SUMMARY OF RESPONSES TO EVALUATION ITEMS AND ACTION ITEMS RECOMMENDED FOR INDEPENDENT ASSESSMENT

Evaluation Item 1: The rounding of back-face deformation measurements

The Phase I report (NRC, 2009, p. 17) suggested that the DOT&E and the Army adopt a common standard for rounding and indicating the appropriate number of significant digits. The specific observation was that the Army should consider using the American Society of Testing and Materials (ASTM) standard ASTM E29-08, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications (ASTM, 2008). During briefings of the Phase I report, both DOT&E and the Army said they agreed with the recommendation.

Evaluation Item 2: Not scoring penetrations of material through the plate as a compete penetration unless broken fibers are observed in the Kevlar backing behind the plate

The Phase I committee was briefed by the COL Jeffrey Holt, Commander of the Aberdeen Test Center (ATC). He said that the command wanted a definition for a “complete penetration” that minimized subjectivity on part of the tester and manufacturer. As a result, ATC adopted a convention that any test round that penetrated the armor plate and continued on to completely break any Kevlar fiber on the back of the shoot pack would be considered a complete penetration. The committee felt this provided a consistent description for the body armor community and virtually eliminated subjectivity when scoring a plate as having been completely penetrated.

As defined in the new DOT&E protocol, “a complete penetration of the test plate sample occurs on any fair record test shot impact in which the projectile, any fragment of the projectile, or any fragment of the armor material is ejected from the rear of the plate and passes into the first ply (minimum of one complete yarn broken) of the soft armor (ballistic package) located behind the test plate sample when it is placed into the soft armor test panel. The first ply of the soft armor (ballistic package) shall serve as a witness plate.” (DOT&E, 2010, p. 4)

Evaluation Item 3: The use of the laser scanner to measure back-face deformations without a full evaluation of its accuracy as it was actually used during testing, to include the use of software modifications and operation under actual test conditions

The Phase I committee was provided a copy of ATC Internal Operating Procedure No. 001: Measurement of Backface Deformation (BFD) Using Faro® Quantum Laser Scan Arm and Geomagic® Qualify® for Hard and Soft Body



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement