ASTM_D_6790_-_D_6790M_-_14.pdf

Designation:D6790/D6790M14Standard Test Method forDetermining Poissons Ratio of Honeycomb Cores1This standard is issued under the fixed designation D6790/D6790M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the sand-wich honeycomb core Poissons ratio from the anticlasticcurvature radii,see Fig.1.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.2.1 Within the text,the inch-pound units are shown inbrackets.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 limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C271/C271M Test Method for Density of Sandwich CoreMaterialsC274 Terminology of Structural Sandwich ConstructionsD883 Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for MoistureAbsorption Prop-erties and Equilibrium Conditioning of Polymer MatrixComposite MaterialsE122 Practice for Calculating Sample Size to Estimate,WithSpecified Precision,the Average for a Characteristic of aLot or ProcessE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE1309 GuideforIdentificationofFiber-ReinforcedPolymer-Matrix Composite Materials in DatabasesE1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases3.Terminology3.1 DefinitionsTerminology D3878 defines terms relatingto high-modulus fibers and their composites.TerminologyC274 defines terms relating to structural sandwich construc-tions.Terminology D883 defines terms relating to plastics.Terminology E456 and Practice E177 define terms relating tostatistics.In the event of a conflict between terms,TerminologyD3878 shall have precedence over the other terminologies.3.2 Symbols:c=chord measurementCV=coefficient of variation statistic of a sample populationfor a given property(in percent)d=depth measurementRa=anticlastic curvature radiusRc=cylinder radiusSn-1=standard deviation statistic of a sample population fora given propertyx1=test result for an individual specimen from the samplepopulation for a given propertyx =mean or average(estimate of mean)of a sample popu-lation for a given propertyv=Poissons ratio4.Summary of Test Method4.1 This test method determines the Poissons ratio ofsandwich honeycomb core by bending the core around acylinder and taking measurements of the anticlastic curvaturethat occurs.5.Significance and Use5.1 Certain sandwich panel analyses require the Poissonsratio of the honeycomb core.It is not possible to measure thehoneycombs Poissons ratio by conventional methods.5.2 This test method provides a standard method of deter-mining the Poissons ratio of honeycomb core materials fordesign properties,material specifications,research and devel-opment applications,and quality assurance.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 1,2014.Published June 2014.Originallyapproved in 2002.Last previous edition approved in 2007 as D6790-02(2007).DOI:10.1520/D6790_D6790M-14.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.3 Factors that influence the Poissons ratio of honeycombcore materials and shall therefore be reported include thefollowing:core material,methods of material fabrication,coregeometry,core thickness,core thickness uniformity,cell wallthickness,specimen geometry,specimen preparation,andspecimen conditioning.6.Interferences6.1 The test method described here is one means of obtain-ing the Poissons ratio of honeycomb core.However,this testmethod has not been widely used,and it is in its conceptualstage.6.2 Material and Specimen PreparationPoor material fab-rication practices and damage induced by improper specimenmachining are known causes of high data scatter for sandwichcores.Important aspects of sandwich core specimen prepara-tion that contribute to data scatter include th