ASTM D1621-2004a Standard Test Method for Compressive Properties Of Rigid Cellular Plastics《硬质泡沫塑料的压缩性能的标准试验方法》.pdf

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1、Designation: D 1621 04aStandard Test Method forCompressive Properties Of Rigid Cellular Plastics1This standard is issued under the fixed designation D 1621; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.

2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 determ

3、iningthe 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 brackets are for information only.1.3 This standard does not purport to address all of thesafety concerns, if any, associate

4、d 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:2

5、D 618 Practice for Conditioning Plastics for TestingE 4 Practices for Force Verification of Testing MachinesE 83 Practice for Verification and Classification of Exten-someter SystemsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO

6、844 Cellular 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 displac

7、ement 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 c

8、om-pressive 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

9、, the 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

10、diagram 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 devi

11、ce used 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 o

12、f thetest specimen expressed in units of length.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.1This test method is under the jurisdiction of

13、ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Plastics.Current edition approved October 1, 2004. Published October 2004. Originallyapproved in 1959. Last previous edition approved in 2004 as D 1621 - 04.2For referenced ASTM standards, visit the AST

14、M 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.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036

15、.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.13 proportional limitthe greatest stress that a materialis capable of sustaining without any deviation from propor

16、-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 a complete load-deformation curveit is possible to compute

17、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 data for research and development, quality control, accep-t

18、ance 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 additionaltests such as impact, creep, and fatigue.4.3 Before proce

19、eding 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 materialsspecification shall take precedence over those mentioned in thistest

20、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 member (crosshead), auniform, controlled velocity with respe

21、ct to the stationarymember (base). The testing machine shall also include thefollowing:5.1.1 Load Measurement SystemA load measurement sys-tem capable of accurately recording the compressive loadimparted to the test specimen. The system shall be indicate theload with an accuracy of 61 % of the measu

22、red value or better.The accuracy of the load measurement system shall be verifiedin accordance with Practices E 4.5.2 Compression PlatensTwo flat plates, one attached tothe stationary base of the testing instrument and the otherattached to the moving crosshead to deliver the load to the testspecimen

23、. 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 surfaces or non-parallelism in the base andcrosshead of

24、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. Thismeasurement is made through use of the test machine c

25、ross-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 compression platens. The accu-racy of the displacement measurement

26、 transducer shall beverified in accordance with Practices E 83 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 compression platen displacement. Thismethod is only app

27、ropriate when it is demonstrated that theeffects of drive system compliance result in displacementerrors of less than 1 % of the measurement or if appropriateX1= 10 % CORE DEFORMATIONX2= DEFLECTION (APPROXIMATELY 13 %)FIG. 1 a Compressive Strength (See 3.1.5 and Section 9) FIG. 1 b Compressive Stren

28、gth (See 3.1.5 and Section 9)D 1621 04a2compliance 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 ofcompliance that is characterized by a variance between ther

29、eported 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 determined to be significant and empirically subtracted

30、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 specimen in place.(3) Start the crosshead moving at 12

31、.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-test location.(5) The recorded load-deflection curve, start

32、ing 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 specimen testcurve at each given load value, subtract the

33、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 to 61 % of themeasured values.6. Test Specimen6.1 The tes

34、t specimen shall be square or circular in crosssection with a minimum of 25.8 cm24 in.2 and maximum of232 cm236 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 the specimen. Care should be taken so thatthe loaded ends of

35、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 thickness. All data that are to be comparedshould be obtained

36、 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 the suspected direction of anisotropy.6.4 A minimum of five s

37、pecimens 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 ConditioningCondition the test specimens at 23 62C 73.4 6 3.6F and 50 6 5 % rela

38、tive humidity for not lessthan 40 h prior to test in accordance with Procedure A ofPractice D 618, unless otherwise specified in the contract orrelevant material specification. In cases of disagreement, thetolerances shall be 61C 61.8F and 62 % relative humid-ity.7.2 Test ConditionsConduct tests in

39、the standard labora-tory atmosphere of 23 6 2C 73.4 6 3.6F and 50 6 5%relative humidity, unless otherwise specified. In cases ofdisagreement, the tolerances shall be 61C 61.8F and62 % relative humidity.8. Procedure8.1 Measure the dimensions of the specimen to a precisionof 61 % of the measurement as

40、 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 cm21 in.2. Hold the pressure of the dialfoot to 0.17 6 0.03 kPa 0.025 6 0.005 psi.8.1.2 Measure dimensions over 25.4 mm 1 in. with a dialgage, a sliding-caliper

41、 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 each dimension as an average of three mea-surements.8.2 Place the specimen betwee

42、n 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 specimen. It will expedite the testing process if,when the specimen is in place, th

43、e 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 direction to compressthe specimen with the rate of crosshead displacement of 2.5 60.

44、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 be modified following 5.3.2.2.8.5 Continue until a yield point is reached or until

45、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 sucha case, compress the specimen approximately 3 % more thanthe deformation specifi

46、ed. 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 the steepeststraight portion of the load-deflection curve examining only thelower po

47、rtion of the load-deflection curve. This establishes theD 1621 04a3“zero deformation” or “zero strain” point (Point O in Fig. 1aand Fig. 1b). Measure all distances for deformation or straincalculations from this point.9.2 Measure from Point O along the zero-load line adistance representing 10 % spec

48、imen 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 the load at Point P.9.2.2 If there is a yield point before Point P (as Point L in

49、Fig. 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 deformation or strain (DistanceO-T) at that point.9.3.1 Calculate