1、Designation: C271/C271M 11Standard Test Method forDensity of Sandwich Core Materials1This standard is issued under the fixed designation C271/C271M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A numbe
2、r in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the densityof sandwich construction core materials. Permissible corematerial forms include thos
3、e with continuous bonding surfaces(such as balsa wood and foams) as well as those withdiscontinuous bonding surfaces (such as honeycomb).1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents
4、; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.2.1 Within the text the inch-pound units are shown inbrackets.1.3 This standard does not purport to address all of thesafety concerns, if any, assoc
5、iated 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.2. Referenced Documents2.1 ASTM Standards:2C274 Terminology of Structural Sandwich ConstructionsD883
6、Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsE122 Practice for Calculating Sample Size to Estimate,With Specified Precision, the Average for a Cha
7、racteristicof a Lot or ProcessE171 Specification for Atmospheres for Conditioning andTesting Flexible Barrier MaterialsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE1309 Guide for Identification of Fiber-ReinforcedPolymer
8、-Matrix Composite Materials in DatabasesE1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in DatabasesE1471 Guide for Identification of Fibers, Fillers, and CoreMaterials in Computerized Material Property Databases3. Terminology3.1 DefinitionsTerminology D3878 de
9、fines terms relatingto high-modulus fibers and their composites. TerminologyC274 defines terms relating to structural sandwich construc-tions. Terminology D883 defines terms relating to plastics.Terminology E456 and Practice E177 define terms relating tostatistics. In the event of a conflict between
10、 terms, TerminologyD3878 shall have precedence over the other terminologies.3.2 Symbols:CVcoefficient of variation statistic of a sample populationfor a given property (in percent)dIPdensity of a test specimen in inch-pound unitsdSIdensity of a test specimen in SI unitsllength of a test specimenSn1s
11、tandard deviation statistic of a sample population fora given propertytthickness of a test specimenxitest result for an individual specimen from the samplepopulation for a given propertyxmean or average (estimate of mean) of a sample popu-lation for a given propertywwidth of a test specimenWmass of
12、a test specimen4. Summary of Test Method4.1 This test method consists of environmentally condition-ing a sandwich core specimen, weighing the specimen, mea-suring the length, width and thickness of the specimen, andcalculating the density.1This test method is under the jurisdiction of ASTM Committee
13、 D30 onComposite Materials and is the direct responsibility of Subcommittee D30.09 onSandwich Construction.Current edition approved April 1, 2011. Published May 2011. Originallyapproved in 1951. Last previous edition approved in 2005 as C271/C271M 05.DOI: 10.1520/C0271_C0271M-11.2For referenced ASTM
14、 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc
15、ken, PA 19428-2959, United States.5. Significance and Use5.1 Density is a fundamental physical property that can beused in conjunction with other properties to characterize thesandwich core. Most sandwich core structural properties, suchas strength and stiffness, are proportional to the density.5.2
16、This test method provides a standard method of obtain-ing sandwich core density data for design properties, materialspecifications, research and development applications, andquality assurance.5.3 Factors that influence the density and shall therefore bereported include the following: core material,
17、methods ofmaterial fabrication, core geometry (nominal cell size), speci-men geometry, specimen preparation, methods of weight anddimensional measurement, specimen conditioning, and mois-ture content during weight and dimensional measurements.6. Interferences6.1 Material and Specimen PreparationPoor
18、 materialfabrication practices and damage induced by improper speci-men machining are known causes of high data scatter incomposites and sandwich structures in general. Importantaspects of sandwich core specimen preparation that contributeto data scatter include the existence of joints, voids or oth
19、ercore discontinuities, out-of-plane curvature, and surface rough-ness.6.2 GeometrySpecific geometric factors that affect sand-wich density measurement include uniformity of core cellgeometry and core thickness.6.3 EnvironmentResults are affected by the environmen-tal conditions under which specimen
20、s are conditioned, as wellas the conditions under which the tests are conducted. Speci-mens tested in various environments, with different ambientmoisture contents, can exhibit significant differences in mea-sured density.7. Apparatus7.1 Oven or Vacuum Drying ChamberAn air-circulatingoven is require
21、d that shall be capable of maintaining therequired uniform temperatures to within 63C 65F. Avacuum drying chamber or a vacuum oven may also be used.7.2 DesiccatorA clean, dry desiccator in which speci-mens being oven-dried shall be brought to laboratory tempera-ture following removal of the specimen
22、s from the oven.7.3 Micrometers and CalipersA micrometer having a flatanvil interface, or a caliper of suitable size, shall be used. Theaccuracy of the instrument(s) shall be suitable for reading towithin 0.5 % of the specimen length, width and thickness. Fortypical specimen geometries, an instrumen
23、t with an accuracyof 625 m 60.001 in. is desirable for length, width, andthickness measurement.7.4 Balance or Weighing ScaleAn analytical balance orweighing scale is required that is capable of measuringaccurately to 60.5 %.7.5 GlovesClean, non-linting gloves for use when han-dling specimens.8. Samp
24、ling and Test Specimens8.1 SamplingTest at least five specimens per test condi-tion unless valid results can be gained through the use of fewerspecimens, as in the case of a designed experiment. Forstatistically significant data, consult the procedures outlined inPractice E122. Report the method of
25、sampling.8.2 GeometryTest specimens shall have a square or rect-angular cross-section. The recommended minimum specimensize is 300 mm 12.0 in. in length by 300 mm 12.0 in. inwidth, with the thickness equal to the sandwich core thickness.NOTE 1The specimens cross-sectional area (length times width) i
26、sdefined in the facing plane, in regard to the orientation that the core wouldbe placed in a structural sandwich construction. For example, for ahoneycomb core the cross-sectional area is defined in the plane of thecells, which is perpendicular to the orientation of the cell walls.8.3 Specimen Prepa
27、ration and MachiningPrepare the testspecimens so that the facing plane surfaces are parallel to eachother and perpendicular to the sides of the specimen. Takeprecautions when cutting specimens from large sheets of coreto avoid notches, undercuts, rough or uneven surfaces due toinappropriate machinin
28、g methods. Obtain final dimensions bylubricated precision sawing, milling, or grinding. The use ofdiamond tooling has been found to be extremely effective formany material systems. Record and report the specimen cuttingpreparation method.8.4 LabelingLabel the test specimens so that they will bedisti
29、nct from each other and traceable back to the sheet oforigin, and will neither influence the test nor be affected by it.9. Calibration9.1 The accuracy of all measuring equipment shall havecertified calibrations that are current at the time of use of theequipment.10. Conditioning10.1 The recommended
30、pre-test condition is effective mois-ture equilibrium as established by Test Method D5229/D5229M; however, if the test requestor does not explicitlyspecify a pre-test conditioning environment, no conditioning isrequired and the test specimens may be tested as prepared.Pre-conditioning is recommended
31、 to promote repeatability andreproducibility of density measurements.10.2 If pre-conditioning is to be performed, subject the testspecimens to one of the following conditions:10.2.1 Standard ASTM Atmospheric Conditions (Specifica-tion E171)of236 3C 73 6 5F and 50 6 5 % relativehumidity, in accordanc
32、e with Procedure C of Test MethodD5229/D5229M.10.2.2 In oven-dried equilibrium at a temperature of 105 63C 220 6 5F, in accordance with Procedure D of TestMethod D5229/D5229M.10.2.3 In oven-dried equilibrium at a temperature of 40 63C 120 6 5F, in accordance with Procedure D of TestMethod D5229/D522
33、9M.10.3 After conditioning, cool the specimens at room tem-perature. Store and test the specimens in accordance with theappropriate procedure of Test Method D5229/D5229M.10.4 The pre-test specimen conditioning process, to includespecified environmental exposure levels and resulting moisturecontent,
34、shall be reported with the test data.NOTE 2The term moisture, as used in Test Method D5229/D5229M,C271/C271M 112includes not only the vapor of a liquid and its condensate, but the liquiditself in large quantities, as for immersion.10.5 If no explicit conditioning process is performed, thespecimen co
35、nditioning process shall be reported as “uncondi-tioned” and the moisture content as “unknown.”11. Procedure11.1 Parameters to Be Specified Before Test:11.1.1 The specimen sampling method, specimen geometry,and conditioning travelers (if required).11.1.2 The properties and data reporting format desi
36、red.NOTE 3Determine specific material property, accuracy, and datareporting requirements prior to test for proper selection of apparatus.11.1.3 The environmental conditioning test parameters.11.1.4 The balance or weighing scale measurement accu-racy.11.2 General Instructions:11.2.1 Report any deviat
37、ions from this test method, whetherintentional or inadvertent.11.2.2 Following final specimen machining, but beforeconditioning and testing, measure the specimen length, widthand thickness. The accuracy of these measurements shall bewithin 0.5 % of the dimension. Measure the specimen length,width an
38、d thickness with an accuracy of 625 m 60.001 in.Record the dimensions to three significant figures in units ofmillimetres inches.11.3 Condition the specimens as required. Store the speci-mens in the conditioned environment until test time, if the testenvironment is different than the conditioning en
39、vironment.11.4 Following final specimen conditioning, but beforetesting, re-measure the specimen length, width, and thicknessas in 11.2.2.11.5 Weigh SpecimenWeigh the specimens in grams lbmto a precision of 60.5 %.12. Validation12.1 Property values shall not be calculated for any speci-men that cont
40、ains some obvious flaw described in 6.1, unlesssuch flaw constitutes a variable being studied. Retests shall beperformed for any specimen on which values are not calcu-lated.13. Calculation13.1 DensityCalculate the density to three significantfigures. Utilize Eq 1 when using SI units and Eq 2 when u
41、singinch-pound units.dSI51 000 000 Wlwt(1)where:dSI= density, kg/m3,W = final mass after conditioning, g,l = final length after conditioning, mm,w = final width after conditioning, mm, andt = final thickness after conditioning, mm.dIP51728 Wlwt(2)where:dIP= density, lbm/ft3,W = final mass after cond
42、itioning, lbm,l = final length after conditioning, in.,w = final width after conditioning, in., andt = final thickness after conditioning, in.NOTE 4Reporting of core density in units of kg/m3or lbm/ft3is anindustry standard.NOTE 5The pound mass is defined such that one pound force impartsan accelera
43、tion of 32.17 feet per second to it. In standard gravity, onepound force is numerically the same as one pound mass.13.2 Density ConversionConversion of density values toinch-pound units from SI units is accomplished using Eq 3.Conversion of density values to SI units from inch-pound unitsis accompli
44、shed using Eq 4.dIP5 0.0624 dSI(3)dSI5 16 dIP(4)13.3 StatisticsFor each series of tests calculate the aver-age value, standard deviation, and coefficient of variation (inpercent) for density:x5 (i51nxi! / n (5)Sn215(i51nxi22 nx2! / n 2 1! (6)CV 5 100 3 Sn21/ x(7)where:x= sample mean (average),Sn1= s
45、ample standard deviation,CV = sample coefficient of variation, %,n = number of specimens, andxi= measured or derived property.14. Report14.1 Report the following information, or references point-ing to other documentation containing this information, to themaximum extent applicable (reporting of ite
46、ms beyond thecontrol of a given testing laboratory, such as might occur withmaterial details or panel fabrication parameters, shall be theresponsibility of the requestor):NOTE 6Guides E1309, E1434 and E1471 contain data reportingrecommendations for composite materials and composite materials test-in
47、g.14.1.1 The revision level or date of issue of this test method.14.1.2 The name(s) of the test operator(s).14.1.3 Any variations to this test method, anomalies noticedduring testing, or equipment problems occurring during testing.14.1.4 Identification of all the materials constituent to thesandwich
48、 core specimen tested, including for each: materialspecification, material type, manufacturers material designa-tion, manufacturers batch or lot number, source (if not frommanufacturer), date of certification, and expiration of certifi-cation.14.1.5 Description of the fabrication steps used to prepa
49、rethe sandwich core including: fabrication start date, fabricationend date, process specification, and a description of theequipment used.C271/C271M 11314.1.6 Method of preparing the test specimen, includingspecimen labeling scheme and method, specimen geometry,sampling method, and specimen cutting method.14.1.7 Results of any nondestructive evaluation tests.14.1.8 Calibration dates and methods for all measurementsand test equipment.14.1.9 Type of balance or weighing scale and measurementaccuracy.14.1.10
