ASTM_D_4255_-_D_4255M_-_20.pdf

Designation:D4255/D4255M20Standard Test Method forIn-Plane Shear Properties of Polymer Matrix CompositeMaterials by the Rail Shear Method1This standard is issued under the fixed designation D4255/D4255M;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method determines the in-plane shear proper-ties of high-modulus fiber-reinforced composite materials byeither of two procedures.In Procedure A,laminates clampedbetween two pairs of loading rails are tested.When loaded intension,the rails introduce shear forces in the specimen.InProcedure B,laminates clamped on opposite edges with atensile or compressive force applied to a third pair of rails inthe center are tested.1.2 Application of this test method is limited to continuous-fiber or discontinuous-fiber-reinforced polymer matrix com-posites in the following material forms:1.2.1 Laminates composed only of unidirectional fibrouslaminae,with the fiber direction oriented either parallel orperpendicular to the fixture rails.1.2.2 Laminates composed only of woven fabric filamentarylaminae with the warp direction oriented either parallel orperpendicular to the fixture rails.1.2.3 Laminates of balanced and symmetric construction,with the 0 direction oriented either parallel or perpendicular tothe fixture rails.1.2.4 Short-fiber-reinforced composites with a majority ofthe fibers being randomly distributed.NOTE1Additional test methods for determining in-plane shearproperties of polymer matrix composites may be found in Test MethodsD3518/D3518M,D5379/D5379M,D5448/D5448M,andD7078/D7078M.1.3 The reproducibility of this test method can be affectedby the presence of shear stress gradients in the gage section andstress concentrations at the gripping areas.Test MethodsD5379/D5379M and D7078/D7078M provide superior shearresponse in comparison to this test method,as their specimenconfigurations produce a relatively pure and uniform shearstress state in the gage section.1.4 The technical content of this standard has been stablesince 2001 without significant objection from its stakeholders.As there is limited technical support for the maintenance of thisstandard,changes since that date have been limited to itemsrequired to retain consistency with other ASTM D30 Commit-tee standards,including editorial changes and incorporation ofupdated guidance on micrometers and calipers,strain gagerequirements,speed of testing,specimen preconditioning andenvironmental testing.Future maintenance of the standard willonly be in response to specific requests and performed only astechnical support allows.1.5 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard.Thevalues stated in each system are not necessarily exact equiva-lents;therefore,to ensure conformance with the standard,eachsystem shall be used independently of the other,and valuesfrom the two systems shall not be combined.1.5.1 Within the text the inch-pounds units are shown inbrackets.1.6 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D792 Test Methods for Density and Specific Gravity(Rela-tive Density)of Plastics by DisplacementD883 Terminology Relating to Plastics1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.04 onLamina and Laminate Test Methods.Current edition approved Oct.1,2020.Published October 2020.Originallyapproved in 1983.Last previous edition approved in 2015 as D4255/D4255M 15a.DOI:10.1520/D4255_D4255M-20.2For 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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,G