1、Designation: F1645/F1645M 12F1645/F1645M 16Standard Test Method forWater Migration in Honeycomb Core Materials1This standard is issued under the fixed designation F1645/F1645M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the ye
2、ar of last revision. 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 water migration in honeycomb core materials.1.2 The values stated i
3、n either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact 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 W
4、ithin the text the inch-pound units are shown in brackets.1.3 This standard does not purport to address all of the safety concerns, 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 applicabili
5、ty of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C271/C271M Test Method for Density of Sandwich Core MaterialsC274 Terminology of Structural Sandwich Constructions (Withdrawn 2016)3D883 Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsD5229/
6、D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix CompositeMaterialsE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot orProcessE177 Practice for Use of the Terms Precision and
7、Bias in ASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases (Withdrawn 2015)3E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdra
8、wn 2015)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 E456 and Pract
9、ice 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:CV = coefficient of variation statistic of a sample population for a given property (in percent)CV = coefficient of variation statis
10、tic of a sample population for a given property (in percent),Sn-1 = standard deviation statistic of a sample population for a given property,x1 = test result for an individual specimen from the sample population for a given property,x = mean or average (estimate of mean) of a sample population for a
11、 given property,1 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, 2012April 1, 2016. Published May 2012May 2016. Originally approved in 1995. Last
12、 previous edition approved in 20072012 asF1645 07.F1645 12. DOI: 10.1520/F1645_F1645M-12.10.1520/F1645_F1645M-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the
13、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 adequately depict all changes accu
14、rately, 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 Conshohocken, PA 19428-2959. United Sta
15、tes1Vc = volume of water necessary to fill one core cell,Vf = volume of water transfused,Wc = mass of specimen after filling the primary cell with water,Wf = mass of specimen after water transfusion, andWi = mass of specimen after conditioning, prior to water introduction.Sn-1 = standard deviation s
16、tatistic of a sample population for a given propertyx1 = test result for an individual specimen from the sample population for a given propertyx5 mean or average (estimate of mean) of a sample population for a given propertyVc = volume of water necessary to fill one core cellVf = volume of water tra
17、nsfusedWc = mass of specimen after filling the primary cell with waterWf = mass of specimen after water transfusionWi = mass of specimen after conditioning, prior to water introduction4. Summary of Test Method4.1 This test method consists of bonding a honeycomb core material to transparent facings u
18、sing a water-resistant adhesive,drilling an access hole through one facing to an individual core cell, filling the cell with water, subjecting the filled cell to a constanthydrostatic pressure by maintaining a specified water column height, then measuring the amount of water transferred into thehone
19、ycomb core specimen (primarily due to diffusion through the cell walls) within a 24-h period. The amount of water transferredis presented as an approximate number of honeycomb core cells filled with water.5. Significance and Use5.1 Water permeability is a fundamental physical property that can be us
20、ed in conjunction with other properties to characterizehoneycomb sandwich core materials. Migration testing can be used to characterize and compare the relative permeability ofhoneycomb core materials to water.5.2 This test method provides a standard method of characterizing the rate of water migrat
21、ion within honeycomb sandwich corematerials for design properties, material specifications, research and development applications, and quality assurance.5.3 Factors that influence water migration rate characteristics of honeycomb sandwich core materials and shall therefore bereported include the fol
22、lowing: core material, methods of material fabrication, core geometry (cell size), core thickness, corethickness uniformity, cell wall thickness, specimen geometry, specimen preparation, specimen conditioning, facing material, facingpermeability, adhesive permeability, adhesive thickness, and method
23、s of mass, volume, and water column height measurement.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 honeycomb sandwich structures in general. Important
24、 aspectsof honeycomb sandwich core specimen preparation that contribute to data scatter include the existence of joints, voids or other corediscontinuities, out-of-plane curvature, and surface roughness.6.2 Core GeometryCore-specific geometric factors that affect honeycomb core material water migrat
25、ion rate include core cellsize, uniformity of core cell geometry, core cell thickness, core cell thickness uniformity, core thickness, and core thicknessuniformity.6.3 FacingsResults are affected by the permeability of the facing material and the flatness of the facing bonding surfaces.6.4 AdhesiveR
26、esults are affected by the permeability of the adhesive, the adhesive thickness, and the thickness uniformity ofthe adhesive. Results are also affected by the presence of voids, cracks, and other defects which compromise the complete bondingof the cell walls to the facings.6.5 EnvironmentResults are
27、 affected by the environmental conditions under which specimens are conditioned, as well as theconditions under which the tests are conducted. Specimens tested in various environments can exhibit differences in watermigration rate.7. Apparatus7.1 Micrometers and CalipersA micrometer having a flat an
28、vil interface, or a caliper of suitable size, shall be used. Theaccuracy of the instrument(s) shall be suitable for reading to within 1.0 % of the sample length, width and thickness. For typicalspecimen geometries, an instrument with an accuracy of 625 m 60.001 in. is desirable for thickness measure
29、ment, whereasan instrument with an accuracy of 6250 m 60.010 in. is acceptable for length and width measurement.7.2 Balance or Weighing ScaleIf the amount of water transferred into the honeycomb core material specimen is to bemeasured by mass, an analytical balance or weighing scale is required that
30、 is capable of measuring the initial mass of thehoneycomb core material specimen accurately to 60.5 %.F1645/F1645M 1627.3 SyringeIf the amount of water transferred into the honeycomb core material specimen is to be measured volumetrically,a graduated syringe is required that is capable of measuring
31、accurately to 610 mm3 60.0005 in.3.7.4 Water Migration SetupThe water migration test setup, shown in Fig. 1, shall consist of a buret, a scale to measure heightsuch as a meter stick yardstick, a support stand, clamps to secure the buret to the support stand, and a flexible hose or tube. Thescale to
32、measure water column height shall be capable of measuring accurately to 61 mm 60.063 in.8. Sampling and Test Specimens8.1 SamplingTest at least five specimens per test condition unless valid results can be gained through the use of fewerspecimens, as in the case of a designed experiment. For statist
33、ically significant data, consult the procedures outlined in PracticeE122. Report the method of sampling.8.2 Test Specimens:8.2.1 Core GeometryHoneycomb core material test specimens shall have a square or rectangular cross-section. Therecommended minimum specimen size is 75 mm 3.0 in. in length by 75
34、 mm 3.0 in. in width by 13 mm 0.5 in. thick.NOTE 1The honeycomb core specimens cross-section is defined to be in the facing plane, in regard to the orientation that the core would be placedin a structural sandwich construction. For a honeycomb core the cross-section is in the plane of the cells, whi
35、ch is perpendicular to the orientation of thecell walls.8.2.2 Core Preparation and MachiningPrepare the honeycomb core material samples so that the facing plane surfaces areparallel to each other and perpendicular to the sides of the core. Take precautions when cutting specimens from large sheets of
36、 corematerial to avoid notches, undercuts, rough or uneven surfaces due to inappropriate machining methods. Obtain final dimensionsby lubricated precision sawing, milling, or grinding. The use of diamond tooling has been found to be extremely effective for manymaterial systems. Record and report the
37、 honeycomb core material specimen cutting preparation method.8.2.3 FacingsThe honeycomb core material shall be bonded to impermeable, transparent facings which permit visualobservation into the honeycomb core cells by illumination. Clear plastic facings are recommended, for ease of locating a hole o
38、vera single cell as well as observation of water migration (see Fig. 2).FIG. 1 Water Migration Test SetupF1645/F1645M 1638.2.4 AdhesiveThe honeycomb core material shall be bonded to the facings using a water-resistant adhesive. Use of a clearadhesive is recommended. The adhesive shall be applied so
39、that fairly heavy fillets form between the honeycomb core materialcell walls and the facings, thus assuring a watertight joint between the facings and core. After bonding the facings to the core, thehoneycomb core material specimen shall be inspected for flawed or damaged cells, porous or cracked ad
40、hesive, and other defectswhich can become pathways for water seepage or flow from cell to cell, thus invalidating results.8.2.5 Specimen Preparation for Water IntroductionAhole shall be drilled through the upper facing over one centrally locatedhoneycomb core material cell.The hole shall permit acce
41、ss of water into only one cell.Asuitable connection, such as a tube bondedover or into the hole, shall be provided for the application of hydrostatic pressure (see Fig. 2). If the amount of water transferredis monitored by mass, an appropriate seal shall be used to cover the hole, to prevent water l
42、oss during weighings.8.3 LabelingLabel the test specimens so that they will be distinct from each other and traceable back to the sheet 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
43、 are current at the time of use of the equipment.10. Conditioning10.1 The recommended pre-test condition is effective moisture equilibrium at a specific relative humidity as established by TestMethod D5229/D5229M; however, if the test requestor does not explicitly specify a pre-test conditioning env
44、ironment, noconditioning is required and the test specimens may be tested as prepared.10.2 The pre-test specimen conditioning process, to include specified environmental exposure levels and resulting moisturecontent, shall be reported with the test data.NOTE 2The term moisture, as used in Test Metho
45、d D5229/D5229M, includes not only the vapor of a liquid and its condensate, but the liquid itselfin large quantities, as for immersion.10.3 If no explicit conditioning process is performed the specimen conditioning process shall be reported as “unconditioned”and the moisture content as “unknown”.11.
46、 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, and data reporting requirements prior t
47、o test for proper selection of apparatus.11.1.3 The environmental conditioning test parameters.11.1.4 The buret measurement accuracy.11.2 General Instructions:11.2.1 Report any deviations from this test method, whether intentional or inadvertent.11.2.2 If honeycomb core material density is to be rep
48、orted, then obtain these samples from the same sheet of honeycomb corematerial being tested. Density may be evaluated in accordance with Test Method C271/C271M.FIG. 2 Water Migration SpecimenF1645/F1645M 16411.2.3 Following final honeycomb core material specimen machining, but before conditioning an
49、d testing, measure thespecimen length and width (including the facings) at three places. The thickness of the specimen (including the facings) shall bemeasured at four locations surrounding the primary honeycomb core cell, and recorded as the average of the four measurements.The accuracy of these measurements shall be within 1.0 % of the dimension. Measure the specimen length and width with anaccuracy of 6250 m 60.010 in. Measure the specimen thickness with an accuracy of 625 m 60.001 in. Record thedimensions to three signifi
