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Ballistic response of skin simulant against fragment simulating projectiles

Defence Technology（防务技术） 2023年第12期30卷 70-82页

作者： Punit Kumar Pandey Atul Harmukh M.K.Khan M.A.Iqbal S.G.Ganpule Department of Mechanical and Industrial Engineering Indian Institute of Technology Roorkee247667India Department of Civil Engineering Indian Institute of Technology Roorkee247667India Department of Design Indian Institute of Technology Roorkee247667India

The response of biological phantoms against high velocity impact is actively sought for applications in defense,space,soft robotics and sensing.Towards this end,we study the ballistic response of silicone based skin simulant against fragment impact.Using a pneumatic gas gun setup,six chisel-nosed and three regular shaped(sphere,cylinder,and cube)fragments were impacted on the skin simulant.The resulting skin simulant response was studied in terms of ballistic limit velocities,energy densities,failure pattern,and the mechanics of interaction.The results indicate that the shape of the fragment affects the ballistic limit velocities.The ballistic limit velocities,energy densities of the chisel-nosed fragment simulating projectiles were relatively insensitive to the size(mass),except for the smallest(0.16 g)and largest(2.79 g)chisel-nosed fragment.For the same size(1 g),ballistic limit velocities and failure are dependent on the shape of the fragment.The skin simulant failed by combined plugging and elastic hole enlargement.Failure in the spherical fragment was dominated by the elastic hole enlargement,whereas plugging failure was dominant in all other fragments.The spherical,cylindrical,and chisel-nosed fragments created circular cavities,and the cubical fragment created a square cavity.In the case of the spherical fragment,slipping of the fragment within the skin simulant was seen.Cubical fragments created lateral cracks emanating from the corners of the square cavity.Interestingly,for all the fragments,the maximum deformation corresponding to the perforation was lower than the non-perforation indicating rate dependent,stress driven failure.The maximum deformation was also dependent on the shape of the fragment.Overall,these results provide unique insights into the mechanical response of a soft simulant against ballistic impact.Results have utility in the calibration and validation of computational models,design of personal protective equipment,and antipersonnel systems.

关键词： Skin simulant fragment Impact Ballistic limit velocity Energy density Failure

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The role of tangential velocity in explosive initiation by fragment impact

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Defence Technology（防务技术） 2022年第12期18卷 2190-2197页

作者： Vitaly Leus Roy Ceder Valentin Ognev Meir Mayseless RAFAEL Ballistic Center P.O.Box 2250HaifaIsrael Faculty of Engineering Sciences Ben-Gurion University of the NegevBeer-Sheva84105Israel

An initiation study is presented in which we examine the effect of the normal and the tangential velocity components of a fragment that impacts a covered and a bare Comp-B explosive. The study is based on calibrated numerical Lagrangian simulations using the LS-Dyna hydrocode. A special procedure was developed to present the estimated initiation point and the shock wave transition into detonation for various impact angles. The influence of the fragment strength and the steel cover thickness on the detonation threshold were also examined. The velocity threshold results are presented and used to modify the Jacobs-Roslund initiation model.

关键词： High explosive initiation Lee-tarver Jacobs-roslund fragment

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fragment Identification and Statistics Method of Hypervelocity Impact SPH Simulation

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Chinese Journal of Aeronautics 2011年第1期24卷 18-24页

作者： ZHANG Xiaotian JIA Guanghui HUANG Hai School of Astronautics Beo'ing University of Aeronautics and Astronautics Beijing 100191 China

A comprehensive treatment to the fragment identification and statistics for the smoothed particle hydrodynamics （SPH） simulation of hypervelocity impact is presented. Based on SPH method, combined with finite element method （FEM）, the computation is performed. The fragments are identified by a new pre- and post-processing algorithm and then converted into a binary graph. The number of fragments and the attached SPH particles are determined by counting the quantity of connected domains on the binary graph. The size, velocity vector and mass of each fragment are calculated by the particles’ summation and weighted average. The dependence of this method on finite element edge length and simulation terminal time is discussed. An example of tungsten rods impacting steel plates is given for calibration. The computation results match experiments well and demonstrate the effectiveness of this method.

关键词： impact simulation smoothed particle hydrodynamics fragment hypervelocity

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On the breakage function for constructing the fragment replacement modes

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Particuology 2019年第3期17卷 207-217页

作者： Wei Zhou Kun Xu Gang Ma Xiaolin Chang State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan 430072 China Changjiang Institute of Survey Planning Design and Research Wuhan 4300 W China Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering Ministry of Education Wuhan University Wuhan 430072 China

The fragment replacement method (FRM), a particle breakage simulation method, is often used in discrete element simulations to investigate the particle breakage effect on the mechanical behavior of granular materials. The fragment size distribution of the fragment replacement mode of FRM, which is generally generated based on the fragmentation characteristics of single particles after uniaxial compression, affects the breakage process and the mechanical behavior of the particle assembly. However, existing fragment replacement modes are seldom generated based on experimental data analysis. To capture the fragmentation process and investigate the breakage function for the construction of the fragment replacement mode, 60 numerical single particle compression tests were implemented by DEM. The bonded-particle model was applied to generate the crushable rock particles. The numerical simulations were qualitatively validated by experimental results, and the fragment size of broken single particles was analyzed. The fractal dimension was used to describe the fragmentation degree of single particles after compression. The fragmentation degree was random, and the fractal dimensions of the 60 tests at the same loading displacement fit the Weibull distribution well. The characteristic fractal dimension increased with increasing loading displacement, indicating that the fragmentation of single particles is a gradual process. According to the overall breakage function of the 60 tests at the first bulk breakage, a two-stage distribution model with 4 parameters was proposed and validated by the numerical and experimental results. The various fracture patterns of a single particle at the first bulk breakage under compression tests were well captured by the two-stage distribution model. Finally, an initial application strategy using the two-stage distribution model to construct fragment replacement modes was discussed and presented.

关键词： Particle breakage Single particle compression test DEM fragment replacement mode Breakage function

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Effect of initiation manners on the scattering characteristics of semi-preformed fragment warhead

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Defence Technology（防务技术） 2018年第5期14卷 578-584页

作者： Xu-yang Wang Xiang-shao Kong Cheng Zheng Wei-guo Wu Key Laboratory of High Performance Ship Technology (Wuhan University of Technology) Ministry of Education Departments of Naval Architecture Ocean and Structural Engineering School of Transportation Wuhan University of Technology

The lethality of a semi-preformed fragment warhead is closely related to the expand velocity and spatial distribution of the fragments from ruptured metal casing. The topic of how to improve the utilization of charge of have been drawing great attention from researchers and designer in this filed. In present paper,in order to investigate the influence of charge initiation manners on the scattering characteristics of semi-preformed fragment warhead, the numerical simulations and experimental test are conducted.Firstly, the influence of grid density on numerical results is investigated, and a proper numerical model with relatively high accuracy and effectiveness is determined. Then. numerical simulations of three kinds of different initiation position of a semi-preformed fragment warhead are carried out. An experimental test of the explosion of a semi-preformed fragment warhead is carried out. By comparing and analyzing the numerical results and experimental data, it is found that the initiation manners have great influence on scattering characteristics of semi-preformed fragment warhead. The researcher work of this paper would provide an effective alternative method to optimize the design of warhead.

关键词： Initiation manners Semi-preformed fragment warhead Deformation pattern

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Parametric study of single confined fragment launch explosive device

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Defence Technology（防务技术） 2019年第2期15卷 179-185页

作者： Pankaj K.Choudha A.Kumaraswamy Kusumkant D.Dhote Armament Research & Development Establishment (DRDO) Defence Institute of Advanced Technology

In this article, parametric study of single confined fragment launch device was carried out. The configuration proposed was further studied to derive the empirical relationship for effect of fragment size,charge size, confinement thickness on fragment velocity. The simulations were carried out using ANSYSAUTODYNE explicit solver. fragment velocities were estimated as a function of different parametric combinations of explosive quantities, charge length to diameter ratio, fragment height to diameter ratio,confinement thickness, fragment material and fragment mass. The data was further converted to charge to metal ratio under fragment and confinement. It was observed that, increase in confinement thickness,charge quantity and decrease in fragment height increases the fragment velocity. It is also noted that,charge to metal mass ratio under fragment significantly affects the fragment velocity. At the end, an empirical relationship for fragment velocity interms of all these parameters was established. Using these relations, two velocities 1831.92 m/s and 2523.9 m/s required for NATO STANAG 4496 IM test were estimated. The design parameters for these velocities are presented. Also, the results estimated using the empirical relationship has been compared with published experimental data. Error in the predicted velocities is within the acceptable range. The empirical relationship proposed will be useful for finalization of design of the fragment launch device.

关键词： Confinement fragment size Empirical relationship fragment velocity Insensitive munition test fragment launching device

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Real-time calculation of fragment velocity for cylindrical warheads

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Defence Technology（防务技术） 2019年第3期15卷 264-271页

作者： David Felix Ian Colwill Elias Stipidis Institution of Engineering and Technology Stevenage England Member of British Computer Society London Institute of Electrical and Electronics Engineers London

To simulate explosion fragments, it is necessary to predict many variables such as fragment velocity, size distribution and projection angle. For active protection systems these predictions need to be made very quickly, before the weapon hits the target. Fast predictions also need to be made in real time simulations when the impact of many different computer models need to be assessed. The research presented in this paper focuses on creating a fast and accurate estimate of one of these variables - the initial fragment velocity. The Gurney equation was the first equation to calculate initial fragment velocity. This equation, sometimes with modifications, is still used today where finite element analysis or complex mathematical approaches are considered too computationally expensive. This paper enhances and improves Breech’s two-dimensional Gurney equation using available empirical data and the principals of conservation of momentum and energy. The results are computationally quick, providing improved accuracy for estimating initial fragment velocity. This will allow the developed model to be available for real-time simulation and fast computation, with improved accuracy when compared to existing approaches.

关键词： Initial fragment velocity Real-time simulation Cylindrical explosion

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Evaluation of radiation environment in the target area of fragment separator HFRS at HIAF

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Nuclear Science and Techniques 2018年第10期29卷 229-235页

作者： Yao Yang You-Wu Su Wu-Yuan Li Jun-Kui Xu Chong Xu Wei-Wei Yan Wang Mao Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

In this work, the radiation environment in the target area of a fragment separator is evaluated using FLUKA code. The energy deposition in quadrupole coils is presented to provide guidance for a radiation-resistant magnets design. Results show that neutrons dominate in the prompt radiation field. A compact shielding design is recommended for high radiation areas along with the minimization of air activation in the tunnel in order to minimize the radiation effect on nearby beam lines. The displacements per atom results for the graphite target and copper coils indicate that the effect is insignificant. In addition, the activation level of the target is estimated for workers under possible hands-on maintenance condition.

关键词： fragment separator FLUKA Radiation levels Radiation damage

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fragment Angular Distributions for ^(40)Ar+^(197)Au Reaction

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Chinese journal of nuclear physics 1995年第1期17卷 21-23页

作者： Liu Guo-xing Chen Ke-liang Yu Xian Zheng Ji-wen Jin Wei-yang Sun Tong-yu Wu Ding-qing Zhao Li-li Zang Xiang Yin Xin-min Qin Zhi (Institute of Modern Physics.Chinese Acaemy of Sciences.Lanzhou 730000) Inst of Modern Physics Chinese Acad of Sciences Lanzhou China

The fragment angular distributions for the 600 MeV 40Ar+197Au reaction aremeasured using off line γ-ray spectroscopy technique.The features of the fragment an-gular distributions and the reaction mechanisms for the p... 详细信息

关键词： fragment angular distribution Intermediate mass fragment

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Data Bucket-Based fragment Management for Solid State Drive Storage System

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Journal of Electronic Science and Technology 2020年第4期18卷 330-340页

作者： Wei Jiang Jun-Long Wang Jin-Yu Zhan Jing-Huan Yu Hai-Bo Hu School of Information and Software Engineering University of Electronic Science and Technology of ChinaChengdu 610054 Computer Science Department City University of Hong KongHong Kong 999077

The current storage mechanism considered little in data’s keeping characteristics.These can produce fragments of various sizes among data sets.In some cases,these fragments may be serious and harm system performance.In this paper,we manage to modify the current storage mechanism.We introduce an extra storage unit called data bucket into the classical data manage architecture.Next,we modify the data manage mechanism to improve our designs.By keeping data according to their visited information,both the number of fragments and the fragment size are greatly reduced.Considering different data features and storage device conditions,we also improve the solid state drive(SSD)lifetime by keeping data into different spaces.Experiments show that our designs have a positive influence on the SSD storage density and actual service time.

关键词： Data structure erasing time fragment solid state driver(SSD)

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