1、Designation: C271/C271M 11C271/C271M 16Standard 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 revi
2、sion. A number 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 density of sandwich construction core materials. Permissible core materialform
3、s include those with continuous bonding surfaces (such as balsa wood and foams) as well as those with discontinuous bondingsurfaces (such as honeycomb).1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be e
4、xact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.2.1 Within the text the inch-pound units are shown in brackets.1.3 This standard does not purport to address all of the safety con
5、cerns, if any, 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.2. Referenced Documents2.1 ASTM Standards:2C274 Terminology of Structural Sandwich C
6、onstructions (Withdrawn 2016)3D883 Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix CompositeMaterialsE122 Practice for Calculating Sample Size to Estimate, With Specifi
7、ed Precision, the Average for a Characteristic of a Lot orProcessE171 Practice for Conditioning and Testing Flexible Barrier PackagingE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE1309 Guide for Identification of Fiber-R
8、einforced Polymer-Matrix Composite Materials in Databases (Withdrawn 2015)3E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn 2015)3E1471 Guide for Identification of Fibers, Fillers, and Core Materials in Computerized Material Property Data
9、bases (Withdrawn2015)33. Terminology3.1 DefinitionsTerminology D3878 defines terms relating to high-modulus fibers and their composites.Terminologycomposites, as C274 defineswell as terms relating to structural sandwich constructions. Terminology D883 definesterms relating to plastics. Terminology E
10、456 and Practice E177 define terms relating to statistics. In the event of a conflict betweenterms, Terminology D3878 shall have precedence over the other terminologies.3.2 Symbols:3.2.1 CVcoefficient of variation statistic of a sample population for a given property (in percent)3.2.2 dIPdensity of
11、a test specimen in inch-pound units1 This test method is under the jurisdiction of ASTM Committee D30 on Composite Materials and is the direct responsibility of Subcommittee D30.09 on SandwichConstruction.Current edition approved April 1, 2011March 15, 2016. Published May 2011March 2016. Originally
12、approved in 1951. Last previous edition approved in 20052011 asC271/C271M 05.C271/C271M 11. DOI: 10.1520/C0271_C0271M-11.10.1520/C0271_C0271M-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsv
13、olume information, refer to the standards Document Summary page on the ASTM website.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 ad
14、equately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoh
15、ocken, PA 19428-2959. United States13.2.3 dSIdensity of a test specimen in SI units3.2.4 llength of a test specimen3.2.5 Sn1 standard deviation statistic of a sample population for a given property3.2.6 tthickness of a test specimen3.2.7 xitest result for an individual specimen from the sample popul
16、ation for a given property3.2.8 xmean or average (estimate of mean) of a sample population for a given property3.2.9 wwidth of a test specimen3.2.10 Wmass of a test specimen4. Summary of Test Method4.1 This test method consists of environmentally conditioning a sandwich core specimen, weighing the s
17、pecimen, measuringthe length, width and thickness of the specimen, and calculating the density.5. Significance and Use5.1 Density is a fundamental physical property that can be used in conjunction with other properties to characterize the sandwichcore. Most sandwich core structural properties, such
18、as strength and stiffness, are proportional to the density.5.2 This test method provides a standard method of obtaining sandwich core density data for design properties, materialspecifications, research and development applications, and quality assurance.5.3 Factors that influence the density and sh
19、all therefore be reported include the following: core material, methods of materialfabrication, core geometry (nominal cell size), specimen geometry, specimen preparation, methods of weight and dimensionalmeasurement, specimen conditioning, and moisture content during weight and dimensional measurem
20、ents.6. Interferences6.1 Material and Specimen PreparationPoor material fabrication practices and damage induced by improper specimenmachining are known causes of high data scatter in composites and sandwich structures in general. Important aspects of sandwichcore specimen preparation that contribut
21、e to data scatter include the existence of joints, voids or other core discontinuities,out-of-plane curvature, and surface roughness.6.2 GeometrySpecific geometric factors that affect sandwich density measurement include uniformity of core cell geometryand core thickness.6.3 EnvironmentResults are a
22、ffected by the environmental conditions under which specimens are conditioned, as well as theconditions under which the tests are conducted. Specimens tested in various environments, with different ambient moisturecontents, can exhibit significant differences in measured density.7. Apparatus7.1 Oven
23、 or Vacuum Drying ChamberAn air-circulating oven is required that shall be capable of maintaining the requireduniform temperatures to within 63C 65F. A vacuum drying chamber or a vacuum oven may also be used.7.2 DesiccatorA clean, dry desiccator in which specimens being oven-dried shall be brought t
24、o laboratory temperaturefollowing removal of the specimens from the oven.7.3 Micrometers and CalipersA micrometer having a flat anvil interface, or a caliper of suitable size, shall be used. The useof alternative measurement devices is permitted if specified (or agreed to) by the test requestor and
25、reported by the testinglaboratory. The accuracy of the instrument(s) shall be suitable for reading to within 0.5 % of the specimen length, width andthickness. For typical specimen geometries, an instrument with an accuracy of 625 m60.025 mm 60.001 in. is desirable forlength, width, and thickness mea
26、surement.measurements.7.4 Balance or Weighing ScaleAn analytical balance or weighing scale is required that is capable of measuring accurately to60.5 %.7.5 GlovesClean, non-linting gloves for use when handling specimens.8. Sampling and Test Specimens8.1 SamplingTest at least five specimens per test
27、condition unless valid results can be gained through the use of fewerspecimens, as in the case of a designed experiment. For statistically significant data, consult the procedures outlined in PracticeE122. Report the method of sampling.8.2 GeometryTest specimens shall have a square or rectangular cr
28、oss-section. The recommended minimum specimen size is300 mm 12.0 in. in length by 300 mm 12.0 in. in width, with the thickness equal to the sandwich core thickness.C271/C271M 162NOTE 1The specimens cross-sectional area (length times width) is defined in the facing plane, in regard to the orientation
29、 that the core would beplaced in a structural sandwich construction. For example, for a honeycomb core the cross-sectional area is defined in the plane of the cells, which isperpendicular to the orientation of the cell walls.8.3 Specimen Preparation and MachiningPrepare the test specimens so that th
30、e facing plane surfaces are parallel to each otherand perpendicular to the sides of the specimen. Take precautions when cutting specimens from large sheets of core to avoidnotches, undercuts, rough or uneven surfaces due to inappropriate machining methods. Obtain final dimensions by lubricatedprecis
31、ion sawing, milling, or grinding. The use of diamond tooling has been found to be extremely effective for many materialsystems. Record and report the specimen cutting preparation method.8.4 LabelingLabel the test specimens so that they will be distinct from each other and traceable back to the sheet
32、 of origin,and will neither influence the test nor be affected by it.9. Calibration9.1 The accuracy of all measuring equipment shall have certified calibrations that are current at the time of use of the equipment.10. Conditioning10.1 The recommended pre-test condition is effective moisture equilibr
33、ium as established by Test Method D5229/D5229M;however, if the test requestor does not explicitly specify a pre-test conditioning environment, no conditioning is required and thetest specimens may be tested as prepared. Pre-conditioning is recommended to promote repeatability and reproducibility of
34、densitymeasurements.10.2 If pre-conditioning is to be performed, subject the test specimens to one of the following conditions:10.2.1 StandardASTMAtmospheric Conditions (Specification E171) of 23 6 3C 73 6 5F and 50 6 5 % relative humidity,in accordance with Procedure C of Test Method D5229/D5229M.1
35、0.2.2 In oven-dried equilibrium at a temperature of 105 6 3C 220 6 5F, in accordance with Procedure D of Test MethodD5229/D5229M.10.2.3 In oven-dried equilibrium at a temperature of 40 6 3C 120 6 5F, in accordance with Procedure D of Test MethodD5229/D5229M.10.3 After conditioning, cool the specimen
36、s at room temperature. Store and test the specimens in accordance with theappropriate procedure of Test Method D5229/D5229M.10.4 The pre-test specimen conditioning process, to include specified environmental exposure levels and resulting moisturecontent, shall be reported with the test data.NOTE 2Th
37、e term moisture, as used in Test Method D5229/D5229M, includes not only the vapor of a liquid and its condensate, but the liquid itselfin large quantities, as for immersion.10.5 If no explicit conditioning process is performed, the specimen conditioning process shall be reported as “unconditioned”an
38、d 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 desired.NOTE 3Determine specific material property, accuracy,
39、and data reporting 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 accuracy.11.2 General Instructions:11.2.1 Report any deviations from this test method, whether intentional or inadver
40、tent.11.2.2 Following final specimen machining, but before conditioning and testing, measure the specimen length, width andthickness. The accuracy of these measurements shall be within 0.5 % of the dimension. Measure the specimen length, width andthickness with an accuracy of 625 m 60.001 in. Record
41、 the dimensions to three significant figures in units of millimetresinches.11.3 Condition the specimens as required. Store the specimens in the conditioned environment until test time, if the testenvironment is different than the conditioning environment.11.4 Following final specimen conditioning, b
42、ut before testing, re-measure the specimen length, width, and thickness as in11.2.2.11.5 Weigh SpecimenWeigh the specimens in grams lbm to a precision of 60.5 %.C271/C271M 16312. Validation12.1 Property values shall not be calculated for any specimen that contains some obvious flaw described in 6.1,
43、 unless such flawconstitutes a variable being studied. Retests shall be performed for any specimen on which values are not calculated.13. Calculation13.1 DensityCalculate the density to three significant figures. Utilize Eq 1 when using SI units and Eq 2 when usinginch-pound units.dSI51000000 Wlwt (
44、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 conditioning, lbm,l = final length after
45、conditioning, in.,w = final width after conditioning, in., andt = final thickness after conditioning, in.NOTE 4Reporting of core density in units of kg/m3 or lbm/ft3 is an industry standard.NOTE 5The pound mass is defined such that one pound force imparts an acceleration of 32.17 feet per second to
46、it. In standard gravity, one poundforce is numerically the same as one pound mass.13.2 Density ConversionConversion of density values to inch-pound units from SI units is accomplished using Eq 3.Conversion of density values to SI units from inch-pound units is accomplished using Eq 4.dIP50.0624 dSI
47、(3)dSI516 dIP (4)13.3 StatisticsFor each series of tests calculate the average value, standard deviation, and coefficient of variation (in percent)for density:xH 5S(i51nxiD/n (5)Sn215S(i51nxi22n xH2D/n 21! (6)CV51003Sn21/xH (7)where:x = sample mean (average),Sn1 = sample standard deviation,CV = samp
48、le coefficient of variation, %,n = number of specimens, andxi = measured or derived property.14. Report14.1 Report the following information, or references pointing to other documentation containing this information, to themaximum extent applicable (reporting of items beyond the control of a given t
49、esting laboratory, such as might occur with materialdetails or panel fabrication parameters, shall be the responsibility of the requestor):NOTE 6Guides E1309, E1434 and E1471 contain data reporting recommendations for composite materials and composite materials testing.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 noticed during testing, or equipment problems occurring during testing.C271/C271M
