ASTM_C_393_-_C_393M_-_16.pdf

Designation:C393/C393M16Standard Test Method forCore Shear Properties of Sandwich Constructions by BeamFlexure1This standard is issued under the fixed designation C393/C393M;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers determination of the core shearproperties of flat sandwich constructions subjected to flexure insuch a manner that the applied moments produce curvature ofthe sandwich facing planes.Permissible core material formsinclude those with continuous bonding surfaces(such as balsawood and 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 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:2C273 Test Method for Shear Properties of Sandwich CoreMaterialsD883 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 FlexureD7250/D7250M Practice for Determining Sandwich BeamFlexural and Shear StiffnessE4 Practices for Force Verification of Testing MachinesE6 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,as 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 terminologies.3.2 Symbols:b=specimen widthc=core thicknessCV=coefficient of variation statistic of a sample populationfor a given property(in percent)d=sandwich total thicknessDF,nom=effective sandwich flexural stiffnessEf=effective facing chord modulus=measuring strain in facingFu=facing ultimate strength(tensile or compressive)Fc=core compression allowable strengthFs=core shear allowable strengthFsult=core shear ultimate strengthFsyield=core shear yield strengthk=core shear strength factor to ensure core failureL=length of loading spanS=length of support spanlpad=length of loading padn=number of specimensP=applied force1This 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 April 1,2016.Published April 2016.Originallyapproved in 1957.Last previous edition approved in 2011 as C393 111.DOI:10.1520/C0393_C0393M-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 Pmax=maximum force carried by test specimen beforefailureFZftu=ultimate flatwise tensile strengthPmax=maximum force carried by test specimen beforefailureSn-1=standard deviation statistic of a sample population fora given property=facing stress or strengtht=facing thicknessx1=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 property4.Summary of Test Method4.1 This test method consists of subjecting a beam ofsandwich construction to a bending moment normal to theplane of the sandwich.Force versus deflection measurementsare recorded.4.2 The only acceptable failure modes are core shear orcore-to-facing bond.Failure of the sandwich facing precedingfailure of the core or core-to-facing bond is not