ASTM_C_480_-_C_480M_-_16.pdf

Designation:C480/C480M16Standard Test Method forFlexure Creep of Sandwich Constructions1This standard is issued under the fixed designation C480/C480M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year 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 the creepcharacteristics and creep rate of flat sandwich constructionsloaded in flexure,at any desired temperature.Permissible corematerial forms include those with continuous bonding surfaces(such as balsa wood and foams)as well as those withdiscontinuous bonding surfaces(such as honeycomb).1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.Within the text theinch-pound units are shown in brackets.The values stated ineither SI units or inch-pound units are to be regarded separatelyas standard.The values stated in each system may not be exactequivalents;therefore,each system shall be used independentlyof the other.Combining values from the two systems mayresult in non-conformance with the standard.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:2C393/C393M Test Method for Core Shear Properties ofSandwich Constructions by Beam FlexureD883 Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for MoistureAbsorption Prop-erties and Equilibrium Conditioning of Polymer MatrixComposite MaterialsD7249/D7249M Test Method for Facing Properties of Sand-wich Constructions by Long Beam FlexureE6 Terminology Relating to Methods of Mechanical TestingE122 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 Statistics3.Terminology3.1 DefinitionsTerminology D3878 defines terms relatingto high-modulus fibers and their composites,a well as termsrelating to sandwich constructions.Terminology D883 definesterms relating to plastics.Terminology E6 defines termsrelating to mechanical testing.Terminology E456 and PracticeE177 define terms relating to statistics.In the event of aconflict between terms,Terminology D3878 shall have prece-dence over the other terminology documents.3.2 Symbols:3.2.1 Adistance between pivot point and point of appliedforce on the specimen3.2.2 bspecimen width3.2.3 Bdistance from pivot point to center of gravity of theloading arm3.2.4 ccore thickness3.2.5 CRIcreep rate at time,ii3.2.6 dsandwich total thickness3.2.7 dinitial static deflection under the same load and atthe same temperature3.2.8 Dtotal deflection at time,t3.2.9 Ffapplied facing stress3.2.10 Fsapplied core shear stress3.2.11 Mdistance between point and weight point3.2.12 nnumber of specimens3.2.13 pmass of loading plate and rod3.2.14 Papplied force3.2.15 Slength of support span3.2.16 wmass of lever arm3.2.17 Wmass of weight(including tray mass)1This specification is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.09 onSandwich Construction.Current edition approved April 1,2016.Published April 2016.Originallyapproved in 1961.Last previous edition approved in 2015 as C480/C480M 08(2015).DOI:10.1520/C0480_C0480M-16.2For 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 4.Summary of Test Method4.1 This test method consists of subjecting a beam ofsandwich construction to a sustained force normal to the planeof the sandwich,using either a 3-point or a 4-point loadingfixture.Deflection versus time measurements are recorded.4.2 For long beam specimens conforming to Test MethodD7249/D7249M,the only acceptable failure modes for sand-wich facesheet strength are those which are internal to one ofthe facesheets.Failure of the sandwich core or the core-to-facesheet bond preceding failure of one of the facesheets is notan acceptable failure mode for this specimen configuration.4.3 For short-beam specimens conforming to Test MethodC393/C393M,the only acceptable failure modes are core shearor core-to-facing bond.Failure of the sandwich facing preced-ing failure of the core or core-to-facing bond is not anacceptable failure mode for this specimen configuration.4.4 Carefu