1、Designation: D 6772 02 (Reapproved 2007)Standard Test Method forDimensional Stability of Sandwich Core Materials1This standard is issued under the fixed designation D 6772; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the sand-wich core dimensional stability in the two plan dimensions.1.
3、2 The values stated in SI units are to be regarded as thestandard. The inch-pound units given may be approximate.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 sa
4、fety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:C 271/C 271M Test Method for Density of Sandwich CoreMaterialsC 274 Terminology of Structural Sandwich Constructions3. Terminology3.1 DefinitionsTerminology C 2
5、74 defines terms relatingto sandwich constructions.3.2 Symbols:Li= initial measured dimensionLf= final measured dimension4. Summary of Test Method4.1 A small piece of honeycomb is placed in an elevatedtemperature environment and after cooling, the dimensionalchanges in the plan dimensions are measur
6、ed and compared tothe initial measurements. A typical honeycomb specimen isshown in Fig. 1.5. Significance and Use5.1 Sandwich panel cores may change plan dimensionswhen heated. It is prudent to know if this may be a problemwith the final part dimensions.6. Interferences6.1 If oven size is limited,
7、smaller specimens may be used.6.2 If the specimen warps, flatten it out while making themeasurements.7. Apparatus7.1 Oven, capable of maintaining a controlled temperature63C (65F).7.2 Scale, capable of measuring accurately to 0.25 mm(0.01 in.).7.3 Micrometer, capable of measuring accurately to 0.025
8、mm (0.001 in.).8. Sampling and Test Specimens8.1 Test at least five specimens per test condition unlessvalid results can be gained through the use of fewer specimens,such as in the case of a designed experiment.8.2 The test specimens, if possible, should be approximately460 by 915 mm (18 by 36 in.)
9、in plan dimension, and thethickness shall be approximately 12.7 mm (0.50 in.). Forhoneycomb cores, the 460-mm (18-in.) dimension is the coresribbon or L direction. Other dimensions can be used, but mustbe reported.9. Calibration9.1 The accuracy of all measuring equipment shall havecertified calibrat
10、ions that are current at the time of use of theequipment.1This 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. Originallyapprov
11、ed in 2002. Last previous edition approved in 2002 as D 6772 - 02.FIG. 1 Dimensional Stability Specimen1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.10. Conditioning10.1 When the physical properties of the material areaffected by m
12、oisture, bring the test specimens to constantweight (61 %) before testing. A temperature of 23 6 3C (736 5F) and a relative humidity of 50 6 5 % are recommended.11. Procedure11.1 Weigh the specimens in grams (pounds) to a precisionof 60.5 %.11.2 Determine the plan dimensions of the specimens inmilli
13、metres (inches) to a precision of 60.5 %.11.3 Measure the thickness of the specimens in millimetres(inches) to the nearest 0.025 mm (0.001 in.).11.4 Mark the specimen in eight locations as shown in Fig.1. For honeycomb core, it is recommended that the cells bepotted with a resin at the eight locatio
14、ns and then marked (seeFig. 2).11.5 Make three measurements in one direction and threemeasurements in the other direction, as shown in Fig. 3.11.6 Preheat the oven to 175 6 3C (350 6 5F) and placethe specimen flat on a wire-mesh-type shelve. Other tempera-tures can be used but must be reported.11.7
15、After 90 min, remove the specimen from the oven andallow to cool.11.8 When the specimen is at room temperature, remeasurethe six dimensions.12. Calculations12.1 Calculate the densities of the specimens using TestMethod C 271.12.2 Calculate the dimensional changes as follows:percent change 5Lf2 Li!Li
16、3 100 %! (1)where:Li= initial measured dimension, andLf= final measured dimension.13. Report13.1 The report shall include the following:13.1.1 Description of the test specimens,13.1.2 Dimensions of the test specimens and densities,13.1.3 Oven temperature and length of time specimens arein oven, and1
17、3.1.4 Individual dimensional changes, average dimen-sional changes, and maximum dimensional changes in percentfor the two directions.14. Precision and Bias14.1 PrecisionThe data required for the development of aprecision statement are not available for this test method.14.2 BiasBias cannot be determ
18、ined for this test methodas no acceptable reference material exists.15. Keywords15.1 core; dimensional stability; honeycombASTM 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 expr
19、essly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revise
20、d, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may
21、attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United State
22、s. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 2 Potted Honeycomb CellFIG. 3 Measurement LocationsD 6772 02 (2007)2
