0
Terminal Ballistics and Impact Physics

Analysis of the Fragmentation of AlON and Spinel Under Ballistic Impact

[+] Author and Article Information
Elmar Strassburger

e-mail: elmar.strassburger@emi.fraunhofer.de

Martin Hunzinger

Fraunhofer Institute for High-Speed Dynamics,
Ernst-Mach-Institute (EMI),
Am Christianswuhr 2,
79400 Kandern, Germany

James W. McCauley

U.S. Army Research Laboratory,
AMSRD-ARL-WM-MD,
Aberdeen Proving Ground, MD 21005

1Corresponding author.

Manuscript received July 30, 2012; final manuscript received December 19, 2012; accepted manuscript posted February 6, 2013; published online April 19, 2013. Assoc. Editor: Bo S. G. Janzon.

J. Appl. Mech 80(3), 031807 (Apr 19, 2013) (11 pages) Paper No: JAM-12-1356; doi: 10.1115/1.4023573 History: Received July 30, 2012; Revised December 19, 2012; Accepted February 06, 2013

It has been demonstrated that significant weight reductions can be achieved, compared to conventional glass-based armor, when a transparent ceramic is used as the strike face on a glass-polymer laminate. Magnesium aluminate spinel (MgAl2O4) and AlON are promising candidate materials for application as a hard front layer in transparent armor. Comprehensive, systematic investigations of the fragmentation of ceramics have shown that the mode of fragmentation is one of the key parameters influencing the ballistic resistance of ceramics. In the study described here, the fragmentation of AlON and three types of spinel was analyzed: two types of fine grained spinel with nominal average grain sizes 0.6 μm and 1.6 μm and a bimodal grain-sized spinel with large grains of 250 μm size in a fine grain (5–20 μm) matrix were examined. The ceramic specimens of 6-mm thickness were glued to an aluminum backing and impacted with armor piercing (AP) projectiles of caliber 7.62 mm at two different velocities—850 m/s and 1100 m/s. The targets were integrated into a target box, which allowed for an almost complete recovery and analysis of the ceramic fragments. Different types of high-speed cameras were applied in order to visualize the different phases of fragment formation and ejection. A laser light-sheet illumination technique was applied in combination with high-speed cameras in order to determine size and speed of ejected ceramic fragments during projectile penetration. The application of the visualization techniques allowed for the analysis of the dynamics of the fragment formation and interaction with the projectile. A significant difference in the fragment size distributions of bimodal grain-sized spinel and AlON was observed.

Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.

References

Patel, P. J., Gilde, G. A., Dehmer, P. G., and McCauley, J. W., 2000, “Transparent Armor,” AMPTIAC Q., 4(3), pp. 1–6.
Patel, P. J., Gilde, G. A., Dehmer, P. G., and McCauley, J. W., 2000, “Transparent Ceramics for Armor and EM Window Applications”, Proc. SPIE, 4102, p. 1. [CrossRef]
Strassburger, E., 2009, “Ballistic Testing of Transparent Armour Ceramics,” J. Eur. Ceram. Soc., 29, pp. 267–273. [CrossRef]
Strassburger, E., Hunzinger, M., and Krell.A., 2010, “Fragmentation of Ceramics Under Ballistic Impact,” Proc. of 25th Int. Symposium on Ballistics, Beijing, May 17–21, pp. 1172–1179.
Shockey, D. A., Bergmannshoff, D., Curran, D. R., and Simons, J. W., 2009, “Physics of Glass Failure During Rod Penetration,” Ceram. Eng. Sci. Proc., 29(6), pp. 23–32. [CrossRef]
Curran, D. R., Seaman, L., and Shockey, D. A., 1977, “Dynamic Failure in Solids,” Phys. Today, 30, p. 46. [CrossRef]
Curran, D. R., Shockey, D. A., and Simons, J. W., 2009, “Mesomechanical Constitutive Relations for Glass and Ceramic Armor,” Ceram. Eng. Sci. Proc., 29(6), pp. 3–13. [CrossRef]
Krell, A., and Strassburger, E., 2008, “Hierarchy of Key Influences on the Ballistic Strength of Opaque and Transparent Armor,” Ceram. Eng. Sci. Proc., 28(5), pp. 45–55. [CrossRef]
Krell, A., and Strassburger, E., “Discrimination of Basic Influences on the Ballistic Strength of Opaque and Transparent Ceramics,” Advances in Ceramic Armor VIII, Jeffrey J. Swab, ed., Ceram. Eng. Sci. Proc., 33(5), pp. 161–176. [CrossRef]
Schardin, H., 1950, “Results of Cinematographic Investigation of the Fracture Process in Glass,” Glastechnische Berichte (Reports on Glass Technology), Vol. 23, Verlag der Deutschen Glastechnischen Gesellschaft, Frankfurt, pp. 325–336.
Yavari, A., and Khezrzadeh, H., 2010, “Estimating Terminal Velocity of Rough Cracks in the Framework of Discrete Fractal Fracture Mechanics,” Eng. Fract. Mech., 77, pp. 1516–1526. [CrossRef]
Roberts, D. K., and Wells, A. A., 1954, “The Velocity of Brittle Fracture,” Engineering, 24, pp. 820–821.
Craggs, J. W., 1960, “On the Propagation of a Crack in an Elastic-Brittle Material,” J. Mech. Phys. Solids, 8, pp. 66–75. [CrossRef]
Steverding, B., and Lehnigk, S. H., 1970, “Response of Cracks to Impact,” J. Appl. Phys., 41(5), pp. 2096–2099. [CrossRef]
Fineberg, J., Gross, S. P., Marder, M., and Swinney, H. L., 1992, “Instability in the Propagation of Fast Cracks,” Phys. Rev. B, 45, pp. 5146–5154. [CrossRef]
Senf, H., Strassburger, E., and Rothenhäusler, H., 1994, “Stress Wave-Induced Damage and Fracture in Impacted Glasses,” J. Phys. IV, 4, pp. 741–746. [CrossRef]
Ravi-Chandar, K., and Knauss, W. G., 1984, “An Experimental Investigation Into Dynamic Fracture: II. Microstructural Aspects,” Int. J. Fract., 26, pp. 65–80. [CrossRef]
Technology Assessment & Transfer, Inc., 2012, “Transparent Spinel Ceramics for Armor and Electro-Optical Applications,” Spinel Data Sheet, TA&T Inc., Annapolis, MD.
Goldman, L. M., Balasubramanian, S., Nagendra, N., and Smith, M., 2010, “ALON® Optical Ceramic Transparencies for Sensor and Armor Applications,” www.surmet.com

Figures

Grahic Jump Location
Fig. 1

Schematic of ballistic test configuration (left) and target (right)

Grahic Jump Location
Fig. 2

Microstructure of the tested materials

Grahic Jump Location
Fig. 3

Photographs of residual projectile material from tests with AlON at 850 m/s (top) and 1100 m/s (bottom)

Grahic Jump Location
Fig. 4

Selection of five high-speed photographs of AP projectile impact on four spinels at 1100 m/s

Grahic Jump Location
Fig. 5

High-speed photographs illustrating crack nomenclature (left) and path-time histories of radial crack propagation and circular damage zone expansion (right) for spinel 205, bimodal spinel, and AlON impacted at 850 m/s

Grahic Jump Location
Fig. 6

High-speed photograph from impact on AlON at 850 m/s, test no. 17,726

Grahic Jump Location
Fig. 7

High-speed photographs of fragment ejection from AlON, impact velocity 850 m/s

Grahic Jump Location
Fig. 8

High-speed photographs of fragment ejection from bimodal spinel, impact velocity 850 m/s

Grahic Jump Location
Fig. 9

Fragment mass distribution from sieve analysis; mean values from three tests with each configuration

Grahic Jump Location
Fig. 10

Fragment mass distribution for AlON at 850 m/s (left) and 1100 m/s (right)

Grahic Jump Location
Fig. 11

Cumulative mass plot; mean values from three tests with each configuration

Grahic Jump Location
Fig. 12

Comparison of AlON and bimodal spinel fragments from 0.2-mm size class

Grahic Jump Location
Fig. 13

Close-up views of AlON and bimodal spinel fragments from 0.2-mm size class

Grahic Jump Location
Fig. 14

Schematic of the laser-light-sheet illumination technique

Grahic Jump Location
Fig. 15

Average fragment size versus time for AlON and bimodal spinel (moving average, mean of ten fragments)

Grahic Jump Location
Fig. 16

Average fragment size versus time for fine-grained spinels 200 and 205 (moving average, mean of ten fragments)

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In