Papers by Keyword: Fragment

Abstract: we analyze the damage effect of different fragments of tank weapon system. The fragment penetrating 125mm smoothbore tube as an example, we established the simulation modeling and setting the initial conditions for the calculation of the. Numerical simulation of damage of fragment penetrating the gun tube by using ANSYS software, we analyze the damage assessment parameters. By using multiple regression method to analyze the results, we conclude that damage rule fragment penetration of gun tube.

Abstract: Based on the design of a conventional Shrike warhead, an improved design of warhead is proposed, which combined the properties of a deformable warhead. The processes of explosive loading and fragments scattering are simulated by the finite element software LS-DYNA, the improved warhead and the conventional Shrike warhead are detonated in different initiating modes. According to data analysis, gains of fragment density and velocity on target have been achieved. Furthermore, the damage effectiveness of fragments against Patriot radar car has been estimated.

Abstract: The work presented in this paper concerns a project on the optimization of protections subjected to explosions (IED’s threat). Explosions generate two types of threats for a protective structure: blast and impact of fragments. Perforating and non-perforating impact tests were performed in our laboratory with steel spherical projectiles impacting a target based on Kevlar^® textile layers and a crushable material, Crushmat^®. These tests required to develop a specific experimental test setup in order to contain the composite protective structure and to be able to measure the relevant parameters. The experiments allow us to determine the ballistic performance and basic parameters of the protection, and to validate finite element numerical models (LS-DYNA) resulting in a performant prediction tool. The approach used for the simulation consists in the representation of the full textile architecture with solid elements. Therefore, the textile material is explicitly represented in the model in order to have a good representation of the physical phenomena occurring during impact. For the crushable material, a representation using SPH was chosen in order to take the granular behaviour of this material into account. Good results are obtained with such models. However, these models are very complicated and computing time consuming. The geometry has to be well adapted and symmetry has to be exploited. On the other hand, representation of a granular material with SPH does not take into account some characteristics of this material during impact, such as the pulverisation process of the granular material. Solutions to take these phenomena into account in the model are proposed.

Abstract: In order to assess the safety of the explosive anti-riots munition, proceeding with the fragment’s force condition was analyzed in the flying process, the dynamical model of the fragment for the explosive anti-riots munition was deduced, then the velocity decay property of different shape fragments were calculated and analyzed also. The results show that the velocity decay of the spherical fragment is slowest, next came the rectangular fragment and the irregular shape fragment, with the same initial velocity (_v0) and separation angle (α), and the velocity decay of the same fragment at α >0 is more quickly than at α <0, with the same initial velocity (v0).

Abstract: The question of the anti-missile fragment produced by the Kinetic Kill Vehicle (KKV) intercepting the Tactical Ballistic Missile (TBM) is studied. It turns out the anti-missile fragment are composite outcome of the impact and explosion. By analysis the National Aeronautics and Space Administration (NASA) impact breakup model is suggested to calculate the fragment charac-teristic. The minimum mass threshold of effective fragment is deduced; the damages probability model that the debris cloud impacts the cooperative target is established based on Poisson distribu-tion. The simulation case indicates that the damage probability can achieve the 10^-3 magnitude, and should attach importance to this threat.

Abstract: With reflection on the spatial morphology continuity of water towns nurtured in the environment of Jiangnan (south of the lower reaches of the Yangtze River), the writer analyses, on the basis of analysis of the prototype elements which constitutes the spatial morphology of the water towns, the characteristics and reasons of the spatial morphology evolution of modern towns and finds that it is an operational method to restore the fragmented morphology starting from the archetype elements, thus putting forward the idea of restoring the ecological corridor of water network, integrating folk house architecture and returning the street to a humanity space.

Abstract: Needing to analyse fragment’s destructive effect for military researching purpose, it is produced after armour-piercing warhead penetrate target. How to reduce physical test expense and acquire believable researching result at the same time have been puzzled problems that must be solved as soon as possible. Discussing techniques of fragment produced in armour-piercing warhead penetration process with the way of numerical simulation based on AUTODYN, it is a program that analyses dynamics in this paper. Techniques mainly include the Lagrange, the SPH, the Lagrange combining with the SPH and the Lagrange combining with restriction invalidation, at the same time, analysed different technique’s merit and demerit by establishing the numeric simulation model of armour-piercing warhead destroying target and obtaining simulation result. By researching the technique of making numeric fragment, establishing favorable base for researching armour-piercing warhead destroying mechanism.

Abstract: In the present work, solidification of hypoeutectic, eutectic and hypereutectic Al-Cu alloys was illustrated by synchrotron X ray imaging, and the CET of hypoeutectic alloy was picked out to thorough investigated. The mechanism of hypoeutectic dendrites fragment behaviors among the nucleation area was studied by in-situ imaging and first-principles computation. The results show that the density difference between the fragments and the enriched melt leads to the movement of the fragments. The ejected fragments contributed to the columnar-eutectic transition and expanded the breadth of mush zone in front of the solid/liquid interface.

Abstract: To reduce safe distance such as inhabited building distance (IBD), a new type magazine, which is referred to as a subsurface magazine, has been proposed and the explosion effects have been discussed. We have conducted explosive tests by using relatively large scale models (23 kg and 78 kg in mass) and examined mass effect (scale effect) of blast waves caused by explosion of high explosives. The magazines were composed of a arch-type explosive storage room with a line hinge along the top of the roof of the wall, a square passage way to ground which will release the blast wave. Explosion hazards from the explosion of subsurface magazines were collected to understand the characteristics of airblast, fragments, and ground shocks. Safety criteria for the subsurface magazine are discussed based on the experimental results.

Abstract: The effect of Thermomechanical Processing (TMP) on the fine structure (dislocation density and fragments evolution), recrystallization, carbide transformations and tendency toward intercrystalline corrosion (ICC) and corrosion-mechanical strength of AISI 321 type steels is described. It’s shown that the grain size and overall amount of carbide phase has almost no effect on ICC. With an increase in dislocation density a tendency is observed toward a reduction in corrosion rate, but increases with an increase in proportion of recrystallized material. This connection is explained by an increasing of the level of local microstresses, which may be arranged structurally in the form of partial disclinations and aggravate ICC. A new test procedure was developed for estimating the corrosion-mechanical strength of steel. It follows from the obtained data that the hot working with the following accelerate cooling under industrial conditions does not develop a tendency toward corrosion cracking in 3% agueous NaCl solution.