Ballistic Helmet Standard

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Ballistic HelmetStandard
Technologies for Critical Incident Preparedness
Conference and Exposition
San Francisco, November 6-8, 2007
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Motivation

• new lightweight composite helmets have increased
  protection against penetration
• non-penetrating impacts may results in large
  backface deformation
• increase risk of serious skull/brain injuries ?
• current test procedures address penetration
  resistance but lack injury risk evaluation for
  non-penetrating impacts

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RD Review
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U.S Army NSC RD Program

• Research approach
• Identify injury mechanism
• Determine physical response measurement
• Develop injury function
• Develop physical surrogate
• Work conducted by Bass et al. (University of
  Virginia

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Injury Function
Transfer Function
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Injury Function
Transfer Function
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Outcomes

• Skull peak pressure is best correlated with
  injury
• Injury function for non-penetrating ballistic
  impacts

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NIJ Standard 0106.01 (1981)

• Penetration Resistance
• Limited number of test samples required
• 2 helmets / test ammunition
• 1st helmet tested at ambient conditions
• 2nd helmet wet-conditioned (immersion 2-4hr)
• 4 impact locations / helmet
• rear, front, left, right
• Requirement for Level I, II-A and II only
• No ballistic limit tests (V50)

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NIJ Standard 0106.01 (1981)

• Transmitted Force
• 1 helmet / test ammunition
• tested at ambient conditions
• 4 impact locations / helmet
• rear, front, left, right
• Peak linear acceleration lt400g
• Correlation with injury unknown

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Other Test Procedures

• HPW-TP-0401.01B (1995)
• Measure maximum deformation in clay
• Correlation with injury unknown
• STANAG 2920
• No requirement for non-penetrating impacts
• ACH Specifications
• Measure maximum deformation in clay
• Correlation with injury unknown

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Proposed Test Method

• confirm penetration resistance with separate
  headform
• implement an impact force measurement headform
• based on injury model developed by Bass et al.
  (2003) using localized skull pressure
• predict risk of skull fracture from dynamic force
  measurements
• evaluate BABT protection performance of ballistic
  helmets

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Penetration Headform
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Impact Force Measurement
Load Cell Module
Pressure Sensitive Film
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Parametric Study

• Energy Absorbing (EA) Material
• Standoff
• Helmet Shell

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Peak Force vs. Impact Speed
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Energy Absorbing Liner
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Outcomes

• Current design new lightweight helmets can have
  comparable BABT attenuation
• ?standoff ?peak impact force
• EA materials ?peak impact force (load
  distribution)

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Standards Activities

• The Canadian Standards Association (CSA) has
  formed a new CSA Technical Committee to create a
  National Standard on ballistic helmets (CSA
  Z613).
• The National Institute of Justice Ballistic
  Helmet standard is under revision.

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