1、Designation: D6112 10Standard 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. Scope1.1 These test methods cover the determination of the creepand creep-rupture properties of plastic lumber and s
3、hapes,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 lum
4、ber 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 be
5、 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 and health practices and det
6、ermine the applica-bility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D543 Practices for Evaluating the Resistance of Plastics toChemical ReagentsD883 Terminology Relating to PlasticsD2990 Test Methods for
7、Tensile, Compressive, and Flex-ural Creep and Creep-Rupture of PlasticsD4000 Classification System for Specifying Plastic Materi-alsD5033 Guide for Development of ASTM Standards Relat-ing to Recycling and Use of Recycled Plastics3D5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE
8、4 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 of initial applied stress tocreep strain.3.1.3 cre
9、ep 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 to be the nonelastic portion ofstrain. However, thi
10、s 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 test methods, it refers to the sum of elasticstrain pl
11、us 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-sion:3.1.6 plastic lumber, na manufactured product co
12、mposedof more than 50 weight percent resin, and in which the productgenerally is rectangular in cross-section and typically suppliedin board and dimensional lumber sizes, may be filled orunfilled, and may be composed of single or multiple resinblends.1These test methods are under the jurisdiction of
13、 ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.20 on Plastic Lumber(Section D20.20.01).Current edition approved Sept. 1, 2010. Published September 2010. Originallyapproved in 1997. Last previous edition approved in 1997 as D6112 - 97(2005).DOI: 10.1520/D6112-10.
14、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.3Withdrawn. The last approved version of this historical stan
15、dard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7 plastic shape, na manufactured product composedof more than 50 weight percent resin, and in which the productgenerally is not rectangular in cros
16、s-section, may be filled orunfilled, and may be composed of single or multiple resinblends.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 co
17、nchoidally. (See TerminologyD883.)3.1.8.1 DiscussionIn a broad 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 calcula
18、ted according to Eq 1.3.1.10 Additional definition of terms applying 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 subj
19、ect to constant flexural or compres-sive load under specified environmental 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.
20、4 These test methods represent modifications of the com-pressive 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 load
21、s and to predict dimensional changes that havethe potential to 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 cert
22、ain conditions, for specificationpurposes.5.3 For many products, 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 produc
23、t specification before using this test method.Table 1 in Classification 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 des
24、ired load. The loading mechanism must allowreproductively rapid 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 syst
25、em shall be verified at least once each year inaccordance with 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
26、 moves during thetest.6.1.2 Compression and Deflection Measurements: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 standardu
27、nder conditions are nearly identical as possible with thoseencountered 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-tach
28、ed to or seated on the specimen so that no slippage occurs.Electrical 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-
29、to-rupture or failure orthe elapsed time of each creep measurement, 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 inrep
30、orting the results.NOTE 2The thermal contraction and expansion 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 t
31、he gauge length of the specimen through-out the test. The temperature 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
32、 to ensure an accuratedetermination of the average test temperature 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 be
33、havior of thematerial under testing has been shown to be unaffected byhumidity. The controlling and measuring instruments shall bestable 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
34、 (10 to40C).)6.1.5.2 If, for any reason, the specified 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.D6112 1026.1.5.3 The composition of the test envir
35、onment shall bemaintained constant throughout the test. (WarningTakespecial 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
36、tests are quite sensitive toshock and vibration. The location of 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 equipm
37、ent during creep or creep-rupture testing. During time-to-rupture 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 theloa
38、d to the unconfined-type specimen (see 8.2). One of theplatens 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
39、center.6.2.2 The compression of specimen gauge length under loadshall 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 thes
40、pecimen can be measured using platen displacement with theentire 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
41、specimen. Inorder to avoid excessive indentation of the specimen, 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 conf
42、ig-ured with loading noses with cylindrical surfaces (see Fig. 1).The radius 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
43、 asshown in Fig. 1.6.3.4 For flexural testing the deflection of the 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 reag
44、ents shall conform to the specifications of the Commit-tee on Analytical 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 l
45、esseningthe accuracy of the determination.7.2 Purity of WaterUnless 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 be
46、as stipulated in the specification.7.4 Standard ReagentsA list of 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 obta
47、in 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 elev
48、ated temperatures), provision shall bemade to test unloaded control specimens alongside the testspecimen so as to provide compensation for changes other thancreep.Aminimum of three control specimens shall be tested ateach test temperature.8.1.3 In creep testing at a single temperature, the minimumnu
49、mber of test specimens at each stress shall be two if four ormore levels of stress are used or three if fewer than four levelsare used.8.1.4 In creep-rupture testing, a minimum of two specimensshall be tested at each of the stress levels specified in 10.2.1 ateach temperature.NOTE 3The scatter of creep-rupture data is considerable, with onehalf to a full decade of variation in time-to-rupture being typical.Therefore, it is some times necessary to test more than two specimens ateach stress level to obtain satisfactory results.8.2 Compressive Creep:4Reagent C
