Table of Content

30 April 2010, Volume 31 Issue 4

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Paper

An Investigation on Instability of Deflagration and Detonation Induced by Conical Shock Wave

DONG Gang, FAN Bao-chun, LI Hong-zhi

2010, 31(4):  401-408.  doi:10.3969/j.issn.1000-1093.2010.04.001

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Numerical simulation was carried out to investigate the structures and instabilities of deflagration and detonation waves induced by an incoming flow of stoichiometric H₂/air premixed gas with Mach Number 6.5 over a cone with half cone angle 32°,based on the multi-component Euler equations with chemical reactions. The reliabilities of numerical model and computational grid were verified using the experimental results in Literature［7］. The numerical results show that the combustion induced by conical shock wave includes both detonation and deflagration modes. Both the modes, which can alternately appear, show the regularly spatial instability and the temporally periodic oscillation instability. The regularly spatial unstable detonation is regarded as a coalescence of the basic triple wave structures, while the unstable deflagration shows a zigzag reaction front. In an oscillation combustion period, the evolution of detonation and deflagration modes is affected by triple wave structure, thermodynamics of unburned gas in the reaction induction region and disturbance of reflected waves from wall, and shows the distinct phenomena of which the chemical reaction induction length increases along the cone wall during the deflagration process and decreases during the detonation process. The results are significant for the combustion chamber design of scramjet or standing detonation engine.

Research on the Actual Combustion and Interior Ballistics Process of the Variable-burning Rate Propellantin Cannon

LIU Lin-lin, MA Zhong-liang, XIAO Zhong-liang

2010, 31(4):  409-413.  doi:10.3969/j.issn.1000-1093.2010.04.002

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A potential equilibrium theory was used to get the location of potential equilibrium point and its parameters in order to study the actual combustion and interior ballistics process of the variable-burning rate propellant in cannon. The actual burning gas formation function of the variable-burning rate propellant with different load was established based on the measured p-t curves of the chamber throat in 30 mm cannon. Then the function, which was substituted for a burning gas formation function assumed by the geometric burning law, was used to solve the approximate equations of interior ballistics based on the point of the potential equilibrium theory to get the results of interior ballistics. The results show that the potential equilibrium theory can be used to describe the combustion rule of the variable-burning rate propellant, and expands its applicability; the combustion properties could be studied qualitatively and quantitatively by analyzing the actual burning gas formation function of variable-burning rate propellant; and the interior ballistics equations can be solved accurately using the actual burning gas function of the variable-burning rate propellant.

A Two-phase Flow Model and Numerical Simulation of Ignition

ZHOU Yan-huang， ZHANG Ling-ke， LU Chun-yi， YU Yong-gang

2010, 31(4):  414-418.  doi:10.3969/j.issn.1000-1093.2010.04.003

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The inconsistent ignition of base bleed igniter for base bleed grain is one of the important factors resulting in rang dispersion. For the sake of investigation the inconsistent causes of ignition and reveal the ignition mechanism of base bleed igniter, the reignition process and characteristics of base bleed grain ignited by igniter after a 155 mm base bleed projectile flied out of the gun muzzle was analyzed. A two-phase flow strengthened ignition model was established based on gas-particle two-phase jet theory. In the model, the coupling process of pure gas and two-phase jet, and a complex heat transfer mechanism, including heat radiation, heat convection and heat conduction, of solid-gas or liquid-gas two-phase flow in solid base bleed grain were considered. To obtain the ignition softening time and ignition delay time of base bleed grain, the reignition process was numerically simulated. The numerically simulated results were basically in agreement with the experimental results. The model is suitable for solid propellant which has the similar ignition process.

Interior Ballistics Modeling and Simulation of Conic-chamber Gun System

HOU Jian₁， WEI Ping₁， LI Jin-xin₂

2010, 31(4):  419-422.  doi:10.3969/j.issn.1000-1093.2010.04.004

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The finite element analysis method and correction subordinate work coefficient method were introduced to achieve the interior ballistics modeling and simulation of conic-chamber gun system based on the classical interior ballistics theory. According to the structural characteristics of conic-chamber gun canal and projectile, the interior ballistics was divided into the first rectilinear-chamber phase, conic-chamber phase and the second rectilinear-chamber phase. The stress and deformation of sabot in the conic-chamber phase was calculated by the finite element analytical software LS-DYNA. And the p-t curves of gun and the v-t curves of projectile body were obtained by using LS-DYNA and MATLAB to calculate the interior ballistics of conic-chamber gun. And the methods were proved to be feasible by comparing the simulated results with the test results of rectilinear-chamber gun.

Numerical Simulation and Experimental Study of High Speed Ignition by Detonation

ZHANG Ding-shan, RUAN Wen-jun, WANG Hao, GUO Jin-yan, WANG Shan-sha

2010, 31(4):  423-428.  doi:10.3969/j.issn.1000-1093.2010.04.005

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In order to find a high speed ignition mode which can satisfy the demands of ignition delay time in engineering application, a high speed ignition experimental set-up was designed and an experimental study of ignition by detonation was completed. A theoretical calculation model of high speed ignition by detonation was set up based on the special structure of experimental set-up. The main parameters of ignition process in typical charge arrangement were calculated by programming language with Runge-Kutta. By comparing the computed results with the experimental results, it is concluded that the ignition delay time can achieve three hundred microseconds by using the ignition method, and the result approaches to practical condition. This conclusion is valuable in the application of high speed ignition by detonation in engineering.

Analysis of Launch Safety of an Equilibrium Launching Individual Anti-armor Weapon at Low Temperature

YUN Lai-feng, RUI Xiao-ting₁, CHEN Tao₃

2010, 31(4):  429-433.  doi:10.3969/j.issn.1000-1093.2010.04.006

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The probability of bore burst is an important performance criterion for evaluating the launch safety of weapons. A method for evaluating the launch safety of propellant charge of equilibrium launching individual anti-armor weapon was studied. The interior ballistic performance of this weapon system was analyzed at low temperature, a method was presented for forecasting the probability of bore burst accident, and the probability of bore burst accident caused by propellant charge was calculated by statistically inferring its maximal barrel pressure at low temperature to obey 3-parameter Weibull distribution. The result shows that the probability of bore burst is very big, and this problem can be overcome by improvement. The forecasting method can be used to analyze the launch safety of weapons, such as equilibrium launching individual anti-armor weapon, mortar and recoilless gun.

Effect of Exploding Foil Size on Flyer Velocity

FU Qiu-bo， JIANG Xiao-hua， GUO Fei， WANG Li-ling， WANG Liang

2010, 31(4):  434-436.  doi:10.3969/j.issn.1000-1093.2010.04.007

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The exploding foil is a key component of slapper detonators. The influence of thickness and size of exploding foils on flyer velocity was investigated through optical methods. The results show that, at the pre-specified conditions (3.4 kV,3.5 kA), the plasma generated by a 3.67 μm thick foil enables the flyer velocity to be up to 2 307 m/s. Additionally, the flyer velocity increases with the reduction in the size of the bridge. Therefore, a critical foil thickness that relates to the maximum flyer velocity exists at a certain initiation energy. When the foil thickness is determined, a smaller energy is needed for exploding foils with smaller bridge to initiate the explosive charge so that the firing threshold of slapper detonators can be decreased by reducing the bridge size.

Research on Similar Conditions and Simulative Experiments of Exterior Ballistics for Low Trajectory

XIAO Liang， WANG Zhong-yuan₁， ZHOU Wei-ping₂， YI Wen

2010, 31(4):  437-441.  doi:10.3969/j.issn.1000-1093.2010.04.008

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Similar simulation is an efficient experimental research method. Based on the fourth similarity of exterior ballistics, the similarity relationships between small-caliber simulative projectiles and medium-caliber former projectiles were analyzed in the case of low trajectory. The similar ballistic parameters of flight velocity and distance, rotational speed, and nutation property were researched. The corresponding similarity conditions were obtained. The exterior ballistics measuring method for similar simulation was worked out, and an experimental data fitting model was established. The experimental data shows that the ballistic parameters of small-caliber simulative projectiles and medium-caliber former projectiles are similar. All of these are useful for application of similar theory in exterior ballistics design.

Research on Range Dispersion of Base Bleed Projectile Caused by Inconsistent Working Characteristics of BaseBleed Unit

ZHANG Ling-ke， ZHOU Yan-huang， YU Yong-gang

2010, 31(4):  442-446.  doi:10.3969/j.issn.1000-1093.2010.04.009

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The main characteristics of base bleed projectile is longer firing rang but bigger dispersion by comparison with traditional projectile. One of the important factors which affects the range dispersion is the working inconsistency of base bleed unit. Three kinds of inconsistent aspects, including the ignition delay time, the working time of base bleed unit and the much bigger mass deviation of base bleed propellant grain caused by fragment peeling off, were investigated using the mathematic simulation method based on the interior ballistics and exterior ballistics models, and the random hypothesis theory. The values of firing range changed by average per-unit ignition delay time, working time of base bleed unit and mass deviation were obtained. The numerical simulation result ( 630 m) of firing range due to unit ignition delay time was in good agreement with the test result (667 m). The results of study provide an important reference for engineering design.

Numerical Simulation of Base Bleed Energy Affecting Aerodynamic Performance of Base Bleed Projectiles

CHEN Xin-hong, HUANG Hua, ZHOU Zhi-chao, ZHAO Run-xiang

2010, 31(4):  447-452.  doi:10.3969/j.issn.1000-1093.2010.04.010

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The long range neutralization weapons play an important role in modern war. The extended range technology has become an important developmental direction of modern artillery technology. Base bleed technology is one of the important methods. The gas generated by grain burning contains high energy. This paper focuses on the effect of energy of base bleed gas on the aerodynamic properties. The base bleed boundary condition of energy was found. The three-dimensional Euler equations were solved with MacCormack scheme to obtain the flow field parameters and aerodynamic coefficients, such as the base drag coefficient. The results show that energy is one of the important factors, which has an effect on the aerodynamic properties of base bleed projectile, affecting the drag reduction and the extended range. Higher base bleed gas temperature leads to longer range under the certain conditions. The results can be used in the further improvement of the base bleed projectiles for reference.

Experiment and Numerical Simulation of Integral Multi-explosively Formed Warhead

WANG Meng, HUANG De-wu₂, LUO Rong-mei₂

2010, 31(4):  453-457.  doi:10.3969/j.issn.1000-1093.2010.04.011

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In order to improve the hit probability of explosively formed penetrator (EFP) and the efficiency of explosive charge, a new integral multi-explosively formed penetrator (MEFP) warhead was presented, of which the holes and grooves were fabricated on the whole liner. The static explosion test and numerical simulation of this warhead show that three EFPs were formed out, and each EFP penetrates 2×15 mm 25SiMnMo armor plates. The penetration holes were distributed in the form of equilateral triangle on the target, and the hit probability was improved greatly. The penetration area of MEFP was increased over three times compared to regular EFP with similar structure.

Anti-perforation Performance of Aramid Composite Against Spheric Projectile

GUO Zhong-ren₁， DU Wen-ze₂， ZHONG Wei-hua₁， JIN Zi-ming₁

2010, 31(4):  458-463.  doi:10.3969/j.issn.1000-1093.2010.04.012

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The anti-perforation performance of aramid composite made by aramid fiber reinforced polyurethane against 2.05 g tungsten ball, 1.03 g steel ball and 4.50 g steel ball was studied in this paper. And the difference of anti-perforation performance of it against three different kinds of representative balls above was also discussed. The results show that the anti-perforation performance of aramid composite varies with the bullets. The anti-perforation performance was lower for 2.05 g tungsten balls, and higher for 1.03 g steel balls, while in the middle for 4.50 g steel balls. Moreover, a new method which is called specific energy absorption per direct effect area (PSEA) was put forward for expressing the anti-perforation performance of aramid composites against different kinds of the spheric projectiles. The experiment result shows that PSEAs are almost the same when the aramid composite is impacted by the same kind of spheric projectiles. The PSEA was lower for tungsten balls than for steel spheres, which may be used in calculating the ballistic limit velocity of aramid composite against the other spheric projectiles. And the validation result shows that the ballistic limit velocity calculated by PSEA differs with the test results about 1% to 6%.

Engineering Research on Radial Crater Growth for the Penetration in Concrete Target by Shaped Charge Jet

XIAO Qiang-qiang， HUANG Zheng-xiang， GU Xiao-hui

2010, 31(4):  464-468.  doi:10.3969/j.issn.1000-1093.2010.04.013

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Crater radius is one of the important design parameters for the penetration in c

Experimental Research on the Dynamic Split Properties of Steel Fiber Reinforced Concrete

JIAO Chu-jie₁, JIANG Guo-ping₂, GAO Le₁

2010, 31(4):  469-472.  doi:10.3969/j.issn.1000-1093.2010.04.014

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A split Hopkinson pressure bar (SHPB) was employed to test the dynamic minimum split tension strength of steel fiber reinforced concrete (SFRC). The experimental results show that the split tension stress-time curves of SFRC are almost a double-peak pattern. The energy dissipation capacity of SFRC increased with the increase in the volume fractions of steel fibers, and the stress waves attenuated quickly. The strengthening and toughening of SFRC can be remarkably increased due to the addition of the steel fibers. Under impacting split loading, the main destruction factor of the SFRC specimens is the bond strength between the matrix and steel fiber rather than the tensile strength of steel fibers.

An Engineering Optimum Design Method for Fire Extinguishing Warhead Power

XU Yu-xin₁, WANG Shu-shan₁, WANG Hai-yan₂, MA Xiao-fei₁

2010, 31(4):  473-476.  doi:10.3969/j.issn.1000-1093.2010.04.015

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The optimum design method for the power of fire extinguishing warhead was described. Based on these, the influence rule of different load coefficients on the fire extinguishing radius was found by the disperse experimentation of extinguisher. Hereby, the power optimum design principle and the fire extinguishing method were advanced. The research result has a direction significance for the optimum design of fire extinguishing warhead power. The research idea and method can be used for reference for other related researches.

Research on Protective Capability Against Armor Piercing Round of a Reduced-scale Steel Tube Model

WANG Shuai, LIU Wei-dong, FENG Rong-xin, LIU Kai-xin

2010, 31(4):  477-481.  doi:10.3969/j.issn.1000-1093.2010.04.016

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Metallic tubes exhibit good capacity to eliminate stress waves and absorb kinetic energy under the action of impact load. To develop the capabilities of metallic tubes in the armor pierced-resistance field, a reduced-scale model consisted of a steel tube system was established. Some experiments of this model were performed using an armor-piercing device, which were carefully compared with those of double steel targets. The experimental results show that the steel tube system can greatly absorb the initial kinetic energy of the projectile body in the form of plastic bending, friction and collision, making the model superior to the double layer steel target in the field of armor pierced-resistance. Furthermore, some numerical simulations were conducted, in which the deformation processes and damage modes were shown to be in reasonable agreements with those in the experiments. This research lays a foundation for developing the high efficient armor pierced-resistance structures made up of metallic tubes.

The Effect of the Second Phases on the Target Deformation in 2519 Aluminum Alloy During High Velocity Impact

CHEN Xi, LI Bo-long, NIE Zuo-ren

2010, 31(4):  482-485.  doi:10.3969/j.issn.1000-1093.2010.04.017

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The evolutionary features of the microstructure and the second phase particles during high velocity impact deformation were investigated by using scanning electron microscope and transmission electron microscope. The experimental results show that the nano-scale precipitates (Al₂Cu) with needle shape have been partly dissolved due to local temperature risen by bullet impact. Since the micron-scale second phase (Al₂Cu) with spherical or near-spherical shape was difficult to deform during bullet impact, it resulted in sectional stress concentration , leading to the formation and early enlargement of micro-cracks.

Experimental Research on Failure Wave of Brittle Materials Under Shock Loading

ZHANG Yan-geng， DUAN Zhuo-ping， ZHANG Lian-sheng， WU Hai-jun

2010, 31(4):  486-490.  doi:10.3969/j.issn.1000-1093.2010.04.018

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In order to investigate the failure wave of brittle materials, such as glasses and ceramics, under dynamic compressive loading, the planar impact experiments of A95 alumina ceramic and soda lime glass were conducted under one-dimensional strain condition. The particle velocities on the rear surfaces of samples were acquired by using the VISAR technique. The results show that a re-compression signal on the temporal curve of soda lime glass which represents the occurrence of failure wave under certain pressure, which is agreement with many results in open literatures ［1,4,8-12,17-21］, but no re-compression signal exists on the temporal curve of alumina ceramic. This shows that the damage or fracture mechanisms of glasses and ceramics under shock loading may be different, which need more research in the future.

Numerical Simulation of the Experiment on a Shape Memory Alloy Cantilever Impacted by a Bullet

ZHANG Xing-hua， TANG Zhi-ping， ZHENG Hang

2010, 31(4):  491-498.  doi:10.3969/j.issn.1000-1093.2010.04.019

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A numerical simulation of the experiment on a TiNi shape memory alloy (SMA ) cantilever at the pseudo elastic state impacted by a bullet was investigated by using the FEA software ANSYS-LSDYNA. The result showed that the SMA model adopted in the simulation captured the main characteristic of the cantilever impact response. The simulation reproduced well the movement and deformation of the cantilever and the wave profile in the experiment which were recorded by the high speed camera and measured by the strain gauges respectively. On the basis of the comparison between simulation and experiment, the impact response of the SMA cantilever was revealed in detail. Firstly, the spatio-temporal evolution regularity of the transformation zones was revealed when the transformation flexural wave propagates and interacts with its reflected wave from the free end. Then the typical recoverable and finite characteristics of a transformation hinge and its effect on the structure response were further analyzed. Finally the energy dissipation mechanism of TiNi cantilever was represented.

Volume Measurement Error Analysis and Method Based on Crossing Dual Gratings

HAN Bao-jun, LU Quan, LIU Shang-qian, WANG Hui-feng

2010, 31(4):  499-503.  doi:10.3969/j.issn.1000-1093.2010.04.020

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An indirect measurement method based on crossing dual gratings was proposed for the accurate measurement of powder chamber volume. The characteristics of powder chamber structure were analyzed, the limit errors of measuring key points were distributed reasonably, and a measurement equipment of powder chamber volume was designed, and its measurement error was analyzed. The experimental results show that the method proposed is quite stable, accurate and efficient. Compared with the traditional methods, the diameter measurement errors are improved from ±0.028 mm to ±0.012 mm, the length measurement errors are improved from ±0.05 mm to ±0.013 mm, the relative errors of volume measurement are improved from 0.8‰ to 0.11‰. And the measuring time was less than 24.8 min/m. The method can be used to improve the precision and speed of powder chamber volume measurement effectively.

Experimental Investigation on Dynamic Response of Spherical Explosive Chamber

CHEN Shi-yong， HU Ba-yi， GU Yan， DONG Qi

2010, 31(4):  504-509.  doi:10.3969/j.issn.1000-1093.2010.04.021

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Experimental investigation was conducted for the dynamic response of a real spherical explosive chamber. The vibration characteristics and dynamic strength of the chamber was analyzed by measuring the strain profiles of six typical points on the chamber. The research results show that the strength design of the chamber is appropriate. The engineering design method of the chamber was also verified by the experiments.

Experimental Observation and Numerical Simulation on the Bulging Process of Reinforced Concrete Surface UnderInternal Blast Loading

SHI Dang-yong， ZHANG Qing-ming₁， FU Yue-sheng₃， XIA

2010, 31(4):  510-515.  doi:10.3969/j.issn.1000-1093.2010.04.022

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The bulging process of reinforced concrete surface under internal blast loading was studied. A high-speed motion analysis system was used to record the dynamic bulging process of reinforced concrete surface to obtain its bulge contour, central displacement and bulging velocity curves. A separable reinforced concrete numerical model and fluid-solid interconnection method were used to predict the development of surface bulge in LS-DYNA. The experimental results show that the velocity of surface bulge is controlled mainly by the pressure of explosive gas, and the stress wave cracks the concrete initially. The blasting crater profile is similar to a ladder. Numerical simulation results show that the numerical model can be used to predict the bulging process of surface, and the numerical results coincide well with the experimental data.

Research on Mechanical Behavior of 2D C/SiC Composites at Elevated Temperature Under Uniaxial Compression

SUO Tao， LI Yu-long， LIU Ming-shuang

2010, 31(4):  516-520.  doi:10.3969/j.issn.1000-1093.2010.04.023

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The quasi-static and dynamic compression mechanical behaviors of a kind of 2D C/SiC composite were investigated at temperatures ranging from 293 K to 873 K using the electronic universal testing machine and the split Hopkinson pressure bar. The experimental results show that the material still has a good carrying capacity even at the elevated temperature. The compressive strength of the composite at 873 K decreases by only 10% comparing with that at 293 K. The catastrophic brittle failures were not observed under both quasi-static and dynamic loading. It has been found through analysis that the decrease in carrying capacity of 2D C/SiC composite at elevated temperature is probably due to two reasons: the first one is the residual stress between the two phases because of the different coefficient of heat conductivity,and the second one is the effect of oxidation, which is considered as the more dominating reason of the softening behavior of 2D C/SiC composite at elevated temperatures.

Research Notes

Optimum Design of Canard Parameters of Air Defense Trajectory Correction Projectile Equipped with a Pair ofCanard Surfaces

CHANG Si-jiang₁， WANG Zhong-yuan₁， LIU Tie-zheng₂

2010, 31(4):  521-524.  doi:10.3969/j.issn.1000-1093.2010.04.024

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To improve the performance of air defense trajectory correction projectile (ADTCP), the operating principle of system and the canard control mode were described briefly for the projectile equipped with a pair of canard surfaces. The trajectory normal correction velocity due to the deflection of canard surfaces under the conditions of full command control signal and steady-state flight was investigated. An estimation formula was given, and an optimum design model of trajectory correction capability was proposed by taking the canard aerodynamic shape parameters as design variables. The simulation was conducted. The result show that the control performance of ADTCP can be enhanced effectively by using the optimum design, and the approach provides a reference for the design of canard shape parameters of ADTCP.

Development of Two-layer Explosion-containment Vessel with 2kg TNT Equivalent

LIANG Zhi-gang, MA Yan-jun₂, QIN Xue-jun₂, ZHONG Fang-ping₂,

2010, 31(4):  525-528.  doi:10.3969/j.issn.1000-1093.2010.04.025

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The paper described the design method of two-layer explosion-containment vessel with 2 kg TNT equivalent. The explosion-containment vessel was measured during explosion. The experimental results show that the design of explosion-containment vessel is practicable, and it meets the safety requirements.