1、Designation: D 4027 98 (Reapproved 2004)Standard Test Method forMeasuring Shear Properties of Structural Adhesives by theModified-Rail Test1This standard is issued under the fixed designation D 4027; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase 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 equipment and procedures tomeasure the shear modulus and shea
3、r strength of adhesivelayers between rigid adherends. The equipment may also beused for determining the adhesives shear creep compliance,the effects of strain history such as cyclic loading upon shearproperties, and a failure criteria for biaxial stress conditionssuch as shear plus tension and shear
4、 plus compression.21.2 High-density wood shall be the preferred substrate. Thepractical upper limit on the shear modulus that can bemeasured is determined by the shear modulus of the adherendsand by the strain measuring device. Thus, the practical limit ofadhesive shear modulus that can be measured
5、using high-density wood adherends is about 690 MPa (1 3 105psi).NOTE 1Wood-base composites, metal, plastic, reinforced plastics,and other common construction materials may also be used for adherends.1.3 The range of specimen dimensions that can be testedare: width 1.59 to 12.70 mm (0.0625 to 0.500 i
6、n.), length 102to 203 mm (4 to 8 in.), and adherend thickness 13 to 25 mm(0.50 to 1.00 in.). The standard specimen dimensions shall be:width 3.18 mm (0.125 in.), length 203 mm (8 in.), andadherend thickness 19 mm (0.75 in.). Bondline thicknessesfrom 0.15 to 3.18 mm (0.006 to 0.125 in.) may be tested
7、.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 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 ap
8、pro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 905 Test Method for Strength Properties of AdhesiveBonds in Shear by Compression LoadingD 907 Terminology of AdhesivesD 4442 Test Methods for Di
9、rect Moisture Content Measure-ment of Wood and Wood-Base MaterialsE 83 Practice for Verification and Classification of Exten-sometersE 229 Test Method for Shear Strength and Shear Modulusof Structural Adhesives43. Terminology3.1 DefinitionsMany terms in this test method are definedin Terminology D 9
10、07.3.1.1 shear modulus, nthe ratio of shear stress to corre-sponding shear strain below the proportional limit. (Comparesecant modulus.)3.1.1.1 DiscussionThe term shear modulus is generallyreserved for materials that exhibit linear elastic behavior overmost of their stress-strain diagram. Many adhes
11、ives exhibitcurvilinear or nonelastic behavior, or both, in which case someother term, such as secant modulus, may be substituted.3.1.2 shear strain, nthe tangent of the angular change,due to force between two lines originally perpendicular to eachother through a point in the body.3.1.2.1 Discussion
12、Shear strain equals adherend slip/adhesive layer thickness.3.1.3 shear strength, nin an adhesive joint, the maximumaverage stress when a force is applied parallel to the joint.3.1.3.1 DiscussionIn most adhesive test methods, theshear strength is actually the maximum average stress at failureof the s
13、pecimen, not necessarily the true maximum stress in thematerial.3.2 Definitions of Terms Specific to This Standard: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 approved A
14、pril 1, 2004. Published April 2004. Originallyapproved in 1981. Last previous edition approved in 1998 as D 4027 98.2Kreuger, G. P., “Tests for the Shear Properties of Adhesives in Adherend-Adhesive Assemblies,” Unpublished report. Michigan Technological Institute,Houghton, MI.3For referenced ASTM s
15、tandards, 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.4Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
16、Conshohocken, PA 19428-2959, United States.3.2.1 loadthe force applied to the specimen at any giventime.3.2.2 load-slip diagrama diagram in which correspondingvalues of load and slip are plotted against each other. Values ofload are usually plotted as ordinates and values of slip asabscissas.3.2.3 n
17、ormal stressthe stress component perpendicular toa plane on which the forces act, that is, perpendicular to theplane of the bondline.3.2.4 proportional limit, nthe maximum stress that amaterial is capable of sustaining without significant deviationfrom proportionality of stress to strain.3.2.5 secan
18、t modulusthe slope of the secant drawn fromthe origin to any specified point on the stress-strain curve.3.2.5.1 DiscussionModulus is expressed in force per unitarea (megapascals, pounds-force per square inch, etc.).3.2.6 shear stressthe stress component tangential to theplane on which the forces act
19、, that is, in the plane of thebondline.3.2.7 slipthe relative collinear displacement of the adher-ends on either side of the adhesive layer in the direction of theapplied load.3.2.7.1 DiscussionThis term differs from that of thestress-strain diagram in that load and slip are not divided bybond area
20、and bond thickness (the constants that convert loadto stress and slip to strain). In actual practice, stress-straininformation is generally collected in the form of a load-slipdiagram for ease in plotting.3.2.8 stressstrain diagrama diagram in which corre-sponding values of stress and strain are plo
21、tted against eachother. Values of stress are usually plotted as ordinates (verti-cally) and values of strain as abscissas (horizontally).4. Summary of Test Method4.1 Shear force is applied to the adhesive through theadherends by a modified-rail shear tool such as shown in Fig.1. The adherends are fi
22、rmly clamped between two pairs of rigidrails as shown in Fig. 2. One pair is fixed and the other ismovable. The rigid rails limit undesired adherend deformationduring testing. The pair of movable rails is fixed to twocounter-moment pivot arms. These arms restrict the attachedrails (and clamped adher
23、end) to collinear motion with respectto the fixed rails (and clamped adherend). The results of usingthis shear tool are nearly uniform stress and strain distributionsand the reduction of normal stress in the adhesive layer underload. Such conditions are necessary for accurate measurementof the adhes
24、ive shear properties.4.2 A known amount of uniform tensile or compressionforce can be applied to the adhesive layer by the shear tool inorder to develop a fracture criteria for the adhesive underFIG. 1 Top, Side, and End Views of the Modified-Rail Shear ApparatusD 4027 98 (2004)2combined states of s
25、tress, such as shear plus tension, or shearplus compression, which commonly occur in bonded struc-tures. Fig. 3 shows combined shear and tensile forces on theclamped specimen.4.3 The basic output of the test method is the bond shearstrength determined as the shear stress at failure, and thestress-st
26、rain diagram determined from the plot of load on theshear tool versus the shear displacement of the bond line.4.4 Bond strength and the stress-strain diagram may beobtained for a variety of environmental and loading conditions.Specific recommendations are made for a minimum testprogram.5. Significan
27、ce and Use5.1 Structural design based on strength of materials prin-ciples or the theory of elasticity requires knowledge of themechanical properties of the structural components, includingadhesives. By the nature of their use, the most importantadhesive properties are shear modulus and shear streng
28、th. Atorsion test, such as described in Test Method E 229, istheoretically the most accurate method for measuring adhesiveshear properties. It is, however, impractical in many situations.For example, certain materials of construction are not readilyadaptable to fabricating the thin-walled cylinders
29、used asadherends in the torsion test. The modified-rail test does nothave this disadvantage.5.2 Two undesirable conditions occur in the modified-railtest specimens that do not occur in butt-joined cylinders;nonuniform shear-stress distribution along the joint, and theaddition of some undefined combi
30、nation of tension and com-pression stresses to the shear stress at a given location in thejoint. The modified-rail shear tool minimizes but does noteliminate these undesirable effects.5.3 Shear modulus, strength, and other properties are mea-sured by the modified-rail method.6. Apparatus6.1 Universa
31、l Testing Machine:6.1.1 The universal testing machine shall have a minimumload capacity of 8900 N (2000 lbf), and a range of crossheadspeed from 0.317 to 10.16 mm/min (0.0125 to 0.40 in./min). Aminimum vertical space of 508 mm (20 in.) and horizontalspace of 305 mm (12 in.) is required to install th
32、e shear tool inthe testing machine.FIG. 2 Top View of the Rail Clamps Showing How the Specimen Is Gripped for TestingD 4027 98 (2004)36.1.2 The testing machine shall have a device capable ofreading the load to the nearest 4.5 6 0.9 N (1.0 6 0.2 lbf). Thisreadout device should preferably be an electr
33、onic load cell tofacilitate simultaneous recording of load with the adhesivedeformation.6.2 Modified-Rail Shear Tool:6.2.1 A shear tool suitable for this test method is illustratedin Fig. 1, Fig. 2, Fig. 4, Fig. 5, and Fig. 6.6.2.2 The shear tool is fitted with a threaded bolt (Adjuster,Fig. 15) to
34、apply normal force for combined stress studies. Themagnitude of the normal force is constant from the outset of thetest. The bolt has a strain gage bonded to it that, with a suitablereadout device and calibration, can be used to set the desirednormal force.6.3 Slip or Strain GageSince the shear stra
35、in of adhesivelayers will normally be very small, an ASTM Class A or ClassB-1 extensometer as described in Practice E 83 shall be used.A mechanical-electrical transducer such as the linear variabledifferential transducer (LVDT) can be used to measure theshear slip indirectly by attachment of the LVD
36、T to thespecimen clamps. Or miniature electrical resistance straingages can be used to measure the shear strain by directattachment to the adhesive joint.7. Materials7.1 The adhesives used shall be selected by the adhesivemanufacturer or by the party requesting these tests.5Complete detail drawings
37、of the modified-rail shear apparatus are availablefrom the Forest Products Laboratory, Forest Service, U.S. Department of Agricul-ture, Madison, WI 53705.NOTE 1During a shear only test the horizontal arrows (tension forces) would be absent.FIG. 3 Side View of the Rail Clamps Showing the Forces On th
38、e Clamps (Specimen) During Combined Shear and Tension LoadingD 4027 98 (2004)47.2 Hard maple shall be the standard material for specimenadherends. Other species may be selected at the option of theadhesive manufacturer or by the party requesting these tests.7.2.1 Generally a high-density wood such a
39、s hard maple,yellow birch, Douglas-fir, or southern pine are desirable tominimize wood deformation effects on the measured adhesiveFIG. 4 Detail Drawings of Modified-Rail Shear ApparatusFIG. 5 Schematic Diagram Showing Use of the Modified-Rail Shear Apparatus With a Universal Test Machine to Apply L
40、oadD 4027 98 (2004)5deformation. The specific gravity of the lumber selected shallequal or exceed average specific gravity for the species asgiven in Table 4-2 of the Wood Handbook.6For hard maple,the average is 0.63. A method of selecting maple lumber ofsatisfactory specific gravity is described in
41、 the appendix to TestMethod D 905.7.2.2 A uniform textured wood such as maple or birch isdesirable to minimize wood density variation effects on theadhesive layer. Coarse-textured woods such as Douglas-fir,hemlock, or southern pine are acceptable however.7.2.3 The wood shall be nominal 25.4 mm (1-in
42、.) flat-sawnlumber presenting a flat grain (tangential surface) for bonding.7.2.4 The lumber shall be straight-grained and free ofdefects including knots, cracks, abrupt grain deviations, decay,and any unusual discolorations within the bond area.8. Sampling8.1 When testing adhesives that form highly
43、 variable bond-lines such as the solvent dispersed construction adhesives,prepare at least three billets for each test condition. Individualspecimens cut from the billets shall be drawn at random forassignment to a given test condition.8.2 Eight specimens shall be tested at every set of condi-tions.
44、9. Test Specimen9.1 Specimen Dimensions:9.1.1 The standard specimen dimensions are shown in Fig.7. The thickness of the specimen may range from 1.59 to 12.7mm (0.06 to 0.50 in.) at the discretion of the party requestingthe tests.9.1.2 The recommended bondline thickness shall be 0.79mm (0.031 in.) wi
45、th the following exceptions:9.1.2.1 Bondline thickness may be varied when this testmethod is used to measure the effects of bondline thicknessupon strength and shear modulus.9.1.2.2 Bondline thickness shall never be greater than theadhesive manufacturers stated maximum thickness.9.1.3 The maximum ra
46、nge of bondline thickness that isacceptable for use in this test method is 0.15 to 3.18 mm (0.006to 0.125 in.).9.2 Specimen Preparation:9.2.1 Cut the lumber into pieces measuring nominal 25 by64 by 305 mm (1 by 2.5 by 12 in.) with the grain in the longdirection. Lightly surface both faces of each pi
47、ece. Conditionthese pieces to an equilibrium moisture content between 7 and10 % (ovendry basis) or to the moisture content specified bythe adhesive manufacturer. Determine moisture content atequilibrium from extra pieces of lumber in accordance withProcedure A of Test Methods D 4442.9.2.2 Prepare on
48、e 64 by 305-mm (2.5 by 12-in.) surface ofeach board for bonding not longer than 2 days prior to bondingby lightly surfacing it with a hand-fed jointer. If a jig is usedduring gluing to control the bondline thickness, the piecesshould be thickness planed on the opposite face to achieve theproper thic
49、kness for the jig and to ensure that the faces areparallel.9.2.3 Follow the adhesive manufacturers instructions whenapplying the adhesive and controlling the assembly time.Ensure that enough adhesive is applied, especially to thickjoints to eliminate voids from this source.9.2.4 To minimize variability along the specimen, controlbondline thickness of gap-filling adhesives during assembly,pressing, and cure by the placement of shims in the bondline orby the use of a jig during cure. Describe the method ofcontrolling thickness in the report.NOTE 2The meth
