): 124-132. doi: 10.11883/bzycj-2016-0248
Coal mine rescue capsules are an indispensable equipment for safe production and effective rescue in coal mines, and their efficiency and stability directly determine the rescue efficiency and the antiknock performance in coal mines. In this paper, a cylindrical shell rescue capsule was designed to guarantee the stability of the capsule under a gas explosion load. Firstly, the load of the explosion field was simulated using ANSYS/LSDYNA and validated with previously reported data. Secondly, the coupling effect between the flow field of the explosion shock wave and the rescue capsule was revealed using the ALE fluid-structure coupling algorithm in real coalmine conditions. Thirdly, the antiknock performance analysis and structural design optimization were conducted on the original model. Finally, the dynamic response, strength and energy variation were compared for the original model and the optimized version qualitatively and quantitatively. The results show that the antiknock performance of the optimized model has reached the required national standards of China.
Flame propagation velocities of cornstarch dust explosion based on RGB color model
ZHANG Hongming, CHEN Xianfeng, ZHANG Ying, NIU Yi, DAI Huaming, HUANG Chuyuan
2018, 38(1): 133-139. doi: 10.11883/bzycj-2016-0278
In order to study the flame propagation process of cornstarch dust explosion, a series of experiments with different dust concentrations were conducted in a small-scale experimental platform. A computational method of the propagation velocity of cornstarch dust explosion flame was established based on the RGB color model. The flame front could be detected by flame recognition and reconstruction and the propagation velocities of dust explosion flame with different mass concentrations were calculated. The results shows that this method can be used to calculate the propagation velocity of the cornstarch dust explosion flame quickly and accurately. The determination of the flame pixel range is the key factor of the flame speed calculation. The flame propagation process in the duct is influenced by the dust concentration. The maximum flame propagation velocities increase firstly and then decrease with the increasing concentration of cornstarch dust cloud. However, the times of the maximum flame propagation velocities have the opposite rules. The maximum flame propagation velocity is up to 7.03 m/s, when the mass concentration of cornstarch dust cloud is 0.63 kg/m3.
Dynamic response of sandwich beam with foldable core under blast loading
ZHANG Peiwen, LI Shiqiang, WANG Zhihua, ZHAO Longmao
2018, 38(1): 140-147. doi: 10.11883/bzycj-2017-0017
In this study four different honeycomb cells were fabricated by changing the original folding angle based on the Tachi-origami pattern that is at present being studied widely, and sandwich beams were made from them by arranging them specifically. The quasi-static mechanical response of the foldable core and dynamic response of the sandwich beam with different foldable core shapes was investigated using the commercial package ABAQUS/explicit. The out-plane Poisson ratio's variation of the foldable core, the back-sheet deflection and the plastic dissipation energy of the sandwich beam were analyzed and compared with the monolithic beam. The anti-explosive performance of the sandwich beams was evaluated by the maximum deflection of the back-sheet. The results show that there is a negative Poisson ratio's performance of the foldable core under quasi-static loading. The blast resistance of the sandwich beam is better than that of the monolithic one. The effect of the original folding angle on the dynamic response is very obvious for the curved web honeycomb. The blast-resistant performance decreases gradually as the original folding angle increases. The blast resistance of the sandwich beam with a straight web honeycomb core is comparatively the worst among the four honeycomb cores.
Fracture behaviors of explosively driven TA2 alloy cylinders under different loadings
YU Xinlu, DONG Xinlong, PAN Shunji
2018, 38(1): 148-154. doi: 10.11883/bzycj-2017-0014
The failure process of an explosively driven TA2 alloy cylinder is related with its material, structure, loading, and so on, with its fracture behavior shown in various ways. In this paper we investigated the mechanism underlying this failure under different explosive loadings using numerical and experimental methods. The results of the finite element analysis showed that, during the driven period, for the ideally homogeneous cylinder, the equivalent plastic strain effect in the inner zone of the cylinder's thick shell, where the secondary plastic zone was formed due to shock wave propagation, was always larger than that on the inner and outer surfaces; under higher blast loading, the cracks originated first in the secondary plastic zone during the driven period and propagated to the inner and outer surfaces in an angle of 45° or 135° to the radial; for lower blast loading, the shear cracks, which originated first in the inner surface, propagated to the outer surface in an angle of 45° or 135° to the radial during the free expanding period; and, although the cracks were all shear cracks, their failure mechanisms differed. The simulated results and experiments agreed pretty well. The phenomenon that cracks originated in the outer surface, as reported earlier concerning some related experiments, might have been affected by the specimens' geometrical and material defects, whose influence on the cylinder's explosion-induced failure needs to be studied further.
Comparison of different methods for source terms in detonation simulation
DENG Li, MA Hu, WU Xiaosong, ZHOU Changsheng
2018, 38(1): 155-163. doi: 10.11883/bzycj-2016-0150
In this study, to solve the stiff source terms resulting from chemical reactions in detonation simulation, we examined the one step method, the asymptotic approach, the α quasi steady state method (αQSS) and the point implicit and compared their performances in coping with the stiff source term problems. We studied the limitations of each method using stability analysis, and investigated their relationships and capabilities in adapting to the changes in chemical reactions, with the shock-induced combustion simulated to compare their efficiencies. The results indicate that the one step method requires at least two times of the smallest time scale while the other three methods have no constraint on the time step. The αQSS can adjust the value of α and the time step with different reaction characteristics, and the one step method and the asymptotic method are the special cases of the αQSS with a constant α. An implicit approach has a better performance in mathematically solving the stiff equations but its low computation efficiency from the inversion of the matrix is sometimes unacceptable. The αQSS method can only consume a half of the CPU time that with the point implicit in shock-induced combustion simulation. In general, the αQSS is a good choice for dealing with stiff source term problems.
Analysis of projectile penetrating into mortar target with elliptical cross-section
WANG Wenjie, ZHANG Xianfeng, DENG Jiajie, ZHENG Yingmin, LIU Chuang
2018, 38(1): 164-173. doi: 10.11883/bzycj-2017-0020
In this work, based on the theory of dynamic spherical cavity expansion, we presented a force model of penetrating projectiles with an elliptical cross-section to study their penetration performance and, using this model, calculated the resistance of the elliptical cross section and the penetration depths. Further, we performed a series of experiments of two typical elliptical cross-sectioned and circular cross-sectioned projectiles with the same mass and length penetrating perpendicularly semi-infinite grout targets at a velocity of 700 m/s to 800 m/s. The results show that the established theoretical model reflected the force condition of the elliptical cross-section and the theoretical results agreed well with the experiment, and that the size of the cross-section had a significant influence on its penetration performance.
Modeling on the reflection and focusing process of the underwater explosion shock waves by an ellipsoidal reflector
GUO Rui, LIU Lei
2018, 38(1): 174-182. doi: 10.11883/bzycj-2017-0024
In the present study, based on the theories of shock wave propagation and nonlinear reflection and focusing, we modelled the reflection and focusing of the underwater explosion shock waves by an ellipsoidal reflector, where the shock wave characteristics in three stages, those of the free propagation, the reflection on the wall and the directional focusing, were discussed respectively, and the corresponding methods on the pressure calculation were introduced. It was found that the discretized calculation domain of the pressure field is determined by employing the approximate geometric equations of the wave fronts and normal lines. Further, the focusing process was simulated and verification was performed by comparison with experimental data, with explanations given. The results indicate that this model can predict the positive focusing pressure with a precision that satisfies engineering requirements, keeping most errors below 10% and draw the focusing process of the shock waves and induced tensile waves in some detail; that the ellipsoidal reflector can focus underwater shock waves efficiently, generating an efficient gain region near the dynamic focus and weakening the attenuation along the closely axial direction; and that the dynamic focus appear ideally in front of the geometric focus, but it is also possible to move backward and even pass the geometric focus, due to actual deformation and backward displacement of the reflector.
Critical penetration velocity of prefabricated fragment in penetrating homogeneous armor steel plate
ZHAO Lijun, JIAO Zhigang, LI Xiaojie, HUANG Xiaojie, ZHAO Dongzhi, ZHU Xiaoping, TANG Hui, WANG Changfu, TIAN Zhen, YU Xinning
2018, 38(1): 183-190. doi: 10.11883/bzycj-2016-0116
In this study, we at first made a mechanical analysis of the process of the prefabricated fragment penetrating fully the homogeneous armor plate using theoretical calculation and experimental study, and derived the penetration velocity respectively for three shapes of prefabricated fragments. Then, by combining live testing with simulation, we obtained this penetration velocity and had it compared with the theoretical calculation results, thereby arriving at the error between them and coming out with the revised coefficient for the critical penetration velocity.
A new method for calculating the detonation velocity of CHNO and CHNOAl explosives
2018, 38(1): 191-196. doi: 10.11883/bzycj-2016-0140
In this work we put forward a new method for calculating the detonation velocity of composite explosive based on the concept of the ideal composite explosive model, and constructed the characteristic detonation velocity equation of air and aluminum with explosive composition. Using this method, we performed calculation of the detonation velocity for 26 mixed CHNO explosives, 13 pure CHNO explosives, and 25 aluminized explosives, all of whose maximum theoretical charge density is more than 85%. The results showed that the calculated detonation velocities were in good agreement with the experimental values. The average relative error was 0.01% and the square of the correlation coefficient is 0.9615. Compared with the commonly adopted methods such as Kamlet and Urizar, the new method was more accurate. The new method not only provides a new way to calculate the detonation velocity of CHNO explosives and CHNOAl explosives, but may also serve as reference for the study of new composite explosives.
Characteristic work capability of non-ideal explosives in concrete
HU Hongwei, FENG Haiyun, CHEN Lang, GU Xiaohui, SONG Pu
2018, 38(1): 197-203. doi: 10.11883/bzycj-2016-0123
In this study we carried out internal blast tests on TNT, PBXN-109, AFX-757 and CL-20 based explosives and measured the concrete cavity volumes of several explosives tested to study the characteristic work capability of non-ideal explosives. A calculation model of the concrete cavity volume was established on the basis of dimensional analysis and experimental dada. The characteristic work capacity of test explosives was evaluated using self-designed concrete cavity volume method. The results show that the concrete cavity volume can be used to evaluate the work capability of non-ideal explosives. The concrete cavity volume and the explosive energy (or detonation heat) forms a linear relationship. The relative work capacity of the explosive in concrete can be determined by the TNT equivalent of the detonation heat.
Effect of hollow ratio on crashworthiness of stainless steel-concrete-steel double-skin tubular columns
WANG Bingbin, WANG Rui
2018, 38(1): 204-211. doi: 10.11883/bzycj-2016-0143
In this paper we simulated the dynamic response of stainless steel-concrete-steel double-skin tubular columns under low speed lateral impact loading using a software of finite element analysis, examined the effect of the hollow rate on the impacting characteristics, and proposed to evaluate the crashworthiness of a structure by using the robust coefficient, by conducting three sets of tests to adjust the typical cases of finite element simulation. The specimen's crashworthiness was analyzed mainly on the basis of its robustness structural stability in the impacting process. The results show that at a hollow rate of 0-0.6, the hollow rate's influence on the value of the impact platform was not obvious and little change in the specimen's crashworthiness was observed; at a hollow rate above 0.73, the value showed an obvious decrease and the crashworthiness was greatly reduced; at a hollow rate of 0-0.6, the specimen's structural robust coefficient was kept relatively high; and at a hollow rate of 0.6-1.0, the specimen's structural robust coefficient was obviously reduced, exhibiting an tendency of decrease in the impacting process.
Heat radiation propagation law of propellant combustion
WANG Yanping, ZENG Dan, ZHANG Tonglai, LI Suling, LIU Ying, WANG Yongtao
2018, 38(1): 212-216. doi: 10.11883/bzycj-2016-0152
In this paper, we presented for the first time a model of the propellant combustion heat radiation propagation by constructing the physical-mathematical model and verifying with experiment. We performed tests under the free field conditions of the single-based propellant combustion heat radiation, compared and analyzed the ball body heat radiation model, and verified that the column model can truly reflect the propellant combustion heat radiation propagation. From the validation tests we found that under the free field conditions the data from 4 types of single-based propellant combustion thermal radiation dose of 1, 3, 5 and 10 kg coincided with the column model, and by fitting the data, obtained the quantitative correlation of the thermal flux, the thermal dose with the dose and the distance. This provided a theoretical foundation for accurate assessment of the damage effect of the single-based propellant combustion.
Theoretical calculation of shock compression properties of MESMs with electronic thermal motion effect
HE Yuan, HE Yong, WANG Chuanting, PAN Xuchao, JIAO Junjie, GUO Lei, YANG Xiangli, LI Quan
2018, 38(1): 217-223. doi: 10.11883/bzycj-2017-0034
In this work, based on the Thomas-Fermi statistical model, we modified the calculation method of the Wu-Jing parameters R and investigated the effect of the electronic thermal motion on such parameters as the particle number, the internal energy, and the pressure, inside the metallic crystal structure so as to truly describe the shock compression properties of porous metal materials. A new equation of state was developed for porous materials in which the contribution of the electronic phases was considered explicitly under the condition of different porosity. The relationship between pressure and particle velocity, shock wave velocity and particle velocity was obtained for typical MESMs, for instance different components of W/Cu alloy (dense) and different dense degrees of Al/Ni alloy. Compared with existing models, the equation of state established in this paper is better fitted with the experimental results. The results show that this model can be used to predict the shock compression properties of metal materials under unreacted conditions. The us-up relationship of porous materials does not exhibit an approximate linear relationship as solid materials, due to the shock compression characteristics that are divided into two distinct phases before and after compaction. The shock compression characteristics of multi-functional energetic structure materials are obviously affected by the porosity and material ratio.
Critical vapour pressure for explosive spalling of high-strength concretebased on Mohr-Coulomb criterion
KANG Yaming, JIA Yan, LUO Yucai, CHEN Jingbo
2018, 38(1): 224-232. doi: 10.11883/bzycj-2016-0305
The explosive spalling probability of high-strength concrete will increase with the increase of water content, which shows that the vapour pressure is one of the main factors causing the explosive spalling, and this pressure affects the strength through changing the effective stress. To determine the effect of vapour pressure on strength quantitatively, a formula of critical vapour pressure was obtained on the basis of the principle of effective stress and Mohr-Coulomb criterion, and its logical rigor was proved from the aspect of mathematics. The main conclusions are as follows. (1) The theoretical formula has a clear physical meaning, and has a good consistency with the existing research results and the practical engineering disaster. (2) The influences of material physical properties on the crack cannot be fully considered in theoretical analyses, so the mechanical tests of concrete at extreme high temperature are the bases for determining the relevant coefficients of theory analysis. (3) Fire accidents should be investigated on the spot. Meanwhile, the destruction form and characteristics of different parts of the building should be analyzed after the fire. On the basis of these, the mechanism is clarified from the two aspects of the stress state and the ultimate failure characteristic of the component. Finally, the deficiencies were improved in theoretical analysis.
Lateral influence rules on explosion-compacted loess embankment by linear explosive bars
WEI Lianyu, LI Haichao, LIU Yanzhu
2018, 38(1): 233-240. doi: 10.11883/bzycj-2016-0298
In order to rationally design the plane layout scheme of drilling holes for explosion compacting the loess embankment of an existing highway, this paper took the loess embankment of a highway reinforced by explosion compaction(EC) as an example and studied the lateral influence rules on EC with linear explosive bar. Firstly, a finite element model was established according to the actual geometry and material parameters of the highway. Then, based on the numerical simulation of sixteen cases carried out by ANSYS/LS-DYNA, the change rules of the horizontal radius of the explosion cavity, the peak values of soil density and their position, the lateral influence radius of explosion compacting loess embankment were obtained. These sixteen cases belong to two kinds of situations. One kind is of explosive bars with equal cross section and unequal length, while another one is of those with equal length and unequal cross section. Moreover, the relationship functions among the increment of soil density after EC with the explosive bar whose cross section was composed of two explosive tubes, the horizontal distance to the core of the explosive bar and the amount of explosive were fitted. Finally, combined with the actual EC engineering of the highway, the application of the above rules in the design of construction scheme was illustrated.