1、Designation: E3068 171Standard Test Method forContact Measurement of Backface Deformation in ClayBacking During Body Armor Testing1This standard is issued under the fixed designation E3068; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEAdded research report footnote to Section 12 editorially in April 2017.1. Scope1.1 This test method descri
3、bes test methods for the contactmeasurement of backface deformation (BFD) in clay backingcaused by a test threat that produces a partial penetration in abody armor test item.1.2 This test method is applicable to testing of planar andnonplanar soft armor and hard armor.1.3 This test method is not app
4、licable to testing of helmets.1.4 The purpose of this test method is to achieve consistentmeasurements between laboratories and reduce differences thatcould result from using different measurement techniques.1.5 It is anticipated that this test method will be referencedby certifiers, purchasers, and
5、 other users in order to meet theirspecific needs.1.6 This test method does not specify BFD performancerequirements for body armor. The performance requirementsare included in other standards or specifications. The decisionrules for determining conformance to specifications and theconsideration of u
6、ncertainty are also included in other stan-dards or specifications.1.7 UnitsThe values stated in SI units are to be regardedas standard. Where appropriate, mathematical conversions tonon-SI units are provided in parentheses for informationalpurposes.1.8 This standard does not purport to address all
7、of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.9 This international standard was developed in accor-dance with
8、 internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:
9、2E3004 Specification for Preparation and Verification of ClayBlocks Used in Ballistic-Resistance Testing of Torso BodyArmorE3005 Terminology for Body Armor2.2 Other Standards:MIL-STD-3027 Department of Defense Test Method Stan-dard for Performance Requirements and Testing of BodyArmor3NIJ Standard 0
10、101.06 Ballistic Resistance of Body Armor4National Research Council Testing of BodyArmor MaterialsPhase III53. Terminology3.1 The terms and definitions of Terminology E3005 applyfor the following terms: backface deformation, backing fixture,backing material, body armor, complete penetration, hardarm
11、or, nonplanar, partial penetration, soft armor, test item, andtest threat.3.2 Definitions of Terms Specific to This Standard:3.2.1 applique, nbacking material intended to fill thespace behind a nonplanar test item during testing or condition-ing procedures.3.2.2 backface deformation (BFD), nthe inde
12、ntation in thebacking material caused by a projectile impact on the test itemduring testing. E30053.2.2.1 DiscussionSee Fig. 1.1This test method is under the jurisdiction of ASTM Committee E54 onHomeland Security Applications and is the direct responsibility of SubcommitteeE54.04 on Personal Protect
13、ive Equipment (PPE).Current edition approved Feb. 1, 2017. Published March 2017. DOI: 10.1520/E3068-17E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standa
14、rds Document Summary page onthe ASTM website.3Available from IHS, 15 Inverness Way East, Englewood, CO 80112, http:/.4Available from National Institute of Justice (NIJ), 810 7th St., NW, Washington,DC 20531, http:/nij.gov.5Available from The National Academies Press, 500 Fifth St., NW, Washington,DC
15、 20001, https:/www.nap.edu.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles
16、for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.3 bridge gauge, nan assembly used for measuring thatconsists of a depth gauge and supports that rest on oppositesides of the backing fixtu
17、re. E30043.2.3.1 DiscussionSee Fig. 2 for a photograph of a bridgegauge.3.2.4 check standard, nstable, durable artifact that may beused for training, comparing among measuring instruments,and checking instruments prior to and after calibration,maintenance, or normal use to detect changes in the inst
18、ru-ments.3.2.5 clay block, na type of backing assembly in whichthe backing material is ROMA Plastilina No. 16modelingclay. E30043.2.5.1 DiscussionSee Fig. 3 for a graphical representa-tion of a clay block.3.2.6 depth gauge, ninstrument (for example, caliper)used to measure the indentations in the ba
19、cking material.6U.S. Government standards require ROMA Plastilina No. 1, from SculptureHouse, Inc., as the backing material for ballistic-resistance testing.FIG. 1 Examples of Backface Deformation (Side View)FIG. 2 Photograph of Bridge GaugeE3068 17123.2.7 floating gauge, na depth gauge that rests o
20、n thesurface of the backing material.3.2.8 striking device, na device used on a clay block toestablish an appropriate, flat surface on the clay backingmaterial with respect to the backing fixture edges. E30044. Summary of Test Method4.1 Ballistic testing of body armor typically requires shoot-ing bo
21、dy armor test items mounted on clay blocks.4.2 One of the ballistic test methods for body armorspecifies that the BFD be measured when shooting of the testitem results in a partial penetration. When the shot results in acomplete penetration, BFD is not measured.4.3 This test method describes the mea
22、surementinstrumentation, the BFD measurand, and the procedure for theuse of contact measurement instruments.5. Significance and Use5.1 U.S. Department of Defense and U.S. Department ofJustice standards for assessing the performance of ballistic-resistant torso body armor require the measurement of B
23、FD onbacking assemblies made with ROMA Plastilina No. 1.5.2 This test method may be applicable for certificationtesting or for research and development testing.6. Equipment and Instrumentation6.1 The measuring instrument shall have a resolution of0.01 mm (0.0004 in.) or better with an accuracy of 60
24、.1 mm(0.004 in.) or better.6.2 Three types of contact measuring instruments may beused:6.2.1 Bridge GaugeThe bridge gauge shall be a rigidassembly that rests on two parallel strike face edges of thebacking fixture and supports a depth gauge that can slide backand forth on the assembly to measure dep
25、ths across the surfaceof the backing material. The bridge shall be sufficiently rigidthat it will not deflect during use or otherwise negatively affectthe measurement.6.2.2 Floating GaugeThe floating gauge shall be a rigidassembly that supports a depth gauge and has a base that restson the clay surf
26、ace. The base shall be at least 25 by 152 mm (1by 6 in.) but not so large that it touches the backing fixtureframe during measurements.6.2.3 Touch ProbeThe touch probe is a coordinate mea-suring machine consisting of an articulating arm, a contactprobe, and software that calculates the BFD measureme
27、nt.6.3 The tip that touches the clay shall be hemispherical orspherical with a diameter of 6.35 6 0.0254 mm or 0.25 60.001 in. and attached to a cylindrical stem having a minimumlength of 38.1 mm (1.5 in.) and maximum diameter of 6.35 mm(0.25 in.) such that only the tip touches the deepest location
28、ofthe BFD. See Fig. 4 for examples of probe tip configurationsthat meet the above requirements.6.4 General lighting on the range should provide adequatelight levels to enable personnel to perform assigned duties.Local lighting to supplement general lighting, if needed, shouldbe available to provide
29、better visibility for tasks associatedwith measurements and instrument readings.NOTE 1Any light sources used on the range, including local lightingto aid measurement, should not change the required laboratory conditionsor alter the surface temperature of the clay backing material.6.5 Check standards
30、 should be used in the laboratory fortraining of technicians, monitoring for changes ininstrumentation, checking instruments after calibration/re-calibration, checking software, and performing intra-laboratoryand inter-laboratory comparisons.6.5.1 These check standards should be calibrated.7. BFD Me
31、asurand7.1 For contact measuring instruments, the BFD measuredis the length of the line segment, parallel to the test threat lineof aim, between a plane passing through the point of aim on thepre-impact surface and a plane passing through the deepestpoint of the post-impact surface; the planes are p
32、arallel to eachother and perpendicular to the test threat line of aim. TheFIG. 3 Side View of Clay Block (After Impact)E3068 1713measurement planes are established by the probe tip as itmakes contact with the clay surface without causing deforma-tion. See Fig. 5.7NOTE 2The deepest point is not neces
33、sarily colinear with the line ofaim.8. BFD Measurement Procedure for Planar Armor8.1 After each shot on the test item, remove the test itemfrom the clay block and strike the clay by drawing the strikingdevice at least once across parallel edges of the backing fixture.8.2 Establish the point-of-aim m
34、easurement plane as “0”based on the clay surface near the impact.8.3 Measure the deformation using either a floating gauge ora touch probe. When using a floating gauge, ensure that no partof the floating gauge touches the backing fixture frame. Whenusing a touch probe, follow the manufacturer instru
35、ctions toensure the resolution and accuracy requirements are achieved.NOTE 3Caution is required when touching the probe tip to the clay toensure that the probe tip does not indent the clay.8.4 Adjust the position of the probe tip so that it contacts thedeepest point of the indentation without distur
36、bing the clay andmeasure the depth of the indentation relative to the established“0”, with the following consideration:8.4.1 At times, the bottom of the BFD is angled into theclay, which may interfere with the probe tip touching thedeepest part of the BFD while maintaining the requiredmeasurement di
37、rection. In those cases, any clay that causesinterference may be moved. Care should be taken such that thedeepest point of the BFD is not influenced by this movement ofclay. Movement of clay for this purpose shall be documented inthe test report.8.5 Record the measured value in millimeters. The rawm
38、easurements shall not be rounded off or truncated but shall bereported to the number of places read.NOTE 4For readings having more than four digits to the right of thedecimal, the result does not need to be reported to more than 0.0001 mm.8.6 All measurements and observations shall be docu-mented an
39、d included in the test report.7Fig. 5 is adapted from a NIST Report dated 17 Feb 2010: DimensionalMetrology Issues of Army Body Armor Testing (unpublished).FIG. 4 Examples of Tip Probe ConfigurationsFIG. 5 BFD Measurand for Contact Measuring InstrumentsE3068 17149. BFD Measurement Procedure for Nonp
40、lanar Armor9.1 Prior to shooting the test item, establish the point-of-aimmeasurement plane as “0” based on the surface of the applique,at the point of aim.9.2 After each shot on the test item, remove the test itemfrom the clay block.9.3 Measure the deformation using either a bridge gauge ora touch
41、probe. When using a bridge gauge, place the bridgegauge on the edges of the clay block and position the depthgauge over the indentation. When using a touch probe, followthe manufacturer instructions to ensure the resolution andaccuracy requirements are achieved. See Note 3 in 8.3.9.4 Position the pr
42、obe tip so that it contacts the deepestpoint of the indentation without disturbing the clay andmeasure the depth of the indentation relative to the established“0”, with the following consideration:9.4.1 At times, the bottom of the BFD is angled into theclay, which may interfere with the probe tip to
43、uching thedeepest part of the BFD while maintaining the requiredmeasurement direction. In those cases, any clay that causesinterference may be moved. Care should be taken such that thedeepest point of the BFD is not influenced by this movement ofclay. Movement of clay for this purpose shall be docum
44、ented inthe test report.9.5 Record the measured value in millimeters. The rawmeasurements shall not be rounded off or truncated but shall bereported to the number of places read. See Note 4 in 8.5.9.6 All measurements and observations shall be docu-mented and included in the test report.10. Laborato
45、ry Documentation10.1 A laboratory shall have documented instructions for allaspects of the BFD measurement process, including the fol-lowing:10.1.1 Use of check standards over the range and directionof interest.10.1.2 Instructions for ensuring that there are no data entryor transposition errors in r
46、ecording measurements.11. Test Report and Data11.1 The type of measuring instrument, hardware, andsoftware used and configuration details shall be reported.11.2 The measured value for each BFD shall be reported, asrecorded in 8.5 or 9.5, without truncation or rounding, as perthe number displayed on
47、the measuring instrument. Observa-tions shall also be included in the test report.11.3 A statement of conformance to specifications, ifrequired, shall be included in the test report.12. Precision and Bias812.1 The repeatability standard deviation from a singleoperator has been determined to be 0.20
48、mm. An interlabora-tory study of this test method will be conducted followingpublication of this test method, and a complete precision andbias statement is expected to be available by December 2018.13. Keywords13.1 backface deformation; back face deformation; bodyarmor; backing material; ballistic-r
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