The depth of penetration (DOP) or thick-backing technique allows the ballistic evaluation and ranking of armor ceramics independent of armor configuration. The test projectile is fired into a ceramic tile backed by a semi-infinite block. The residual penetration into the backing material is measured and compared to the penetration of the projectile into a monolithic block of the backing material. This report adapts this technique to evaluate armor ceramics for personnel protection using the caliber .30 armor-piercing M2 (APM2) and armor-grade aluminum alloy 5083 (Al 5083), MEL-A-46027, as the backing material.Penetration of the APM2 into monolithic Al 5083 was determined over a range of velocities. Several thicknesses of boron carbide (B 4 C), silicon carbide (SiC), and aluminum oxide (A1 2 0 3 ) were tested to deteraiine ballistic performance as a function of ceramic areal density. Projectile cores were recovered and analyzed. Postmortem condition of the cores was correlated to DOP results.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) March 20052. REPORT TYPE PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U. S. Army Research Laboratory ATTN: AMSRD-ARL-WM-TD Aberdeen Proving Ground, MD 21005-5066 PERFORMING ORGANIZATION REPORT NUMBER ARL-TR-3437 SPONSOR/MONITOR'S ACRONYM(S) 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTWe analyzed data from quasistatic, uniaxial tension tests on single-ply specimens of plain-woven, 600-denier KM2. Failure strains were found to range from 0.120 to 0.144 for warp-loaded and from 0.143 to 0.160 for fill-loaded tests. Failure stresses (strengths) ranged from 0.424 to 0.543 GPa for warp-loaded and from 0.593 to 0.642 GPa for fill-loaded tests. A least-squares fit, in the form of a rational function, was obtained to the second Piola-Kirchhoff stress vs. Green-St. Venant strain data for a representative warp-direction and a representative filldirection test. In addition, averaged least-square fits to all the warp data and to data from four out of five fill tests were obtained, also in the form of a rational function. These fits are intended to inform constitutive modeling in numerical simulations.