1、Designation: D6112 18Standard Test Methods forCompressive and Flexural Creep and Creep-Rupture ofPlastic Lumber and Shapes1This standard is issued under the fixed designation D6112; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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. Scope*1.1 These test methods cover the determination of the creepand creep-rupture properties of plastic lumber and
3、shapes,when loaded in compression or flexure under specified envi-ronmental conditions. Test specimens in the “as-manufactured”form are employed. As such, these are test methods forevaluating the properties of plastic lumber or shapes as aproduct and not material property test methods.1.2 Plastic lu
4、mber and plastic shapes are currently madepredominantly with recycled plastics. However, this testmethod would also be applicable to similar manufacturedplastic products made from virgin resins where the product isnon-homogenous in the cross-section.1.3 The values stated in inch-pound units are to b
5、e regardedas standard. The values given in parentheses are for informa-tion only.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, health, and environmental
6、practices and deter-mine the applicability of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Princip
7、les 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:2D543 Practices for Evaluating the Resistance of Plastics toChemical ReagentsD883 Terminology Rel
8、ating to PlasticsD2990 Test Methods for Tensile, Compressive, and FlexuralCreep and Creep-Rupture of PlasticsD4000 Classification System for Specifying Plastic Materi-alsD5033 Guide for Development ofASTM Standards Relatingto Recycling and Use of Recycled Plastics (Withdrawn2007)3D5947 Test Methods
9、for Physical Dimensions of SolidPlastics SpecimensE4 Practices for Force Verification of Testing Machines3. Terminology3.1 Definitions:3.1.1 compressionin a compressive creep test, the de-crease in length produced in the gauge length or the total lengthof a test specimen.3.1.2 creep modulusthe ratio
10、 of initial applied stress tocreep strain.3.1.3 creep strainthe total strain, at any given time,produced by the applied stress during a creep test.3.1.3.1 DiscussionThe term creep, as used in this testmethod, reflects current plastics engineering usage. In scientificpractice, creep is often defined
11、to be the nonelastic portion ofstrain. However, this definition is not applicable to existingengineering formulas. Plastics have a wide spectrum of retar-dation times, and elastic portions of strain cannot be separatedin practice from nonelastic. Therefore, wherever “strain” ismentioned in these tes
12、t methods, it refers to the sum of elasticstrain plus the additional strain with time.3.1.4 deflectionin a flexural creep test, the change inmid-span position of a test specimen.3.1.5 deformationa change in shape, size or position of atest specimen as a result of compression, deflection, or exten-si
13、on:1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.20 on Plastic Lumber(Section D20.20.01).Current edition approved June 1, 2018. Published June 2018. Originallyapproved in 1997. Last previous edition approved in 2
14、013 as D6112 - 13. DOI:10.1520/D6112-18.2For 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.3The last approved ve
15、rsion of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance wit
16、h internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.6 plastic lumber, na manufactured pro
17、duct made pri-marily from plastic materials (filled or unfilled), typically usedas a building material for purposes similar to those of tradi-tional lumber, which is usually rectangular in cross-section.(Terminology D883)3.1.6.1 DiscussionPlastic lumber is typically supplied insizes similar to those
18、 of traditional lumber board, timber anddimension lumber; however the tolerances for plastic lumberand for traditional lumber are not necessarily the same.(Terminology D883)3.1.7 plastic shape, na manufactured product made pri-marily from plastic materials (filled or unfilled), which is notnecessari
19、ly rectangular in cross section.3.1.8 resin, na solid or pseudo-solid organic materialoften of high molecular weight, that exhibits a tendency to flowwhen subjected to stress, usually has a softening or meltingrange, and usually fractures conchoidally. (Terminology D883)3.1.8.1 DiscussionIn a broad
20、sense, the term is used todesignate any polymer that is a basic material for plastics.3.1.9 stressfor compressive creep, the ratio of the appliedload to the initial cross-sectional area. For flexural creep,maximum fiber stress is calculated according to Eq 1.3.1.10 Additional definition of terms app
21、lying to this testmethod appear in Terminology D883 and Guide D5033.4. Summary of Test Method4.1 These test methods consist of measuring the deflectionor compression as a function of time and time-to-rupture, orfailure of a specimen subject to constant flexural or compres-sive load under specified e
22、nvironmental conditions.4.2 The four-point loading a outlined in this testing standardshall be used for the flexural creep tests.4.3 Compressive loading as outlined in this testing standardshall be used for the compressive creep tests.4.4 These test methods represent modifications of the com-pressiv
23、e and flexural creep and creep rupture test methodsspecified in Test Methods D2990.5. Significance and Use5.1 Data from creep and creep-rupture tests are necessary topredict the creep modulus and strength of materials underlong-term loads and to predict dimensional changes that havethe potential to
24、occur as a result of such loads.5.2 Data from these test methods can be used to characterizeplastic lumber: for comparison purposes, for the design offabricated parts, to determine long-term performance underconstant load, and under certain conditions, for specificationpurposes.5.3 For many products
25、, it is possible that there will be aspecification that requires the use of this test method, but withsome procedural modifications that take precedence whenadhering to the specification. Therefore, it is advisable to referto that product specification before using this test method.Table 1 in Classi
26、fication D4000 lists the ASTM materialsstandards that currently exist.6. Apparatus6.1 General:6.1.1 Loading System:6.1.1.1 The loading system must be so designed that theload applied and maintained on the specimen is within 61%of the desired load. The loading mechanism must allowreproductively rapid
27、 and smooth loading as specified in 11.1.3.In creep-rupture tests, provision must be made to ensure thatshock loading, caused by a specimen failure, is not transferredto other specimens undergoing testing. The accuracy of theloading system shall be verified at least once each year inaccordance with
28、Practices E4.6.1.1.2 Loading systems that provide a mechanical advan-tage require careful design to maintain constant load through-out the test. For example, lever systems must be designed sothat the load does not change as the lever arm moves during thetest.6.1.2 Compression and Deflection Measurem
29、ents:6.1.2.1 The accuracy of the deformation measuring deviceshall be within 61 % of the deformation to be measured.6.1.2.2 Deformation measuring devices shall be calibratedagainst a precision micrometer screw or other suitable standardunder conditions are nearly identical as possible with thoseenco
30、untered in the test. Caution is necessary when usingdeformation measuring devices whose calibration is subject todrifting with time and is dependent on temperature andhumidity.6.1.2.3 Deformation measuring devices shall be firmly at-tached to or seated on the specimen so that no slippage occurs.Elec
31、trical resistance gauges are suitable only if the materialtested will permit perfect adhesion to the specimen and if theyare consistent with 6.2.16.1.3 Time MeasurementThe accuracy of the time mea-suring device shall be 61 % of the time-to-rupture or failure orthe elapsed time of each creep measurem
32、ent, or both.6.1.4 Temperature Control and Measurement:6.1.4.1 The temperature of the test space, especially close tothe gauge length of the specimen, shall be maintained within62C by a suitable automatic device and shall be stated inreporting the results.NOTE 2The thermal contraction and expansion
33、associated with smalltemperature changes during the test has the potential to produce changesin the apparent creep rate, especially near transition temperatures.6.1.4.2 Care must be taken to ensure accurate temperaturemeasurements over the gauge length of the specimen through-out the test. The tempe
34、rature measuring devices shall bechecked regularly against temperature standards and shallindicate the temperature of the specimen gauge area.6.1.4.3 Temperature measurements shall be made at fre-quent intervals, or continuously recorded to ensure an accuratedetermination of the average test tempera
35、ture and compliancewith 6.1.5.6.1.5 Environmental Control and Measurements:6.1.5.1 When the test environment is air, the relative humid-ity shall be controlled to 50 6 5 % during the test unlessotherwise specified, or unless the creep behavior of thematerial under testing has been shown to be unaffe
36、cted byhumidity. The controlling and measuring instruments shall beD6112 182stable for long time intervals and accurate to within 61%.(The control of relative humidity is known to be difficult attemperatures much outside the range from 50 to 104F (10 to40C).)6.1.5.2 If, for any reason, the specified
37、 relative humiditycannot be achieved or the test is conducted to determine thesensitivity of the product to high humidity, report the actualaverage value and fluctuation of relative humidity used.6.1.5.3 The composition of the test environment shall bemaintained constant throughout the test. (Warnin
38、gTakespecial precautions to avoid personal contact, to eliminate toxicvapors, and to guard against explosion hazards in accordancewith any possible hazardous nature of the particular environ-ment being used.)6.1.6 Vibration ControlCreep tests are quite sensitive toshock and vibration. The location o
39、f the apparatus, the testequipment, and mounting shall be so designated that thespecimen is isolated from vibration. Multiple-station testequipment must be of sufficient rigidity so that no significantdeflection occurs in the test equipment during creep or creep-rupture testing. During time-to-ruptu
40、re or failure, means toprevent jarring of other test specimens by the falling load froma failed test specimen shall be provided by a suitable net orcushion.6.2 Compressive Creep:6.2.1 PlatensParallel platens shall be used to apply theload to the unconfined-type specimen (see 8.2). One of theplatens
41、of the machine shall preferably be self-aligning andshall, so that it is possible to apply the load evenly over the faceof the specimen, be arranged so that the specimen is accuratelycentered and the resultant of the load is through its center.6.2.2 The compression of specimen gauge length under loa
42、dshall be measured by means of any device that will notinfluence the specimen behavior by mechanical (undesirabledeformation, notches, etc.) physical (heating of specimen, etc.),or chemical effects. Alternatively, the compression of thespecimen can be measured using platen displacement with theentir
43、e length of the specimen serving as the gauge length.6.3 Flexural Creep:6.3.1 Test RackA rigid test rack shall be used to providesupport of the test specimen at both ends with a span equal to16 (tolerant +4 and 2) times the depth of the specimen. Inorder to avoid excessive indentation of the specime
44、n, the radiusof the support shall be a minimum of 0.5 in. (12.7 mm) and upto 1.5 times the depth of the specimen. Sufficient space must beallowed below the specimen for dead-weight loading.6.3.2 Loading BeamThe loading beam shall be configuredwith loading noses with cylindrical surfaces (see Fig. 1)
45、. Theradius of noses shall be at least 0.5 in. (12.7 mm) or allspecimens. For large specimens it is possible that the radius ofthe supports will be up to 1.5 times the specimen depth.6.3.3 A four point loading arrangement shall be used asshown in Fig. 1.6.3.4 For flexural testing the deflection of t
46、he specimenshall be measured at the midpoint of the load span at thebottom face of the specimen.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Ana
47、lytical Reagents of the American Chemical Society,where such specification are available4. It is acceptable to useother grades, provided it is first ascertained that the reagent isof sufficiently high purity to permit its use without lesseningthe accuracy of the determination.7.2 Purity of WaterUnle
48、ss otherwise indicated, referencesto water shall be understood to mean distilled water or water ofequal purity.7.3 Specified ReagentsIf this test method is referenced ina material specification, the specific reagent to be used shall beas stipulated in the specification.7.4 Standard ReagentsA list of
49、 standard reagents is alsoavailable in Test Method D543.8. Test Specimen8.1 General:8.1.1 It is acceptable to make test specimens by any of thetechniques normally employed to produce plastic lumber.When the testing objective is to obtain design data, the methodof sample fabrication shall be the same as that used in theapplication.8.1.2 In the case of materials whose dimensions are knownto change significantly due to the specified environment alone(for example, the shrinkage of some thermosetting plastics dueto post-curing at elevated temperatures), provisio
