1、Designation: D1621 10Standard Test Method forCompressive Properties of Rigid Cellular Plastics1This standard is issued under the fixed designation D1621; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method describes a procedure for determinin
3、gthe compressive properties of rigid cellular materials, particu-larly expanded plastics.1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated
4、 with its use. 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.NOTE 1This test method and ISO 844 are technically equivalent.2. Referenced Documents2.1 ASTM Standards:2D
5、618 Practice for Conditioning Plastics for TestingE4 Practices for Force Verification of Testing MachinesE83 Practice for Verification and Classification of Exten-someter SystemsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 844 C
6、ellular PlasticsCompression Test of Rigid Ma-terials33. Terminology3.1 Definitions:3.1.1 compliancethe displacement difference between testmachine drive system displacement values and actual specimendisplacement.3.1.2 compliance correctionan analytical method ofmodifying test instrument displacement
7、 values to eliminate theamount of that measurement attributed to test instrumentcompliance.3.1.3 compressive deformationthe decrease in length pro-duced in the gage length of the test specimen by a compressiveload expressed in units of length.3.1.4 compressive strainthe dimensionless ratio of com-pr
8、essive deformation to the gage length of the test specimen orthe change in length per unit of original length along thelongitudinal axis.3.1.5 compressive strengththe stress at the yield point if ayield point occurs before 10 % deformation (as in Fig. 1a) or,in the absence of such a yield point, the
9、 stress at 10 %deformation (as in Fig. 1b).3.1.6 compressive stress (nominal)the compressive loadper unit area of minimum original cross section within the gageboundaries, carried by the test specimen at any given moment,expressed in force per unit area.3.1.7 compressive stress-strain diagrama diagr
10、am inwhich values of compressive stress are plotted as ordinatesagainst corresponding values of compressive strain as abscis-sas.3.1.8 compressive yield pointthe first point on the stress-strain diagram at which an increase in strain occurs without anincrease in stress.3.1.9 deflectometera device us
11、ed to sense the compres-sive deflection of the specimen by direct measurement of thedistance between the compression platens.3.1.10 displacementcompression platen movement afterthe platens contact the specimen, expressed in millimetres orinches.3.1.11 gage lengththe initial measured thickness of the
12、test specimen expressed in units of length.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Materials -Plastics and Elastomers.Current edition approved April 1, 2010. Published April 2010. Originallyappro
13、ved in 1959. Last previous edition approved in 2004 as D1621 - 04a. DOI:10.1520/D1621-10.2For 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 Summ
14、ary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoh
15、ocken, PA 19428-2959, United States.3.1.12 modulus of elasticitythe ratio of stress (nominal) tocorresponding strain below the proportional limit of a materialexpressed in force per unit area based on the minimum initialcross-sectional area.3.1.13 proportional limitthe greatest stress that a materia
16、lis capable of sustaining without any deviation from propor-tionality of stress-to-strain (Hookes law) expressed in forceper unit area.4. Significance and Use4.1 This test method provides information regarding thebehavior of cellular materials under compressive loads. Testdata is obtained, and from
17、a complete load-deformation curveit is possible to compute the compressive stress at any load(such as compressive stress at proportional-limit load orcompressive strength at maximum load) and to compute theeffective modulus of elasticity.4.2 Compression tests provide a standard method of obtain-ing
18、data for research and development, quality control, accep-tance or rejection under specifications, and special purposes.The tests cannot be considered significant for engineeringdesign in applications differing widely from the load - timescale of the standard test. Such applications require addition
19、altests such as impact, creep, and fatigue.4.3 Before proceeding with this test method, reference shallbe made to the specification of the material being tested. Anytest specimen preparation, conditioning, dimensions, or testingparameters, or a combination thereof, covered in the materialsspecificat
20、ion shall take precedence over those mentioned in thistest method. If there are no material specifications, then thedefault conditions apply.5. Apparatus5.1 Testing MachineA testing instrument that includesboth a stationary and movable member and includes a drivesystem for imparting to the movable m
21、ember (crosshead), auniform, controlled velocity with respect to the stationarymember (base). The testing machine shall also include thefollowing:5.1.1 Load Measurement SystemAload measurement sys-tem capable of accurately recording the compressive loadimparted to the test specimen. The system shall
22、 be indicate theload with an accuracy of 61 % of the measured value or better.The accuracy of the load measurement system shall be verifiedin accordance with Practices E4.5.2 Compression PlatensTwo flat plates, one attached tothe stationary base of the testing instrument and the otherattached to the
23、 moving crosshead to deliver the load to the testspecimen. These plates shall be larger than the specimenloading surface to ensure that the specimen loading is uniform.It is recommended that one platen incorporate a sphericalseating mechanism to compensate for non-parallelism in thespecimens loading
24、 surfaces or non-parallelism in the base andcrosshead of the testing instrument.5.3 Displacement Measurement SystemA displacementmeasurement system capable of accurately recording the com-pressive deformation of the test specimen during testing to anaccuracy of 61 % of the measured value or better.
25、Thismeasurement is made through use of the test machine cross-head drive system or using a direct measurement of compres-sion platen displacement.5.3.1 Direct Compression Platen DisplacementThis sys-tem shall employ a deflectometer that directly reads the distantbetween the upper and lower compressi
26、on platens. The accu-racy of the displacement measurement transducer shall beverified in accordance with Practices E83 and shall be classi-fied as a Class C or better.5.3.2 Test Machine Crosshead Drive SystemThis systemshall employ the position output from the crosshead drivesystem as a indicator of
27、 compression platen displacement. ThisX1= 10 % CORE DEFORMATIONX2= DEFLECTION (APPROXIMATELY 13 %)FIG. 1 a Compressive Strength (See 3.1.5 and Section 9) FIG. 1 b Compressive Strength (See 3.1.5 and Section 9)D1621 102method is only appropriate when it is demonstrated that theeffects of drive system
28、 compliance result in displacementerrors of less than 1 % of the measurement or if appropriatecompliance correction methods are employed to reduce themeasurement error to less than 1 %.5.3.2.1 Determining Drive System ComplianceTesting in-strument drive systems always exhibit a certain level ofcompl
29、iance that is characterized by a variance between thereported crosshead displacement and the displacement actuallyimparted to the specimen. This variance is a function of loadframe stiffness, drive system wind-up, load cell complianceand fixture compliance. This compliance can be measured then,if de
30、termined to be significant and empirically subtracted fromtest data to improve test accuracy. The procedure to determinecompliance follows:(1) Configure the test system to match the actual testconfiguration.(2) Position the two compression platens very close to eachother simulating a zero thickness
31、specimen in place.(3) Start the crosshead moving at 12.5 mm (0.5 in.)/min inthe compression direction recording crosshead displacementand the corresponding load values.(4) Increase load to a point exceeding the highest loadexpected during specimen testing. Stop the crosshead andreturn to the pre-tes
32、t location.(5) The recorded load-deflection curve, starting when thecompression platens contact one another, is defined as testsystem compliance5.3.2.2 Performing Compliance CorrectionUsing theload-deflection curve created in 5.3.2.1, measure the systemcompliance at each given load value. On each sp
33、ecimen testcurve at each given load value, subtract the system compliancefrom each recorded displacement value. This will be the newload-deflection curve for use in calculations starting in Section9.5.4 Micrometer Dial Gage, caliper, or steel rule, suitable formeasuring dimensions of the specimens t
34、o 61 % of themeasured values.6. Test Specimen6.1 The test specimen shall be square or circular in crosssection with a minimum of 25.8 cm2(4 in.2) and maximum of232 cm2(36 in.2) in area. The minimum height shall be 25.4mm (1 in.) and the maximum height shall be no greater than thewidth or diameter of
35、 the specimen. Care should be taken so thatthe loaded ends of the specimen are parallel to each other andperpendicular to the sides.NOTE 2Cellular plastics are not ideal materials, and the compressivemodulus may appear significantly different, depending on the test condi-tions, particularly the test
36、 thickness. All data that are to be comparedshould be obtained using common test conditions.6.2 All surfaces of the specimen shall be free from largevisible flaws or imperfections.6.3 If the material is suspected to be anisotropic, thedirection of the compressive loading must be specified relativeto
37、 the suspected direction of anisotropy.6.4 A minimum of five specimens shall be tested for eachsample. Specimens that fail at some obvious flaw should bediscarded and retests made, unless such flaws constitute avariable the effect of which it is desired to study.7. Conditioning7.1 ConditioningCondit
38、ion the test specimens at 23 62C (73.4 6 3.6F) and 50 6 10 % relative humidity for notless than 40 h prior to test in accordance with Procedure A ofPractice D618, unless otherwise specified in the contract orrelevant material specification. In cases of disagreement, thetolerances shall be 61C (61.8F
39、) and 65 % relative humid-ity.7.2 Test ConditionsConduct tests in the standard labora-tory atmosphere of 23 6 2C (73.4 6 3.6F) and 50 6 10 %relative humidity, unless otherwise specified. In cases ofdisagreement, the tolerances shall be 61C (61.8F) and65 % relative humidity.8. Procedure8.1 Measure th
40、e dimensions of the specimen to a precisionof 61 % of the measurement as follows:8.1.1 Thicknesses up to and including 25.4 mm (1 in.) shallbe measured using a dial-type gage having a foot withminimum area of 6.45 cm2(1 in.2). Hold the pressure of the dialfoot to 0.17 6 0.03 kPa (0.025 6 0.005 psi).
41、8.1.2 Measure dimensions over 25.4 mm (1 in.) with a dialgage, a sliding-caliper gage, or a steel scale. When a sliding-caliper gage is employed, the proper setting shall be that pointat which the measuring faces of the gage contact the surfacesof the specimen without compressing them.8.1.3 Record e
42、ach dimension as an average of three mea-surements.8.2 Place the specimen between the compression platensensuring that the specimen center-line is aligned with thecenter-line of the compression platens and the load will bedistributed as uniformly as possible over the entire loadingsurface of the spe
43、cimen. It will expedite the testing process if,when the specimen is in place, the upper platen is positionedclose to, but not touching, the specimen.8.2.1 If following 5.3.2.1, attach the deflectometer or com-pression extensometer to the compression platens.8.3 Start the crosshead moving in the dire
44、ction to compressthe specimen with the rate of crosshead displacement of 2.5 60.25 mm (0.1 6 0.01 in.)/min for each 25.4 mm (1 in.) ofspecimen thickness.8.4 Record compression platen displacement and the corre-sponding load data. This recorded curve will be used directly iffollowing 5.3.2.1 or could
45、 be modified following 5.3.2.2.8.5 Continue until a yield point is reached or until thespecimen has been compressed approximately 13 % of itsoriginal thickness, whichever occurs first.8.5.1 When specified, a deformation other than 10 % maybe used as the point at which stress shall be calculated. In
46、sucha case, compress the specimen approximately 3 % more thanthe deformation specified. Substitute the specified deformationwherever “10 % deformation” is cited in Sections 9 and 10.9. Calculation9.1 Using a straightedge or through the use of computersoftware, carefully extend to the zero load line
47、the steepestD1621 103straight portion of the load-deflection curve examining only thelower portion of the load-deflection curve. This establishes the“zero deformation” or “zero strain” point (Point O in Fig. 1aand Fig. 1b). Measure all distances for deformation or straincalculations from this point.
48、9.2 Measure from Point O along the zero-load line adistance representing 10 % specimen deformation. At thatpoint (Point M in Fig. 1a and Fig. 1b), draw a vertical lineintersecting the load-deflection or load-strain curve at Point P.9.2.1 If there is no yield point before Point P (as in Fig. 1b),read
49、 the load at Point P.9.2.2 If there is a yield point before Point P (as Point L inFig. 1), read the load and measure the percent core deformationor strain (Distance O-R) at the yield point.9.2.3 Calculate the compressive strength by dividing theload (9.2.1 or 9.2.2) by the initial horizontal cross-sectionalarea of the specimen.9.3 If compressive modulus is requested, choose any con-venient point (such as Point S in Fig. 1b) along the steepeststraight line portion of the load-deflection or load-strain curve.Read the load and measure the deformatio
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1