1、Designation: E3068 17Standard 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 revi
2、sion, 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.1. Scope1.1 This test method describes test methods for the contactmeasurement of backface deformation (BFD) in
3、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 applicable to testing of helmets.1.4 The purpose of this test method is to achie
4、ve 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 other users in order to meet theirspecific needs.1.6 This test method does n
5、ot 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 uncertainty are also included in other stan-dards or specifications.1.7 UnitsT
6、he 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 of thesafety concerns, if any, associated with its use. It is theresponsibili
7、ty 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.2. Referenced Documents2.1 ASTM Standards:2E3004 Specification for Preparation and Verification of ClayBlocks Used in Ballistic-Resistance Tes
8、ting 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 0101.06 Ballistic Resistance of Body Armor4National Research Council Testing of BodyArmor MaterialsPh
9、ase III53. Terminology3.1 The terms and definitions of Terminology E3005 applyfor the following terms: backface deformation, backing fixture,backing material, body armor, complete penetration, hardarmor, nonplanar, partial penetration, soft armor, test item, andtest threat.3.2 Definitions of Terms S
10、pecific 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 indentation in thebacking material caused by a projectile impact on the test itemduring testing. E30053.
11、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 Protective Equipment (PPE).Current edition approved Feb. 1, 2017. Published March 2017. DOI: 10.1520/E3068-
12、17.2For 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 standards Document Summary page onthe ASTM website.3Available from IHS, 15 Inverness Way East, Englewood, CO
13、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 20001, https:/www.nap.edu.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consh
14、ohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Org
15、anization 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 fixture. E30043.2.3.1 DiscussionSee Fig. 2 for a photograph of a bridgegauge.3.2.4 check standard, nstable,
16、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 instru-ments.3.2.5 clay block, na type of backing assembly in whichthe backing material is ROMA Plastilina
17、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 backing material.6U.S. Government standards require ROMA Plastilina No. 1, from SculptureHouse, Inc., as
18、the backing material for ballistic-resistance testing.FIG. 1 Examples of Backface Deformation (Side View)FIG. 2 Photograph of Bridge GaugeE3068 1723.2.7 floating gauge, na depth gauge that rests on thesurface of the backing material.3.2.8 striking device, na device used on a clay block toestablish a
19、n 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 body armor test items mounted on clay blocks.4.2 One of the ballistic test methods for body armorspecifies
20、 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 measurementinstrumentation, the BFD measurand, and the procedure for theuse of contact measurement instrume
21、nts.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 BFD onbacking assemblies made with ROMA Plastilina No. 1.5.2 This test method may be applicable for certi
22、ficationtesting 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 60.1 mm(0.004 in.) or better.6.2 Three types of contact measuring instruments may beused:6.2.1 Bridge Gaug
23、eThe 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 depths across the surfaceof the backing material. The bridge shall be sufficiently rigidthat it will not de
24、flect 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 surface. The base shall be at least 25 by 152 mm (1by 6 in.) but not so large that it touches the backing fi
25、xtureframe 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 measurement.6.3 The tip that touches the clay shall be hemispherical orspherical with a diameter of 6.35 6 0.0254
26、 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 ofthe BFD. See Fig. 4 for examples of probe tip configurationsthat meet the above requirements.6.4 Gener
27、al 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 better visibility for tasks associatedwith measurements and instrument readings.NOTE 1Any light sources
28、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 should be used in the laboratory fortraining of technicians, monitoring for changes ininstrumentation,
29、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 Measurand7.1 For contact measuring instruments, the BFD measuredis the length of the line segment, paralle
30、l 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 parallel to eachother and perpendicular to the test threat line of aim. TheFIG. 3 Side View of Clay Block
31、 (After Impact)E3068 173measurement 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 necessarily colinear with the line ofaim.8. BFD Measurement Procedure for Planar Armor8.1 After each shot on t
32、he 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 measurement plane as “0”based on the clay surface near the impact.8.3 Measure the deformation using either
33、 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 instructions toensure the resolution and accuracy requirements are achieved.NOTE 3Caution is required when touc
34、hing 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 disturbing the clay andmeasure the depth of the indentation relative to the established“0”, with the following
35、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 direction. In those cases, any clay that causesinterference may be moved. Care should be taken such that th
36、edeepest 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 rawmeasurements shall not be rounded off or truncated but shall bereported to the number of places read.NOTE
37、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 and included in the test report.7Fig. 5 is adapted from a NIST Report dated 17 Feb 2010: DimensionalMetrolo
38、gy Issues of Army Body Armor Testing (unpublished).FIG. 4 Examples of Tip Probe ConfigurationsFIG. 5 BFD Measurand for Contact Measuring InstrumentsE3068 1749. BFD Measurement Procedure for Nonplanar Armor9.1 Prior to shooting the test item, establish the point-of-aimmeasurement plane as “0” based o
39、n 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 probe. When using a bridge gauge, place the bridgegauge on the edges of the clay block and position the de
40、pthgauge 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 probe tip so that it contacts the deepestpoint of the indentation without disturbing the clay andmeasure the
41、 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 touching thedeepest part of the BFD while maintaining the requiredmeasurement direction. In those cases, any
42、 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.9.5 Record the measured value in millimeters. The rawmeasurements shall not be rou
43、nded 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. Laboratory Documentation10.1 A laboratory shall have documented instructions for allaspects of the BFD measurement
44、 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 recording measurements.11. Test Report and Data11.1 The type of measuring instrument, hardware, andsoftware
45、 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 the measuring instrument. Observa-tions shall also be included in the test report.11.3 A statement of conf
46、ormance to specifications, ifrequired, shall be included in the test report.12. Precision and Bias12.1 The repeatability standard deviation from a singleoperator has been determined to be 0.20 mm. An interlabora-tory study of this test method will be conducted followingpublication of this test metho
47、d, 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-resistantASTM International takes no position respecting the validity of any patent rights asserted in conne
48、ction with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsi
49、ble technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below
