1、Designation: C 364/C 364M 07Standard Test Method forEdgewise Compressive Strength of SandwichConstructions1This standard is issued under the fixed designation C 364/C 364M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year o
2、f last revision. A number 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 compressive properties ofstructural sandwich construction in a direction parallel to th
3、esandwich facing plane. Permissible core material forms includethose with continuous bonding surfaces (such as balsa woodand foams) as well as those with discontinuous bondingsurfaces (such as honeycomb).1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as sta
4、ndard. 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 nonconformance with thestandard.1.3 This standard does not pu
5、rport 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:C
6、274 Terminology of Structural Sandwich ConstructionsD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 2584 Test Method for Ignition Loss of Cured ReinforcedResinsD 2734 Test Methods for Void Content of Reinforce
7、d Plas-ticsD 3039/D 3039M Test Method for Tensile Properties ofPolymer Matrix Composite MaterialsD 3171 Test Methods for Constituent Content of CompositeMaterialsD 3878 Terminology for Composite MaterialsD 5229/D 5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Pol
8、ymer Ma-trix Composite MaterialsD 5687/D 5687M Guide for Preparation of Flat CompositePanels with Processing Guidelines for Specimen Prepara-tionE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 122 Practice for Calculating Sample Size
9、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 456 Terminology Relating to Quality and StatisticsE 1012 Practice for Verification of Test Frame and Speci-men Alignment Under
10、Tensile and Compressive AxialForce ApplicationE 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 DatabasesE 1471 Guide for Identification of Fibers, Fillers, and
11、CoreMaterials in Computerized Material Property Databases3. Terminology3.1 DefinitionsTerminology 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 plast
12、ics.Terminology E6defines terms relating to mechanical testing.Terminolgoy E 456 and Practice E 177 define terms relating tostatistics. In the event of a conflict between terms, TerminologyD 3878 shall have precedence over the other terminologies.3.2 Symbols:b = width of specimenCV = coefficient of
13、variation statistic of a sample populationfor a given property (in percent)L = length of specimenP = force on specimenSn-1= standard deviation statistic of a sample population fora given property1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct
14、 responsibility of Subcommittee D30.09 onSandwich Construction.Current edition approved April 1, 2007. Published April 2007. Originallyapproved in 1955. Last previous edition approved in 2006 as C 364/C 364M 06.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
15、19428-2959, United States.tc= core thicknesstfs= nominal facesheet thicknessxi= test result for an individual specimen from the samplepopulation for a given propertyx = mean or average (estimate of mean) of a samplepopulation for a given propertys = facesheet compressive stress4. Summary of Test Met
16、hod4.1 This test method consists of subjecting a sandwich panelto monotonically increasing compressive force parallel to theplane of its faces. The force is transmitted to the panel througheither clamped or bonded end supports. Stress and strength arereported in terms of the nominal cross-sectional
17、area of the twofacesheets, rather than total sandwich panel thickness, althoughalternate stress calculations may be optionally specified.4.2 The only acceptable failure modes for edgewise com-pressive strength of sandwich constructions are those occurringaway from the supported ends. The sandwich co
18、lumn, nomatter how short, usually is subjected to a buckling type offailure unless the facings are so thick that they themselves arein the short column class. The failure of the facings manifestsitself by wrinkling of the facing, in which the core deforms tothe wavy shape of the facings; by dimpling
19、 of the facings intothe honeycomb cells; by bending of the sandwich, resulting incrimping near the ends as a result of shear failure of the core;or by failure in the facing-to-core bond and associatedfacesheet buckling.5. Significance and Use5.1 The edgewise compressive strength of short sandwichcon
20、struction specimens provides a basis for judging the load-carrying capacity of the construction in terms of developedfacing stress.5.2 This test method provides a standard method of obtain-ing sandwich edgewise compressive strengths for panel designproperties, material specifications, research and d
21、evelopmentapplications, and quality assurance.5.3 The reporting section requires items that tend to influ-ence edgewise compressive strength to be reported; theseinclude materials, fabrication method, facesheet lay-up orien-tation (if composite), core orientation, results of any nonde-structive insp
22、ections, specimen preparation, test equipmentdetails, specimen dimensions and associated measurementaccuracy, environmental conditions, speed of testing, failuremode, and failure location.6. Interferences6.1 Material and Specimen PreparationPoor materialfabrication practices, lack of control of fibe
23、r alignment, anddamage induced by improper specimen machining are knowncauses of high data scatter in composites in general. Specificmaterial factors that affect sandwich composites include vari-ability in core density and degree of cure of resin in both facingmatrix material and core bonding adhesi
24、ve. Important aspectsof sandwich panel specimen preparation that contribute to datascatter are incomplete or nonuniform core bonding to facings,misalignment of core and facing elements, the existence ofjoints, voids or other core and facing discontinuities, out-of-plane curvature, facing thickness v
25、ariation, and surface rough-ness.6.2 System AlignmentUnintended loading eccentricitieswill cause premature failure. Every effort should be made toeliminate undesirable eccentricities from the test system. Sucheccentricities may occur as a result of misaligned grips, poorspecimen preparation, or poor
26、 alignment of the loading fixture.If there is any doubt as to the alignment inherent in a given testmachine, then the alignment should be checked as discussed inTest Method D 3039/ D 3039M.6.3 GeometrySpecific geometric factors that affect edge-wise compressive strength of sandwich panels includefac
27、esheet fiber waviness, core cell geometry (shape, density,orientation), core thickness, specimen shape (L/W ratio), andadhesive thickness.6.4 EnvironmentResults are affected by the environmen-tal conditions under which the tests are conducted. Specimenstested in various environments can exhibit sign
28、ificant differ-ences in both static strength and failure mode. Critical envi-ronments must be assessed independently for each sandwichconstruction tested.7. Apparatus7.1 MicrometersThe micrometer(s) shall use a 4- to 6-mm0.16- to 0.25-in. nominal diameter ball-interface on irregularsurfaces such as
29、the bag-side of a facing laminate, and a flatanvil interface on machined edges or very smooth-tooledsurfaces. The accuracy of the instrument(s) shall be suitable forreading to within1%ofthesample length, width andthickness. For typical specimen geometries, an instrument withan accuracy of 625 m 60.0
30、01 in. is desirable for thickness,length and width measurement. .7.2 Test Fixtures:7.2.1 Spherical Bearing Block, preferably of the suspended,self-aligning type.7.2.2 Lateral End SupportsVia (1) clamps made of rect-angular steel bars fastened together so as to clamp thespecimen lightly between them
31、(the cross-sectional dimensionsof each of these bars shall be not less than 6 mm 0.25 in.,such as that shown in Fig. 1;(2) fitting the specimen snuglyinto a lengthwise slot in a round steel bar, where such bars shallhave a diameter not less than the thickness of the sandwich plus6 mm 0.25 in., and a
32、re suitably retained on the sphericalbearing block surfaces; or (3) casting the ends of the specimensin resin or other suitable molding material. The cast ends of thespecimen should be ground flat and parallel, meeting orexceeding the specimen end tolerances shown in Fig. 2 andFig. 3.7.3 Testing Mac
33、hineThe testing machine shall be inaccordance with Practices E4and shall satisfy the followingrequirements:7.3.1 Testing Machine ConfigurationThe testing machineshall have both an essentially stationary head and a movablehead.7.3.2 Drive MechanismThe testing machine drive mecha-nism shall be capable
34、 of imparting to the movable head acontrolled velocity with respect to the stationary head. TheC 364/C 364M 072velocity of the movable head shall be capable of beingregulated in accordance with 11.6.7.3.3 Force IndicatorThe testing machine force-sensingdevice shall be capable of indicating the total
35、 force beingcarried by the test specimen. This device shall be essentiallyfree from inertia lag at the specified rate of testing and shallindicate the force with an accuracy over the force range(s) ofinterest of within 61 % of the indicated value.7.3.4 Strain GageCapable of measuring strain to at le
36、ast0.0001 mm/mm 0.0001 in./in. and having a gage length notgreater than two thirds of the unsupported length of thespecimens to be tested, nor less than three unit cells if thefacesheet is a composite fabric material form.7.4 Conditioning ChamberWhen conditioning materialsat non-laboratory environme
37、nts, a temperature/vapor-levelcontrolled environmental conditioning chamber is required thatshall be capable of maintaining the required temperature towithin 63C 65F and the required relative humidity levelto within 63 %. Chamber conditions shall be monitored eitheron an automated continuous basis o
38、r on a manual basis atregular intervals.7.5 Environmental Test ChamberAn environmental testchamber is required for test environments other than ambienttesting laboratory conditions. This chamber shall be capable ofmaintaining the entire test specimen at the required testenvironment during the mechan
39、ical test.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 E 122. Rep
40、ort the method of sampling.8.2 GeometryThe test specimens shall be as shown in Fig.2 (inch-pound units) and Fig. 3 SI units.8.3 Specimen Preparation and MachiningGuide D5687/D 5687M provides recommended specimen preparationpractices and should be followed where practical. Of particularnote in this e
41、nd-loaded compression test is the machiningquality and dimensional accuracy of the loaded ends, and theoverall flatness and parallelism of the sandwich panel, asdenoted in Fig. 2 and Fig. 3.8.3.1 LabelingLabel the test specimens so that they willbe distinct from each other and traceable back to the
42、panel 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 The recommended pre-test specimen condition is ef-fective mois
43、ture equilibrium at a specific relative humidity asFIG. 1 Edgewise Compression Test SetupC 364/C 364M 073established by Test Method D5229/D5229M; however, it thetest requester does not specify a pre-test conditioning environ-ment, conditioning is not required and the test specimens maybe tested as p
44、repared.NOTE 1The term moisture, as used in Test Method D5229/D5229M,includes not only the vapor of a liquid and its condensate, but the liquiditself in large quantities, as for immersion.10.2 The pre-test specimen conditioning process, to includespecified environmental exposure levels and resulting
45、 moisturecontent, shall be reported with the data.10.3 If there is no explicit conditioning process, the condi-tioning process shall be reported as “unconditioned” and themoisture content as “unknown.”11. Procedure11.1 Parameters to be Specified Before Test:11.1.1 The specimen sampling method, speci
46、men geometry,and conditioning travelers (if required).11.1.2 The properties and data reporting format desired.NOTE 2Determine specific material property, accuracy, and datareporting requirements prior to test for proper selection of instrumentationand data recording equipment. Estimate the specimen
47、strength to aid intransducer selection, calibration of equipment, and determination ofequipment settings.11.1.3 The environmental conditioning parameters.11.1.4 If performed, sampling method, specimen geometry,and test parameters used to determine facing density andreinforcement volume.11.2 General
48、Instructions:11.2.1 Report any deviations from this test method, whetherintentional or inadvertent.11.2.2 If specific gravity, density, facing reinforcement vol-ume, or facing void volume are to be reported, then obtainthese samples from the same panels being tested. Specificgravity and density may
49、be evaluated in accordance with TestMethods D 792. Volume percent of composite facing constitu-ents may be evaluated by one of the matrix digestion proce-dures of Test Method D 3171, or, for certain reinforcementmaterials such as glass and ceramics, by the matrix burn-offtechnique in accordance with Test Method D 2584. The voidDimension Recommended RangeLength, L (in.) L # 8 3 tWidth, W (in.) 2.00 # W # L; W $ 2 3 t;W$ 4 3 cell widths (honeycomb only)t, total panel thickness (in.) As required, in order to be representative of intended useFacesheet
