1、Designation: D3983 98 (Reapproved 2011)Standard Test Method forMeasuring Strength and Shear Modulus of NonrigidAdhesives by the Thick-Adherend Tensile-Lap Specimen1This standard is issued under the fixed designation D3983; the number immediately following the designation indicates the year oforigina
2、l 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 describes a method of measuring theshear modulus
3、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 modu
4、lus 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 parent
5、heses 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 limitation
6、s prior to use.2. Referenced Documents2.1 ASTM Standards:2D143 Test Methods for Small Clear Specimens of TimberD905 Test Method for Strength Properties of AdhesiveBonds in Shear by Compression LoadingD907 Terminology of AdhesivesD1151 Practice for Effect of Moisture and Temperature onAdhesive BondsD
7、2651 Guide for Preparation of Metal Surfaces for Adhe-sive BondingE6 Terminology Relating to Methods of Mechanical TestingE83 Practice for Verification and Classification of Exten-someter SystemsE104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous SolutionsE229 Test Method for
8、 Shear Strength and Shear Modulus ofStructural Adhesives33. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminologies E6 and D907.3.1.1 initial tangent modulus, nthe slope of the stress-strain curve at the origin.3.1.2 nominal stress, nthe stress at a point c
9、alculated 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 thebondline
10、.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 DiscussionModulus
11、 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 elastic behavi
12、or 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 perpendicular toea
13、ch other through a point in the body.3.1.7.1 DiscussionShear strain equals adherend slip/adhesive layer thickness.3.1.8 shear strength, nin an adhesive joint, the maximumaverage stress when a force is applied parallel to the joint.1This test method is under the jurisdiction of ASTM Committee D14 onA
14、dhesives and is the direct responsibility of Subcommittee D14.70 on ConstructionAdhesives.Current edition approved Jan. 1, 2011. Published January 2011. Originallyapproved in 1981. Last previous edition approved in 2004 as D3983 98 (2004).DOI: 10.1520/D3983-98R11.2For referenced ASTM standards, visi
15、t 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.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1C
16、opyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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
17、.3.1.9 shear stress, nthe stress component tangential to theplane of which the forces act, that is, the plane 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
18、.3.1.11 stress, nthe intensity at a point in a body of theinternal forces or components of force that act 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
19、 as ordinates (verti-cally) and values of strain as abscissas (horizontally).3.2 Definitions of Terms Specific 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
20、 other.Values of load are usually plotted as ordinates (vertically) andvalues of slip as abscissas (horizontally).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 ob
21、tain stress and slip is divided by adhesive layerthickness to obtain strain. Examples of various types ofload-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 sid
22、e of the adhesive layer in the directionof the applied load.3.3 Symbols:3.3.1 c = half the overlap length = L/2, mm or in.3.3.2 G= estimate of shear modulus of adhesive, MPa orpsi.3.3.3 G = shear modulus of adhesive, MPa or psi.NOTE 1Case load and unload diagrams and modulus line are congru-ent.FIG.
23、 1 Load-Slip Diagram of Linear Elastic Adhesive Under CyclicLow-Level LoadingNOTE 1The modulus is represented by the secant modulus line atsome load P2less than the load to cause failure.FIG. 2 Load-Slip Diagram of Nonlinear Adhesive Under CyclicLow-Level Loading Showing Both Elastic and Viscoelasti
24、cRecovering DiagramsNOTE 1The modulus may be represented by the initial tangent, thesecant drawn to the ultimate load, or the secant drawn to some interme-diate load.FIG. 3 Load-Slip Diagram of Adhesive Loaded to FailureD3983 98 (2011)23.3.4 E = tensile modulus of adherend, MPa or psi.3.3.5 t = thic
25、kness of adherend, mm or in.3.3.6 h = thickness of adhesive, mm or in.3.3.7 Pmax= failure load for 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
26、 bythe bond, MPa or psi.4. Summary of Test Method4.1 Lap-shear specimens are prepared with the adhesive 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. Thi
27、s estimate is used to determine the optimized jointgeometry for best attainable uniformity of stress 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 env
28、ironmental and experimental conditions.4.2 The test method is based upon the theoretical analysisby 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 fact
29、or in the Goland and Reissner equations is acomposite of essentially three ratios which can be manipulatedto 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
30、 modulus of the adhesive, and by (2)increasing adherend and adhesive thickness while minimizingoverlap 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 modu
31、lusand shear strength values for adhesives with accuracy suitablefor use by design engineers in predicting the characteristics ofbuilding assemblies bonded with nonrigid adhesives. Adhesiveformulators will also find the method useful during thedevelopment of new adhesive systems. In general, the thi
32、ckadherend lap-shear test is a useful tool in research duringstudies of both short- and long-term 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 i
33、s consideredto be a condition of pure shear.5.2 The user is cautioned that pure shear strength cannot 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 beconservati
34、ve. If pure shear strength is demanded, then TestMethod E229 should be used.6. Equipment6.1 Test 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 capa
35、bility of 0 to 200 kg/min (0 to400 lb/min) or a crosshead movement rate of 0 to 1 mm/min (0to 0.040 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 appro
36、ximately 450 by 450 mm (18 by 18 in.) isdesirable to accommodate the specimen grips and the installa-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 ad
37、hesive layers is usually small.Thin layers of relatively rigid adhesives (greater than 50 MPa(7000 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-elec
38、trical transducer, the linear variabledifferential transformer (LVDT), is well suited for these 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 properl
39、y designed.6.2.2.1 The LVDT should have a linear output over adisplacement range of 62.5 mm (60.10 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
40、0.5 mm/cm (5 3 105and 0.05 in./m) ofchart paper.6.2.3 The slip gage shall employ two LVDTs as described 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 ro
41、tation is shown in Fig. 5, Fig.A1.1, and Fig. A1.2. The gage consists of three components:the gage itself on which two LVDTs are mounted, the follower,4Goland, M., and Reissner, E., “The Stresses in Cemented Joints,” Journal ofApplied Mechanics , November 1944, pp. A17A27.FIG. 4 Incline Tension Grip
42、s with Specimen Bolted in Place Ready for TestingD3983 98 (2011)3and a gage block. The gage and 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
43、 the knife edges. The gage is clamped to the stationary ordownward moving adherend and the follower 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 scre
44、w for each LVDT. These screws areused to null mechanically and electrically each LVDT prior totesting.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
45、 components should befabricated of corrosion-resistant materials.6.3 X-Y Recorder A general-purpose 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 haves
46、everal precalibrated input ranges and a preamplifier to scalethe transducer signals conveniently. 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
47、 determinethe effects of temperature and moisture and to minimizevariability in test results due 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), an
48、d constantrelative humidity within the limits of 44 to 98 6 2 % at a giventemperature.6.4.3 A suitable 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
49、 method. Other dense species withcomparable modulus of elasticity such as yellow birch, Dou-glas 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 D905.7.2 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
