1、Designation: C 271/C 271M 05Standard Test Method forDensity of Sandwich Core Materials1This standard is issued under the fixed designation C 271/C 271M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A n
2、umber in parentheses indicates the year of last reapproval.A superscript epsilon (e) 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
3、 those 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. Within the text theinch-pound units are shown in bracke
4、ts. The values stated ineach system are not exact equivalents; therefore, each systemmust be used independently of the other. Combining valuesfrom the two systems may result in nonconformance with thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated
5、 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:2C 274 Terminology of Structural Sandwich ConstructionsD 883 Ter
6、minology Relating to PlasticsD 3878 Terminology for Composite MaterialsD 5229/D 5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsE 122 Practice for Calculation of Sample Size to Estimate,With a Tolerable Specified Error, the Avera
7、ge for Charac-teristic of a Lot or ProcessE 171 Specification for Standard Atmospheres for Condi-tioning and Testing Flexible Barrier MaterialsE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 456 Terminology Relating to Quality and StatisticsE 1309 Guide for Identification
8、 of Fiber-ReinforcedPolymer-Matrix Composite Materials in DatabasesE 1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in DatabasesE 1471 Guide for Identification of Fibers, Fillers, and CoreMaterials in Computerized Material Property Databases3. Terminology3.1 De
9、finitionsTerminology D 3878 defines terms relatingto high-modulus fibers and their composites. TerminologyC 274 defines terms relating to structural sandwich construc-tions. Terminology D 883 defines terms relating to plastics.Terminology E 456 and Practice E 177 define terms relating tostatistics.
10、In the event of a conflict between terms, TerminologyD 3878 shall have precedence over the other terminologies.3.2 Symbols:CV = coefficient of variation statistic of a sample populationfor a given property (in percent)dIP= density of a test specimen in inch-pound unitsdSI= density of a test specimen
11、 in SI unitsl = length of a test specimenSn1= standard deviation statistic of a sample population fora given propertyt = thickness of a test specimenxi= test result for an individual specimen from the samplepopulation for a given propertyx= mean or average (estimate of mean) of a sample popu-lation
12、for a given propertyw = width of a test specimenW = mass of 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.1
13、This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.09 onSandwich Construction.Current edition approved April 1, 2005. Published April 2005. Originallyapproved in 1951. Last previous edition approved in 1999 as C
14、 271 99.2For 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.1Copyright ASTM International, 100 Barr Harbor Drive,
15、 PO Box C700, West Conshohocken, 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 prop
16、ortional to the density.5.2 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 th
17、e following: core material, 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
18、and Specimen PreparationPoor 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 exist
19、ence of joints, voids or othercore 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 con
20、ditions under which specimens 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 ai
21、r-circulatingoven is required 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 follo
22、wing removal of the specimens 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 speci
23、men geometries, an instrument 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
24、 han-dling specimens.8. Sampling 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
25、 E 122. Report the method of 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-sectiona
26、l area (length times width) isdefined 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
27、cell walls.8.3 Specimen Preparation 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
28、 due toinappropriate machining 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 specim
29、ens so that they will bedistinct 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. Cond
30、itioning10.1 Subject the test specimens to one of the followingconditions:10.1.1 Standard ASTM Atmospheric Conditions (Specifica-tion E 171)of236 3C 73 6 5F and 50 6 5 % relativehumidity, in accordance with Procedure C of Test MethodD 5229/D 5229M.10.1.2 In oven-dried equilibrium at a temperature of
31、 105 63C 220 6 5F, in accordance with Procedure D of TestMethod D 5229/D 5229M.10.1.3 In oven-dried equilibrium at a temperature of 40 63C 120 6 5F, in accordance with Procedure D of TestMethod D 5229/D 5229M.10.2 After conditioning, cool the specimens at room tem-perature. Store and test the specim
32、ens in accordance with theappropriate procedure of Test Method D 5229/D 5229M.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 desired.NOTE 2Determi
33、ne 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.C 271/C 271M 05211.2 General Instructions:11.2.1 Report any deviati
34、ons 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 and
35、 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 env
36、ironment.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 conta
37、ins 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 us
38、inginch-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 condi
39、tioning, lbm,l = final length after conditioning, in.,w = final width after conditioning, in., andt = final thickness after conditioning, in.NOTE 3Reporting of core density in units of kg/m3or lbm/ft3is anindustry standard.NOTE 4The pound mass is defined such that one pound force impartsan accelerat
40、ion 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 accomplis
41、hed 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= sa
42、mple 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 item
43、s beyond thecontrol of a given testing laboratory, such as might occur withmaterial details or panel fabrication parameters, shall be theresponsibility of the requestor):NOTE 5Guides E 1309, E 1434 and E 1471 contain data reportingrecommendations for composite materials and composite materials test-
44、ing.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 thesandwi
45、ch 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 pre
46、parethe sandwich core including: fabrication start date, fabricationend date, process specification, and a description of theequipment used.14.1.6 Method of preparing the test specimen, includingspecimen labeling scheme and method, specimen geometry,sampling method, and specimen cutting method.14.1.
47、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 Measured length, width, and thickness for eachspecimen (prior to and after conditioning, if appropriat
48、e).14.1.11 Mass of specimen.14.1.12 Conditioning parameters and results.14.1.13 Relative humidity and temperature of the testinglaboratory.14.1.14 Number of specimens tested.C 271/C 271M 05314.1.15 Individual densities and average value, standarddeviation, and coefficient of variation (in percent) f
49、or thepopulation.15. Precision and Bias15.1 PrecisionThe data required for the development of aprecision statement is not available for this test method.15.2 BiasBias cannot be determined for this method as noacceptable reference standards exist.16. Keywords16.1 core; density; sandwichASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any
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