1、Designation: F 1645/F 1645M 07Standard Test Method forWater Migration in Honeycomb Core Materials1This standard is issued under the fixed designation F 1645/F 1645M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of watermigration in honeycomb core materials.1.2 The values stated in either SI
3、 units or inch-pound unitsare to be regarded separately as standard. Within the text theinch-pound units are shown in brackets. 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
4、 nonconformance with thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated 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 limitat
5、ions prior to use.2. Referenced Documents2.1 ASTM Standards:2C 271/C 271M Test Method for Density of Sandwich CoreMaterialsC 274 Terminology of Structural Sandwich ConstructionsD 883 Terminology Relating to PlasticsD 3878 Terminology for Composite MaterialsD 5229/D 5229M Test Method for Moisture Abs
6、orptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsE 122 Practice for Calculating Sample Size to Estimate,With a Specified Tolerable Error, the Average for aCharacteristic of a Lot or ProcessE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE
7、 456 Terminology Relating to Quality and StatisticsE 1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materials in DatabasesE 1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases3. Terminology3.1 DefinitionsTerminology D 3878 def
8、ines 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. In the event of a conflict betw
9、een 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)Sn-1= standard deviation statistic of a sample population fora given propertyx1= test result for an individual sp
10、ecimen from the samplepopulation for a given propertyx = mean or average (estimate of mean) of a samplepopulation for a given propertyVc= volume of water necessary to fill one core cellVf= volume of water transfusedWc= mass of specimen after filling the primary cell withwaterWf= mass of specimen aft
11、er water transfusionWi= mass of specimen after conditioning, prior to waterintroduction4. Summary of Test Method4.1 This test method consists of bonding a honeycomb corematerial to transparent facings using a water-resistant adhesive,drilling an access hole through one facing to an individual corece
12、ll, filling the cell with water, subjecting the filled cell to aconstant hydrostatic pressure by maintaining a specified watercolumn height, then measuring the amount of water transferredinto the honeycomb core specimen (primarily due to diffusionthrough the cell walls) within a 24-h period. The amo
13、unt ofwater transferred is presented as an approximate number ofhoneycomb core cells filled with water.5. Significance and Use5.1 Water permeability is a fundamental physical propertythat can be used in conjunction with other properties tocharacterize honeycomb sandwich core materials. Migration1Thi
14、s 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 May 1, 2007. Published June 2007. Originallyapproved in 1995. Last previous edition approved in 2005 as F 1645
15、00 (2005).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 Driv
16、e, PO Box C700, West Conshohocken, PA 19428-2959, United States.testing can be used to characterize and compare the relativepermeability of honeycomb core materials to water.5.2 This test method provides a standard method of charac-terizing the rate of water migration within honeycomb sand-wich core
17、 materials for design properties, material specifica-tions, research and development applications, and qualityassurance.5.3 Factors that influence water migration rate characteris-tics of honeycomb sandwich core materials and shall thereforebe reported include the following: core material, methods o
18、fmaterial fabrication, core geometry (cell size), core thickness,core thickness uniformity, cell wall thickness, specimen geom-etry, specimen preparation, specimen conditioning, facingmaterial, facing permeability, adhesive permeability, adhesivethickness, and methods of mass, volume, and water colu
19、mnheight measurement.6. Interferences6.1 Material and Specimen PreparationPoor materialfabrication practices and damage induced by improper speci-men machining are known causes of high data scatter incomposites and honeycomb sandwich structures in general.Important aspects of honeycomb sandwich core
20、 specimenpreparation that contribute to data scatter include the existenceof joints, voids or other core discontinuities, out-of-planecurvature, and surface roughness.6.2 Core GeometryCore-specific geometric factors thataffect honeycomb core material water migration rate includecore cell size, unifo
21、rmity of core cell geometry, core cellthickness, core cell thickness uniformity, core thickness, andcore thickness uniformity.6.3 FacingsResults are affected by the permeability of thefacing material and the flatness of the facing bonding surfaces.6.4 AdhesiveResults are affected by the permeability
22、 ofthe adhesive, the adhesive thickness, and the thickness unifor-mity of the adhesive. Results are also affected by the presenceof voids, cracks, and other defects which compromise thecomplete bonding of the cell walls to the facings.6.5 EnvironmentResults are affected by the environmen-tal conditi
23、ons under which specimens are conditioned, as wellas the conditions under which the tests are conducted. Speci-mens tested in various environments can exhibit differences inwater migration rate.7. Apparatus7.1 Micrometers and CalipersA micrometer having a flatanvil interface, or a caliper of suitabl
24、e size, shall be used. Theaccuracy of the instrument(s) shall be suitable for reading towithin 1.0 % of the sample length, width and thickness. Fortypical specimen geometries, an instrument with an accuracyof 625 m 60.001 in. is desirable for thickness measure-ment, whereas an instrument with an acc
25、uracy of 6250 m60.010 in. is acceptable for length and width measurement.7.2 Balance or Weighing ScaleIf the amount of watertransferred into the honeycomb core material specimen is to bemeasured by mass, an analytical balance or weighing scale isrequired that is capable of measuring the initial mass
26、 of thehoneycomb core material specimen accurately to 60.5 %.7.3 SyringeIf the amount of water transferred into thehoneycomb core material specimen is to be measured volu-metrically, a graduated syringe is required that is capable ofmeasuring accurately to 610 mm360.0005 in.3.7.4 Water Migration Set
27、upThe water migration test setup,shown in Fig. 1, shall consist of a buret, a scale to measureheight such as a meter stick yardstick, a support stand, clampsto secure the buret to the support stand, and a flexible hose ortube. The scale to measure water column height shall becapable of measuring acc
28、urately to 61mm60.063 in.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 inPrac
29、tice E 122. Report the method of sampling.8.2 Test Specimens:8.2.1 Core GeometryHoneycomb core material test speci-mens shall have a square or rectangular cross-section. Therecommended minimum specimen size is 75 mm 3.0 in. inlength by 75 mm 3.0 in. in width by 13 mm 0.5 in. thick.NOTE 1The honeycom
30、b core specimens cross-section is defined tobe in the facing plane, in regard to the orientation that the core would beFIG. 1 Water Migration Test SetupF 1645/F 1645M 072placed in a structural sandwich construction. For a honeycomb core thecross-section is in the plane of the cells, which is perpend
31、icular to theorientation of the cell walls.8.2.2 Core Preparation and MachiningPrepare the hon-eycomb core material samples so that the facing plane surfacesare parallel to each other and perpendicular to the sides of thecore. Take precautions when cutting specimens from largesheets of core material
32、 to avoid notches, undercuts, rough oruneven surfaces due to inappropriate machining methods.Obtain final dimensions by lubricated precision sawing, mill-ing, or grinding. The use of diamond tooling has been found tobe extremely effective for many material systems. Record andreport the honeycomb cor
33、e material specimen cutting prepara-tion method.8.2.3 FacingsThe honeycomb core material shall bebonded to impermeable, transparent facings which permitvisual observation into the honeycomb core cells by illumina-tion. Clear plastic facings are recommended, for ease oflocating a hole over a single c
34、ell as well as observation of watermigration (see Fig. 2).8.2.4 AdhesiveThe honeycomb core material shall bebonded to the facings using a water-resistant adhesive. Use ofa clear adhesive is recommended. The adhesive shall beapplied so that fairly heavy fillets form between the honey-comb core materi
35、al cell walls and the facings, thus assuring awatertight joint between the facings and core. After bondingthe facings to the core, the honeycomb core material specimenshall be inspected for flawed or damaged cells, porous orcracked adhesive, and other defects which can become path-ways for water see
36、page or flow from cell to cell, thusinvalidating results.8.2.5 Specimen Preparation for Water IntroductionAholeshall be drilled through the upper facing over one centrallylocated honeycomb core material cell. The hole shall permitaccess of water into only one cell. A suitable connection, suchas a tu
37、be bonded over or into the hole, shall be provided for theapplication of hydrostatic pressure (see Fig. 2). If the amountof water transferred is monitored by mass, an appropriate sealshall be used to cover the hole, to prevent water loss duringweighings.8.3 LabelingLabel the test specimens so that t
38、hey 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. Conditioning10.1
39、The recommended pre-test condition is effective mois-ture equilibrium at a specific relative humidity as establishedby Test Method D 5229/D 5229M; however, if the test re-questor does not explicitly specify a pre-test conditioningenvironment, no conditioning is required and the test speci-mens may b
40、e tested as prepared.10.2 The pre-test specimen conditioning process, to includespecified environmental exposure levels and resulting moisturecontent, shall be reported with the test data.NOTE 2The term moisture, as used in Test Method D 5229/D 5229M,includes not only the vapor of a liquid and its c
41、ondensate, but the liquiditself in large quantities, as for immersion.10.3 If no explicit conditioning process is performed thespecimen conditioning 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
42、 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, and datareporting requirements prior to test for proper selection of apparatus.11.1.3 The environmental
43、conditioning test parameters.11.1.4 The buret measurement accuracy.11.2 General Instructions:11.2.1 Report any deviations from this test method, whetherintentional or inadvertent.11.2.2 If honeycomb core material density is to be reported,then obtain these samples from the same sheet of honeycombcor
44、e material being tested. Density may be evaluated inaccordance with Test Method C 271/C 271M.11.2.3 Following final honeycomb core material specimenmachining, but before conditioning and testing, measure thespecimen length and width (including the facings) at threeplaces. The thickness of the specim
45、en (including the facings)shall be measured at four locations surrounding the primaryhoneycomb core cell, and recorded as the average of the fourmeasurements. The accuracy of these measurements shall bewithin 1.0 % of the dimension. Measure the specimen lengthand width with an accuracy of 6250 m 60.
46、010 in. Measurethe specimen thickness with an accuracy of 625 m 60.001in. Record the dimensions to three significant figures in unitsof millimeters inches.11.2.4 If the amount of water transferred into the honey-comb core material specimen is to be measured by mass,determine the mass of the specimen
47、 (including the facings andseal) with an accuracy of 60.5 %.FIG. 2 Water Migration SpecimenF 1645/F 1645M 07311.3 Condition the specimens as required. Store the speci-mens in the conditioned environment until test time, if the testenvironment is different than the conditioning environment.11.4 Follo
48、wing final specimen conditioning, but beforetesting, re-measure the specimen length, width and thickness asin 11.2.3. If the amount of water transferred is to be measuredby mass, re-measure the specimen mass (including the facingsand seal) as in 11.2.4.11.5 Using a syringe, fill the primary honeycom
49、b corematerial cell with distilled or deionized water. If the amount ofwater transferred is to be measured by volume, record thevolume of water required to fill the cell. It is recommended toadd a colored dye to the water to make it easier to see wherethe water has migrated. If the amount of water transferred is tobe measured by mass, seal the hole in the facing and re-measure the specimen mass as in 11.4, with the primary cellfilled with water.11.6 Place the test specimen in the water migration testsetup. Using the flexible hose or
