ASTM_D_6068_-_10.pdf

Designation:D606810Standard Test Method forDetermining J-R Curves of Plastic Materials1This standard is issued under the fixed designation D6068;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of theJ-integral versus crack growth resistance(J-R)curves forpolymeric materials.1.2 This test method is intended to characterize the slow,stable crack growth resistance of bend-type specimens in sucha manner that it is geometry insensitive within limits set forthin this test method.1.3 The recommended specimens are the three-point bend(SE(B)and pin-loaded compact tension(C(T)specimens.Both specimens have in-plane dimensions of constant propor-tionality for all sizes.Specimen configurations other than thoserecommended in this test method may require different proce-dures and validity requirements.1.4 This test method describes a multiple specimen methodthat requires optical measurement of crack extension fromfracture surfaces.It is not recommended for use with materialsin which the crack front cannot be distinguished from addi-tional deformation processes in advance of the crack tip.1.5 The values stated in SI units are to be regarded as thestandard.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 and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1There is no equivalent ISO standard.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD4066 Classification System for Nylon Injection and Extru-sion Materials(PA)D5045 Test Methods for Plane-Strain Fracture Toughnessand Strain Energy Release Rate of Plastic MaterialsE399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic MaterialsE616 Terminology Relating to Fracture Testing(Discontin-ued 1996)(Withdrawn 1996)3E1152 Test Method for Determining-J-R-CurvesE1737 Test Method forJ-Integral Characterization of Frac-ture Toughness(Withdrawn 1998)3F1473 Test Method for Notch Tensile Test to Measure theResistance to Slow Crack Growth of Polyethylene Pipesand Resins3.Terminology3.1 DefinitionsTerminology related to fracture testingcontained in Terminology E616 is applicable to this testmethod.3.2 Definitions of Terms Specific to This Standard:3.2.1 J-integral,J(FL1)a mathematical expression,aline or surface integral over a path that encloses the crack frontfrom one crack surface to the other,used to characterize thelocal stress-strain field around the crack front.See TerminologyE616 for additional discussion.3.2.2 J-R curvea plot of resistance to stable physical crackextension,ap.3.2.3 net thickness,BN(L)the distance between the rootsof the side grooves in side grooved specimens.3.2.4 original crack size,a0(L)the physical crack size atthe start of testing.3.2.5 original uncracked ligament,b0(L)the distancefrom the original crack front to the back edge of the specimen(b0=W a0).3.2.6 physical crack extension,ap(L)an increase inphysical crack size(ap=ap a0).3.2.7 physical crack size,ap(L)the distance from a refer-ence line to the observed crack front.The distance may be acalculated average of several measurements along the crackfront.The reference line depends on the specimen geometry1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved July 1,2010.Published July 2010.Originally approvedin 1996.Last previous edition approved in 2002 as D6068-96(2002)1.DOI:10.1520/D6068-10.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 and is normally defined as in 3.2.10.The reference line isdefined prior to specimen deformation.3.2.8 specimen span,S(L)the distance between specimensupports for the SE(B)specimen.3.2.9 specimen thickness,B(L)the side-to-side dimensionof the test specimen(shown in Fig.2).3.2.10 specimen width,W(L)a physical dimension on atest specimen measured from the rear surface of the specimento a reference line(for example,the front edge of a bendspecimen or the load line of a compact specimen).4.Summary of Test Method4.1 This test method describes a multiple specimen tech-nique for determining the J-R curve for polymeric materials.The J-R c