ASTM D4027-98(2004)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4027 – 98 (Reapproved 2004)
Standard Test Method for
Measuring Shear Properties of Structural Adhesives by the
Modified-Rail Test
This standard is issued under the fixed designation D4027; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method describes equipment and procedures to 2.1 ASTM Standards:
measure the shear modulus and shear strength of adhesive D905 Test Method for Strength Properties of Adhesive
layers between rigid adherends. The equipment may also be Bonds in Shear by Compression Loading
used for determining the adhesive’s shear creep compliance, D907 Terminology of Adhesives
the effects of strain history such as cyclic loading upon shear D4442 Test Methods for Direct Moisture Content Measure-
properties, and a failure criteria for biaxial stress conditions ment of Wood and Wood-Base Materials
such as shear plus tension and shear plus compression. E83 Practice for Verification and Classification of Exten-
1.2 High-density wood shall be the preferred substrate. The someter Systems
practical upper limit on the shear modulus that can be E229 TestMethodforShearStrengthandShearModulusof
measured is determined by the shear modulus of the adherends Structural Adhesives
and by the strain measuring device. Thus, the practical limit of
3. Terminology
adhesive shear modulus that can be measured using high-
density wood adherends is about 690 MPa (1 3 10 psi). 3.1 Definitions—Many terms in this test method are defined
in Terminology D907.
NOTE 1—Wood-base composites, metal, plastic, reinforced plastics,
3.1.1 shear modulus, n—the ratio of shear stress to corre-
and other common construction materials may also be used for adherends.
sponding shear strain below the proportional limit. (Compare
1.3 The range of specimen dimensions that can be tested
secant modulus.)
are: width 1.59 to 12.70 mm (0.0625 to 0.500 in.), length 102
3.1.1.1 Discussion—The term shear modulus is generally
to 203 mm (4 to 8 in.), and adherend thickness 13 to 25 mm
reserved for materials that exhibit linear elastic behavior over
(0.50 to 1.00 in.). The standard specimen dimensions shall be:
most of their stress-strain diagram. Many adhesives exhibit
width 3.18 mm (0.125 in.), length 203 mm (8 in.), and
curvilinear or nonelastic behavior, or both, in which case some
adherend thickness 19 mm (0.75 in.). Bondline thicknesses
other term, such as secant modulus, may be substituted.
from 0.15 to 3.18 mm (0.006 to 0.125 in.) may be tested.
3.1.2 shear strain, n—the tangent of the angular change,
1.4 The values stated in SI units are to be regarded as the
due to force between two lines originally perpendicular to each
standard. The values given in parentheses are for information
other through a point in the body.
only.
3.1.2.1 Discussion—Shear strain equals adherend slip/
1.5 This standard does not purport to address all of the
adhesive layer thickness.
safety concerns, if any, associated with its use. It is the
3.1.3 shear strength, n—in an adhesive joint, the maximum
responsibility of the user of this standard to establish appro-
average stress when a force is applied parallel to the joint.
priate safety and health practices and determine the applica-
3.1.3.1 Discussion—In most adhesive test methods, the
bility of regulatory limitations prior to use.
shearstrengthisactuallythemaximumaveragestressatfailure
ofthespecimen,notnecessarilythetruemaximumstressinthe
material.
3.2 Definitions of Terms Specific to This Standard:
This test method is under the jurisdiction of ASTM Committee D14 on
Adhesives and is the direct responsibility of Subcommittee D14.70 on Construction
Adhesives.
Current edition approved April 1, 2004. Published April 2004. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 1981. Last previous edition approved in 1998 as D4027 – 98. DOI: contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
10.1520/D4027-98R04. Standards volume information, refer to the standard’s Document Summary page on
Kreuger, G. P., “Tests for the Shear Properties of Adhesives in Adherend- the ASTM website.
Adhesive Assemblies,” Unpublished report. Michigan Technological Institute, Withdrawn. The last approved version of this historical standard is referenced
Houghton, MI. on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4027 – 98 (2004)
FIG. 1 Top, Side, and End Views of the Modified-Rail Shear Apparatus
3.2.1 load—the force applied to the specimen at any given to stress and slip to strain). In actual practice, stress-strain
time. information is generally collected in the form of a load-slip
3.2.2 load-slip diagram—adiagraminwhichcorresponding diagram for ease in plotting.
values of load and slip are plotted against each other.Values of 3.2.8 stress–strain diagram—a diagram in which corre-
load are usually plotted as ordinates and values of slip as sponding values of stress and strain are plotted against each
abscissas. other. Values of stress are usually plotted as ordinates (verti-
3.2.3 normal stress—the stress component perpendicular to cally) and values of strain as abscissas (horizontally).
a plane on which the forces act, that is, perpendicular to the
4. Summary of Test Method
plane of the bondline.
3.2.4 proportional limit, n—the maximum stress that a 4.1 Shear force is applied to the adhesive through the
material is capable of sustaining without significant deviation adherends by a modified-rail shear tool such as shown in Fig.
from proportionality of stress to strain. 1.Theadherendsarefirmlyclampedbetweentwopairsofrigid
3.2.5 secant modulus—the slope of the secant drawn from rails as shown in Fig. 2. One pair is fixed and the other is
the origin to any specified point on the stress-strain curve. movable. The rigid rails limit undesired adherend deformation
3.2.5.1 Discussion—Modulus is expressed in force per unit during testing. The pair of movable rails is fixed to two
area (megapascals, pounds-force per square inch, etc.). counter-moment pivot arms. These arms restrict the attached
3.2.6 shear stress—the stress component tangential to the rails (and clamped adherend) to collinear motion with respect
plane on which the forces act, that is, in the plane of the to the fixed rails (and clamped adherend). The results of using
bondline. this shear tool are nearly uniform stress and strain distributions
3.2.7 slip—the relative collinear displacement of the adher- and the reduction of normal stress in the adhesive layer under
ends on either side of the adhesive layer in the direction of the load. Such conditions are necessary for accurate measurement
applied load. of the adhesive shear properties.
3.2.7.1 Discussion—This term differs from that of the 4.2 A known amount of uniform tensile or compression
stress-strain diagram in that load and slip are not divided by force can be applied to the adhesive layer by the shear tool in
bond area and bond thickness (the constants that convert load order to develop a fracture criteria for the adhesive under
D4027 – 98 (2004)
FIG. 2 Top View of the Rail Clamps Showing How the Specimen Is Gripped for Testing
combined states of stress, such as shear plus tension, or shear For example, certain materials of construction are not readily
plus compression, which commonly occur in bonded struc- adaptable to fabricating the thin-walled cylinders used as
tures. Fig. 3 shows combined shear and tensile forces on the adherends in the torsion test. The modified-rail test does not
clamped specimen. have this disadvantage.
4.3 The basic output of the test method is the bond shear 5.2 Two undesirable conditions occur in the modified-rail
strength determined as the shear stress at failure, and the test specimens that do not occur in butt-joined cylinders;
stress-strain diagram determined from the plot of load on the nonuniform shear-stress distribution along the joint, and the
shear tool versus the shear displacement of the bond line. addition of some undefined combination of tension and com-
4.4 Bond strength and the stress-strain diagram may be pression stresses to the shear stress at a given location in the
obtainedforavarietyofenvironmentalandloadingconditions. joint. The modified-rail shear tool minimizes but does not
Specific recommendations are made for a minimum test eliminate these undesirable effects.
program. 5.3 Shear modulus, strength, and other properties are mea-
sured by the modified-rail method.
5. Significance and Use
6. Apparatus
5.1 Structural design based on strength of materials prin-
ciples or the theory of elasticity requires knowledge of the 6.1 Universal Testing Machine:
mechanical properties of the structural components, including 6.1.1 The universal testing machine shall have a minimum
adhesives. By the nature of their use, the most important load capacity of 8900 N (2000 lbf), and a range of crosshead
adhesive properties are shear modulus and shear strength. A speed from 0.317 to 10.16 mm/min (0.0125 to 0.40 in./min).A
torsion test, such as described in Test Method E229,is minimum vertical space of 508 mm (20 in.) and horizontal
theoretically the most accurate method for measuring adhesive space of 305 mm (12 in.) is required to install the shear tool in
shear properties. It is, however, impractical in many situations. the testing machine.
D4027 – 98 (2004)
NOTE 1—During a shear only test the horizontal arrows (tension forces) would be absent.
FIG. 3 Side View of the Rail Clamps Showing the Forces On the Clamps (Specimen) During Combined Shear and Tension Loading
6.1.2 The testing machine shall have a device capable of 6.2.2 The shear tool is fitted with a threaded bolt (Adjuster,
readingtheloadtothenearest4.5 60.9N(1.0 60.2lbf).This Fig. 1 ) to apply normal force for combined stress studies. The
readout device should preferably be an electronic load cell to magnitudeofthenormalforceisconstantfromtheoutsetofthe
facilitate simultaneous recording of load with the adhesive test.The bolt has a strain gage bonded to it that, with a suitable
deformation. readout device and calibration, can be used to set the desired
6.2 Modified-Rail Shear Tool: normal force.
6.2.1 Ashear tool suitable for this test method is illustrated 6.3 Slip or Strain Gage—Since the shear strain of adhesive
in Fig. 1, Fig. 2, Fig. 4, Fig. 5, and Fig. 6. layers will normally be very small, anASTM ClassAor Class
Complete detail drawings of the modified-rail shear apparatus are available
from the Forest Products Laboratory, Forest Service, U.S. Department of Agricul-
ture, Madison, WI 53705.
D4027 – 98 (2004)
FIG. 4 Detail Drawings of Modified-Rail Shear Apparatus
FIG. 5 Schematic Diagram Showing Use of the Modified-Rail Shear Apparatus With a Universal Test Machine to Apply Load
B-1 extensometer as described in Practice E83 shall be used.A shear slip indirectly by attachment of the LVDT to the
mechanical-electrical transducer such as the linear variable specimen clamps. Or miniature electrical resistance strain
differential transducer (LVDT) can be used to measure the
D4027 – 98 (2004)
FIG. 6 Schematic Diagram Showing Use of the Modified-Rail Shear Apparatus With an Integral Hydraulic Cylinder to Apply Load
gages can be used to measure the shear strain by direct 9. Test Specimen
attachment to the adhesive joint.
9.1 Specimen Dimensions:
9.1.1 The standard specimen dimensions are shown in Fig.
7. Materials
7. The thickness of the specimen may range from 1.59 to 12.7
7.1 The adhesives used shall be selected by the adhesive
mm (0.06 to 0.50 in.) at the discretion of the party requesting
manufacturer or by the party requesting these tests.
the tests.
7.2 Hard maple shall be the standard material for specimen
9.1.2 The recommended bondline thickness shall be 0.79
adherends. Other species may be selected at the option of the
mm (0.031 in.) with the following exceptions:
adhesive manufacturer or by the party requesting these tests.
9.1.2.1 Bondline thickness may be varied when this test
7.2.1 Generally a high-density wood such as hard maple,
method is used to measure the effects of bondline thickness
yellow birch, Douglas-fir, or southern pine are desirable to
upon strength and shear modulus.
minimize wood deformation effects on the measured adhesive
9.1.2.2 Bondline thickness shall never be greater than the
deformation. The specific gravity of the lumber selected shall
adhesive manufacturer’s stated maximum thickness.
equal or exceed average specific gravity for the species as
given in Table 4-2 of the Wood Handbook. For hard maple,
9.1.3 The maximum range of bondline thickness that is
the average is 0.63. A method of selecting maple lumber of
acceptableforuseinthistestmethodis0.15to3.18mm(0.006
satisfactoryspecificgravityisdescribedintheappendixtoTest
to 0.125 in.).
Method D905.
9.2 Specimen Preparation:
7.2.2 A uniform textured wood such as maple or birch is
9.2.1 Cut the lumber into pieces measuring nominal 25 by
desirable to minimize wood density variation effects on the
64 by 305 mm (1 by 2.5 by 12 in.) with the grain in the long
adhesive layer. Coarse-textured woods such as Douglas-fir,
direction. Lightly surface both faces of each piece. Condition
hemlock, or southern pine are acceptable however.
these pieces to an equilibrium moisture content between 7 and
7.2.3 The wood shall be nominal 25.4 mm (1-in.) flat-sawn
10 % (ovendry basis) or to the moisture content specified by
lumber presenting a flat grain (tangential surface) for bonding.
the adhesive manufacturer. Determine moisture content at
7.2.4 The lumber shall be straight-grained and free of
equilibrium from extra pieces of lumber in accordance with
defects including knots, cracks, abrupt grain deviations, decay,
Procedure A of Test Methods D4442.
and any unusual discolorations within the bond area.
9.2.2 Prepare one 64 by 305-mm (2.5 by 12-in.) surface of
each board for bonding not longer than 2 days prior to bonding
8. Sampling
by lightly surfacing it with a hand-fed jointer. If a jig is used
8.1 When testing adhesives that form highly variable bond-
during gluing to control the bondline thickness, the pieces
lines such as the solvent dispersed construction adhesives,
should be thic
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