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Terminal Ballistics and Impact Physics

Penetration Efficiency as a Function of Target Obliquity and Projectile Pitch

[+] Author and Article Information
Charles E., Jr. Anderson

Engineering Dynamics Department,
Southwest Research Institute,
P.O. Drawer 28510,
San Antonio, TX 78228-0510

Thilo Behner

Fraunhofer Institute Kurzzeitdynamik,
Ernst-Mach-Institut, Eckerstr. 4,
79104 Freiburg, Germany

Volker Hohler

Retired
Fraunhofer Institute Kurzzeitdynamik,
Ernst-Mach-Institut, Eckerstr. 4,
79104 Freiburg, Germany

It is noted that there is little difference between α1 and total yaw for large angles of yaw (that is, α2 is negligible) as is evident by examining Tables 5–7, and as discussed in the Appendix.

Manuscript received June 4, 2012; final manuscript received August 22, 2012; accepted manuscript posted January 9, 2013; published online April 19, 2013. Assoc. Editor: Bo S. G. Janzon.

J. Appl. Mech 80(3), 031801 (Apr 19, 2013) (11 pages) Paper No: JAM-12-1215; doi: 10.1115/1.4023342 History: Received June 04, 2012; Revised August 22, 2012; Accepted January 09, 2013

The influence of pitch (vertical yaw) angle on the penetration reduction of rod projectiles into oblique targets has been investigated for tungsten sinter alloy rods with a blunt nose and L/D = 20. Semi-infinite RHA targets with an obliquity of 30 deg, 45 deg, and 60 deg were impacted at 1650 m/s. The pitch angles were varied between ±90 deg. The strong asymmetric behavior of the target crater is dependent on whether the pitch is positive or negative relative to the obliquity of the target. The experiments provide a good overview of the penetration characteristics of long rods for the whole pitch angle range. The penetration data are described by empirical relations that show good agreement with the experiments.

Copyright © 2013 by ASME
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References

Figures

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Fig. 1

Impact orientations: the rod is rotated in the direction of target obliquity for pitch up, and more normal to the target for pitch down

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Fig. 2

Definitions of αcrit

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Fig. 3

Target positioning: negative target obliquity with positive pitch corresponds to positive target obliquity and negative pitch (see Fig. 1)

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Fig. 4

Definition of penetration depth

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Fig. 5

Normalized penetration depth versus yaw angle for 0 deg obliquity

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Fig. 6

Crater cross sections for negative pitch at 30 deg obliquity. The pointed arrow indicates the rod with pitch angle, tip and orientation with respect to the target.

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Fig. 7

Crater cross sections for positive pitch at 30 deg obliquity. The pointed arrow indicates the rod with pitch angle, tip and orientation with respect to the target.

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Fig. 8

Crater cross sections for negative pitch at 45 deg obliquity. The pointed arrow indicates the rod with pitch angle, tip and orientation with respect to the target.

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Fig. 9

Crater cross sections for positive pitch at 45 deg obliquity. The pointed arrow indicates the rod with pitch angle, tip and orientation with respect to the target.

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Fig. 10

Crater cross sections for negative pitch and without pitch (g) at 60 deg obliquity. The pointed arrow indicates the rod with pitch angle, tip and orientation with respect to the target.

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Fig. 11

Crater cross sections for positive pitch at 60 deg obliquity. The pointed arrow indicates the rod with pitch angle, tip and orientation with respect to the target.

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Fig. 12

Exp. 9839: X-ray photograph (double exposure) of penetrating rod and crater surface (θ = 60 deg, α1 = −88.8 deg)

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Fig. 13

Normalized penetration depth versus pitch for 60 deg obliquity, cosine and sine models

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Fig. 14

Normalized penetration depth versus pitch for 60 deg obliquity, ISL and EMI models

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Fig. 15

Normalized penetration versus pitch for all target obliquities

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Fig. 16

Normalized penetration versus normalized pitch angle

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Fig. 17

Definition of angles

Tables

Errata

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