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Research Papers

# Critical Impact Yaw for Long-Rod Penetrators

[+] Author and Article Information
Xiangzhen Kong

State Key Laboratory for Disaster Prevention
and Mitigation of Explosion and Impact,
PLA University of Science and Technology,
Nanjing, Jiangsu Province 210007, China
e-mail: ouckxz@163.com

Q. M. Li

School of Mechanical, Aerospace
and Civil Engineering,
The University of Manchester,
Pariser Building,
Sackville Street,
Manchester M13 9PL, UK;
State Key Laboratory of Explosion Science
and Technology,
Beijing Institute of Technology,
Beijing 100081, China
e-mail: Qingming.Li@manchester.ac.uk

Qin Fang

State Key Laboratory for Disaster Prevention
and Mitigation of Explosion and Impact,
PLA University of Science
and Technology,
Nanjing, Jiangsu Province 210007, China
e-mail: fangqinjs@139.com

1Corresponding authors.

Contributed by the Applied Mechanics Division of ASME for publication in the JOURNAL OF APPLIED MECHANICS. Manuscript received July 24, 2016; final manuscript received September 1, 2016; published online September 27, 2016. Assoc. Editor: Weinong Chen.

J. Appl. Mech 83(12), 121008 (Sep 27, 2016) (8 pages) Paper No: JAM-16-1374; doi: 10.1115/1.4034620 History: Received July 24, 2016; Revised September 01, 2016

## Abstract

This paper presents an improved model for the critical impact yaw (or simply the critical yaw) in long-rod penetration with considering the deceleration and rotation of the rod and the crater shape of the target. Two critical yaws, $θc1$ and $θc2$, under normal impact were identified, below which there is no contact between the rod and crater sidewall (for $θc1$) and between the rod and the crater entrance (for $θc2$) during the entire penetration process. Contact functions and iterative algorithms were proposed in order to obtain these two critical yaws numerically. The influences of four dominant nondimensional numbers (i.e., the ratio of the target resistance to the rod strength $λ$, Johnson's damage number of the rod $ς$, square root of the target–projectile density ratio $μ$, and the diameter–length ratio of the rod $ψ$) on two critical yaws were studied for three typical rod–target systems (tungsten alloy rods penetrating steel targets, steel rods penetrating aluminum alloy targets, and steel rods penetrating steel targets). The relationship between two critical yaw angles was also discussed. A new empirical formula for the critical yaw $θc2$ was proposed based on the parametric study results and dominant nondimensional numbers, which extends the valid application range of the existing empirical formula.

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Topics: Steel , Rods , Yaw , Shapes , Tungsten alloys
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## References

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## Figures

Fig. 1

The orientation and position of the eroding rod

Fig. 2

Locations of the rod and crater sidewalls: (a) P(t)<le(t) and (b) P(t)≥le(t)

Fig. 3

Comparison of the calculated crater shape with experimental observation from Ref. [3]: (a) predicted crater shape and (b) experimental observation [3]

Fig. 4

Comparison of the predicted yaw angle with experiments and simulation results: (a) V = 1400 m/s, L/d = 10 [9,17] and (b) V = 1650 m/s, L/d = 20 [18]

Fig. 5

Comparison of the predicted critical yaw angle with empirical formula [3]

Fig. 6

Variation of yaw angel during the penetration

Fig. 7

The influence of λ, ς, and ψ on critical yaws for a given tungsten alloy rod and steel targets

Fig. 8

Relationship between θc1 and θc2 for λ=2, ψ=1/10 at different striking velocities

Fig. 9

The influence of λ, ς, and ψ on critical yaws for steel rods and a given aluminum alloy target

Fig. 10

The influence of λ, ς, and ψ on critical yaws for steel rods and steel targets

Fig. 11

Comparisons of the new empirical formula with the predicted results from iterative algorithm: (a) tungsten alloy rod penetrating steel targets, (b) steel rods penetrating aluminum alloy target, and (c) steel rods penetrating steel targets

Fig. 12

Comparisons of the new empirical formula (Eq. (19)) with the empirical formula proposed in Ref. [3]

## Errata

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