1、Designation: D 3983 98 (Reapproved 2004)Standard Test Method forMeasuring Strength and Shear Modulus of NonrigidAdhesives by the Thick-Adherend Tensile-Lap Specimen1This standard is issued under the fixed designation D 3983; the number immediately following the designation indicates the year oforigi
2、nal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a method of measuring theshear modul
3、us and rupture stress in shear of adhesives inbonded joints. The method employs lap-shear specimens withwood, metal, or composite adherends, with adhesives havingshear moduli ranging up to 700 MPa (100 000 psi). This testmethod is suitable generally for joints in which the ratio ofadherend tensile m
4、odulus to adhesive shear modulus is greaterthan 300 to 1. It is not suitable for adhesives that have a highshear modulus in the cured state and that also require elimina-tion of volatile constituents during cure.1.2 The values stated in SI units are to be regarded asstandard. The values given in par
5、entheses are for informationonly.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 limitat
6、ions prior to use.2. Referenced Documents2.1 ASTM Standards:2D 143 Test Methods for Small Clear Specimens of TimberD 905 Test Method for Strength Properties of AdhesiveBonds in Shear by Compression LoadingD 907 Terminology of AdhesivesD 1151 Practice for Effect of Moisture and Temperature onAdhesive
7、 BondsD 2651 Guide for Preparation of Metal Surfaces for Adhe-sive BondingE6 Terminology Relating to Methods of Mechanical Test-ingE83 Practice for Verification and Classification of Exten-someter SystemE 104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous SolutionsE 229 Test
8、Method for Shear Strength and Shear Modulusof Structural Adhesives33. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminologies E6and D 907.3.1.1 initial tangent modulus, nthe slope of the stress-strain curve at the origin.3.1.2 nominal stress, nthe stress at
9、 a point calculated onthe net cross section by simple elastic theory without takinginto account the effect on the stress produced by discontinuitiessuch as holes, grooves, fillets, etc.3.1.3 normal stress, nthe stress component perpendicularto a plane on which the forces act, that is, the plane of t
10、hebondline.3.1.4 proportional limit, nthe maximum stress that amaterial is capable of sustaining without significant deviationfrom proportionality of stress to strain.3.1.5 secant modulus, nthe slope of the secant drawnfrom the origin to any specified point on the stress-strain curve.3.1.5.1 Discuss
11、ionModulus is expressed in force per unitarea (MPa, lb/in.2, etc.).3.1.6 shear modulus, nthe ratio of shear stress to corre-sponding shear strain below the proportional limit. (Comparesecant modulus.)3.1.6.1 DiscussionThe term shear modulus is generallyreserved for materials that exhibit linear elas
12、tic behavior overmost of their stress-strain diagram. Many adhesives exhibitcurvilinear or nonelastic behavior, or both, in which case someother term, such as secant modulus, may be substituted.3.1.7 shear strain, nthe tangent of the angular change,due to force, between two lines originally perpendi
13、cular toeach other through a point in the body.3.1.7.1 DiscussionShear strain equals adherend slip/adhesive layer thickness.1This test method is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.70 on ConstructionAdhesives.Current edition a
14、pproved April 1, 2004. Published April 2004. Originallyapproved in 1981. Last previous edition approved in 1998 as D 3983 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
15、refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.8 shear strength, nin an adhesive joint, the maximumaverage stress when a force is applied parallel to the
16、 joint.3.1.8.1 DiscussionIn most adhesive test methods, theshear strength is actually the maximum average stress at failureof the specimen, not necessarily the true maximum stress in thematerial.3.1.9 shear stress, nthe stress component tangential to theplane of which the forces act, that is, the pl
17、ane of the bondline.3.1.9.1 DiscussionNominal shear stress equals load/bondarea.3.1.10 strain, nthe unit change due to force, in the size orshape of a body referred to its original size or shape.3.1.11 stress, nthe intensity at a point in a body of theinternal forces or components of force that act
18、on a given planethrough the point.3.1.12 stress-strain diagram, na diagram in which corre-sponding values of stress and strain are plotted against eachother. Values of stress are usually plotted as ordinates (verti-cally) and values of strain as abscissas (horizontally).3.2 Definitions of Terms Spec
19、ific to This Standard:3.2.1 load, nthe force applied to the specimen at anygiven time.3.2.2 load-slip diagram, na diagram in which correspond-ing values of load and slip are plotted against each other.Values of load are usually plotted as ordinates (vertically) andvalues of slip as abscissas (horizo
20、ntally).3.2.2.1 DiscussionStress-strain behavior is commonly re-corded in the form of a load-slip diagram. The differencebetween the two is simply one of scale. Load is divided bybond area to obtain stress and slip is divided by adhesive layerthickness to obtain strain. Examples of various types ofl
21、oad-slip diagrams and modulus are shown in Figs. 1-3.3.2.3 rate of strain, nrate of slip per unit adhesivethickness.3.2.4 slip, nthe relative collinear displacement of theadherends on either side of the adhesive layer in the directionof the applied load.3.3 Symbols:Symbols:3.3.1 c = half the overlap
22、 length = L/2, mm or in.3.3.2 G= estimate of shear modulus of adhesive, MPa orpsi.NOTE 1Case load and unload diagrams and modulus line are congru-ent.FIG. 1 Load-Slip Diagram of Linear Elastic Adhesive Under CyclicLow-Level LoadingNOTE 1The modulus is represented by the secant modulus line atsome lo
23、ad P2less than the load to cause failure.FIG. 2 Load-Slip Diagram of Nonlinear Adhesive Under CyclicLow-Level Loading Showing Both Elastic and ViscoelasticRecovering DiagramsNOTE 1The modulus may be represented by the initial tangent, thesecant drawn to the ultimate load, or the secant drawn to some
24、 interme-diate load.FIG. 3 Load-Slip Diagram of Adhesive Loaded to FailureD 3983 98 (2004)23.3.3 G = shear modulus of adhesive, MPa or psi.3.3.4 E = tensile modulus of adherend, MPa or psi.3.3.5 t = thickness of adherend, mm or in.3.3.6 h = thickness of adhesive, mm or in.3.3.7 Pmax= failure load fo
25、r the bond, N or lbf.3.3.8 L = overlap length, mm or in.3.3.9 A = bond area, mm2or in.23.3.10 d = adherend slip at load equivalent to 0.1 Pmax,mm or in.3.3.11 tmax= maximum nominal shear stress sustained bythe bond, MPa or psi.4. Summary of Test Method4.1 Lap-shear specimens are prepared with the ad
26、hesive inquestion using selected adherends. The load-deformation prop-erties of the specimens are measured under specific recom-mended conditions to yield a “first estimate” of adhesive shearmodulus. This estimate is used to determine the optimized jointgeometry for best attainable uniformity of str
27、ess distribution inthe joint. A second set of specimens is prepared having theoptimized joint geometry. The final values for load-deformation properties are then measured under a variety ofcontrolled environmental and experimental conditions.4.2 The test method is based upon the theoretical analysis
28、by Goland and Reissner4relating stress concentrations (that is,nonuniformity) in single-lap joints to the geometry of the jointand the mechanical properties of the materials involved. Thecontrolling factor in the Goland and Reissner equations is acomposite of essentially three ratios which can be ma
29、nipulatedto improve the stress uniformity in the joint, and therebycontrol the accuracy of measurement. Stress uniformity isimproved by (1) increasing the adherend tensile modulus inrelation to the shear modulus of the adhesive, and by (2)increasing adherend and adhesive thickness while minimizingov
30、erlap length. Because of these relationships, the practice wasdeveloped to use high-modulus adherends in thick crosssections.5. Significance and Use5.1 This test method is capable of providing shear modulusand shear strength values for adhesives with accuracy suitablefor use by design engineers in p
31、redicting the characteristics ofbuilding assemblies bonded with nonrigid adhesives. Adhesiveformulators will also find the method useful during thedevelopment of new adhesive systems. In general, the thickadherend lap-shear test is a useful tool in research duringstudies of both short- and long-term
32、 load-deformation proper-ties of adhesives. This thick adherend lap-shear test yields auniformity of stress distribution approaching that obtained inthin tubular butt joints subjected to torsion, which is consideredto be a condition of pure shear.5.2 The user is cautioned that pure shear strength ca
33、nnot beobtained by this test method, because some tensile and com-pression stresses and stress concentrations are present in thejoint. The estimate of shear strength by this test method will beconservative. If pure shear strength is demanded, then TestMethod E 229 should be used.6. Equipment6.1 Test
34、 Machine A tension test machine with electronicload cell capacities of 0 to 100 and 0 to 1000 kg (0 to 200 and0 to 2000 lb) is satisfactory for this test method. The machineshould have a loading rate capability of 0 to 200 kg/min (0 to400 lb/min) or a crosshead movement rate of 0 to 1 mm/min (0to 0.
35、040 in./min). Closed-loop control of load level and loadingrate, or crosshead position and movement rate, is desirable tofacilitate testing under controlled cyclic loading conditions. Aworking space approximately 450 by 450 mm (18 by 18 in.) isdesirable to accommodate the specimen grips and the inst
36、alla-tion of a chamber for environmental control. In-line tensiongrips, shown in Fig. 4, are used for transmitting the load to thespecimen.6.2 Slip Gage and Signal Conditioner:6.2.1 The shear strain in adhesive layers is usually small.Thin layers of relatively rigid adhesives (greater than 50 MPa(70
37、00 psi) require an ASTM Class A extensometer. Class B-1or B-2 extensometers suffice for thicker layers and moreflexible adhesives. Extensometer classes are described inPractice E83.6.2.2 A mechanical-electrical transducer, the linear variabledifferential transformer (LVDT), is well suited for these
38、tests.The LVDT with suitable signal conditioning will satisfy therequirements of Class B and A extensometers. They are ruggedenough to remain fastened to the specimen through failure ifthe gage is properly designed.6.2.2.1 The LVDT should have a linear output over adisplacement range of 62.5 mm (60.
39、10 in.) to accommodateadhesive layers varying in shear modulus and thickness.6.2.2.2 The LVDT transducers with signal conditionershould provide several ranges of displacement resolutionbetween 0.0005 and 0.5 mm/cm (5 3 105and 0.05 in./m) ofchart paper.6.2.3 The slip gage shall employ two LVDTs as de
40、scribed in6.2.2, positioned in such a manner as to measure and compen-sate for rotation of the adherends as well as slip.6.2.4 A gage design that has been found to compensatesatisfactorily for adherend rotation is shown in Fig. 5, Fig.A1.1, and Fig. A1.2. The gage consists of three components:4Golan
41、d, M., and Reissner, E., “The Stresses in Cemented Joints,” Journal ofApplied Mechanics, November 1944, pp. A17A27.FIG. 4 Incline Tension Grips with Specimen Bolted in Place Ready for TestingD 3983 98 (2004)3the gage itself on which two LVDTs are mounted, the follower,and a gage block. The gage and
42、follower attach to opposingadherends by clamping knife edges. One knife edge on eachcomponent may be advanced or retracted by a captive screw.The gage block is placed between the gage and follower toalign the knife edges. The gage is clamped to the stationary ordownward moving adherend and the follo
43、wer to the upwardmoving adherend, so the LVDT core moves out of the LVDTduring loading. This prevents damage to the LVDT uponfailure of the specimen. The follower is equipped with aknurled adjustment screw for each LVDT. These screws areused to null mechanically and electrically each LVDT prior tote
44、sting.6.2.5 The slip gage shall be equipped with a switching andsignal-conditioning device to permit recording the signal fromeach LVDT individually or the sum of the signals.6.2.6 The LVDTs and slip gage components should befabricated of corrosion-resistant materials.6.3 X-Y Recorder A general-purp
45、ose X-Y recorder withinputs compatible with the outputs of the load cell and slipgage is required. The load is connected to the recorder of theY-axis and the LVDTs to the X-axis. The recorder should haveseveral precalibrated input ranges and a preamplifier to scalethe transducer signals conveniently
46、. The required ranges willdepend upon the voltage output of the load cells and the LVDTtransducers and their signal conditioner.6.4 Environmental Chamber:6.4.1 A controlled test environment is required to determinethe effects of temperature and moisture and to minimizevariability in test results due
47、 to changes in environmentalconditions.6.4.2 The combined test chamber and conditioning unitshould be capable of maintaining a constant temperature withinthe limits from 23 to 71 6 1C (80 to 160 6 2F), and constantrelative humidity within the limits of 44 to 98 6 2 % at a giventemperature.6.4.3 A su
48、itable test chamber is described in Annex A2.7. Materials7.1 Adherend:7.1.1 WoodHard maple (Acer saccharum or Acer nigrum)with a minimum specific gravity of 0.60 is the standard woodadherend for this test method. Other dense species withcomparable modulus of elasticity such as yellow birch, Dou-glas
49、 fir, western hemlock, or southern pine may be used. Thelumber shall be of straight grain and free of defects, includingknots, birdseye, short grain, decay, and any unusual discolora-tions within the shearing area. Criteria for lumber selectionshall be those described in Test Method D 905.7.2 MetalUse cold-rolled steel or aluminum-alloy barstock, machined to a surface finish of 16 in. or better in thebond area, for adhesives that contain no volatile constituents,and have a shear modulus in the range from 50 to 700 MPa(7 000 to 100 000 psi).7.3
