1、Designation: D1621 10D1621 16Standard 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 revi
2、sion. A 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 U.S. Department of Defense.1. Scope*1.1 This test method describes a procedure f
3、or determining the compressive properties of rigid cellular materials, particularlyexpanded plastics.1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if a
4、ny, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.NOTE 1This test method and ISO 844 are technically equivalent.2. Referenced Documents2.1 ASTM S
5、tandards:2D618 Practice for Conditioning Plastics for TestingE4 Practices for Force Verification of Testing MachinesE83 Practice for Verification and Classification of Extensometer SystemsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2.2 ISO Standar
6、d:ISO 844 Cellular PlasticsCompression Test of Rigid Materials33. Terminology3.1 Definitions:3.1.1 compliancethe displacement difference between test machine drive system displacement values and actual specimendisplacement.3.1.2 compliance correctionan analytical method of modifying test instrument
7、displacement values to eliminate the amountof that measurement attributed to test instrument compliance.3.1.3 compressive deformationthe decrease in length produced in the gage length of the test specimen by a compressive loadexpressed in units of length.3.1.4 compressive strainthe dimensionless rat
8、io of compressive deformation to the gage length of the test specimen or thechange in length per unit of original length along the longitudinal axis.3.1.5 compressive strengththe stress at the yield point if a yield point occurs before 10 % deformation (as in Fig. 1a) or, inthe absence of such a yie
9、ld point, the stress at 10 % deformation (as in Fig. 1b).3.1.6 compressive stress (nominal)the compressive load per 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-strai
10、n diagrama diagram in which values of compressive stress are plotted as ordinates againstcorresponding values of compressive strain as abscissas.1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.22 on Cellular Material
11、s - Plasticsand Elastomers.Current edition approved April 1, 2010May 1, 2016. Published April 2010May 2016. Originally approved in 1959. Last previous edition approved in 20042010 asD1621 - 04a.D1621 - 10. DOI: 10.1520/D1621-10.10.1520/D1621-16.2 For referencedASTM standards, visit theASTM website,
12、www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/
13、www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users cons
14、ult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
15、 PA 19428-2959. United States13.1.8 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 used to sense the compressive deflection of the specimen by direct measurement of the distancebetween
16、 the compression platens.3.1.10 displacementcompression platen movement after the platens contact the specimen, expressed in millimetres or inches.3.1.11 gage lengththe initial measured thickness of the test specimen expressed in units of length.3.1.12 modulus of elasticitythe ratio of stress (nomin
17、al) to corresponding strain below the proportional limit of a materialexpressed in force per unit area based on the minimum initial cross-sectional area.3.1.13 proportional limitthe greatest stress that a material is capable of sustaining without any deviation from proportionalityof stress-to-strain
18、 (Hookes law) expressed in force per unit area.4. Significance and Use4.1 This test method provides information regarding the behavior of cellular materials under compressive loads. Test data isobtained, and from a complete load-deformation curve it is possible to compute the compressive stress at a
19、ny load (such ascompressive stress at proportional-limit load or compressive strength at maximum load) and to compute the effective modulus ofelasticity.4.2 Compression tests provide a standard method of obtaining data for research and development, quality control, acceptanceor rejection under speci
20、fications, and special purposes. The tests cannot be considered significant for engineering design inapplications differing widely from the load - time scale of the standard test. Such applications require additional tests such asimpact, creep, and fatigue.4.3 Before proceeding with this test method
21、, reference shall be made to the specification of the material being tested. Any testspecimen preparation, conditioning, dimensions, or testing parameters, or a combination thereof, covered in the materialsspecification shall take precedence over those mentioned in this test method. If there are no
22、material specifications, then the defaultconditions apply.5. Apparatus5.1 Testing MachineAtesting instrument that includes both a stationary and movable member and includes a drive system forimparting to the movable member (crosshead), a uniform, controlled velocity with respect to the stationary me
23、mber (base). Thetesting machine shall also include the following:5.1.1 Load Measurement SystemA load measurement system capable of accurately recording the compressive load impartedto the test specimen. The system shall be indicate the load with an accuracy of 61 % of the measured value or better. T
24、he accuracyof the load measurement system shall be verified in accordance with Practices E4.X1 = 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 1625.2 Compression PlatensTwo
25、 flat plates, one attached to the stationary base of the testing instrument and the other attachedto the moving crosshead to deliver the load to the test specimen. These plates shall be larger than the specimen loading surfaceto ensure that the specimen loading is uniform. It is recommended that one
26、 platen incorporate a spherical seating mechanism tocompensate for non-parallelism in the specimens loading surfaces or non-parallelism in the base and crosshead of the testinginstrument.5.3 Displacement Measurement SystemAdisplacement measurement system capable of accurately recording the compressi
27、vedeformation of the test specimen during testing to an accuracy of 61 % of the measured value or better. This measurement is madethrough use of the test machine crosshead drive system or using a direct measurement of compression platen displacement.5.3.1 Direct Compression Platen DisplacementThis s
28、ystem shall employ a deflectometer that directly reads the distantbetween the upper and lower compression platens. The accuracy of the displacement measurement transducer shall be verified inaccordance with Practices E83 and shall be classified as a Class C or better.5.3.2 Test Machine Crosshead Dri
29、ve SystemThis system shall employ the position output from the crosshead drive system asa indicator of compression platen displacement. This method is only appropriate when it is demonstrated that the effects of drivesystem compliance result in displacement errors of less than 1 % of the measurement
30、 or if appropriate compliance correctionmethods are employed to reduce the measurement error to less than 1 %.5.3.2.1 Determining Drive System ComplianceTesting instrument drive systems always exhibit a certain level of compliancethat is characterized by a variance between the reported crosshead dis
31、placement and the displacement actually imparted to thespecimen. This variance is a function of load frame stiffness, drive system wind-up, load cell compliance and fixture compliance.This compliance can be measured then, if determined to be significant and empirically subtracted from test data to i
32、mprove testaccuracy. The procedure to determine compliance follows:(1) Configure the test system to match the actual test configuration.(2) Position the two compression platens very close to each other simulating a zero thickness specimen in place.(3) Start the crosshead moving at 12.5 mm (0.5 in.)/
33、min in the compression direction recording crosshead displacement andthe corresponding load values.(4) Increase load to a point exceeding the highest load expected during specimen testing. Stop the crosshead and return to thepre-test location.(5) The recorded load-deflection curve, starting when the
34、 compression platens contact one another, is defined as test systemcompliance5.3.2.2 Performing Compliance CorrectionUsing the load-deflection curve created in 5.3.2.1, measure the system complianceat each given load value. On each specimen test curve at each given load value, subtract the system co
35、mpliance from each recordeddisplacement value. This will be the new load-deflection curve for use in calculations starting in Section 9.5.4 Micrometer Dial Gage,Gauge, caliper, or steel rule, suitable for measuring dimensions of the specimens to 61 % of themeasured values.6. Test Specimen6.1 The tes
36、t specimen shall be square or circular in cross section with a minimum of 25.8 cm2 (4 in.2) and maximum of 232cm2 (36 in.2) in area. The minimum height shall be 25.4 mm (1 in.) and the maximum height shall be no greater than the widthor diameter of the specimen. Care should be taken so that the load
37、ed ends of the specimen are parallel to each other andperpendicular to the sides.NOTE 2Cellular plastics are not ideal materials, and the compressive modulus may appear significantly different, depending on the test conditions,particularly the test thickness. All data that are to be compared should
38、be obtained using common test conditions.6.2 All surfaces of the specimen shall be free from large visible flaws or imperfections.6.3 If the material is suspected to be anisotropic, the direction of the compressive loading must be specified relative to thesuspected direction of anisotropy.6.4 Aminim
39、um of five specimens shall be tested for each sample. Specimens that fail at some obvious flaw should be discardedand retests made, unless such flaws constitute a variable the effect of which it is desired to study.7. Conditioning7.1 ConditioningCondition the test specimens at 23 6 2C (73.4 6 3.6F)
40、and 50 6 10 % relative humidity for not less than40 h prior to test in accordance with Procedure A of Practice D618, unless otherwise specified in the contract or relevant materialspecification. In cases of disagreement, the tolerances shall be 61C (61.8F) and 65 % relative humidity.7.2 Test Conditi
41、onsConduct tests in the standard laboratory atmosphere of 23 6 2C (73.4 6 3.6F) and 50 6 10 % relativehumidity, unless otherwise specified. In cases of disagreement, the tolerances shall be61C (61.8F) and65 % relative humidity.8. Procedure8.1 Measure the dimensions of the specimen to a precision of
42、61 % of the measurement as follows:D1621 1638.1.1 Thicknesses up to and including 25.4 mm (1 in.) shall be measured using a dial-type gagegauge having a foot withminimum area of 6.45 cm2 (1 in.2). Hold the pressure of the dial foot to 0.17 6 0.03 kPa (0.025 6 0.005 psi).8.1.2 Measure dimensions over
43、 25.4 mm (1 in.) with a dial gage,gauge, a sliding-caliper gage,gauge, or a steel scale. When asliding-caliper gagegauge is employed, the proper setting shall be that point at which the measuring faces of the gagegauge contactthe surfaces of the specimen without compressing them.8.1.3 Record each di
44、mension as an average of three measurements.8.2 Place the specimen between the compression platens ensuring that the specimen center-line is aligned with the center-lineof the compression platens and the load will be distributed as uniformly as possible over the entire loading surface of the specime
45、n.It will expedite the testing process if, when the specimen is in place, the upper platen is positioned close to, but not touching, thespecimen.8.2.1 If following 5.3.2.1, attach the deflectometer or compression extensometer to the compression platens.8.3 Start the crosshead moving in the direction
46、 to compress the specimen with thea rate of crosshead displacement of 2.560.25mm (0.1 6 0.01 in.)/min for each 25.4 mm (1 in.) of specimen thickness.equal to 10 % of the sample thickness per minute 60.25mm (60.01 in.)/min.8.4 Record compression platen displacement and the corresponding load data. Th
47、is recorded curve will be used directly iffollowing 5.3.2.1 or could be modified following 5.3.2.2.8.5 Continue until a yield point is reached or until the specimen has been compressed approximately 13 % of its originalthickness, whichever occurs first.8.5.1 When specified, a deformation other than
48、10 % may be used as the point at which stress shall be calculated. In such a case,compress the specimen approximately 3 % more than the deformation specified. Substitute the specified deformation wherever“10 % deformation” is cited in Sections 9 and 10.9. Calculation9.1 Using a straightedge or throu
49、gh the use of computer software, carefully extend to the zero load line the steepest straightportion of the load-deflection curve examining only the lower portion of the load-deflection curve. This establishes the “zerodeformation” or “zero strain” point (Point O in Fig. 1a and Fig. 1b). Measure all distances for deformation or strain calculationsfrom this point.9.2 Measure from Point O along the zero-load line a distance representing 10 % specimen deformation. At that point (Point Min Fig. 1a and Fig. 1b), draw a vertical line intersecting the
