1、Designation: F2018 00 (Reapproved 2010)Standard Test Method forTime-to-Failure of Plastics Using Plane Strain TensileSpecimens1This standard is issued under the fixed designation F2018; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 covers the requirements to determinethe time-to-failure of thermoplastic resins for pi
3、ping applica-tions by uniaxial loading of a grooved tensile test specimen.This grooved tensile specimen achieves a multi-axial stresscondition, which mimics the stress condition found in pressur-ized solid-wall plastic pipe. The ratio of the stress in the axialdirection to the transverse direction a
4、pproximates that for apressurized solid-wall pipe specimen.1.2 It is intended that the data generated on these specimensbe analyzed according to the methodology set forth in TestMethod D2837 to generate a long-term strength design valuefor the material.1.3 The values stated in SI units are to be reg
5、arded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all 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 deter
6、mine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1598 Test Method for Time-to-Failure of Plastic PipeUnder Constant Internal PressureD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD2837 Test Method for Obtaining Hydrostatic Desig
7、n Basisfor Thermoplastic Pipe Materials or Pressure Design Basisfor Thermoplastic Pipe ProductsD2990 Test Methods for Tensile, Compressive, and FlexuralCreep and Creep-Rupture of PlasticsD1928 Practice for Preparation of Compression-MoldedPolyethylene Test Sheets and Test Specimens (Withdrawn2001)3D
8、4703 Practice for Compression Molding ThermoplasticMaterials into Test Specimens, Plaques, or SheetsF412 Terminology Relating to Plastic Piping Systems2.2 Other Document:PPI TR-4 HDB Listed Materials43. Terminology3.1 Definitions:3.1.1 Definitions are in accordance with Terminology F412,and abbrevia
9、tions are in accordance with Terminology D1600.3.1.2 long-term strength (LTS)the estimated tensile stressin the test specimen that when applied continuously will causefailure of the specimen at 100 000 h. This is the intercept of thestress regression line with the 100 000-h coordinate.4. Summary of
10、Test Method4.1 This test method consists of a description of the groovedtensile test specimen and its use in various environments toobtain the long-term strength capacity for piping materials.Such a controlled environment may be accomplished by, but isnot limited to, immersing the specimens in a con
11、trolled-temperature water bath or circulating-air oven.5. Significance and Use5.1 The data obtained by this test method are useful forestablishing stress versus failure-time relationships in a con-trolled environment. The long-term strength (LTS) is deter-mined primarily for materials used in moldin
12、g applications.The LTS categorized in accordance with Table 1 of ASTMD2837 is known as the SDB (strength design basis).NOTE 1These SDB values will be published in PPI TR-4 for materialsused in molding applications only.1This test method is under the jurisdiction of ASTM Committee F17 on PlasticPipin
13、g Systems and is the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved Aug. 1, 2010. Published November 2010. Originallyapproved in 2000. Last previous edition approved in 2006 as F201800(2006). DOI:10.1520/F2018-00R10.2For referenced ASTM standards, visit the ASTM
14、 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.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from Plastic
15、s Pipe Institute (PPI), 105 Decker Court, Suite 825,Irving, TX 75062, http:/www.plasticpipe.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 The test method can also be used on an experimentalbasis for pipe-grade materials as a
16、n indicator of stress-ruptureperformance. The long-term strength or SDB values obtainedby this test method are not intended to replace the HDBdetermined for pressure pipe tested in accordance with TestMethod D1598.5.3 In order to determine how plastics will perform in pipefitting applications, it is
17、 necessary to establish the stress-failuretime relationships over four or more decades of time (hours) ina controlled environment. Because of the nature of the test andspecimens employed, no single line can adequately representthe data, and therefore the confidence limits should be estab-lished.NOTE
18、 2Some materials may exhibit a nonlinear relationship betweenlog-stress and log-failure time, usually at short failure-times. In suchcases, the 105- hour stress value computed on the basis of short-term testdata may be significantly different than the value obtained when adistribution of data points
19、 in accordance with Test Method D2837 isevaluated. However, these data may still be useful for quality control orother applications, provided correlation with long-term data has beenestablished.6. Apparatus6.1 Constant-Temperature SystemA reservoir capable ofmaintaining a fluid bath at a uniform tem
20、perature shall be used.If water or other liquid medium is used, agitation is permittedto stabilize the temperature throughout the fluid bath. If an airor other gaseous environment is used, provision shall be madefor adequate circulation. The test may be conducted at 23C(73F) or other selected temper
21、atures as required and thetemperature tolerance requirements shall be 6 2C (6 3.6F).A typical test setup is shown in Fig. 1.6.2 Loading SystemAny device that is capable of continu-ously applying constant load on the specimen may be used.The device shall be capable of reaching the test load withoutex
22、ceeding it and of holding it within the tolerances shown in6.5 for the duration of the test. A typical loading system isshown in Fig. 2, which utilizes a pressurized cylinder to applyload to the specimen. Other creep load frames can be used,such as those described in Test Methods D2990 for tensilecr
23、eep. The loading system shall be checked with a load cell thathas a calibration certificate traceable to National Institute forStandards and Technology (NIST).6.3 Load or Pressure GageA load gage or, for use with anair cylinder, a pressure gage that meets the tolerance require-ments in 6.5 is requir
24、ed.6.4 Timing DeviceThe timing device shall be capable ofmeasuring the time-to-failure with sufficient accuracy to meetthe requirements listed in 6.5.6.5 Time and Force ToleranceWhen added together, thetolerance for the timing device and the tolerance for the forcemeasuring device shall not exceed 6
25、2%.7. Test Specimen7.1 Test Specimen DimensionsThe shape of the test speci-men is shown in Fig. 3. A round groove is produced along thefull width of the specimen on both sides. The opposing groovesshould be parallel and centered in the specimen to within60.127 mm (0.005 in.). A specimen that has bee
26、n used success-fully for polyethylene is shown in Fig. 3. The critical dimen-sions of this specimen are shown below in Table 1.7.1.1 The reduced thickness in the groove shall be measuredat three locations, the center of the groove, and at the edges ofthe specimen. All three measurements must conform
27、 to thedimensions specified in Table 1.7.2 MeasurementsDimensions shall be determined in ac-cordance with Test Method D4703.7.3 Specimen FabricationPlane-strain specimens may befabricated from plaques of materials which are injection-molded, extruded, or compression-molded (for example, inFIG. 1 Sch
28、ematic Diagram of Typical Experimental SetupF2018 00 (2010)2accordance with Practice D4703 for compression molding ofpolyethylene). The specimens machined from these plaquesshall be free of voids. Test plaques may also be formed byflattening thick-wall pipe sections. All specimens used for aparticul
29、ar data set must be prepared in the same manner, that is,all compression-molded or all injection-molded using the samegate configuration.7.3.1 MachiningThe compression-molded or injection-molded sample can be machined to size by milling, and theedges should be smooth and free from burrs. The groove
30、shallbe machined in such a way that the groove surface will besmooth, minimizing any machining marks on the groovesurface.A3.175 mm (0.125 in.) radius, 4-flute ball end mill hasbeen used successfully for machining the grooves. Appropriatefixturing is necessary to ensure that the grooves on both side
31、sof the specimen coincide with one another. In all machiningoperations, care shall be taken to minimize any heating of thesample.7.3.2 Injection-MoldingSamples may be injection-moldedto the appropriate dimensions. In this case the grooves wouldbe molded-in, as opposed to above, where the sample isma
32、chined from an injection-molded plaque. All specimens in atest lot must be prepared the same way, whether withmolded-in grooves or machined grooves. The location of thegate can affect the material orientation in the sample and thussignificantly affect the results of the testing.NOTE 3Use of an injec
33、tion-molded sample may allow study of knitFIG. 2 Schematic Diagram of Pneumatic Tensile Loading Fixture AssemblyTABLE 1 Dimensions of Plane-Strain SpecimenDimensionmm (in.)Tolerancemm(in.)Width (W) 38.0 (1.5) 0.5 (0.02)Groove Radius 3.18 (0.125) 1.0 (0.04)Groove Height 6.35 (0.25) 0.5 (0.02)Unreduce
34、d Thickness 7.62 ( 0.3) NAReduced Thickness 2.54 (0.1) 0.25 (0.01)Overall Length (L)AMinimum 76 (3.0) 6.4 (0.25)Maximum 152.4 (6.0) 6.4 (0.25)AThe overall length of the specimen can vary from approximately 76 mm (3 in.) To152 mm (6 in.), as long as the ends of the grips do not extend closer than 10
35、mm(0.39 in.) to the edge of the grooves.F2018 00 (2010)3lines and other variables important for pipe fitting applications.8. Conditioning8.1 Specimens shall be conditioned at the test temperaturebefore loading. Specimens in a liquid bath shall be conditionedfor a minimum of 1 h before loading. Speci
36、mens in a gaseousmedium shall be conditioned for a minimum of 16 h beforeloading. All specimens in a test lot must be tested in the samemedium. Newly molded specimens shall be preconditioned fora minimum of 40 h at 23 6 2C (73.4 6 3.6F) prior to test.9. Procedure9.1 Attach grips to the test specimen
37、 and load into the testfixture for conditioning at the selected test-temperature. Theends of the grips shall be at least 10 mm (0.39 in.) from thegrooved area.9.2 Apply the load to the specimen gradually within aperiod of about 5 to 10 s without any impact of the specimen.9.3 Record the time-to-fail
38、ure of each specimen. The time-to-failure shall not include periods of time during which thespecimen was under no load. Failure occurs when the twohalves of the specimen separate completely or extension of thegroove section causes the timer to be shut off (approximately12.5 mm (0.5 in.) deflection).
39、10. Calculation10.1 Calculate the stress in the grooved tensile test speci-men as follows:S 5 P/Wt! (1)where:S = stress, MPa (psi),P = tensile load, N (lbs),W = width of specimen, mm (in), andt = minimum thickness at grooved notch of specimen, mm(in).11. Report11.1 Report the following information:1
40、1.1.1 Complete identification of the specimens, includingmaterial type, manufacturers name and code number, speci-men preparation, and previous history,11.1.2 Test temperature,11.1.3 Test environment, including conditioning time,11.1.4 Test load, calculated stress, and time-to-failure foreach specim
41、en,11.1.5 Failure mode, any unusual effects of prolongedexposure, and the type of failure,11.1.6 Date test was started and report date,11.1.7 Any deviations in dimensions from 7.1, and11.1.8 Name of test laboratory and supervisor of this test.12. Precision and Bias12.1 The repeatability standard dev
42、iation has been deter-mined to be 636 %, based on limited data. The reproducibilityof this test method is being determined and will be available onor before January 1, 2005.FIG. 3 Dimensions of Plane-Strain SpecimenF2018 00 (2010)4ASTM International takes no position respecting the validity of any p
43、atent rights asserted in connection 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 revisi
44、on 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 co
45、mments 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.This standard is copyrigh
46、ted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 00 (2010)5
