1、Designation: D 6478 08Standard Test Method forDetermining Specific Packability of Fabrics Used inInflatable Restraints1This standard is issued under the fixed designation D 6478; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、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 covers procedures for determining theability to fold and pack fabrics used for inflatable res
3、traintsusing an index of specific packability.1.2 Procedures in this test method describe operator tech-niques that must be followed closely to obtain repeatable andaccurate results. Since these techniques are difficult to conveyin writing, supplemental training for operators is required. Atraining
4、video is available from ASTM (see AdjunctsADJD6478 and ADJD6478A and ).1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system are not exact equivalents; therefore, each systemmust be used independent of the other.1.4 Pro
5、cedures and apparatus other than those stated in thispractice may be used as agreed upon between the purchaserand the supplier with specific deviations from this practiceacknowledged in the report.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its us
6、e. 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.2. Referenced Documents2.1 ASTM Standards:2D 123 Terminology Relating to TextilesD 1776 Practice for Conditioning and
7、 Testing TextilesD 2904 Practice for Interlaboratory Testing of a Textile TestMethod that Produces Normally Distributed DataD 2906 Practice for Statements on Precision and Bias forTextilesD 6799 Terminology Relating to Inflatable RestraintsE 691 Practice for Conducting an Interlaboratory Study toDet
8、ermine the Precision of a Test Method2.2 ASTM Adjuncts:ADJD6478 17 Detailed Drawings3ADJD6478A- Videotape-Supplemental Training33. Terminology3.1 For all terminology relating to D13.20, Inflatable re-straints, refer to Terminology D 6799.3.1.1 The following terms are relevant to this standard:inflat
9、able restraint, packability, specific packability.3.2 For all other terms related to textiles, see TerminologyD 123.4. Summary of Practice4.1 Afabric specimen is folded uniformly in a “Z” pattern inthe warp and fill directions.4.2 The folded specimen is placed into a transparent boxthat confines the
10、 specimen securely during compression.4.3 The folded specimen is compressed using a tensile testeroutfitted with special hardware, and the resulting volume isrecorded at specified loads. The total of all the individualvolumes recorded at each specified cell is the specific pack-ability of the fabric
11、.5. Significance and Use5.1 This test method is useful for determining the specificpackability of uncoated and coated airbag fabrics. Fabricpackability is an important factor in the design of airbagmodules due to their inherent spacial contraints.5.2 A folded specimen exhibits better specific packab
12、ility ifit occupies a lower total volume at the specified loads com-pared to another specimen.5.3 The time required to test one sample (four specimensfrom the same lot of fabric) is approximately 1.5 h using thistest method. Due to the length of time required by this testmethod to perform a single t
13、est, this test method is mostsuitable for use in design and development analysis or for1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.20 on Inflatable Restraints.Current edition approved July 1, 2008. Published July 2
14、008. Originally approvedin 1999. Last previous edition in 2007 as D 647802(2007)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
15、onthe ASTM website.3Available from ASTM International Headquarters. For 17 Detailed CADDrawings, Order Adjunct No. ADJD6478. For Videotape-Supplemental Training,Order ADJD6478A.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.inclusio
16、n in a list of required tests conducted for annualcertification of an airbag fabric.6. Apparatus6.1 Tensile Tester, outfitted with a rigid base to support thespecimen box, and a compression foot attached to the load cellwith a coupling having adjustment and locking capability tomaintain fixed parall
17、el alignment to the base. Tensile testershould be calibrated annually by an independent agency whoseresults are traceable to the National Institute of Science andTechnology (NIST) or other national standards laboratory.NOTE 1The frame of the tensile tester can be used as the rigid base ifit is a sol
18、id metal surface which can support compression loading of 200Nwithout deforming, is perfectly flat, and supports the entire footprint of thespecimen box.6.2 Apparatus Manufactured in Accordance With Drawings4(See Fig. 1):6.2.1 Rectangular Box , 100 by 1506 0.1mm with 99 by149 6 0.1 mm cover plate co
19、nstructed of transparent polycar-bonate material.6.2.2 Rectangular Template and Rotary Cutting Pad, 750 by800 mm 6 0.5 mm , for cutting specimens from fabric samples(optional).6.2.3 Jig, consisting of two sets of slats (wide and narrow)for making the folds and a frame that holds the slats in positio
20、nduring folding.6.2.4 Compression Gage Blocks, with thickness of 10, 20and 30 6 0.1 mm.6.2.5 All dimensions shall be verified at time of manufac-ture using measuring devices traceable to the National Instituteof Science and Technology (NIST) or other national standardslaboratory.6.3 Rotary Razor Cut
21、ter.6.4 Large Paperclips (Three), preferably with a serratedsurface to improve gripping capability.6.5 Permanent Marking Pen, pen with fine tip.7. Specimen Preparation7.1 Condition fabric samples for a minimum of3hinthestandard atmosphere for testing textiles in accordance withPractice D 1776.7.2 Wi
22、thout fraying or fusing the edges, cut four 750 by 8006 5 - mm specimens from each sample, with the 800 mmdimension aligned in the warp direction and the cuts alignedwith the warp and weft yarns in the fabric.7.3 Write the fabric sample identification and the specimennumber on the lower right corner
23、 of the specimen (warp yarnsrunning up/down and weft yarns running right/left relative tothe operator) at a location about 50 mm from the bottom edgeand 50 mm from the right edge.8. Procedure8.1 Tensile Tester Set-Up and Calibration Check:8.1.1 Set tensile tester for compression mode, install loadce
24、ll with maximum force rating of 200 to 1000N, set crossheadspeed to 25.0 6 1.0 mm/min, set data acquisition equipment torecord thickness with an accuracy of 0.1 mm at loads of 20 to180N in 20N increments (nine total points), set samplingfrequency at $ 25 Hz and set test endpoint at 200N8.1.2 Mount t
25、he rigid base to the tensile tester frame, mountthe coupling to the load cell, and attach the compression foot tothe coupling, leaving the adjustment locking mechanism loose.(See Note 1)8.1.3 Lower the crosshead slowly until 200 6 50N force isachieved and lock the compression foot into position.8.1.
26、4 Raise the crosshead until there is a gap of approxi-mately 1mm between the compression foot and the base andvisually check for parallel alignment in both directions.8.1.5 Raise the crosshead, place the specimen box on thetensile tester base, and insert the top cover plate into the box.8.1.6 Raise
27、the specimen box by hand until the compressionfoot is inside the box, then lower the crosshead and boxtogether until the box rests on the support base and thecompression foot is not touching the cover plate. Position thebox so that the compression foot is in the approximate centerof the box.NOTE 2Ex
28、ercise caution to avoid possible operator injuy from thepinch-point between the compression foot and the specimen box.8.1.7 Lower the crosshead until a force of 100 6 30N isachieved and set zero.NOTE 3An alternate zero can be used to simplify the test. To use thealternate zero, set the true zero as
29、specified, raise the crosshead to thedesired point, and zero the crosshead position again. The position of thealternate zero should be selected such that the compression foot does nottouch the cover plate when the fabric specimen is in the box. A positionof +35 mm is suitable for most airbag fabrics
30、8.1.8 Raise the crosshead, place the specimen box on thetensile tester base, insert the 10- mm gage block and then thecover plate into the box.8.1.9 Raise the specimen box by hand until the compressionfoot is inside the box, then lower the crosshead and boxtogether until the box rests on the support
31、 base and thecompression foot is not touching the cover plate. Position thebox so that the compression foot is in the approximate centerof the box.8.1.10 Initiate the compression test and record thickness atall specified loads.8.1.11 Repeat 8.1.8-8.1.10 using the 20 and 30- mm gageblocks.8.1.12 Ensu
32、re that the thickness measured for each gageblock at 100N force is within 6 5.0 % of the actual thickness.Excessive variation indicates the need for equipment servicing.8.2 Specimen Folding:8.2.1 Place the folding jig on a table approximately 0.8 m inheight with the “A” side of the jig to the left o
33、f the operator,and place all slats on the table in ascending numerical orderfrom top to bottom. The “A” and “B” identification marks onthe jig base and all slats indicate correct orientation forinstallation, and numbers on the slats indicate the correctsequence for installation.8.2.2 Place the base
34、slat in the jig.4Equipment designed by AlliedSignal Performance Fibers, is manufacturedaccording to drawing #61-27A-7906-2 and is available from Precision MachineCompany, Inc., 2915 West Lehigh Street, Richmond, VA23230. Copyright for CADdrawings held by AlliedSignal and provided to ASTM with full u
35、nlimited authori-zation to distribute copies and/or to designate other parties to distribute copies.D64780828.2.3 Place the fabric specimen in the jig with the identifi-cation mark up and at the bottom right corner, nearest theoperator, and align the edges of the specimen with the outerguide lines o
36、n the jig base.8.2.4 Fold the specimen using the wide slats, #1 to #5,visually inspecting and adjusting at each step to ensure that allfolds are straight, are aligned to within 6 1 mm and that thefabric is tight around the slats.NOTE 4If slippage or misalignment occurs, the following procedurecan be
37、 repeated using the same specimen if there is sufficient fabricremaining for the trimming step at the beginning and end of the foldingprocess.FIG. 1 ApparatusD64780838.2.4.1 Install slat #1 on top of the fabric specimen. Slidethe specimen into position so that the fabric protrudes approxi-mately 5mm
38、 under the back edge of the slat.8.2.4.2 Run the rotary razor cutter along the back edge ofslat #1 and remove the trimmed excess fabric.8.2.4.3 Pull the fabric front to back across the top of slat #1,and install slat #2.8.2.4.4 Pull the fabric from back to front across the top ofslat #2, and install
39、 slat #3.8.2.4.5 Pull the fabric from front to back across the top ofslat #3, and install slat #4.8.2.4.6 Pull the fabric from back to front across the top ofslat #4, and install slat #5.8.2.4.7 Run the rotary razor cutter along the front edge ofslat #5 and remove the trimmed excess fabric.8.2.5 Pos
40、ition the jig so that the “B” side faces toward theoperator.8.2.6 Using a fine-tip permanent marker, make thin horizon-tal marks on the fabric at three locations along the right side ofslots #2 and #4 as indicated by guide lines on the jig base.Make thin vertical marks on the fabric specimen adjacen
41、t to thehorizontal marks using a vertical edge of the 30mm gage blockas a guide. When making the vertical marks, insert the pen tipslightly under slat #1 so that the bottom single layer of fabricalso will be marked.8.2.7 Remove the slat bracket on the “B” side.8.2.8 Remove the wide slats one at a ti
42、me from top tobottom.8.2.8.1 Slide slat #5 out and slightly left.8.2.8.2 Slide slat #4 out and slightly left.8.2.8.3 Slide slat #3 out and slightly right.8.2.8.4 Slide slat #2 out and slightly left.8.2.8.5 Slide slat #1 out and slightly right.8.2.9 Pinch the fabric folds and the single layer of fabr
43、ictogether using the horizontal and vertical marks to align theedges directly on top of each other. Insert a large papercliphalfway over the tow folds and the edge of the single layer offabric at each of the three locations marked.8.2.10 Invert the folded stack and adjust the individual foldsand the
44、 edge of the single fabric layer so that the alignment isexact at each of the three locations clipped. Carefully revert thefolded stack so that the specimen identification mark is on thetop.8.2.11 Reinstall the slat bracket on the B-side.8.2.12 Position the jig with the “A” side left of the operator
45、,position the folded stack so the specimen identification mark isat the front edge of the jig facing the operator, and align theedges of the folded stack with the inner guidelines on the jigbase.8.2.13 Fold the specimen using the narrow slats #1 to #7,visually inspecting and adjusting at each step t
46、o insure that allfolds are straight, are aligned to within 6 1 mm and that thefabric is tight around the slats.NOTE 5If slippage or misalignment occurs, the procedure below canbe repeated using the same specimen if there is sufficient fabric remainingfor the trimming step at the beginning and end of
47、 the folding process.8.2.13.1 Install slat #1 on top of the fabric specimen. Slidethe specimen into position so that the fabric protrudes approxi-mately 5 mm under the back edge of the slat.8.2.13.2 Check and adjust the relative alignment of thefolded edges under slat #1 so that they are directly on
48、 top ofeach other.8.2.13.3 Use the back edge of slat #1 to hold the foldedspecimen in position and remove the paperclip under the slat.8.2.13.4 Run the rotary razor cutter along the back edge ofslat #1 and remove the trimmed excess fabric.8.2.13.5 Pull the fabric from front to back across the top of
49、slat #1, and install slat #2.8.2.13.6 Pull the fabric from back to front across the top ofslat #2, and install slat #3.8.2.13.7 Pull the fabric from front to back across the top ofslat #3, and install slat #4.8.2.13.8 Remove the second paperclip from under slat #4.8.2.13.9 Pull the fabric from back to front across the top ofslat #4, and install slat #5.8.2.13.10 Pull the fabric from front to back across the top ofslat #5, and install slat #6.8.2.13.11 Pull the fabric from back to front across the top ofslat #6, and install slat #7.8.2.13.12 Remove the third paperclip from unde
