A number in parentheses indicates the year of last reapproval. Asuperscript epsilon e indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. This standard does not purport toaddress all of the safety concerns associated with its use. It isthe responsibility of the user of this standard to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.
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A number in parentheses indicates the year of last reapproval. Asuperscript epsilon e indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.
This standard does not purport toaddress all of the safety concerns associated with its use. It isthe responsibility of the user of this standard to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.
Referenced Documents2. Themounting tab should be as thin as practicable to minimizefilament misalignment. This compliance must be deter-mined experimentally for a given combination of test machineconditions, grip system and mounted specimen. It must besubtracted from the indicated elongation to yield true specimenelongation in the gage length Note 1.
System compliancecorrection will not apply when elongation in the specimen gagelength is determined by direct measurement. NOTE 1—The magnitude of the system compliance can be a significantportion of the indicated compliance.
Extreme care must be exercised in thedetermination of this correction as outlined in 8. Summary of Test Method4. The filaments are center-line mounted onspecial slotted tabs. The tabs are gripped so that the testspecimen is aligned axially in the jaws of a constant-speedmovable-crosshead test machine. The filaments are thenstressed to failure at a constant strain rate. Alternative methods of area de-termination such as optical gages, image-splitting microscope,linear weight-density method, etc, may also be used.
Significance and Use5. Very short filaments, such as whiskers ofnonuniform cross section, call for highly specialized testtechniques not covered by this test method. Current edition approved Feb. Published April The apparatus described hereinshall use a constant-strain-rate tensile testing machine with atest specimen bonded to a suitable tab. It shallcontain an adaptor, on the machine centerline, for the other partof the specimen grip assembly.
Its accuracy shall be verified inaccordance with Practices E 4. For this test method, chart and crossheadspeeds shall be provided to produce acceptable data. Alternative methods of specimen mountingmay be used. Test Specimens7. A statistically significant number of single-filamenttest specimens are gently separated from the strand bundle. Selection should be random.
The critical considerations arethat the filament be not visibly damaged or attached to anotherfilament, and have sufficient length. Determine the length to the nearest NOTE 2—For this test method, the specimen gage length shall bebetween 20 and 30 mm. The tab shape should be proportioned as shownin Fig. Center thespecimen over the tab slot with one end taped to the tab. Courtwright No. Ordinary sealing wax has provenequally effective. Visually check the axial specimenalignment. If specimen damage occurs, discard the specimen.
Where doubt exists as to thecross-sectional area of a test specimen, prepare and measure itsbroken ends by this method. Use a magnification of to on the photomicrographs for this technique. However, an optical method may be used todetect gage section elongation directly. Use an alternativemeans for determining the true gage length elongation fromanalysis of the chart speed, crosshead speed, and the systemcompliance.
It must be subtracted from the chart indicated compliance toyield the actual specimen elongation in the gage length. These tabs must bemade of the same material as that used in the procedureoutlined herein.
Determine the gage length to the nearest Measure the chart extension in millimetres as shown. Calculate the indicated compliance, Ca, for each sample as in9. Draw the best fit line through each setof points to intersect the zero gage length axis.
The verticaldisplacement indicated shall be called the zero gage lengthintercept or the system compliance, Cs. A suitable conversionfactor must be used for inch-pound units. 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 responsible 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.
ASTM 3379 - 75
ASTM D3379-75 PDF