ASTM_D_4896_-_01_2008e1.pdf

Designation:D489601(Reapproved 2008)1Standard Guide forUse of Adhesive-Bonded Single Lap-Joint Specimen TestResults1This standard is issued under the fixed designation D4896;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.1NOTEThe units statement in subsection 1.2 was corrected editorially in April 2008.INTRODUCTIONThe true strength of an adhesive is a material property independent of the joint geometry,adherendproperties,and load,and is a good starting point for determining an allowable design stress.Allowablestresses in shear and tension are needed to design safe,efficient,adhesively bonded joints andstructures.The true shear strength,however,cannot be easily determined using single-lap specimens.Many factors affect the apparent shear strength of an adhesive when measured with a smalllaboratory specimen,and in particular,with a single-lap specimen.For example,the failure of a typicalsingle-lap specimen,is usually controlled by the tensile stress in the adhesive,and not by the shearstress.The factors that control the tensile stress in lap-joint specimen,and thus,the apparent shearstrength are the size and shape of the specimen,the properties of the adherends,the presence ofinternal stresses or flaws,and the changes that take place in the specimen due to adhesive cure and theenvironment.Similarly these factors affect the apparent tensile strength of an adhesive in butt-joint testspecimens.Due to the effects of these factors,the apparent shear strength obtained through measurements onsmall laboratory specimens may vary widely from the true shear-or tensile-strength values needed todetermine allowable shear and tension design stresses.The objectives of this guide are:to develop an appreciation of the factors that influence strength andother stress measurements that are made with small laboratory test specimens;to foster the acceptableuses of the widely used thin-adherend single-lap-joint test;and,specifically,to prevent misuse of thetest results.1.Scope1.1 This guide is directed toward the safe and appropriateuse of strength values obtained from test methods usingsingle-lap adhesive joint specimens.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 The discussion focuses on shear strength as measuredwith small thin-adherend,single-lap specimens.Many factors,however,apply to shear modulus,tensile strength,and tensilemodulus measured by small laboratory specimens in general.This discussion is limited to single-lap specimens and shearstrength only for simplification.2.Referenced Documents2.1 ASTM Standards:2D896 Practice for Resistance of Adhesive Bonds to Chemi-cal ReagentsD906 Test Method for Strength Properties of Adhesives inPlywood Type Construction in Shear by Tension LoadingD907 Terminology of AdhesivesD1002 Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Ten-sion Loading(Metal-to-Metal)D1144 Practice for Determining Strength Development ofAdhesive Bonds1This guide is under the jurisdiction ofASTM Committee D14 on Adhesives andis the direct responsibility of Subcommittee D14.80 on Metal Bonding Adhesives.Current edition approved April 1,2008.Published April 2008.Originallyapproved in 1989.Last previous edition approved in 2001 as D4896 01.DOI:10.1520/D4896-01R08E01.2For 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 D1151 Practice for Effect of Moisture and Temperature onAdhesive BondsD1183 Practices for Resistance of Adhesives to CyclicLaboratory Aging ConditionsD1780 Practice for Conducting Creep Tests of Metal-to-Metal AdhesivesD2294 Test Method for Creep Properties of Adhesives inShear by Tension Loading(Metal-to-Metal)D2295 Test Method for Strength Properties of Adhesives inShear by Tension Loading at Elevated Temperatures(Metal-to-Metal)D2339 Test Method for Strength Properties of Adhesives inTwo-Ply Wood Construction in Shear by Tension LoadingD2919 Test Method for Determining Durability of AdhesiveJoints Stressed in Shear by Tension LoadingD3163 Test Method for Determining Strength of AdhesivelyBonded Rigid Plastic Lap-Shear Joints in Shear by Ten-sion LoadingD3164 Test Method for Strength Properties of AdhesivelyBonded Plastic Lap-Shear Sandwich Joints in Shear byTension LoadingD3165 Test Method for Strength Properties of Adhesives inShear by Tension Loading