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Review of Department of Defense Test Protocols for Combat Helmets (2014) / Chapter Skim
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5 Helmet Performance Measures and Trends in Test Data
Pages 32-38

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From page 32...
... Most ballistic impacts penetrate the helmet to the BFD thresholds is around 0.005 or less. The distributions some degree, so the DOT&E FAT and LAT testing protocols of the BFD data also demonstrate significant differences distinguish between complete and partial penetrations.
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From page 33...
... Because of this difference, the –6.844 –8.502 DOT&E FAT protocol defines a V50 complete penetration as –10.161 a shot where –11.819 Impacting projectile or any fragment thereof, or any frag ment of the test specimen perforates the witness plate result ing in a crack or hole which permits light passage. A break in the witness plate by the helmet deformation is not scored as a complete penetration.4 FIGURE 5-1 Illustrative backface deformation laser scan.
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From page 34...
... projectile Recommendation 5-3. The Department of Defense should shot at a randomly selected ACH, under test conditions, is examine the basis for backface deformation thresholds and unlikely -- with only a 0.1 percent chance -- of completely develop appropriate ones based on scientific studies and data.
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From page 35...
... the committee has also pooled the data across the environ ments. The horizontal solid lines in the figure are the BFD Data Set 1 upper limits of 25.4-mm for back and front shot locations and 16-mm for left, right, and crown shot locations.
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From page 36...
... ability of exceeding the limit, based on this outcome, is about 9 percent, so the 10 percent standard is met in this regard. Data Set 3 Figure 5-6 shows that the differences among shot loca tions for the XL helmet size have a pattern substantially Data Set 3 was from a test of Helmet 3, a repeat of the different from those of the other three sizes.
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From page 37...
... rately to the two groups of locations with different thresh olds: back and front in one group and crown, left, and right in another. The specific approach involves computing 90/90 Data Set 4 upper tolerance limits (UTLs)
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From page 38...
... U.S. Army whether the helmet sizes that passed FAT can be procured or Research Laboratory, Aberdeen Proving Ground, Md.
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Key Terms

  • backface deformation
  • test data
  • complete penetration
  • helmet sizes
  • helmet performance

  • bfd measurements
  • shot location
  • solid lines
  • defense test
  • helmet size

  • test protocols
  • shot locations
  • helmet testing
  • upper confidence
  • clay surface

  • witness plate
  • available bfd
  • helmet deformation
  • test conditions
  • operational test

  • bfd distributions
  • bfd thresholds
  • body armor
  • front location
  • lat testing

  • head injury
  • protective capabilities
  • crown front
  • penetration probability
  • acceptance testing


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