Experimental and Theoretical Study of the Cavity Growth of Spherical Fragment Penetrating Liquid-Filled Container

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Anran Chen ◽  
Xiangdong Li ◽  
Lanwei Zhou ◽  
Yangziyi Ji
Keyword(s):  
Theoretical Study ◽  
Cavity Growth ◽  
Acoustic Velocity ◽  
Velocity Range ◽  
Improved Method ◽  
Cavity Shape ◽  
Boundary Constraints ◽  
Hydrodynamic Ram ◽  
Aircraft Fuel ◽  
Liquid Type

Abstract When high-velocity penetrator impacts and penetrates a liquid-filled container such as an aircraft fuel tank, the hydrodynamic ram (HRAM) event occurs. This process could be roughly divided into four phases, each of which could cause different degrees of damage to the liquid-filled container or the surrounding equipment. Spherical fragment impacting tests of different velocities were performed on two sizes of liquid-filled containers to investigate the effect of boundary constraints on cavity growth. The velocity range in the experiment was from 600 m/s to 1400 m/s. Through theoretical analysis and experimental results, it is found that the radial disturbance range of the cavity is not constant in different containers and under different impact velocities. An improved method is presented to modeling the cavity growth in the drag-cavity phases of HRAM events. The approach quantitatively describes the radial disturbance range of the cavity and is appropriate for the calculation of the cavity growth in HRAM. Moreover, the effect of liquid type on cavity growth is studied theoretically. When the fragment velocity is less than Mach 0.5, the length and radius of the cavity are mainly affected by the density of the liquid. When the fragment velocity exceeds Mach 0.5, the characteristics of cavity shape are mainly affected by the acoustic velocity in the liquid.

Numerical Analysis of the Effect of Diffusion and Creep Flow on Cavity Growth

2007 ◽  
Author(s):  
Frederick W. Brust ◽  
Joonyoung Oh
Keyword(s):  
Growth Rate ◽  
Numerical Method ◽  
Cavity Growth ◽  
Volume Growth ◽  
Numerical Results ◽  
Shape Evolution ◽  
Cavity Volume ◽  
Cavity Shape ◽  
Cavity Growth Rate ◽  
Fully Coupled

In this paper, intergranular cavity growth in regimes, where both surface diffusion and deformation enhanced grain boundary diffusion are important, is studied. In order to continuously simulate the cavity shape evolution and cavity growth rate, a fully-coupled numerical method is proposed. Based on the fully-coupled numerical method, a gradual cavity shape change is predicted and this leads to an adverse effect on the cavity growth rates. As the portion of the cavity volume growth due to jacking and viscoplastic deformation in the total cavity volume growth increases, the initially spherical cavity evolves to V-shaped cavity. The numerical results are physically more realistic compared to results in the previous studies. The present numerical results suggest that the cavity shape evolution and cavity growth rate based on an assumed cavity shape, whether spherical or crack-like, cannot be used in this regime due to transitional coupled growth mechanisms.

Short term characteristics of ion-acoustic type radio auroral echoes

1978 ◽  
Vol 56 (2) ◽  
pp. 292-301 ◽  
Author(s):  
Christos Haldoupis ◽  
George Sofko
Keyword(s):  
Signal Amplitude ◽  
Acoustic Velocity ◽  
Velocity Range ◽  
Short Term ◽  
Backscatter Signal ◽  
Ion Acoustic ◽  
Longitudinal Plasma ◽  
Digital Demodulation ◽  
Signal Fading ◽  
Time Sequences

Digital demodulation techniques and spectral analysis are used to study the short term (<1 s) characteristics of the ion-acoustic radio auroral echoes. Examination of 0.4 s time sequences indicates that the signal amplitude undergoes a deep and quasi-periodic fading with strongly marked periodicities in the 2–10 Hz range. Evidence shows that the fading is not due to interference but to the appearance and disappearance of independent scatterers, causing a sequence of backscatter signal bursts. If the assumption is made that these scatterers are longitudinal plasma density waves, the observed signal fading can be interpreted in terms of the growth and decay of individual regions of plasma instability rather than as interference between signals from separated coexisting scattering regions. Investigation of a large number of records suggests the following features for the irregularities associated with the ion-acoustic echoes: (1) their lifetime is in the 0.05–0.25 s range. (2) their growth (or decay) rate is in the 10–60 s−1 range, (3) their velocity remains fairly constant, even during growth and decay, and is always within the ion-acoustic velocity range in the medium.

scholarly journals Numerical Analysis of the Hydrodynamic Ram Phenomenon in Aircraft Fuel Tanks

AIAA Journal ◽  
2012 ◽  
Vol 50 (7) ◽  
pp. 1621-1630 ◽  
Author(s):  
D. Varas ◽  
J. López-Puente ◽  
R. Zaera
Keyword(s):  
Numerical Analysis ◽  
Hydrodynamic Ram ◽  
Aircraft Fuel ◽  
Fuel Tanks

SIMULATION OF HYDRODYNAMIC RAM OF AIRCRAFT FUEL TANK BY BALLISTIC PENETRATION AND DETONATION

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1525-1530 ◽  
Author(s):  
JONG H. KIM ◽  
SEUNG M. JUN
Keyword(s):  
Fluid Structure Interaction ◽  
Fuel Tank ◽  
Explicit Calculation ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Intermediate Complexity ◽  
Hydrodynamic Ram ◽  
Aircraft Fuel ◽  
Ram Effect ◽  
Ballistic Penetration

Airframe survivability and hydrodynamic ram effect of aircraft are investigated. Penetration and internal detonation of a simple tank and ICW(Intermediate Complexity Wing) are simulated by nonlinear explicit calculation. Structural rupture and fluid burst are analytically realized using general coupling of FSI(Fluid-Structure Interaction) and adaptive master-slave contact. Besides, multi-material Eulerian solver and porosity algorithm are employed to model explosive inside fuel and tank bays which are defined in multi-coupling surfaces. Structure and fluid results are animated on the same viewport for enhanced visualization.

Roles of Impurities and Implantation Depth on He+- Cavity Shape in Silicon

2005 ◽  
Vol 864 ◽  
Author(s):  
Gabrielle Regula ◽  
Rachid El Bouayadi ◽  
Maryse Lancin ◽  
Esidor Ntsoenzok ◽  
Bernard Pichaud ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Cavity Growth ◽  
Cavity Shape ◽  
Distribution Shape ◽  
Transmission Electron ◽  
Implantation Depth ◽  
Cavity Characteristics ◽  
Free Environment ◽  
Shape And Size

AbstractSilicon samples were implanted with He+ ions at energies varying from 10keV to 1.55MeV using doses ranging from 1.45×1016 cm-2 to 5×1016cm-2 to obtain similar He concentration at each projection range (Rp). In few samples, gold, platinum, nickel or silver was introduced prior to He+ implantation by diffusion at temperatures ranging from 870°C to 1050°C. All samples were annealed in the 400°C–1050°C temperature range to determine the equilibrium stage of the growth of the cavity. The cavity characteristics (distribution, shape and size) were studied by cross section transmission electron microscopy (XTEM). Their morphology demonstrates the validity of the chemisorption hypothesis when they grow in silicon intentionally contaminated by metal. A consequence of the surface proximity on the cavity characteristics was verified and allows stepping forward two regimes of cavity growth: one, very fast, taking place in a He-free environment and another one, slower, occurring in a He-rich atmosphere.

An Improved Method for the Preparation and TEM Examination of Sharp Pointed Tips used in APFIM and STM

1990 ◽  
Vol 48 (2) ◽  
pp. 102-103
Author(s):  
E.A. Fischione ◽  
P.E. Fischione ◽  
J.J. Haugh ◽  
M.G. Burke
Keyword(s):  
Atom Probe ◽  
Preparation Process ◽  
Improved Method ◽  
Ion Milling ◽  
Polishing Process ◽  
Probe Field ◽  
Scanning Tunnelling ◽  
Stm Tips ◽  
Tunnelling Microscopy ◽  
Ion Microscopy

A common requirement for both Atom Probe Field-Ion Microscopy (APFIM) and Scanning Tunnelling Microscopy (STM) is a sharp pointed tip for use as either the specimen (APFIM) or the probe (STM). Traditionally, tips have been prepared by either chemical or electropolishing techniques. Recently, ion-milling has been successfully employed in the production of APFIM tips [1]. Conventional electropolishing techniques are applicable to a wide variety of metals, but generally require careful manual adjustments during the polishing process and may also be time-consuming. In order to reduce the time and effort involved in the preparation process, a compact, self-contained polishing unit has been developed. This system is based upon the conventional two-stage electropolishing technique in which the specimen/tip blank is first locally thinned or “necked”, and subsequently electropolished until separation occurs.[2,3] The result of this process is the production of two APFIM or STM tips. A mechanized polishing unit that provides these functions while automatically maintaining alignment has been designed and developed.

Immunoelectron microscopic localization of elastic tissue in archival material using an improved method

1990 ◽  
Vol 48 (3) ◽  
pp. 794-795
Author(s):  
J. C. Fanning ◽  
J. F. White ◽  
R. Polewski ◽  
E. G. Cleary
Keyword(s):  
Normal Animal ◽  
Animal Tissue ◽  
Elastic Tissue ◽  
Human Tissues ◽  
Improved Method ◽  
Tissue Samples ◽  
Archival Material ◽  
Immuno Electron Microscopy ◽  
Arteries And Veins ◽  
Biochemical Examination

Elastic tissue is an important component of the walls of arteries and veins, of skin, of the lungs and in lesser amounts, of many other tissues. It is responsible for the rubber-like properties of the arteries and for the normal texture of young skin. It undergoes changes in a number of important diseases such as atherosclerosis and emphysema and on exposure of skin to sunlight.We have recently described methods for the localizationof elastic tissue components in normal animal and human tissues. In the study of developing and diseased tissues it is often not possible to obtain samples which have been optimally prepared for immuno-electron microscopy. Sometimes there is also a need to examine retrospectively samples collected some years previously. We have therefore developed modifications to our published methods to allow examination of human and animal tissue samples obtained at surgery or during post mortem which have subsequently been: 1. stored frozen at -35° or -70°C for biochemical examination; 2.

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