NUMERICAL ESTIMATION OF SHAPED CHARGES EFFICIENCY

2019 ◽  
Vol 149 (1) ◽  
pp. 7-22
Author(s):  
Jan Bagrowski ◽  
Rafał Bazela ◽  
Jacek Borkowski ◽  
Paweł Podgórzak ◽  
Karol Jach
Keyword(s):  
Experimental Data ◽  
Shaped Charge ◽  
Numerical Calculations ◽  
Numerical Estimation ◽  
Maximal Extension ◽  
Minimal Velocity ◽  
Penetration Depths

The paper shows the estimations of maximal penetration depths of shaped charge jets in a steel armour as a function of stand-off distance to the liner base. The data – in-stantaneous coordinates of positions, masses, and velocities of jet elements were received as results of numerical calculations for selected examples of designs of shaped charges. It was shown that the crater’s depth is a function of acceptable maximal extension of jet elements and their minimal velocity. The results were compared with experimental data.

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

2021 ◽  
pp. 204141962110377
Author(s):  
Yaniv Vayig ◽  
Zvi Rosenberg
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Dynamic Pressure ◽  
Oblique Impacts ◽  
Simulation Results ◽  
The Impact ◽  
Penetration Depths ◽  
Resistance To Penetration ◽  
Good Agreement

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

scholarly journals Analytical Formula for the Ratio of Central to Minimum Film Thickness in a Circular EHL Contact

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 80 ◽  
Author(s):  
Petr Sperka ◽  
Ivan Krupka ◽  
Martin Hartl
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Analytical Formula ◽  
Numerical Calculations ◽  
Constant Ratio ◽  
Viscosity Coefficients ◽  
Wide Range ◽  
Minimum Film Thickness ◽  
Film Parameter ◽  
Ehl Contact

Prediction of minimum film thickness is often used in practice for calculation of film parameter to design machine operation in full film regime. It was reported several times that majority of prediction formulas cannot match experimental data in terms of minimum film thickness. These standard prediction formulas give almost constant ratio between central and minimum film thickness while numerical calculations show ratio which spans from 1 to more than 3 depending on M and L parameters. In this paper, an analytical formula of this ratio is presented for lubricants with various pressure–viscosity coefficients. The analytical formula is compared with optical interferometry measurements and differences are discussed. It allows better prediction, compared to standard formulas, of minimum film thickness for wide range of M and L parameters.

Viscous Dissipation in Laminar Water Flows in Micro-Tubes

2007 ◽  
Author(s):  
In-Hwan Yang ◽  
Mohamed S. El-Genk
Keyword(s):  
Experimental Data ◽  
Viscous Dissipation ◽  
Temperature Rise ◽  
Experimental Results ◽  
Numerical Calculations ◽  
Analytical Expression ◽  
Water Flows ◽  
Good Agreement

Numerical calculations are performed to investigate the effect of viscous dissipation on the temperature rise and friction numbers for laminar water flows in micro-tubes. The calculated values are compared with those determined from reported experimental data for glass and diffused silica micro-tubes (D = 16 – 101 μm and L/D = 625 – 1479). The results confirm a definite slip at the wall with slip lengths of ∼ 0.7 μm and 1.0 μm, which decrease the friction number and the temperature rise in the micro-tubes, but their effect gradually diminishes as either D or L/D increases. The friction number decreases exponentially as D decreases and, to a lesser extent, as L/D increases. The effect of L/D on the friction number is insignificant for micro-tube diameters ≤ 20 μm. For D > 400 μm, the friction number approaches that of Hagen-Posieuille of 64 for macro-tubes when L/D > 1500, but approaches higher values at smaller L/D. The dimensionless analytical expression developed for calculating the friction number and the temperature rise for water flows in micro-tubes is in good agreement with both the numerical and experimental results.

scholarly journals Magnetische Widerstandsänderung von Kupfer-und Silber-Einkristallen

1969 ◽  
Vol 24 (6) ◽  
pp. 922-929 ◽  
Author(s):  
W. Neubert ◽  
W. Neubert
Keyword(s):  
Experimental Data ◽  
Magnetic Fields ◽  
Fermi Surface ◽  
Single Crystals ◽  
Analytical Representation ◽  
Numerical Calculations ◽  
Scattering Mechanism ◽  
Weak Magnetic Fields

Abstract Magnetoresistance measurements of Copper and Silver single crystals in weak magnetic fields at 4.2 K are reported. In addition, the magnetosresistance has been calculated. The model used is based on ROAF's analytical representation of the Fermi surface. In view of the simplifying as­ sumptions made about bandstructure and scattering mechanism, the experimental data are found to agree reasonably well with the results of the numerical calculations.

Numerical and Experimental Investigations of Wave Field Around a Circular Island with the Presence of Weak Currents

2002 ◽  
Vol 18 (1) ◽  
pp. 35-42
Author(s):  
Ming-Chung Lin ◽  
Chao-Min Hsu ◽  
Shou-Cheng Wang ◽  
Chao-Lung Ting
Keyword(s):  
Experimental Data ◽  
Wave Field ◽  
Wave Height ◽  
Incident Wave ◽  
Numerical Calculations ◽  
Experimental Investigations ◽  
Wave Refraction ◽  
Circular Island ◽  
Incident Waves ◽  
A Current

ABSTRACTThis study elucidated the complicated phenomena of wave refraction and diffraction around a circular island due to random incident waves traveling with a current. Various combinations of random incident wave and current conditions were used to investigate the wave height distributions around a circular island numerically and experimentally. Numerical calculations were carried out based on the theory derived by Lin & Hsu [1]. According to the results, it shows that numerical calculations can predict experimental data quantitatively well.

Calculations of the Spontaneous Polarizations and Dielectric Constants for AlN, GaN, InN, and SiC

2010 ◽  
Vol 645-648 ◽  
pp. 1203-1206
Author(s):  
Sergey Y. Davydov ◽  
Alexander A. Lebedev
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Spontaneous Polarization ◽  
Reasonable Agreement ◽  
Low Frequency ◽  
Analytical Form ◽  
Dielectric Constants ◽  
Numerical Calculations ◽  
Ab Initio Methods ◽  
Theoretical Results

Within the scope of the Harrison’s bond orbital model the spontaneous polarization, high- and low frequency dielectric constants are obtained in an analytical form. Theoretical results are in a reasonable agreement with the experimental data available and the numerical calculations based on the ab initio methods.

A New Slip Theory of Plasticity

1974 ◽  
Vol 41 (3) ◽  
pp. 587-592 ◽  
Author(s):  
T. H. Lin ◽  
Y. M. Ito ◽  
C. L. Yu
Keyword(s):  
Experimental Data ◽  
Equilibrium Condition ◽  
Numerical Calculations ◽  
Thin Wall ◽  
Face Centered Cubic ◽  
Stress Strain ◽  
Elastic Range ◽  
Theory Of Plasticity ◽  
Face Centered ◽  
Good Agreement

A slip theory is presented for the calculation of the incremental stress-strain relations of a face-centered cubic polycrystal such as aluminum and its alloys, from its experimental uniaxial curves. This theory satisfies the conditions of equilibrium, condition of continuity of displacement as well as the slip characteristics of the component crystals. Numerical calculations based on this theory give results which are in good agreement with known experimental data on thin wall cylinders subject to different ratios of incremental axial and torsional loadings after being compressed beyond the elastic range.

Model of a Thin Rod with Viscoelastic Magnetizablematerial in the Alternating Magnetic Field

2012 ◽  
Vol 190 ◽  
pp. 629-632 ◽  
Author(s):  
Klaus Zimmermann ◽  
Igor Zeidis ◽  
V.A. Naletova ◽  
S.A. Kalmykov ◽  
V.A. Turkov
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Vertical Plane ◽  
Alternating Magnetic Field ◽  
Numerical Calculations ◽  
Theoretical Results ◽  
2D Model

The motion of a thin rod with viscoelastic magnetizable material in a channelunder the action of the alternating magnetic field of the coils is considered experimentally andtheoretically. The dynamic 2D model of a thin rod with viscoelastic magnetizable material isused. Numerical calculations of the rod motion in a vertical plane under the action of alternatingmagnetic field, gravity and friction are performed using this model. An influence of parametersof the problem on the rod velocity is studied theoretically. Theoretical results are comparedwith experimental data.

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