Perforation of Aluminum Plates with 7.62 APM2 Bullets
We conducted an experimental analytical study to understand the mechanisms and dominant parameters for 7.62mm APM2 bullets that perforate 6082-T651 aluminum plates at oblique impacts. Tests were conducted with the full bullet and the hard core only to sho
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Perforation of Aluminum Plates with 7.62 APM2 Bullets Michael J. Forrestal, T.L. Warren, and T. Børvik
Abstract We conducted an experimental analytical study to understand the mechanisms and dominant parameters for 7.62 mm APM2 bullets that perforate 6082-T651 aluminum plates at oblique impacts. Tests were conducted with the full bullet and the hard core only to show that the hard core dominates the perforation process. Models show good agreement with measured residual and ballistic-limit velocities. Keywords Perforation • Aluminum plates • APM2 Bullets
48.1
Introduction
For this paper, we study the perforation of 6082-T651 aluminum armor plates with 7.62 mm APM2 bullets at oblique impacts. We conducted perforation experiments with the full 10.7 g, APM2 bullets and only the 5.25 g, hard steel cores from the full bullet. Our data shows the perforation process is dominated by the hard steel core. Other papers concerned with 7.62 APM2 bullets are presented in [1–5]. In the next sections, we describe the projectiles and targets, and present residual and ballistic-limit velocity data.
48.2
Projectiles
Figure 48.1 shows the dimensions and the parts that make up the APM2 bullet. The 7.62 mm-diameter, 10.7 g, APM2 bullet consists of a brass jacket, an end cap, lead filler, and a 5.25 g, ogive-nose, hard steel core. The steel core has density rp ¼ 7,850 kg/m3, hardness Rc 63, and c ¼ CRH ¼ 3.0 (caliber-radius-head).
M.J. Forrestal (*) 1805 Newton Pl, NE Albuquerque, NM 87106, USA e-mail: [email protected] T.L. Warren 3804 Shenandoah Pl, NE Albuquerque, NM 87111, USA e-mail: [email protected] T. Børvik Structural Impact Laboratory (SIMLab), Centre for Research-based Innovation (CRI) Department of Structural Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway e-mail: [email protected] V. Chalivendra et al. (eds.), Dynamic Behavior of Materials, Volume 1: Proceedings of the 2012 Annual Conference on Experimental and Applied Mechanics, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-1-4614-4238-7_48, # The Society for Experimental Mechanics, Inc. 2013
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Fig. 48.1 Geometry and dimensions of the 7.62 mm APM2 bullet (in mm)
48.3
6082-T651 Aluminum Target Plate
We obtained 20-mm-thick plate material from Alcoa Europe. The supplier provided inspection certification sheets with tensile data from four tests in the rolling direction. The ultimate tensile strengths were between su ¼ 298–302 MPa, and yield strengths at the 0.2 % offset were between so ¼ 256–261 MPa. As a check, we also conducted three tensile tests in the rolling direction. We obtained su ¼ 290–291 MPa and so ¼ 264–266 MPa. Therefore, tensile data from Alcoa Europe are in close agreement with our tensile data.
48.4
Ballistic Results
We conducted tests at normal impact, b ¼ 0 , and at oblique impacts of b ¼ 15, 30, and 45 . Figures 48.2, 48.3, 48.4, 48.5, and 48.6 show residual velocity versus striking velocity data. In the figures, the full bul
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