ASTM E3068-20

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of the standard as published by ASTM is to be considered the official document.
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Designation: E3068 − 17 E3068 − 20
Standard Test Method for
Contact Measurement of Backface Deformation in Clay
Backing During Body Armor Testing
This standard is issued under the fixed designation E3068; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Added research report footnote to Section 12 editorially in April 2017.
1. Scope
1.1 This test method describes test methods for the contact measurement of backface deformation (BFD) in clay backing caused
by a test threat that produces a partial penetration in a body armor test item.
1.2 This test method is applicable to testing of planar and nonplanar soft armor and hard armor.
1.3 This test method is not applicable to testing of helmets.
1.4 The purpose of this test method is to achieve consistent measurements between laboratories and reduce differences that
could result from using different measurement techniques.
1.5 It is anticipated that this test method will be referenced by certifiers, purchasers, and other users in order to meet their
specific needs.
1.6 This test method does not specify BFD performance requirements for body armor. The performance requirements are
included in other standards or specifications. The decision rules for determining conformance to specifications and the
consideration of uncertainty are also included in other standards or specifications.
1.6.1 In this test method, “other standards and specifications” and “unless specified elsewhere” refer to documents (for example,
military standards, purchase specifications) that require the use of this test method. Certifiers, purchasers, and other users are
responsible for the “other standards and specifications” and for specifying any requirements that supersede those of this test
method.
1.7 Units—The values stated in SI units are to be regarded as standard. Where appropriate, mathematical conversions to non-SI
units are provided in parentheses for informational purposes.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E3004 Specification for Preparation and Verification of Clay Blocks Used in Ballistic-Resistance Testing of Torso Body Armor
E3005 Terminology for Body Armor
This test method is under the jurisdiction of ASTM Committee E54 on Homeland Security Applications and is the direct responsibility of Subcommittee E54.04 on
Personal Protective Equipment (PPE).
Current edition approved Feb. 1, 2017April 1, 2020. Published March 2017April 2020. Originally approved in 2017. Last previous edition approved in 2017 as
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E3068 – 17 . DOI: 10.1520/E3068-17E01.10.1520/E3068-20.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E3068 − 20
2.2 Other Standards:
MIL-STD-3027 Department of Defense Test Method Standard for Performance Requirements and Testing of Body Armor
NIJ Standard 0101.06 Ballistic Resistance of Body Armor
National Research Council Testing of Body Armor Materials Phase III
3. Terminology
3.1 The terms and definitions of Terminology E3005 apply for the following terms: applique, backface deformation, backing
fixture, backing material, body armor, complete penetration, bridge gauge, check standard, clay block, complete penetration, depth
gauge, floating gauge, hard armor, nonplanar, partial penetration, soft armor, striking device, test item, and test threat.
3.1.1 Examples of backface deformation (BFD) are provided in Fig. 1.
3.1.2 See Fig. 2 for a photograph of a bridge gauge.
3.1.3 See Fig. 3 for a graphical representation of a clay block.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 applique, n—backing material intended to fill the space behind a nonplanar test item during testing or conditioning
procedures.
3.2.2 backface deformation (BFD), n—the indentation in the backing material caused by a projectile impact on the test item
during testing. E3005
3.2.2.1 Discussion—
FIG. 1 Examples of Backface Deformation (Side View)
Available from IHS, 15 Inverness Way East, Englewood, CO 80112, http://www.global.ihs.com.
Available from National Institute of Justice (NIJ), 810 7th St., NW, Washington, DC 20531, http://nij.gov.
Available from The National Academies Press, 500 Fifth St., NW, Washington, DC 20001, https://www.nap.edu.
E3068 − 20
FIG. 2 Photograph of Bridge Gauge
FIG. 3 Side View of Clay Block (After Impact)
See Fig. 1.
3.2.3 bridge gauge, n—an assembly used for measuring that consists of a depth gauge and supports that rest on opposite sides
of the backing fixture. E3004
3.2.3.1 Discussion—
See Fig. 2 for a photograph of a bridge gauge.
3.2.4 check standard, n—stable, durable artifact that may be used for training, comparing among measuring instruments, and
checking instruments prior to and after calibration, maintenance, or normal use to detect changes in the instruments.
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3.2.5 clay block, n—a type of backing assembly in which the backing material is ROMA Plastilina No. 1 modeling clay.
E3004
3.2.5.1 Discussion—
See Fig. 3 for a graphical representation of a clay block.
3.2.6 depth gauge, n—instrument (for example, caliper) used to measure the indentations in the backing material.
3.2.7 floating gauge, n—a depth gauge that rests on the surface of the backing material.
3.2.8 striking device, n—a device used on a clay block to establish an appropriate, flat surface on the clay backing material with
respect to the backing fixture edges. E3004
E3068 − 20
4. Summary of Test Method
4.1 Ballistic testing of body armor typically requires shooting body armor test items mounted on clay blocks.
4.2 One of the ballistic test methods for body armor specifies that the BFD be measured when shooting of the test item results
in a partial penetration. When the shot results in a complete penetration, BFD is not measured.
4.3 This test method describes the measurement instrumentation, the BFD measurand, and the procedure for the use of contact
measurement instruments.
5. Significance and Use
5.1 U.S. Department of Defense and U.S. Department of Justice standards for assessing the performance of ballistic-resistant
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torso body armor require the measurement of BFD on backing assemblies made with ROMA Plastilina No. 1 . .
5.2 This test method may be applicable for certification testing or for research and development testing.
6. Equipment and Instrumentation
6.1 The measuring instrument shall have a resolution of 0.01 mm (0.0004 in.) or better with an accuracy of 60.1 mm (0.004
in.) or better.
6.2 Three types of contact measuring instruments may be used:
6.2.1 Bridge Gauge—The bridge gauge shall be a rigid assembly that rests on two parallel strike face edges of the backing
fixture and supports a depth gauge that can slide back and forth on the assembly to measure depths across the surface of the backing
material. The bridge shall be sufficiently rigid that it will not deflect during use or otherwise negatively affect the measurement.
6.2.2 Floating Gauge—The floating gauge shall be a rigid assembly that supports a depth gauge and has a base that rests on
the clay surface. The base shall be at least 25 by 152 mm (1 by 6 in.) but not so large that it touches the backing fixture frame
during measurements. The depth gauge shall be centered
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